Section 9: Inspection of Buried Piping (API 570 pg 70-75)

Question 1

1. Inspection of buried process piping is different from other process piping, because of:

A. The potential for significant internal corrosion that cannot be monitored
B. The potential for significant external corrosion due to corrosive soils
C. Potential overhead traffic that increases stress on pipe
D. Excess water content in soils

Answer 1

B. The potential for significant external corrosion due to corrosive soils

Question 2

2. Which of the following methods is effective in finding active external corrosion on a buried underground pipe?

A. Wenner Four-Pin
B. Cathodic protection
C. Closed-interval potential survey
D. Acoustic emission testing

Answer 2

C. Closed-interval potential survey

Question 3

3. A coated buried pipe has been in service for a number of years. What method can be used to evaluate the effectiveness of the coating?

A. ACVG
B. DCVG
C. ACPR
D. DCPR

Answer 3

B. DCVG

Question 4

4. The corrosiveness of the soil for buried piping can be determined by measuring the soil resistivity. As soil resistance increases, the soil:

A. becomes-non corrosive
B. becomes less corrosive
C. becomes more corrosive
D. clay content increases

Answer 4

B. becomes less corrosive

Question 5

Lower levels of soil resistivity are:

A. Non-corrosive
B. Less corrosive
C. More corrosive
D. Less conductive of CP protective currents

Answer 5

C. More corrosive

Question 6

6. When measuring soil resistivity, the recommended tool to use is

A. The Wenner Four-Pin Method
B. A holiday tester
C. A close-interval potential survey
D. a CP potential survey

Answer 6

A. The Wenner Four-Pin Method

Question 7

7. When The Wenner Four-Pin Method is used to measure soil resistance, it should be done in accordance with

A. API 651
B. API 2201
C. ASTM A307
D. ASTM G57

Answer 7

D. ASTM G57

Question 8

8. When monitoring cathodic protection, refer to the requirements in:

A. API 651
B. API 2201
C. ASTM A307
D. ASTM G57

Answer 8

A. API 651

Question 9

9. Which of the following should be checked when evaluating a CP system?

A. Pipe resistance
B. Pipe-to-soil potential
C. Soil inductance
D. Soil-to-pipe current

Answer 9

B. Pipe-to-soil potential

Question 10

10. Which of the following is an acceptable way to determine the wall thickness of buried piping?

A. Intelligent pigging
B. Video cameras
C. Holiday testing
D. Close interval potential survey

Answer 10

A. Intelligent pigging

Question 11

11. Guided wave examination may be used to inspect buried piping. One installation (equipment setup) may be able to screen:

A. 15 feet or longer
B. 25 feet or longer
C. 50 feet or longer
D. 100 feet or longer

Answer 11

A. 15 feet or longer

Question 12

12. During a guided wave examination, the distance the wave travels and the accuracy of the measurements is based on several factors. Which of the following is NOT a factor?

A. Degree of corrosion
B. External coatings
C. Grade of carbon steel
D. Soil conditions

Answer 12

C. Grade of carbon steel

Question 13

13. What is the suggested interval for the above-grade visual surveillance on a buried pipe? (Open Book)

A. 6 months
B. 1 year
C. 5 years
D. 10 years

Answer 13

A. 6 months

Question 14

14. Who is responsible to ensure that the above grade visual surveillance is performed at the required intervals

A. Authorized inspector
B. Piping engineer
C. Owner / User
D. Tank farm operations supervisor

Answer 14

C. Owner / User

Question 15

15. For poorly coated buried piping systems where cathodic protecting potential are inconsistent, the pipe-to-soil potential survey may be performed every:

A. 1-2 years
B. 3-5 years
C. 5-10 years
D. 10-15 years

Answer 15

B. 3-5 years

Question 16

16. For buried piping systems in lengths greater than 100 feet and not cathodically protected, evaluations of soil resistivity should be performed at what interval?

A. Every 1 year
B. Every 5 years
C. Every 10 years
D. Based on likelihood resistivity has changed

Answer 16

D. Based on likelihood resistivity has changed

Question 17

17. When buried piping is inspected by excavating, what is the minimum length to excavate?

A. 2 to 4 feet
B. 4 to 6 feet
C. 6 to 8 feet
D. 8 to 10 feet

Answer 17

C. 6 to 8 feet

Question 18

18. Significant external damage to the coating is discovered on an excavated pipe. The damage extends into the wall of soil. What should be done?

A. Cover it up. Out of sight out of mind!
B. Cover it up. The likelihood of a failure during my remaining plant years is quite low.
C. Cover it up and report it to the engineer. That way if it fails, you’ll both go to jail. Be sure to pick an engineer that you like!
D. Dig further. Obviously, you’re a boring inspector who doesn’t like take chances

Answer 18

D. Dig further. Obviously, you’re a boring inspector who doesn’t like take chances

Question 19

19. If a buried piping system is contained inside a casing pipe, which of the following is NOT something the inspector should verify?

A. Both ends of the casing extend beyond the ground line
B. The casing ends are properly sealed
C. The pressure carrying pipe is properly coated and wrapped
D. The minimum distance between the casing pipe and the process pipe is 6”

Answer 19

D. The minimum distance between the casing pipe and the process pipe is 6”

Question 20

20. A buried pipe in the tank farm area does not have any cathodic protection. The soil resistivity is 1000 ohm-cms. What is the recommended interval for excavating or pigging this pipe? (Open Book)

A. 2.5 years
B. 5 years
C. 10 years
D. 15 years
E. Whenever the AI believes it is necessary

Answer 20

B. 5 years

Question 21

21. A buried pipe does NOT have effective cathodic protection. The soil resistivity is about 8000 ohm-cms. What is the recommended interval for excavating or pigging this pipe? (Open Book)

A. 5 years
B. 7.5 years
C. 10 years
D. 15 years
E. Whenever the AI believes it is necessary

Answer 21

C. 10 years

Question 22

22. A buried pipe does NOT have effective cathodic protection. The soil resistivity is about 12,000 ohm-cms. What is the recommended interval for excavating or pigging this pipe? (Open Book)

A. 5 years
B. 7.5 years
C. 10 years
D. 15 years
E. Whenever the AI believes it is necessary

Answer 22

D. 15 years

Question 23

23. Which of the following is an alternative to inspecting buried piping by excavation?

A. Leak test at a pressure 10% greater than maximum operating pressure
B. Leak test at a pressure 10% greater than design pressure
C. Holiday testing
D. Close interval potential survey

Answer 23

A. Leak test at a pressure 10% greater than maximum operating pressure

Question 24

24. An underground pipe is leak tested in lieu of excavation. The maximum operation pressure is 70 psig. The pipe design pressure is 180 psig. What is the recommended test pressure?

A. 70 psig
B. 77 psig
C. 105 psig
D. 180 psig
E. 198 psig
F. 270 psig

Answer 24

B. 77 psig

Question 25

25. An underground pipe is going to be leak tested in lieu of excavation. This leak test should be maintained for a total of: A. 2 hours B. 4 hours C. 6 hours D. 8 hours

Answer 25

D. 8 hours

Question 26

26. An underground pipe is going to be leak tested in lieu of excavation. The pressure should be checked and the line repressurized after: A. 2 hours B. 4 hours C. 6 hours D. 8 hours

Answer 26

B. 4 hours

Question 27

27. An underground pipe is going to be leak tested in lieu of excavation. The piping should be excavated and inspected when the pressure at the end of the test decreases by more than: A. 1% B. 3% C. 5% D. 10%

Answer 27

C. 5%

Question 28

28. A buried pipe in the tank farm area does not have any cathodic protection. The soil resistivity is 1000 ohm-cms. What is the recommended interval for leak testing this pipe? (Open Book) A. 2.5 years B. 5 years C. 10 years D. 15 years E. Whenever the AI believes it is necessary

Answer 28

A. 2.5 years

Question 29

29. A buried pipe does NOT have effective cathodic protection. The soil resistivity is about 12,000 ohm-cms. What is the recommended interval for leak testing this pipe? (Open Book) A. 5 years B. 7.5 years C. 10 years D. 15 years

Answer 29

B. 7.5 years

Question 30

30. A buried pipe has effective cathodic protection. The soil resistivity is about 8,000 ohm-cms. What is the recommended interval for leak testing this pipe? (Open Book) A. 5 years B. 7.5 years C. 10 years D. 15 years

Answer 30

C. 10 years

Question 31

31. An underground pipe is leak tested in lieu of excavation. The maximum test pressure is 180 psig. What is the minimum acceptable pressure allowed at the end of this test? (Open Book) A. 162 psig B. 170 psig C. 171 psig D. 175 psig E. 180 psig

Answer 31

C. 171 psig

Question 32

32. An underground pipe is leak tested in lieu of excavation. The maximum test pressure is 150 psig. What is the minimum acceptable pressure allowed at the end of this test? (Open Book) A. 140 psig B. 142.5 psig C. 145 psig D. 150 psig

Answer 32

B. 142.5 psig

Question 33

33. Which of the following is an alternative to leak testing an underground pipe? A. Holiday survey B. Potential survey C. Tracer gas test D. Wenner evaluation

Answer 33

C. Tracer gas test

Question 34

34. Which of the following gases are typically used in a tracer gas test? A. Helium or sulfur hexafluoride B. Chlorine or fluoride C. Hydrohexadramine or freon D. Hydrogen or propane (for smokers - makes finding leaks a memorable experience!)

Answer 34

A. Helium or sulfur hexafluoride

Question 35

35. What is a recommended way to inspect repairs on coatings that have been performed on buried piping? A. A low-voltage holiday detector B. A high-voltage holiday detector C. Low-voltage Wenner Four Pin D. High-voltage Wenner Four Pin

Answer 35

B. A high-voltage holiday detector

Question 36

36. A leak is discovered on a buried pipe in the tank farm. The pipe is excavated and clamped. The clamp location shall be: A. Covered and forgotten B. Surface marked in the field C. Recorded in the inspection records and may be surface marked in field D. Recorded in the inspection records and shall be surface marked in field

Answer 36

C. Recorded in the inspection records and may be surface marked in field

Question 37

37. A leak is discovered on a buried pipe in the tank farm. The pipe is excavated and is repaired with a non-welded clamp. This clamp: A. Must be removed and the pipe repaired at the first opportunity unless a piping engineer approves an extension B. Can we considered a permanent repair if approved by an engineer C. Can can be considered a permanent repair if approved by an engineer and inspector D. Can be considered a permanent repair if approved by the jurisdiction

Answer 37

A. Must be removed and the pipe repaired at the first opportunity unless a piping engineer approves an extension