understanding api icp653 reading 6 worksheet 03 part 1

Understanding APIICP653Reading 6 Worksheet-03 Part 1 of 2My Pre-exam Self Study Notes8th February 2015

Charlie Chong/ Fion Zhang

Refinery



Oil Sand

Oil Export Terminal



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API 653 Exam Administration -- Publications Effectivity Sheet FOR: November 2015, March 2016 and July 2016 Listed below are the effective editions of the publications required for this exam for the date(s) shown above. API Recommended Practice 571, Damage Mechanisms Affecting Fixed Equipment in the Refining Industry, Second Edition, April 2011


ATTENTION: Only the following sections / mechanisms from RP 571 are included on the exam:

Section 3, Definitions Par. 4.2.7 Brittle Fracture 4.2.16 Mechanical Fatigue 4.3.2 Atmospheric Corrosion 4.3.3 Corrosion Under insulation (CUI) 4.3.8 Microbiologically Induced Corrosion (MIC) 4.3.9 Soil Corrosion 4.3.10 Caustic Corrosion 4.5.1 Chloride Stress Corrosion Cracking (Cl-SCC) 4.5.3 Caustic Stress Corrosion Cracking (Caustic Embrittlement) 5.1.1.10 Sour Water Corrosion (Acidic) 5.1.1.11 Sulfuric Acid Corrosion



• API Recommended Practice 575, Inspection of Atmospheric and Low-Pressure Storage Tanks, Third Edition, April 2014

• API Recommended Practice 577 – Welding Inspection and Metallurgy, Second Edition, December 2013

• API Standard 650, Welded Tanks for Oil Storage, Twelfth Edition, March 2013 with Addendum 1 (September 2014), Errata 1 (July 2013), andErrata 2 (December 2014).

• API Recommended Practice 651, Cathodic Protection of AbovegroundPetroleum Storage Tanks, Fourth Edition, September 2014.

• API Recommended Practice 652, Lining of Aboveground Petroleum Storage Tank Bottoms, Fourth Edition, September 2014

• API Standard 653, Tank Inspection, Repair, Alteration, and Reconstruction, Fifth Edition, November 2014.


• American Society of Mechanical Engineers (ASME), Boiler and Pressure Vessel Code, 2013 Edition i. ASME Section V, Nondestructive Examination, Articles 1, 2, 6, 7 and

23 (section SE-797 only) ii. Section IX, Welding and Brazing Qualifications (Welding Only)

See end of this study note for API Official BOK

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API 650 PRACTICE QUESTIONS - STUDENT COPY SECTION 1 - SCOPEQ1. API 650 covers material, design, fabrication, erection, and testing requirements for aboveground welded steel storage tanks. Internal pressure allowed for these tanks approximates atmospheric pressure. However, the internal pressures must not:a. be more than the specific gravity of the product in the tank.b. exceed the weight of the roof plates.c. be more than ½ ounce per square inch.d. exceed purchaser’s recommendation. ANS: B

Q2. Tanks that have bottoms that are not uniformly supported are:a. not covered by API 650.b. covered by Appendix B of API 620.c. covered by API 650.d. not covered by Appendix B of API 653. ANS: A


Q3. Tanks covered by API 650 are restricted to a maximum operating temperature of _______ degrees F, unless additional requirements of Appendix M of API 650 are followed.a. 500b. 300c. 200d. 100ANS: C

Q4. Who decides whether tanks constructed to API 650 will have SI dimensions and comply with applicable SI unit standards or have USCustomary dimensions and comply with applicable US Customary unit standards?a. The jurisdiction.b. The purchaser.c. The manufacturer.d. The Inspector. ANS:B


Q 5. Appendix A provides alternative simplified design requirements for tanks where the stressed components, such as shell plates and reinforcing plates, are limited to a maximum nominal thickness of ½ inch, including corrosion allowance. What is ½ inch in SI units?a. 10 mb. 12.7 cmc. 25.4 mmd. 12.5 mm ANS: D

Q6. Who is responsible for complying with all of the provisions of API 650 when a new tank is built?a. The purchaser.b. The inspector.c. The jurisdiction.d. The manufacturer. ANS: D


API-650 ANSWER KEY


SECTION 2-MATERIALSQ1. Material used to construct a tank shall conform to the specifications of

API 650; however, other material may be used:a. provided that the material meets all requirements of a material listed in API

650 and the purchaser approves.b. if nothing else is available and the inspector and the purchaser approve its

use.c. provided that the material is certified to meet all requirements of a material

listed in API 650 and the purchaser approves.d. if the material is certified to meet all requirements of a material listed in

API 650 and the inspector approves. ANS: C

Q2. When any new or unused plate and pipe material cannot be completely identified by records that are satisfactory, the material may be used in the construction of tanks covered by API 650 only if the:

a. material passes tests prescribed in Appendix N of API 650.b. inspector authorizes its use.c. material is equivalent to material listed in API 653, 2.2.2, ASTM

Specifications.d. owner/user furnishes the material and authorizes its use. ANS: A


API650: 4.1.2 Materials used in the construction of tanks shall conform to thespecifications listed in this section, subject to the modifications and limitations indicated in this standard. Material produced to specifications other than those listed in this section may be employed, provided that the material is certified to meet all of the requirements of an applicable material specificationlisted in this standard and the material’s use is approved by the Purchaser. The Manufacturer’s proposal shall identify the material specifications to be used. When this standard does not address material requirements for miscellaneous items and appurtenances, the Purchaser and/or the Manufacturer shall supply additional material requirements using a supplement to the Data Sheet.


Q3. Whether an edge-thickness or a weight basis is used in the ordering of plate for construction of tanks, an under run not more than ______ inch from the computed design thickness or the minimum permitted thickness is acceptable.a. 0.01b. 0.02c. 0.03d. 0.04 ANS: A

Q4. Shell plates for API 650 tanks are limited to what maximum thickness?a. 2.25 inches.b. 2.00 inches.c. 1.75 inches.d. 1.50 inches. ANS: C


API650: 4.2.1.2.3 Whether an edge-thickness or a weight basis is used, an underrun not more than 0.3 mm (0.01 in.) from the computed design thickness or the minimum permitted thickness is acceptable.


Q5. Plates thicker than ______ inches shall be normalized or quenchtempered, killed, made to fine-grain practice, and impact tested.a. 1.25b. 1.50c. 1.75d. 2.00 ANS: B

API650: 4.2.1.4 Shell plates are limited to a maximum thickness of 45 mm (1.75 in.) unless a lesser thickness is stated in this standard or in the plate specification. Plates used as inserts or flanges may be thicker than 45 mm (1.75 in.). Plates, as designated in 4.2.10.1 and thicker than 40 mm (1.5 in.), shall be normalized or quench tempered, killed, made to fine-grain practice, and impact tested.


Q6. A purchaser requires a tank to be built from ASTM A-283 Grade C plate. What maximum thickness limitation is placed on this plate?a. 1.00 inch.b. 1.50 inches.c. 1.75 inches.d. 2.50 inches. ANS: A

API650: 4.2.2 ASTM Specifications c) ASTM A283M/A283, Grade C, for plates to a maximum thickness of 25 mm (1 in.).


Material ThicknessAPI 650 Maximum Thickness – 1.75 inchesAPI 650 N/QT/Killed/Fine Grain – 1.5 inches


Q7. An impact specimen is removed from a 1.25” thick ASTM A-516 Grade 55 plate. Three impact tests are taken from the specimen. What average longitudinal impact value must the tests meet?a. 13 foot-poundsb. 15 foot-poundsc. 20 foot-poundsd. 30 foot-pounds ANS: B


Q8. An impact specimen is removed from a 1.375” thick ASTM A-516 Grade 60 plate. Three longitudinal impact tests are made. The values of the tests are 10, 10, & 25 foot-pounds. These values are:a. not acceptable because two values are less than 2/3 the specified

minimum value.b. acceptable because their average value is 15 foot-pounds.c. not acceptable because two values are less than the specified minimum

value.d. acceptable because only one value is over the specified minimum value.

ANS: C

4.2.9.3 An impact test shall be performed on three specimens taken from a single test coupon or test location. The average value of the specimens (with no more than one specimen value being less than the specified minimum value) shall comply with the specified minimum value. If more than one value is less thanthe specified minimum value, or if one value is less than two-thirds the specified minimum value, three additional specimens shall be tested, and each of these must have a value greater than or equal to the specified minimum value.


Q9. Which of the following 3 longitudinal impact values for a 1.5” thick ASTM A-516 Grade 55 plate is acceptable?a. 03, 17, 30 foot-poundsb. 05, 15, 20 foot-poundsc. 10, 10, 25 foot-poundsd. 10, 15, 20 foot-pounds ANS: D

Q10. A 1.0” thick ASTM A-516 Grade 60 plate (as rolled, killed, fine-grain practice) is to be used for constructing an aboveground storage tank. If no impact tests are performed, what is the design metal temperature for the tank?a. -23 degrees F.b. -40 degrees F.c. -10 degrees F.d. -12 degrees F. ANS:C


Q11. An aboveground storage tank is to be built in Mobile, Alabama. No other information is available. What design temperature would you use for this tank?a. 10 degrees F.b. 15 degrees F.c. 25 degrees F.d. 30 degrees F. ANS: 5 ⁰F + 15 ⁰F = 20⁰F


Alabama- Montgomery/ Birmingham

ANS: 5 ⁰F + 15 ⁰F = 20⁰F

ANS: 10 ⁰F + 15 ⁰F = 25⁰F


API-650 ANSWER KEY


SECTION 4--FABRICATIONQ1. When material for building a tank requires straightening, the work shall be done by:a. heating and dogging the material prior to any layout or shaping.b. pressing or another non-injurious method prior to any layout or shaping.c. hammering the material prior to any layout or shaping.d. work the metal by clamping and bending it prior to any layout or shaping. ANS: B

Q2. What is deemed sufficient to prove the quality of the plate steel furnished for fabrication of an AST?a. A hydrotest.b. A test by a nuclear analyzer.c. A shop inspection.d. A mill test.ANS: D


API-650 ANSWER KEY


SECTION 5--ERECTIONQ1. Welding of API 650 AST’s must be performed according to the welding procedures qualified in accordance with:a. Section V of the NBIC.b. Section IX of the ASME Code.c. Section V of the ASME Code.d. Section I of the ASME Code. ANS: B

Q2. When the temperature of the base metal of the tank is 0⁰F to 32 ⁰F or the thickness of the base metal is in excess of 1.25”, the base metal within ____ of the place where welding is to be started shall be heated to a temperature warm to the hand (140 ⁰F).a. 3 inchesb. 4 inchesc. 6 inchesd. 8 inches ANS: ANote: t≥1.5” Preheat to 200 ⁰F


Q3. When fabricating a new AST, what is the maximum acceptable undercut for a vertical butt weld of the shell?a. 1/64 inch.b. 1/32 inch.c. 1/16 inch.d. 1/8 inch. :ANS: A

Q4. When fabricating a new AST, what is the maximum acceptable undercut for a horizontal butt weld of theshell?a. 1/8”b. 1/16”c. 1/32”d. 1/64”ANS:C


Q5. A course of a new AST is made of 3/4” thick plate. The inspector is concerned about vertical weld reinforcement. What maximum reinforcement thickness is acceptable on each side of the plate?a. 1/8”b. 1/16”c. 3/16”d. 3/32”ANS:A

Q6. Tack welds used during the assembly of vertical joints of a new AST when manual welding is the method of fabrication shall be:a. removed and shall not remain in the finished joint.b. cleaned of all welding slag but need not be removed if they are sound.c. checked by visual and magnetic particle inspection and left in place.d. removed unless made by a welder qualified to Section IX of ASME B&PV Code. ANS: A


Q7. When constructing a new AST in accordance with API 650, what welds should be practically completed before welding out the bottom plates?a. The manway welds.b. The bottom to sump welds.c. The shell to the bottom welds.d. The roof support welds. ANS: C

Q8. What is the usual size of a vacuum testing box (the size given in API 650)?a. 4” wide by 24” long.b. 6” wide by 30” long.c. 5” wide by 24” long.d. 8” wide by 36” long. ANS: B


Q9. What partial vacuum pressure should the gage on the vacuum box register during the testing of an AST bottom seam?a. 3.5 pounds per square inch gage.b. 2 pounds per square inch gage..c. 2.5 pounds per square inch gage.d. 3 pounds per square inch gage. ANS: D

Q10. A reinforcing pad is installed on a NPS 8 nozzle. What pneumatic pressure should be used between the tank shell and the reinforcement plate to test the welds of the repad?a. 2 pounds per square inch gage.b. 10 pounds per square inch gage.c. 15 pounds per square inch gage.d. 20 pounds per square inch gage. ANS: C


Q11. When hydrotesting the shell of a new AST that has a tight roof, how high should the tank be filled if not restricted by overflows, an internal floating roof, or other freeboard agreed to by the purchaser and the manufacturer?

a. Fill to 3" above the weld connecting the roof plate or compression bar to the top angle or shell.

b. Fill to the maximum height of the point of the cone of the tank's roof.c. Fill to 2" above the weld connecting the roof plate or compression bar to

the top angle or shell.d. Fill to 1 inch below the largest fitting on the roof.ANS: C

Q12. A new AST has a gas tight roof made from 1/4 inch thick plate. The tank has a supported cone roof with a slope of 2” in 12”. The tank is 90’ in diameter and it is 32’ high. What is the maximum pneumatic pressure (psi) that may be put on the tank to check the roof using a soap solution?

a. 0.100 psi b. 0.094 psic. 0.053 psi. d. 0.071 psi. ANS: D


API650: 7.3.7 Testing of the Roof 7.3.7.1 Upon completion, the roof of a tank designed to be gas-tight (except for roofs designed under 7.3.7.2, F.4.4, and E.7.5) shall be tested by one of the following methods.

a) Applying internal air pressure not exceeding the weight of the roof plates and applying to the weld joints a bubble solution or other material suitable for the detection of leaks.

b) Vacuum testing the weld joints in accordance with 8.6 to detect any leaks.

7.3.7.2 Upon completion, the roof of a tank not designed to be gas-tight, such as a tank with peripheral circulation vents or a tank with free or open vents, shall receive only visual examination of its weld joints, unless otherwise specified by the Purchaser.

8.6.3 A partial vacuum of 21 kPa (3 lbf/in.2, 6 in. Hg) to 35 kPa (5 lbf/in.2, 10 in Hg) gauge shall be used for the test. If specified by the Purchaser, a second partial vacuum test of 56 kPa (8 lbf/in.2, 16 in. Hg) to 70 kPa (10 lbf/in.2, 20 in. Hg) shall be performed for the detection of very small leaks.


Partial Vacuum Test3psi ~ 5psi Normal Vacuum Box Test8psi ~ 10psi Detect very small leak (if specified by Purchaser)


Q13. A new AST under hydrostatic test, has a leak in a horizontal weld seam in the bottom of the fourth course. The tank is 125 feet diameter and 40 feet high (5 eight feet courses). To what level must the water be lowered to repair the weld or what height would the water be from the bottom of the tank?a. 31 feet.b. 23 feet.c. 24 feet.d. 32 feet. ANS:B

Q14. A new AST, 40 feet high by 120 feet diameter, is checked for out-of-plumbness (top of shell to the bottom of the shell). The inspector checks API 650 and finds the permissible out-of-plumbness must not exceed:a. 0.20 inches. b. 1.75 inches.c. 4.8 inches. d. 2.4 inches. ANS:D


API650: 7.4.4 Repairs of defects discovered after the tank has been filled with water for testing shall be made with the water level at least 0.3 m (1 ft) below any point being repaired or, if repairs have to be made on or near the tank bottom, with the tank empty. Welding shall not be done on any tank unless all connecting lines have been completely blinded. Repairs shall not be attempted on a tank that is filled with oil or that has contained oil until the tank has been emptied, cleaned, and gas freed. Repairs on a tank that has contained oil shall not be attempted by the Manufacturer unless the manner of repair has been approved in writing by the Purchaser and the repairs are made in the presence of the Purchaser’s inspector.


API650: 7.5.2 Plumbness a) The maximum out-of-plumbness of the top of the shell relative to the bottom of the shell shall not exceed 1/200 of the total tank height. The out-of-plumbness in one shell course shall not exceed the permissible variations for flatness and waviness as specified in ASTM A6M/A6, ASTM A20M/A20, or ASTM A480M/A480, whichever is applicable.

API653: 10.5.2 Plumbness10.5.2.1 The maximum out-of-plumbness of the top of the shell relative to the bottom of the shell shall not exceed 1/100 of the total tank height, with a maximum of 5 in. The 1/100 criteria, with a maximum of 5 in., shall also apply to fixed roof columns. For tanks with internal floating roofs, apply the criteria of this section or API 650, Section 7.5.2 and Annex H, Section H.4.1.1, whichever is more stringent.10.5.2.2 The out-of-plumbness in one shell course shall not exceed the values specified for mill tolerances in ASTM A6 or ASTM A20, whichever is applicable.


7.5.2 Plumbness a) The maximum out-of-plumbness of the top of the shell relative to the bottom of the shell shall not exceed 1/200 of the total tank height. The out-of-plumbness in one shell course shall not exceed the permissible variations for flatness and waviness as specified in ASTM A6M/A6, ASTM A20M/A20, or ASTM A480M/A480, whichever is applicable.


Q15. The bottom course of a new AST, 120 feet in diameter by 40 feet high, is checked 1 foot above the bottom to shell weld for out-of-roundness (radius tolerance). What is the maximum acceptable out of tolerance?a. +1/2”b. +3/4”c. +1”d. +1.25”ANS: B

Q16. How long are the sweep boards used for checking peaking and banding of a new AST shell?a. 24 inches.b. 28 inches.c. 32 inches. d. 36 inches. ANS: D


Q17. A board used for checking for peaking shall be:a. straight.b. cut to the nominal radius of the tank.c. cut to the diameter of the tank.d. cut with slots to account for horizontal welds. ANS: B


API-650 ANSWER KEY


SECTION 6--METHODS OF INSPECTING JOINTSQ1. When radiographing AST plate welds, plates shall be considered of the same thickness when the difference in their specified or design thickness does not exceed:a. 1/16 inch.b. 1/32 inch.c. 1/8 inch.d. 1/64 inch. ANS: C

Q2. The butt weld around the periphery of an insert manhole or nozzle shall be:a. completely radiographed.b. partially radiographed.c. spot radiographed.d. 25% radiographed. ANS: A


Q3. When constructing a new AST, for butt-welded joints in which the thinner shell plate is less than or equal to 3/8 inch thick, one spot radiograph shall be taken in the first 10 feet of completed vertical joint of each type and thickness welded by each welder or welding operator. Thereafter, without regard to the number of welders or welding operators, one additional spot radiograph shall be taken in each additional __________ feet (approximately) and any remaining major fraction of vertical joint of the same type and thickness.a. 75b. 100c. 150d. 200 ANS:B


Q4. When constructing a new AST, one spot radiograph shall be taken in the first 10 feet of a completed horizontal butt joint of the same type and thickness (based on the thickness of the thinner plate at the joint) without regard to the number of welders or welding operators. Thereafter, one radiograph shall be taken in each additional ____________ feet (approximately) and any remaining major fraction of horizontal joint of the same type and thickness.a. 100b. 150c. 200d. 250 ANS: C


Q5. Personnel who perform and evaluate radiographic examinations according to Section 6, API 650, shall be qualified and certified by the manufacturer as meeting the requirements of certification as generally outlined:a. Level l or Level II of ASNT SNT-TC-IBb. Level II or Level III of ASNT SNT-TC-1Ac. Levels I through IV of ASNT SNT-TC-ICd. Level one or level 2 of ANST STN-CT-IA ANS: B

Q6. If a section of weld is shown by a radiograph to be unacceptable under the provisions of API 650, Section 6, Paragraph 6.1.5, or the limits of the deficient welding are not defined by the radiograph:a. two spots adjacent to the deficient section shall be radiographed.b. 100% of subsequent welds must be radiographed.c. all welder-welder operator welds must be subsequently 100% radiographed.d. radiographs of the subsequent welds must be taken every 10 feet. ANS: A


Q7. After construction of a new AST, all radiographic films shall be:a. destroyed.b. the property of the manufacturer of the tank.c. the property of the purchaser unless otherwise agreed.d. stored by a third party for a period of 10 years. ANS: C

Q8. Each magnetic particle examiner must have vision capable of being able to read a _______ standard chart at a distance of not less than ______ .a. Jorganson Type 2; 12 centimeters.b. Jaeger Type 2; 12 inches.c. Jaeger Type 2; 12 feet.d. Julian Type 1; 12 meters ANS: B


Q9. Examiners who perform ultrasonic examinations according to Section 6, API 650, shall be qualified and certified by the manufacturer as meeting the requirements of certification as generally outlined:a. Level l or Level II of ASNT SNT-TC-IBb. Level II or Level III of ASNT SNT-TC-1Ac. Levels I through IV of ASNT SNT-TC-ICd. Level one or level 2 of ANST STN-CT-IA ANS: B


API-650 ANSWER KEY


SECTION 7--WELDING PROCEDURE AND WELDER QUALIFICATIONSQ1. An angle joint is defined in API 650, Section 7, as a joint between two members that intersect at an angle between 0 degrees (a butt joint) and _________ degrees (a corner joint).a. 60b. 45c. 90d. 30 ANS: C

Q2. If a protective coating has been applied to weld edge preparations, the coating shall be included as:a. an essential variable of the WPS.b. a non-essential variable of the WPS.c. a material that must be removed.d. a supplemental essential variable of the WPS. ANS:A


Q3. What two types of weld joints need not have a welder identification?a. Shell to bottom welds and flush type clean-out connections.b. Vertical shell welds and floor plate welds.c. Horizontal shell welds and nozzles to shell welds.d. Roof plate welds and flange-to-nozzle-neck welds. ANS:D


API-650 ANSWER KEY


SECTION 8--MARKINGQ1. Where is the nameplate of a new AST attached?a. Adjacent to a ladder at the tank bottom that provides access to the tank roof.b. Adjacent to a manhole or to a manhole reinforcing plate above the manhole.c. At eye level on the side of the tank that is adjacent to an access road.d. Near the egress of a ladder at the top of a tank. ANS: B


API-650 ANSWER KEY


PRACTICE QUESTIONS API RP 651-SECTION 1 - SCOPEQ1. The purpose of API Recommended Practice 651 is to:a. present procedures and practices for achieving effective corrosion control

on aboveground storage tank bottoms through the use of anodic protection. b. present procedures and practices for achieving effective corrosion control

on below ground storage tanks through the use of cathodic protection c. present procedures and practices for achieving effective corrosion control

on aboveground storage tank bottoms through the use of cathodic protection

d. present procedures and practices for achieving effective electrical control on aboveground storage tank bottoms through the use of anodic protection

ANS: C

Q2. API 651 is intended to serve _________ to persons interested in cathodic protection.

a. as a standardb. only as a guidec. as a coded. only as a design document ANS: B


PRACTICE QUESTIONS API RP 651-SECTION 3-DEFINITIONSQ1. In API 651, an aboveground storage tank is defined as a stationary container of greater than 500 barrel capacity, usually cylindrical in shape, consisting of a metallic roof, shell, bottom and support structure wheremore than ________ percent is above surface grade.a. 95b. 100c. 85d. 90ANS: D

Q2. An electrode of an electrochemical cell at which oxidation (corrosion) occurs is called:a. a cathodeb. an anodec. an electrolyted. GalvanodeANS:B


API RP 651 ANSWER CODE


Not AST Tank


Q3. The deterioration of a material, usually a metal, because of a reaction with its environment is called:a. corrosion.b. cathodic protection.c. electrical isolation.d. differential aeration. ANS: A

Q4. A deep anode groundbed uses one or more anodes installed in a single vertical hole typically _______ below the earth’s surface.a. less than 20 feetb. at least 100 inchesc. 10 feetd. 50 feet or more ANS:D


Q5. A chemical substance containing ions that migrate in an electric field is referred to as an electrolyte. In API 651, an electrolyte refers to the:

a. metallic connection designed to control electrical current interchange between metallic systems.

b. conductor of a known electrical resistance through which current flow may be measured.

c. soil or liquid adjacent to and in contact with the bottom of an aboveground storage tank.

d. system beneath a storage tank to contain any accidentally escaped electrons.

e. ANS: C

Q6. A __________ is a device for converting alternating current to direct current.

a. membraneb. rectifierc. resistord. Capacitor ANS:B


Q7. Current flowing through paths other than the intended circuit is called:a. a stationary current.b. an impressed current.c. an interference current.d. a stray current. ANS: D

Q8. The fracture of a metal by the combined action of corrosion and tensile stress is referred to as:a. differential circuit brittleness.b. stray current corrosion.c. stress corrosion cracking.d. relative potential failure. ANS:C


API RP 651-SECTION 4-CORROSION OF ABOVE GROUND STEEL STORAGE TANKSQ1. Corrosion may be defined as the deterioration of a:a. tank interior due to defective seals.b. metal interior of a tank due to inferior material.c. metal due to a reaction with its environment.d. tank due to product storage of a long period of time. ANS: C

Q2. At the anode, the base metal __________ by releasing electrons and forming positive metal ions.a. conductsb. corrodesc. convertsd. combines ANS: B


Q3. The electrolyte for external tank bottoms is usually:a. sea water.b. sludge.c. ethylene glycold. moist soil. ANS: D

Q4. Individual corrosion cells are large (?) and a distinct anode and cathode area can be identified in ____________ corrosion.a. generalb. pittingc. cathodicd. ElectrolyteANS: B


Q5. In _________ corrosion, the individual corrosion cells are larger and distinct anode and cathode areas can be identified.

a. General b. cathodicc. Electrolytic d. pitting ANS: D

Q6. Physical and chemical properties of the electrolyte may influence the location of cathodic areas on the metal surface. Areas of lower oxygen concentrations become anodic and areas with higher oxygen concentrations become cathodic. This can cause corrosion in areas where:

a. clay or other debris contacts a steel tank bottom constructed on a sand cushion foundation.

b. the concrete contacts a steel tank bottom when the tank is built on a concrete foundation.

c. the asphaltic coating contacts a steel tank bottom when the tank is on a concrete foundation.

d. sand contacts a steel tank bottom on a tank bottom constructed on a sand cushion foundation.

ANS: A


Q7. Interference currents travel through the soil electrolyte and on to structures for which they are not intended. These currents are also known as:a. ionization currents.b. alternating currents.c. stray currents.d. direct currents.ANS: C

Q8. Direct stray currents are generated from grounded DC electric power systems such as:a. power lines, transformers, and forms of static electricity.b. connected pipelines, sludge in the tank bottoms, and lightning strikes.c. electric railroads, welding machines, and other cathodic protection systems.d. loss of proper electrolyte, oxygen concentration, and pH of surrounding moist soil.ANS: C


Q9. Electric current takes the path of ________ resistance.a. Most b. severec. Least d. optimum ANS: C

Q10. The two most significant factors in galvanic corrosion in the corrosion of a tank bottom when a stainless steel or a copper pipe is connected to a tank are the:

a. moisture content of the tank's sand cushion and the location of the magnetic poles.

b. reaction rates of the anode and cathode and the location of all mechanical joints.

c. ions contained in the electrolyte and the component of the ionic movement during the highest electrical spikes.

d. relative areas of the cathode and anode and the relative position of the cathode and anode in the galvanic series.

ANS: D


Q11. Current, in galvanic corrosion, is considered to flow from the:a. metal closest to the source of a stray current that affects the corrosion.b. more active metal (anode) to the less active metal (cathode).c. less active metal (anode) to the more active metal (cathode).d. interior of the tank bottom where there is a water bottom to the more active

underside of the tank bottom. ANS: B

Q12. We learned earlier in Section 4 that there are 2 major types of corrosion, general and pitting. To a lesser extent there is another problem that can be considered a manner of corrosion mechanisms. What is it?

a. mechanical damage.b. environmental cracking.c. ionic corrosion.d. stray current corrosion. ANS: B


API RP 651-SECTION 5-DETERMINATION OF NEED FOR CATHODIC PROTECTIONQ1. The decisions governing the need for cathodic protection should be

based:a. on economical operation history; requirements of the owner/user; location

of the tank; and recommendations of API Standard 650.b. on data from corrosion surveys; operating records; prior test results on

similar tank systems; jurisdictional requirements and recommendations of API 651.

c. on studies in accordance with API Standard 650; effectiveness of internal coatings; foundation design; and expected life of the facility.

d. on limitations of external cathodic protection; general resistivity of the sand cushion under the tank; and requirements of API 652.

ANS: B


Q2. Corrosion control by cathodic protection for new aboveground storage tanks should be maintained:a. until the government says it is not required.b. as long as it is profitable.c. during the service life of the tank.d. until a leak occurs in the tank bottom. ANS: C

Q3. Studies should be made within a suitable time frame in accordance with API Standard 653 concerning the possible need for cathodic protection. When these studies indicate that corrosion will affect the _______ oreconomic operation of the system, adequate corrosion control measures should be used.a. Life b. safec. Cost d. ValueANS: B


Q4. What is generally used to reduce or eliminate corrosion on the internal surfaces of aboveground storage tanks?a. cathodic protection systemsb. corrosion inhibitorsc. coatingsd. filming amines ANS: C

Q5. Internal cathodic protection under certain conditions can be _______ in protecting against corrosion at holidays in the coating over the tank bottom.a. ineffectualb. uselessc. effectived. EliminatedANS: C


Q6. Prior to determining the need for cathodic protection of an aboveground storage tank:a. a full evaluation of tank history is advised.b. a check of the tank's welds is advised.c. a full cost evaluation should be made.d. a check of regulatory requirements should be made.ANS: A

Q7. Information about an aboveground storage tank such as the type of product stored, the product temperature, the presence and depth of water bottoms, and the frequency of fill and discharge, all make up:a. the inspection and corrosion history of the tank.b. the type of service the tank is in.c. the tank design and construction history.d. the information that makes up other factors of corrosion.ANS: A (?)


Q8. If internal corrosion is known to be a problem with an aboveground storage tank:a. a corrosion inhibitor should be placed in the product.b. the cathodic protection should be limited.c. the tank cushion should be redesigned.d. use of an internal lining should be considered.ANS: D

Q9. If large particle sizes are used in the cushion beneath a tank bottom, differential aeration _________may result at points where the large particles or debris contact the bottom.a. containmentb. corrosionc. attenuationd. Resonance ANS: B


Q10. Soils with a resistivity range, OHM-CM, of less than 500 indicates it is probably:

a. rather corrosive.b. mildly corrosive.c. moderately corrosive.d. very corrosive. ANS: D (<500, 500-1000, 1000-2000, 2000-10000, >10000)

Q11. A properly designed concrete tank cushion constructed on a stable, properly prepared subsoil may be effective in eliminating:

a. intrusion of groundwater, soil-side corrosion, and the need for cathodic protection.

b. intrusion of contaminants, internal corrosion and the need for cathodic protection.

c. intrusion of stray currents, shell corrosion and the need for linings.d. intrusion of other structures, external corrosion, and the need for corrosion

protection. e. ANS: A


Q12. Corrosion from the soil may be prevented by a:a. moist sand fill.b. concrete pad.c. well graded fill.d. stabilizing material.ANS: B

Q13. Where a non-continuous concrete pad is utilized oxygen entry is not restricted. In situations where watermay condense on the tank bottom or water is retained above the concrete pad, ____________ may occur.a. reduced corrosion.b. bimetallic corrosionc. galvanic corrosiond. accelerated atmospheric corrosionANS: D


Q14. Asphalt degrades with time and can provide a path for water anddissolved chemicals to come into contact with the steel tank bottom, allowing __________ to occur.a. ionizationb. corrosionc. aerationd. HydrogenationANS: B

Q15. A useful test of native soil cushion for helping to determine whether potential corrosion activity will be high enough to make cathodic protection necessary is:a. a soil analysis test.b. an ionization test.c. a disbondment test.d. a capillary action test. ANS: A


Q16. The presence of aggressive ions such as chlorides and sulfates in the native soil cushion are very helpful in corrosion analysis. If the chlorides are measured to be between 300 and 1000 ppm, this indicates that the soil cushion is:a. not corrosive.b. mildly corrosive.c. corrosive.d. very corrosive.ANS: C (D?)

Q17. When soil analysis data indicates that a native soil cushion for a tank is corrosive, what measures should be considered?a. Find another location for the tank or completely change out the soil cushion.b. Install a drainage system and provide pumps to keep the area totally dry.c. Install cathodic protection or take other corrosion control measures.d. Install secondary containment and a cathodic monitoring system for the tank.ANS: C


API651: 5.3.2.1 Sand Pad Materialg) Measuring pH indicates the hydrogen ion content of a soil. Corrosion of steel is fairly

independent of pH when it is in the range of 5.0 to 8.0. The rate of corrosion increases appreciably when pH is < 5.0 and decreases when pH is > 8.0. pH may be determined in accordance with ASTM G51 or equivalent.

h) Chlorides will affect the resistivity of soil, and act as a depolarizing agent which will increase the current requirement for cathodic protection of steel. Pitting corrosion on steel can begin at chloride levels of 10 ppm. Chloride content may be determined in accordance with ASTM D512 or equivalent. There is currently no industry consensus on an acceptable range for chloride levels, therefore the tank owner/operator should specify the acceptable chloride level. There are practical and possible economic limitations in achieving minimum levels of chloride content.

i) Sulfate levels > 200 ppm frequently indicate high concentrations of organic matter. Sulfate content may be determined in accordance with ASTM D516 or equivalent. There is currently no industry consensus on an acceptable range for sulfate levels, therefore the tank owner/operator should specify the acceptable sulfate level. There are practical and possible economic limitations in achieving minimum levels of sulfate content.

j) Sulfide levels > 0.10 ppm, may indicate that sulfates have been reduced by bacteria. Sulfide content may be determined in accordance with EPA 0376.1 or equivalent. There is currently no industry consensus on an acceptable range for sulfide levels, therefore the tank owner/operator should specify the acceptable sulfide level. There are practical and possible economic limitations in achieving minimum levels of sulfide content.


Q18. If oil alone is added to the clean sand beneath a tank bottom, industry experience shows that it:a. increases the effectiveness of cathodic protection.b. eliminates the need for cathodic protection.c. does not eliminate the need for cathodic protection.d. provides effective corrosion control. ANS: C

Q19. If a tank with water bottoms leaks into the tank's cushion, theenvironment under the tank may become:a. more corrosive.b. more ionized.c. aerated.d. neutral.ANS: A


Q20. Cathodic protection is __________ in areas beneath a tank bottom where a leak has washed away part of the foundation material.a. not effectiveb. partially effectivec. somewhat effectived. effective ANS: A

Q21. Accelerated corrosion can occur on the external surface of the bottom of heated tanks due to elevated temperatures if the area is:a. dry.b. wet.c. porous.d. aerated. ANS: B


Q22. To reduce the environmental impact of a tank bottom leak:a. primary containment may be used.b. an alarm system may be used.c. an internal tank liner may be used.d. secondary containment may be used.ANS: D

Q23. Thick-film, laminated, corrosion and chemical resistant linings are installed in tanks primarily to prevent:a. external corrosion.b. degradation of product.c. internal corrosion.d. loss of cathodic protection. ANS: C


Q24. A thick-film, laminated, internal tank bottom lining:a. is not designed for structural strength.b. is designed for structural strength.c. eliminates the need for external cathodic protection.d. influences the potential corrosion on the external tank bottom. ANS: A


API RP 651-SECTION 6-METHODS OF CATHODIC PROTECTION FOR CORROSION CONTROLQ1. There are two methods of cathodic protection for corrosion control:a. alternating and direct current.b. anodic and depressed current.c. cathodic and alternating current.d. galvanic and impressed current. ANS: D

Q2. A galvanic cathodic protection system uses a metal more _________ than the structure to be protected to supply the current required to stop corrosion.a. ionizedb. noblec. actived. cathodicANS:C


Q3. Metals commonly used as sacrificial anodes in soil are:a. magnesium and zinc.b. lead and sodium.c. mercury and steel.d. cast iron and steel.ANS: A

Q4. Galvanic systems are normally applied only to:a. large diameter tanks.b. large oil refinery tanks.c. hazardous chemical tanks.d. small diameter tanks. ANS: D


Q5. No external power supply is required, installation is relatively easy, capital investment is low for small diameter tanks, maintenance costs are minimal, stray current problems are rare, and less monitoring is required. These are all advantages of:a. an impressed current system.b. a membrane liner system.c. a corrosion series system.d. a galvanic system.ANS: D

Q6. Driving potential is limited, current output is low, the method is limited to use in low resistivity soils, and the method is not practical for protection of large bare structures. These are all disadvantages of:a. an impressed current system.b. a galvanic system.c. a galvanic series.d. an AC system. ANS: B


Q7. Impressed current systems of cathodic protection use:a. pulsating current.b. direct current.c. stray current.d. driving current.ANS: B

Q8. In an impressed current system, direct current is used. This current is provided by:a. a rectifier attached to a DC power source.b. a Van de Graaff generator powered by an AC power source.c. a rectifier attached to an AC power source.d. a transformer connected to a commercial power system. ANS: C


Q9. A typical cathodic protection rectifier has two major components:a. a step-down transformer to reduce AC supply voltage & rectifying

elements to produce DC output.b. a step-up transformer to raise AC supply voltage & rectifying elements to

produce DC output.c. a step-down transformer to reduce DC supply voltage & rectifying

elements to produce AC output.d. a step-down transformer to reduce DC supply voltage & rectifying

elements to produce AC output.ANS: A

Q10. A cathodic protection rectifier unit may be obtained with either:a. copper or aluminum rectifier elements.b. carbon or graphite rectifier elements.c. selenium or silicon rectifier elements.d. zinc or magnesium rectifier elements. ANS:C


Q11. Impressed current anodes are made of materials such as:a. zinc, aluminum, magnesium, selenium or mixed metal oxides on silicon.b. graphite, steel, high silicon cast iron, or mixed metal oxides on titanium.c. bronze, silicon, nickel, manganese, or mixed tin oxides on chromium.d. antimony, potassium, sodium, lithium, or mixed barium oxide on silver.ANS: B

Q12. Impressed current anodes are usually buried in a _______ to extend their life and reduce circuit resistance.a. coke breeze backfillb. boron backfillc. wet soil backfilld. potassium draught backfill ANS: A


API RP 651-SECTION 7-DESIGN OF CATHODIC PROTECTION SYSTEMSTHIS SECTION IS NOT COVERED BECAUSE THE API “BODY OF KNOWLEDGE” EXCLUDES “DESIGNOF CATHODIC PROTECTION SYSTEMS” FROM THE TEST.


API RP 651-SECTION 8-CRITERIA FOR CATHODIC PROTECTIONQ1. A successfully operating cathodic protection system can usually be determined by measuring the minimum voltage across the structure-electrolyte interface relative to a saturated copper-copper sulfate reference electrode. This measurement should be at least how many volts?a. -550 mV b. +750 mVc. +850 mV d. -850 mVANS: D

Q2. A successfully operating cathodic protection system can usually be determined by measuring the minimum cathodic polarization between the structure surface and a stable reference electrode contacting the electrolyte. The formation or decay of this polarization can be used in this criterion. Thismeasurement should be a minimum of how many volts?a. 50 mV b. 100 mVc. 150 mV d. 200 mV ANS: B


Q3. The standard method of determining the effectiveness of cathodic protection on a tank bottom is the tank-to-soil:a. thickness measurement.b. potential measurement.c. power measurement.d. resistance measurement.ANS: B

Q4. Tank-to-soil potential measurements are commonly made with a reference electrode in the soil:a. at the center of the tank.b. on the north side of the tank.c. at the perimeter of the tank.d. on the south side of the tank. ANS: C


Q5. Tank-to-soil potential measurement at the tank perimeter:a. will accurately represent the same tank-to-soil potential that is found at the

tank center.b. will not represent the same tank-to-soil potential that would be found at the

tank center.c. is the most accurate method of taking tank-to-soil potential readings.d. may not represent the same tank-to-soil potential that would be found at

the tank center.ANS: D

Q6. Tank-to-soil potential measurements are typically taken with:a. the current applied.b. a Wheatstone bridge.c. the power supply off.d. a ground fault interrupter.ANS: A


Q7. Monitoring the actual structure-to-soil potential under the tank should be considered. This may be done by:

a. using a permanently installed reference cell or by inserting a reference cell under the tank through a perforated tube.

b. using a reference battery or by hooking a battery to wire previously installed under the tank.

c. measuring the polarization between the tank bottom and a stable structure that exists nearby.

d. measuring the voltage necessary to provide excess capacity in the system to avoid damage due to voltage overloads.

ANS: A


API RP 651-SECTION 9-INSTALLATION OF CATHODIC PROTECTION SYSTEMSTHIS SECTION IS NOT COVERED BECAUSE THE API “BODY OF KNOWLEDGE” EXCLUDES “DESIGNOF CATHODIC PROTECTION SYSTEMS” FROM THE TEST.API RP 651-SECTION 10-INTERFERENCE CURRENTSTHIS SECTION IS NOT COVERED BECAUSE THE API “BODY OF KNOWLEDGE” EXCLUDES “DESIGNOF CATHODIC PROTECTION SYSTEMS” FROM THE TEST.


API RP 651-SECTION 11-OPERATION AND MAINTENANCE OF CATHODIC PROTECTION SYSTEMSQ1. When cathodic protection systems are turned off, sufficient time must be allowed for ___________ before opening connection.a. Depolarization b. coolingc. Polarization d. ionizationANS: A

Q2. Immediately after any cathodic protection system is energized or repaired, a survey should be conducted to determine that it operates properly. An initial survey to verify that it satisfies applicable criteria should be conducted after adequate polarization has occurred. Generally polarization to a steady state occurs within:a. 3-6 months.b. 6-8 months.c. several months.d. 12-24 months. ANS: C


Q3. Cathodic protection surveys are recommended to ensure effectiveness every:

a. 12 months. b. 18 months.c. 24 months. d. 36 months.ANS: A

Q4. Tank bottoms should be examined for evidence of corrosion whenever access to the bottom is possible. This may be done during repairs or modifications, or in conjunction with inspections required by API Standard 653. Examination for bottom side corrosion may be done by:

a. coupon cutouts or by NDT methods such as radiograph, or magneticparticle inspection.

b. coupon cutouts or by NDT methods such as ultrasonic inspections or electromagnetic flux leakage.

c. eddy current inspection, wet fluorescent magnetic particle inspection, or penetrant inspection.

d. visual inspection, vacuum box inspection, or structure to soil potential measurements.

ANS: B


Q5. Records related to the effectiveness of cathodic protection should be retained for a period of ________ years unless a shorter period is specifically allowed by regulation.a. 2b. 3c. 5d. 7ANS: C

Q6. Records sufficient to demonstrate the need for corrosion control measures should be retained:a. as long as the facility involved remains in service.b. 10 years or one half the facility's service life.c. 15 years or one half the facility's service life.d. 20 years or one half the facility's service life. ANS: A


PRACTICE QUESTION API RP 6521. API 652, Lining of Aboveground Petroleum Storage Tank Bottoms, is intended to:a. provide detailed recommendations for tank bottom linings.b. give definite steps for tank bottom linings.c. serve only as a guide for tank bottom linings.d. furnish chemical reactivity uses of epoxy linings. ANS: C


API RP 652-SECTION 3-DEFINITIONSQ1. An aboveground storage tank is a stationary container, usually cylindrical in shape, consisting of a metallic roof, shell, bottom, and support structure where more than _____________ percent of the tank volume is above the surface grade.a. 90b. 85c. 80d. 75ANS: A

Q2. An adduct is a curing agent, generally an _________, that has been combined with a portion of resin, usually an epoxy.a. aromaticb. electrolytec. amined. Epoxy ANS:C


Q3. An _______ is an electrode of an electrochemical cell at which oxidation (corrosion) occurs.a. amineb. aromaticc. epoxyd. anodeANS: D

Q4. _________ is the deterioration of a material, usually a metal, because of a reaction with its environment.a. Forced-curingb. Corrosionc. Curingd. AdductANS:B


Q5. An _____________ is a chemical substance containing ions that migrate in an electric field.a. epoxyb. aminec. adductd. Electrolyte ANS: D


API-652 ANSWER CODE


API RP 652-SECTION 4-CORROSION MECHANISMSQ1. Corrosion ____________ in crude oil or product service with no water present.a. is less than 5 mils per yearb. would not be expectedc. at an accelerated rate takes placed. is greater than 8 mils per yearANS: B

Q2. Chemical corrosion, concentration cell corrosion, galvanic cell corrosion, sulfate-reducing bacteria corrosion and erosion/corrosion are:a. all common mechanisms of internal storage tank bottom corrosion.b. all common mechanisms of external storage tank bottom corrosion.c. all mechanisms of internal storage tank bottom lining deterioration mechanisms.d. all types of external storage tank bottom lining deterioration mechanisms. ANS: A


Q3. Chemical attack of tank bottoms is prevalent in corrosive services such as:a. crude oil at ambient temperature, treated lube oils, and boiler feed water.b. filming amines, sweet crudes, and motor oils.c. treated gasoline, bisphenol-A-polyester, and coal tar epoxy.d. caustic, sulfuric acid, ballast water, and water neutralization services.ANS: D

Q4. In concentration cell corrosion, pitting of a bare steel storage tank bottom may occur at a rate as high as ________ mils per year.a. 2b. 80c. 100d. 200ANS: C


Q5. What type of corrosion can occur on a steel tank bottom that has a corrodent, dissolved oxygen and mill scale with breaks present?a. chemicalb. generalc. pittingd. metabolicANS: C

Q6. The mere physical presence of bacterial deposits can promote aggressive pitting corrosion. This type of corrosion is referred to as:a. Concentration Cell Electrolyte Corrosion.b. Sulfate-Reducing Bacteria Corrosion.c. Chemical-Erosion/Corrosion.d. Deterioration-Producing Virus Corrosion.ANS: B


Q7. Erosion/corrosion occurs in wastewater treating or mixing tanks where ____________ are present with the product stored.a. soil or small abrasive aggregateb. acid or causticc. electrolytes and waterd. galvanic cells ANS: A


API-652 ANSWER CODE


API RP 652-SECTION 5-DETERMINATION OF THE NEED FOR TANK BOTTOM LININGQ1. Corrosion prevention, tank design, tank history, environmental considerations, flexibility of service change, upset conditions, and jurisdictional requirements are all considerations used to:a. provide justification for a new storage tank.b. establish the need for an internal tank bottom lining.c. constitute the need for externally painting a tank.d. command the use of internal cathodic protection.ANS: B

Q2. Considering the corrosion history of tanks in similar service is one way to establish a _____________ for a new tank.a. electrolytic strengthb. growth classc. flexible aggregated. corrosion rateANS: D


Q3. The tank pad material beneath the steel bottom of a tank has a significant effect on underside:a. abrasionb. galvanizationc. corrosiond. erosionANS: C

Q4. What should be considered on tank bottoms for cone-roof column supports and floating-roof support columns?a. Add support or landing plates beneath the columns.b. Coat the support or landing columns.c. Ground all the columns to the tank floor.d. Insulate the support or landing columns. ANS: A


Q5. If a tank has an old lining and a new lining is used, the new lining must be:a. non-compatible with the old lining or the old lining must be renewed.b. compatible with the old lining or the old lining must be completely removed.c. only installed after the old lining has been roughened thoroughly to provide suitable anchor.d. only installed after the old lining has been repaired or completely removed.ANS: B

Q6. A properly applied tank bottom lining may provide _______ years of service life.a. 5-10b. 5-15c. 10-20d. 15-25ANS:C


20 Years


+20 Years


API652: 6.5.5 Flexibility for Service ChangeChanges in tank service may affect the performance of an existing tank bottom lining. Tank linings do not offer universal resistance. A properly applied tank bottom lining may provide more than 20 years of service life in storing a particular product. A lining that has provided many years of satisfactory protection in one product may have inadequate resistance to a new service environment. The need for operational flexibility at some facilities requires that some tanks be available for swing service. Such factors should be considered during the selection and design of a lining system. Many linings will need to recover between product changes. Consult the manufacturer to determine if there are any specific recommendations (e.g. cleaning, ventilation, etc.) when changing the stored product.


API-652 ANSWER CODE


API RP 652-SECTION 6-TANK BOTTOM LINING SELECTIONQ1. A thin-film liner is considered to be _______ mils or less thick.a. 5b. 10c. 15d. 20 ANS: D

Q2. A thick-film liner is considered to be any liner greater than _______ mils.a. 30b. 20c. 15d. 10 ANS: B


Q3. What type of lining would you select, using Tables in API 652, 6.3, for foul water service and crude oil at an operating temperature of 1500 F?a. thin-film epoxy phenolicb. thin-film coal tar epoxyc. thick-film vinyl esterd. thick-film epoxyANS: B

Q4. What type of lining would you select, using Tables in API 652 4.3, for crude oil & aromatics at an operating temperature of 2000 F.a. thick-film epoxyb. thin-film coal tar epoxyc. thin-film epoxy polyamided. thick-film vinyl ester ANS:


Q5. Linings (thin or thick film) are both applied after:a. scratching the surface thoroughly.b. scraping the surface thoroughly.c. white or near-white abrasive blasting.d. brush blasting.ANS: C

Q6. What type of lining is preferred where internal corrosion has occurred?a. thick filmb. thin filmc. mill scaled. primer coatANS: A


Q7. Storage tank bottom linings generally cover the entire tank bottom and extend ____________ up the shell of the tank.a. 8-16 inchesb. 10-12 inchesc. 12-20 inchesd. 18-24 inchesANS: D

Q8. How many coats is often required to give a thin-film lining?a. 1-2 coatsb. 2-3 coatsc. 4-5 coatsd. 5-6 coatsANS: B


Q9. A thick-film liner in an older tank that has experienced corrosion is usually __________ mil thick.a. 35-55b. 80-120c. 15-20d. 130-150ANS:B


API-652 ANSWER CODE


API RP 652-SECTION 7-SURFACE PREPARATIONQ1. What is the major cause of lining failure?a. Inadequate surface preparation.b. Use of out of date lining material.c. Using thick-film coatings where thin-film would work.d. Using thin-film coatings where thick-film is required.ANS: A

Q2. Cleaning of a tank for installation of a liner is typically followed by a ______________ to ensure complete removal of soluble salts and cleaning chemicals.a. chemical neutralizationb. sodium chloride water rinsec. fresh water rinsed. hand cleaning ANS: C


Q3. What is the preferred technique for the repair of perforations of a steel tank bottom?a. Install a fiber glass patch.b. Weld on a steel patch plate.c. Pad weld.d. Install a wooden patch.ANS: B

Q4. Abrasive blasting should not be performed if the temperature of the steel surface is less than ________ degrees F. above the dew point.a. 0b. 3c. 5d. 7ANS: C


Q5. Abrasive blasting should not be performed if the relative humidity is greater than ___________ percent.a. 70b. 80c. 90d. 100ANS: B

Q6. The anchor pattern required for installation of linings is typically __________ mils and generally increaseswith the thickness of the lining.a. 1.5-4b. 4-8c. 8-10d. 10-13ANS: A


API-652 ANSWER CODE


API RP 652-SECTION 8-LINING APPLICATIONQ1. In lining application, ___________ recommendations should be followed.a. owner/user'sb. liner inspector'sc. jurisdiction'sd. manufacturer'sANS: D

Q2. _____________ -curing of a tank liner may be achieved by circulating warmed, dehumidified air.a. Forcedb. Slowc. Graduald. Regular ANS:A


API-652 ANSWER CODE


API RP 652-SECTION 9-INSPECTIONQ1. In order that liner specifications are met, the liner should be inspected during application and _____________.a. once every 5 years after installation.b. after the tank has been placed in service.c. once every 10 years after installation.d. upon completion of the work.ANS: D

Q2. For linings in excess of 20 mils, holiday testing shall be carried out with:a. ultrasonic equipment.b. a high voltage detector.c. dye penetrant testing.d. low voltage (67.5 volts) wet sponge detector. ANS: B


API-652 ANSWER CODE


API RP 652-SECTION 10-REPAIR OF TANK BOTTOM LININGSQ1. A properly applied lining will provide a service life of ______________ years.a. 25+b. 20-30c. 15-25d. 10-20ANS: D

Q2. Before deciding how to repair a lining, the _____________ of any failure must be established.a. cause and extentb. age and datec. purpose and timed. materials and dateANS: A


API652: 6.5.5 Flexibility for Service ChangeChanges in tank service may affect the performance of an existing tank bottom lining. Tank linings do not offer universal resistance. A properly applied tank bottom lining may provide more than 20 years of service life in storing a particular product. A lining that has provided many years of satisfactory protection in one product may have inadequate resistance to a new service environment. The need for operational flexibility at some facilities requires that some tanks be available for swing service. Such factors should be considered during the selection and design of a lining system. Many linings will need to recover between product changes. Consult the manufacturer to determine if there are any specific recommendations (e.g. cleaning, ventilation, etc.) when changing the stored product.


Q3. Spot repairs, topcoating an existing lining, and complete relining are the three _______________.a. types of materials used for repairs.b. names of tank failures.c. basic tank lining repair methods.d. forms of tank roof repair methods.ANS: C


API-652 ANSWER CODE


API RP 652-SECTION 11-SAFETYQ1. Prior to the application of internal tank linings, proper _________ of employees regarding safe work procedures and the provision of the necessary supervision and/or inspection throughout the progress of the job is required.a. Training b. selectingc. Hiring d. testingANS: A

Q2. The chemical make-up of high performance internal tank lining materials can present health hazards to workers if not handled properly. Which of the sources of information listed below should be consulted by all employees where they can be concisely informed about the materials being used.?a. NACE recommendations.b. Owner/user requirements.c. MSDS sheets.d. OCAW data sheets. ANS: C


API-652 ANSWER CODE


PRACTICE QUESTIONS - - API-653 SECTION 1Q1. API Standard 653 covers carbon and low alloy steel tanks built to:a. API Standard 620 and its predecessor UL 142.b. API Code 510 and its predecessor API/ASME PV Code.c. API Standard 650 and its predecessor 12C.d. API Recommended Practice 651 and 652.ANS: C

Q2. What API Standard always governs for tanks that have been placed in service?a. API Standard 653.b. API Standard 650.c. API Standard 620.d. API RP-575. ANS: A


Q3. API Standard 653 employs the principles of:a. API Standard 653.b. API Standard 620.c. API Standard 650.d. API Standard 2000.ANS: C

Q4. API Standard 653 may be applied to:a. only to steel tanks built to API Standard 650 or its predecessor 12C.b. only to steel tanks built to API Standards 650 or 620.c. only to steel tanks built to API Standard 650 and Underwriters Laboratories Standard UL 142.d. any steel tank constructed in accordance with a tank specification.ANS: D


Q5. When design and construction details are not given and are not available in the standard to which the tank was originally constructed, then details that will provide a level of integrity equal to the level provided by the current edition of:a. API Standard 650 must be used.b. Underwriters Laboratories Standard UL 142 must be used.c. API Standard 620 must be used.d. National Board Inspection Code must be used.ANS: A

Q6. Who has the ultimate responsibility for complying with the provisions of API 653?a. authorized inspector.b. owner/operator.c. jurisdiction.d. API 653 inspector.ANS: B


Q7. If any provision of API Standard 653 presents a direct or implied conflict with any statutory regulation, the regulation will govern. In the event that API Standard 653 provisions are more stringent than statutory regulations:a. API Standard 653 will govern.b. API Standard 650 will govern.c. API Standard 620 will govern.d. statutory regulations will govern.ANS A:

Q8. A typical example of an alteration to a tank could be:a. the renewal of an existing nozzle.b. the complete renewal of a tank roof.c. the renewal of the tanks pressure vacuum relief devices.d. the addition of manways and nozzles greater than 12 inch nominal pipe size.ANS: D


Q9. Applicable standard refers to the original standard of construction such as API, UL, etc. unless the original standard of construction has been superseded or withdrawn from publication. In this event, applicable standard means the current edition of the:a. National Board Code.b. appropriate standard.c. OSHA standard.d. ASME Code.ANS: B

Q10. Internal pressure in tanks up to but not exceeding 2.5 pounds per square inch gauge is referred to as:a. atmospheric pressure.b. low pressure.c. moderate pressure.d. vacuum pressure.ANS: A


Q11. When an independent organization or individual acts as an authorized inspection agency, who or what provides the controls necessary for use to inspect aboveground storage tanks?a. ASME’s inspection program.b. OSHA’ s guidelines and inspection program.c. API’s inspection program.d. The owner or operator’s inspection program.ANS: D

Q12. The total metal loss divided by the period of time over which the metal loss occurred is known as:a. reconstruction rate.b. critical rate.c. corrosion rate.d. remaining corrosion allowance.ANS: C


Q13. The portion of the bottom sketch plate or annular plate within 3 inches of the inside edge of the shell measured radially inward is called:a. the chime.b. critical zone.c. heat affected zone.d. stressed area.ANS: B

Q14. The work necessary to reassemble a tank that has been dismantled and relocated to a new site is referred to as:a. repairs.b. reconstruction.c. a change in service.d. demolition/construction.ANS: B


Q15. Any work necessary to maintain or restore a tank to a condition suitable for safe operation is ______.a. reconstruction.b. repairs.c. a change in service.d. construction.ANS: B


API-653 ANSWER KEY


API-653 SECTION 2Q1. When the results of a tank inspection show that a change has occurred from the original physical condition of that tank:a. the results of the inspection shall be recorded and presented to the owner/operator.b. an evaluation shall be made to determine its suitability for continued use.c. the legal entity responsible for tanks shall be notified.d. the tank shall be removed from service.ANS: B

Q2. Tank roof plates which corrode to an average thickness of less than _______ inch in any 100 square inches area shall be repaired or replaced.a. 0.10b. 0.05c. 0.09d. 0.12ANS: C


Q3. What part of the roof support system should be given particular attention due to the difficulty of finding the corrosion?a. double angle rafters.b. roof plates.c. girders.d. pipe columns.ANS: D

Q4. Guidance for the evaluation of existing floating roofs shall be based on the criteria of API Standard 650, Appendix C for external floating roofs, and Appendix H for internal floating roofs. However, upgrading to meet this standard is:a. mandatory.b. not mandatory.c. recommended.d. required.ANS: B


Q5. The roof support structure (if any), and the roof-to-shell junction shall be evaluated for the effects of a design partial vacuum. The criteria outlined in _____________ shall be used.a. API Standard 650b. API Standard 620c. API Standard 2000 (venting)d. API Standard A370ANS:B

Q6. All requirements of API Standard 650, Appendix M, shall be considered before changing the service of a tank to operation at temperatures above:a. 100 ⁰F.b. 150 ⁰F.c. 200 ⁰F.d. 250 ⁰F.ANS: C


Q7. What three anticipated loadings listed below should be considered in addition to the fluid static head loading on an AST.a. tornado loads, vibration loads, fluid dynamic loads.b. wind loads, seismic loads, and nozzle loads.c. traffic loads, crash loads, full vacuum loads.d. explosion loads, wheel loads, puncture loads.ANS: B

Q8. What form of corrosion does not represent a significant threat to the overall structural integrity of a tank shell unless it is present in a severe and numerous form?a. general uniform loss of metal.b. pitting.c. stress corrosion cracking.d. hydrogen attack.ANS: B


API-653 ANSWER KEY


API-653 SECTION 3Q1. Section 3 of API Standard 653 provides a procedure to assess the risk of failure due to brittle fracture of tankage. The procedure applies to:a. only welded tanks.b. only API Standard 650 tanks.c. only tanks under 200 feet in diameter.d. both welded and riveted tanks. ANS: D

Q2. In all reported incidents of tank failure due to brittle fracture, failure occurred shortly after erection:a. during hydrostatic testing, on the first filling, after a change in service or after a repair/alteration.b. during hydrostatic testing, on the first filling in cold weather, after a change to lower temperature service, or after a repair/alteration.c. during hydrostatic testing in cold weather, on the first filling after a change in service, or after a repair/alteration.d. during testing, on the first filling in cold weather, after a change to a higher temperature service, or after a repair/alteration.ANS: B


Q3. The risk of brittle fracture failure in continued service after a tank has demonstrated the ability to withstand the combined effects of maximum liquid level (highest stresses) and lowest operating temperature without failing is:a. maximum.b. not changed.c. zero.d. minimal.ANS: D

Q4. In the event of a change to a more severe service (such as operating at a lower temperature or handling product at a higher specific gravity) it is necessary to:a. consider the need for a hydrostatic test to demonstrate fitness for the new more severe service.b. make sure the tank meets API Standard 650 requirements.c. lower the maximum filling height of the product to be stored in the tank.d. change out the course of the tank to maintain the fill height and to stand the additional loading on thetank.ANS: A


Q5. If a tank shell thickness is no greater than ____, the risk of failure due to brittle fracture is minimal, provided that an evaluation for suitability of service per Section 2 of API Standard 653 has been performed.a. 1.00 inchb. 1.25 inchesc. 0.50 inchd. 0.75 inchANS: C

Q6. Using the Figure 3-2 of API Standard 653, determine the lowest temperature that a tank constructed from carbon steel of unknown toughness may be used if its maximum shell thickness is 0.75 inches.a. 60 degreesb. 52 degreesc. 49 degreesd. 45 degreesANS: B


API-653 ANSWER KEY


API-653 SECTION 4 -Q1. The purpose of in-service inspections of AST’s is to assure:a. continued tank integrity.b. that OSHA requirements are met.c. that the EPA requirements are satisfied.d. that API standards are met.ANS: A

Q2. What type of inspection may be done by owner/operator personnel and/or authorized inspectors?a. Internal inspection.b. External ultrasonic thickness inspection.c. Visual external inspection.d. Routine in-service inspection.ANS: ANS: D


Q3. The external condition of storage tanks shall be monitored by close visual inspection from the ground on a routine basis. This inspection can be done by owner/operator personnel, and can be done by other than an Authorized Inspector. The interval of such inspections shall not exceed:a. 24 months.b. 12 months.c. 6 months.d. 1 month.ANS: D

Q4. All tanks shall be given a visual external inspection by an Authorized Inspector, at least every:a. 5 years or at RCA /4N years, whichever is less.b. 10 years or at RCA /2N years, whichever is less.c. 2 years or at RCA/N years, whichever is less.d. 1 year or at RCA/ 3N years, whichever is less. ANS: A


Q5. External ultrasonic thickness measurements of the shell, when used and when the corrosion rate is not known, are taken at intervals not to exceed:a. 2 years.b. 5 years.c. 1 year.d. 10 years.ANS: B

Q6. Determine from the information given below, the maximum interval for in-service ultrasonic thickness measurements of the shell. The minimum thickness of a 125 feet diameter by 40 foot high storage tank is 0.539 inches. The tank was built with a corrosion allowance of 0.125" and the lower shell course was built with 11/16 inch thick plate. The tank has been in service 6 years & the current in-service thickness measurement is 0.58 in.a. 2.93 yearsb. 2.28 yearsc. 1.14 yearsd. 15.0 yearsANS: C

N = (0.6875-0.58)/6 = 0.0179”/yrNext interval = (0.58-0.539)/2N = 1.14yrExcluding corrosion allowance


API653: 6.3.3 Ultrasonic Thickness Inspection6.3.3.1 External, ultrasonic thickness measurements of the shell can be a means of determining a rate of uniform general corrosion while the tank is in service, and can provide an indication of the integrity of the shell. The extent of such measurements shall be determined by the owner/operator.

6.3.3.2 When used, the ultrasonic thickness measurements shall be made at intervals not to exceed the following. a) When the corrosion rate is not known, the maximum interval shall be five years. Corrosion rates may be estimated from tanks in similar service based on thickness measurements taken at an interval not exceeding five years. b) When the corrosion rate is known, the maximum interval shall be the smaller of RCA/2N years (where RCA is the difference between the measured shell thickness and the minimum required thickness in mils, (including or excluding corrosion allowance?) and N is the shell corrosion rate in mils per year) or 15 years.


Q7. Who assures the competency of the personnel performing cathodicprotection (CP) surveys?a. American Petroleum Institute.b. Owner/operator.c. American Electrician Association.d. API authorized inspector.ANS: B

Q8. Two reasons for an internal inspection of an aboveground storage tank are ensure that the:a. bottom is not severely corroded and to gather data on the minimum bottom & shell thicknesses.b. top is not severely corroded and to gather UT readings of the tank shell.c. bottom is not severely corroded and to check the tank interior for fouling.d. top is not severely corroded and to satisfy jurisdictional requirements.ANS: A


Q9. Who assures the quality and completeness of NDE results obtained during a formal internal inspection?

a. The owner or operator.b. The American Petroleum Institute.c. The API authorized inspector.d. The Jurisdiction.ANS: C

Q10. If an internal inspection is required solely for the purpose of determining the condition and integrity of the tank bottom, the internal inspection:

a. may be accomplished with the tank in-service using robotic UT measurements.

b. must be made only after the tank is removed from service and readied for entry.

c. may be extended by using finite element analysis of the last inspection results.

d. can be accomplished with the tank in-service by jacking up the tank for a UT survey.

ANS: A


Q11. The internal inspection interval for an aboveground storage tank shall not exceed _____ years.a. 10b. 20c. 25d. 30ANS: B

Q12. A tank’s bottom is inspected. What thickness must the bottom plate be at the next inspection?The tank bottom/foundation design has no means for detection andcontainment of a bottom leak.a. 0.05 inchesb. 0.08 inchesc. 0.10 inchesd. 0.15 inchesANS: C


Q13. When corrosion rates are not known and similar service experience is not available to determine the bottom plate minimum thickness at the next inspection, the actual bottom thickness shall be determined by inspection(s) within the next _____ years of tank operation to establish corrosion rates.a. 5b. 10c. 15d. 20ANS: B

Q14. As an alternate to the set maximum intervals of internal inspection given in paragraph 4.4.2 of API 653, an owner-operator may establish the internal inspection interval using:a. finite relativity inspection (FRI) procedures.b. electromagnetic inspection (EMI) methods.c. ultrasonic robotic thickness (URT) measurements.d. risk-based inspection (RBI) procedures.ANS: D


Q15. Name the three types of records the owner/operator is required to keep for AST’s.a. construction records, gage readings, inspection history.b. inspection history, building permits, and repair/alteration history.c. construction records, inspection history, and repair/alteration history.d. product type and temperature records, strapping records, and inspection history.ANS: C

Q16. Personnel performing ___________ shall meet the qualifications identified in paragraph 10.1.1.2 of API 653, but need not be certified in accordance with Appendix D of API 653.a. Nondestructive examinations.b. Hammer testing.c. Hydro-testing.d. Pneumatic testing.ANS:A


API-653 ANSWER KEY


API-653 SECTION 5Q1. All new materials used for repair, alterations or reconstruction shall conform to:a. original standard of construction.b. owner/operator specifications.c. current applicable tank standards.d. ASTM 653 Standard.ANS: C

Q2. Each original individual plate used for reconstructed tanks for which adequate identification does not exist shall be:a. discarded and not be used for reconstruction.b. marked and inspected thoroughly after one year service.c. trial welded and the weld radiographed for possible defects.d. subjected to chemical analysis and mechanical tests as required in ASTM A6 & A370. ANS: D


Q3. Flange material shall meet the minimum requirements of the material specifications in the:a. original standard of construction.b. owner/operator specifications.c. current applicable tank standard.d. ASTM 653 Standard.ANS: A

Q4. Fasteners shall meet the material specification of the:a. original standard of construction.b. owner/operator specifications.c. current applicable standard.d. ASTM 653 Standard.ANS:C


API653: 7.3.3 Flanges and Fasteners7.3.3.1 Flange material shall meet the minimum requirements of the material specifications in the as-built standard.7.3.3.2 Fasteners shall meet the material specifications of the current applicable standard.


Q5. If existing plates are to be used to reconstruct a tank, the plates shall be checked for:a. deformation and penetrations.b. excessive corrosion and pitting.c. substandard existing welds.d. excess loss of metal during dismantling.ANS: B


API-653 ANSWER KEY


API-653 SECTION 6Q1. New weld joint details on a reconstructed tank shall meet the welding requirements of the:a. applicable standard.b. owner/operator.c. original standard of construction.d. Standard, ASTM 653.ANS: A

Q2. The thickness to be used for each shell course when checking the tank design for reconstruction shall bebased on measurements taken within _______ prior to relocation.a. 90 daysb. 120 daysc. 150 daysd. 180 daysANS: D


Q3. An AST is disassembled according to API 653 and reconstructed on a new site. The tank is to be hydrostatically tested. The tank has a diameter of 123 feet and an operating height of 42 feet. The tank will store hydrocarbon with a 0.90 specific gravity. No old vertical or horizontal welds will remain in the reconstructed tank. The tank has six courses of 7 feet height each. The first course is 0.87 inch thick. The second course is 0.80 inch thick. The third course is 0.70 inch thick. The fourth course is 0.55 inch thick. The fifth course is 0.38 inch thick and the sixth course is 0.23 inch thick. The tank material is ASTM A-283 Grade C. What is the allowable stress to be used in calculating the maximum liquid level for the hydrostatic test.a. 20000 psib. 22500 psic. 24000 psid. 21000 psiANS: B


Q4. Shell penetrations on reconstructed tanks shall be designed, detailed, welded and examined to meet the requirements of the:a. owner/operator specifications.b. original standard of construction.c. current applicable standard.d. Standard ASTM 653.ANS: C

Q5. Existing penetrations on reconstructed tanks shall be evaluated for compliance with the:a. owner/operator specifications.b. original standard of construction.c. current applicable standard.d. Standard ASTM 653.ANS: B


Q6. Roof designs for reconstructed tanks shall meet the:a. owner/operator specifications.b. original standard of construction.c. applicable standard.d. Standard ASTM 653.ANS: C (B or C ?)

API653: 8.7 Roofs8.7.1 Roof designs shall meet the requirements of the as-built standard.8.7.2 If the new site requires a larger design load than the original site, the adequacy of the existing roof shall be evaluated using the current applicable standard.


API-653 ANSWER KEY


API-653 SECTION 7Q1. The basis for repairs and alterations shall be ______________.a. API Standard 2000 equivalence.b. API RP 651 equivalence.c. API Standard 620 equivalence.d. API Standard 650 equivalence.ANS: D

Q2. The minimum thickness of a replacement plate shall be _________ in accordance with the applicable standard.a. enumeratedb. calculatedc. furnishedd. ChangedANS: B


Q3. The thickness of a replacement shell plate shall not be less than the greatest nominal thickness of any plate in the same course adjoining the replacement plate except where the adjoining plate is:a. calculated by the variable design point method.b. a door sheet.c. a thickened insert plate.d. required because of plate availability.ANS: C

Q4. The minimum dimension for a replacement shell plate is ______ or 12 times the thickness of the replacement plate, whichever is greater.a. 18 inchesb. 12 inchesc. 10 inchesd. 20 inchesANS: B


API653: 9.2.2.1 The minimum dimension for a replacement shell plate is 12 in. or 12 times the thickness of the replacement be circular, oblong, square with rounded corners, or rectangular with rounded corners except when an entire shell plate is replaced. See Figure 9.1 for typical details of acceptable replacement shell plates.


Q5. Replacement shell plate may be circular, oblong, square with rounded corners or rectangular with rounded corners except when:a. an entire shell plate is replaced.b. one half a shell plate is replaced.c. bounded by a junction of vertical and horizontal weld.d. the complete weld is radiographed.ANS: A

Q6. Shell replacement plates shall be welded with butt joints with complete penetration and complete fusion, except as:a. noted in National Board repair requirements.b. permitted for lapped patch shell repairs.c. set forth in AISC standards.d. detailed in Underwriter Laboratory standards.ANS: B


Q7. Joints in lap-welded shell tanks:a. may be repaired according to the original standard of construction.b. must be repaired according to the current applicable tank standard.c. are not permitted and the tanks should not be used.d. must be repaired according to National Board requirements.ANS: A

Q8. A 7/8 inch circular butt welded repair plate is installed in the 0.875” thick lower course of a tank. What is the minimum weld spacing required from the vertical and horizontal plate welds of the lower course?a. 6” & 6”b. 7” & 7”c. 8.75” & 8.75”d. 10” & 10”ANS: D


Q9. Lapped patch shell repairs are:a. an acceptable form of repairs for butt-welded and riveted tank shells only

when specified by the Authorized Inspector.b. an acceptable form of repairs for butt-welded, lap-welded, and riveted tank

shells only when specified by the owner.c. not an acceptable form of repairs for butt-welded, lap-welded, and riveted

tank shells even if specified by the owner or the Authorized Inspector.d. only a temporary form of repairs for butt-welded, lap-welded, and riveted

tank shells and must be authorized by the owner and the Inspector.ANS: B

Q10. Lapped patch shell repairs shall not be used on any shell course thickness (original construction) that exceeds ____ inch.

a. 1.0b. 0.875c. 0.750d. 0.500ANS: D


API653: 9.3.1.2 Lapped patch shell repairs shall not be used on any shell course thickness (original construction) that exceeds ½ in., nor to replace doorsheets or shell plates.


Q11. Lapped patch shell repairs shall not be used to replace:a. annular plates or anything on the top course.b. manways or large nozzles openings.c. doorsheets or shell plates.d. sump sheets or tank heaters.ANS:C

Q12. Lapped patch plates shall not have a thickness less than:a. 0.1875 inches. (3/16”, 4.8mm)b. 0.2500 inches.c. 0.1250 inches.d. 0.3750 inchesANS: A


Q13. If a lapped patch plate is installed on a tank, what corner(s) may be exempt from being rounded to a minimum radius?a. The joint intersecting with a door sheet.b. The joint at the shell to bottom intersection.c. The joint adjacent to a manway over 24 inches in diameter.d. The joint butting a level controller.ANS: B

Q14. A lapped repair plate is installed across a butt-welded vertical seam. The seam is ground flush and checked by ultrasonics. The inspector must specify the minimum overlap of the patch plate. What minimum distance is selected?a. 2 inches beyond the shell seam.b. 6 inches beyond the shell seam.c. 12t beyond the shell seam.d. 3 inches beyond the shell seam.ANS: B


API653: 9.3.1.5 The repair plate may cross any butt-welded vertical or horizontal shell seams that have been ground flush, but must overlap a minimum of 6 in. beyond the shell seam. The weld spacing requirements of Figure 9.1 shall be used as a basis for locating repair plates relative to butt-welded, fillet-welded, and riveted seams and other repair plates.


Q15. Lapped repair plates positioned on the tank shell interior shall be located such that the toe-to-toe weld clearances are a minimum of ________ to the shell-to-bottom weld.a. 6 inchesb. 2 inchesc. 3 inchesd. 5 inchesANS: A

Q16. The maximum vertical and horizontal dimension of a lapped patch repair plate is:a. 72 inches in both directions.b. 24 inches and 48 inches respectively.c. 36 inches and 60 inches respectively.d. 48 inches and 72 inches respectively. (4’ x 6’)ANS:D (minimum 4”)


API653: 9.3.1.6 Repair plates may extend to and intersect with the external shell-to-bottom joint if the vertical sides intersect the tank bottom at a 90°angle and the shell-to-bottom weld is in conformance with Figure 9.6. Repair plates positioned on the shell interior shall be located such that the toe-to-toe weld clearances are a minimum of 6 in. to the shell-to-bottom weld. (?)

9.3.1.7 The maximum vertical and horizontal dimension of the repair plate is 48 in. and 72 in., respectively. The minimum repair plate dimension is 4 in. The repair plate shall be formed to the shell radius.


Q17. The minimum lapped patch repair plate dimension is:a. 9 inches.b. 4 inches.c. 8 inches.d. 6 inches.ANS: D (4”?)

Q18. An owner-user wants to put a NPS 8 shell opening (nozzle) in an AST shell. Which of the below would not be acceptable to API 653?a. within a lapped patch shell repair.b. within a butt-welded shell repair.c. within a door sheet.d. within a NPS 36 blind flange.ANS: A


API653: 9.3.1.7 The maximum vertical and horizontal dimension of the repair plate is 48 in. and 72 in., respectively. The minimum repair plate dimension is 4 in. The repair plate shall be formed to the shell radius.


Q19. Prior to application of a lapped patch shell repair, the areas to be welded shall be __________ for plate defects and remaining thicknesses.a. VT’db. PT’dc. UT’dd. MT’dANS: C

Q20. An inspector finds a 36 inch by 48 inch lapped repair patch that has a thin area near its center. The owner-user asks that a lapped repair plate be installed. This installation:a. is permitted according to API 653.b. may be used providing the owner-user approves.c. may be used if an API authorized inspector approves.d. is not permitted according to API 653.ANS: D


Q21. What is the minimum hole diameter caused by the removal of an existing shell opening that may be repaired by a lapped repair plate?a. 3 inchesb. 1 inchc. 2 inchesd. No minimum is listed.ANS: C

Q22. What joint efficiency is used to calculate the required thickness of a lapped repair plate installed over a shell opening caused by the removal of an existing nozzle?a. 1.0b. 0.85c. 0.35d. 0.7ANS: D


Q23. An NPS 3 nozzle is removed from the 0.325” thick third course of an AST. The reinforcing pad is removed from around the nozzle and the welds are ground smooth. The hole left by removing the NPS 3 nozzle is 3.75” in diameter. You are required to only have the minimum overlap over the hole by the lapped repair plate as required by API 653. What is the diameter of the lapped repair plate? a. 6.00 inchesb. 5.75 inches (min)c. 6.35 inchesd. 8.95 inches (max)ANS: A, E= 0.7 (B?)

Q24. What maximum joint efficiency may be used for a lapped patch repair plate with a full fillet perimeter weld that is used to repair a thin area of a tank shell?a. 0.25b. 0.35c. 0.60d. 0.70ANS: B


API653: 9.3.2.1 The welding shall be continuous on the outer perimeter of the repair plate and the inner perimeter of the hole in the shell plate. The minimum hole diameter is 2 in. Shell openings due to plate removal shall have a minimum corner radius of 2 in. 9.3.2.2 Nozzle necks and reinforcing plates shall be entirely removed prior to installation of a repair plate.9.3.2.3 The repair plate thickness selection shall be based on a design that conforms to the as-built standard and API 653, using a joint efficiency not exceeding 0.70. The welds of the repair plate shall be full fillet welds. The minimum repair plate dimension shall be 4 in. with a minimum overlap of 1 in. and a maximum overlap of 8 times the shell thickness (8t).


Q25. An AST has a thin area caused by external corrosion on the third shell course. The original thickness of the shell course was 3/8 inch. It has thinned to 0.06 inch in a 13” by 17” rectangular area. The lap patch is to be installed over the area to a point where the shell thickness is at original thickness. What is the maximum thickness lap patch that you could use to repair this thinned spot? a. 7/16” b. 15/32”c. 3/8” d. 1/2”ANS: D. (C?)

API653: 9.3.1.3 Except as permitted in 9.3.3.2 and 9.3.4.3, the repair plate material shall be the smaller of 1/2 in. or the thickness of the shell plate adjacent to the repairs, but not less than 3/16 in.


Q26. The area of metal on the tank shell that has thinned and been repaired by using a lapped patch: a. shall not be considered as effective in carrying the calculated service or

hydrotest loads.b. may be considered as effective in carrying the calculated service or

hydrotest loads.c. may be considered as carrying the calculated service loads but not the

hydrotest loads.d. may not be considered as carrying the service loads but may be used for

hydrotest loads.ANS: A, (B?)


API653: 9.3.3 Lapped patch repair plates may be used to reinforce areas of severely deteriorated shell plates that are not able to resist the service loadsto which the tank is to be subjected. Lapped patch repair plates may also be used for hell plates that are below the retirement thickness, providing the following additional requirements are satisfied.


Q27. Lapped patch repair plates may be used to repair small shell leaks. The repair plate must be designed to withstand hydrostatic pressure load between the repair plate and the shell. The joint efficiency used for this calculation is:a. 0.60b. 0.50c. 0.35d. 0.30ANS: C

Q28. If a lapped patch repair plate is used to repair a small shell leak on an AST, what are the maximum and minimum thicknesses of the repair plate?a. 3/16” & 1/8”b. 3/8” & 1/4"c. 1/2” & 3/16”d. 5/8” & 1/8”ANS: C


Q29. Which of the conditions listed below would be unacceptable as an application of a lapped patch repair plate to repair a small shell leak?

a. If the dimensions of the repair exceeds the vertical dimension of 36” and the horizontal dimension of 60 inches then this repair method shall not be used.

b. If exposure of the fillet welds to the product will produce crevice corrosion then this repair method shall not be used.

c. If the product in the tank is an inactive, inert or benign substance then this repair method shall not be used.

d. If exposure of the plate to the elements outside the tank will produce significant corrosion then this repair method shall not be used.

ANS: B


API-653 ANSWER KEY


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understanding api icp653 reading 6 worksheet 03 part 1

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