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API 653

REVIEW Section 7

1. The basis for repairs and alterations shall be ______________. API Standard 650 equivalence. 7.1.1

2. The minimum thickness of a replacement plate shall be ________ in accordance with the applicable standard.

Calculated. 7.2.1

3. 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 thickened insert plate. 7.2.1

4. The minimum dimension for a replacement shell plate is _____ or 12 times the thickness of the replacement plate, whichever is greater.

12 inches. 7.2.2.1

5. Replacement shell plate may be circular, oblong, square with rounded corners, or rectangular with rounded corners except when:

An entire shell plate is replaced. 7.2.2.16. Shell replacement plates shall be welded with butt joints with complete penetration and complete fusion, except as:

Permitted for lapped patch shell repairs. 7.2.3.1

7. Joints in lap-welded shell tanks:

May be repaired according to the original standard of construction. 7.2.3.2

8. A 7/8 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?

10 and 10. 7.2.3.3 & Figure 7-1

9. Lapped patch shell repairs are:

An acceptable form of repairs for butt-welded, lap-welded, and riveted tank shells only when specified by the owner. 7.3.110. Lapped patch shell repairs shall not be used on any shell course thickness (original construction) that exceeds _______ inch.

0.500. 7.3.1.2

11. Lapped patch shell repairs shall not be used to replace:

Door sheets or shell plates. 7.3.1.2

12. Lapped patch plates shall not have a thickness less than:

0.1875 inches. 7.3.1.3

13. If a lapped patch is installed on a tank, what corner(s) may be exempt from being rounded to a minimum radius? The joint at the shell to bottom intersection. 7.3.1.4

14. 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?

6 inches beyond the shell seam. 7.3.1.5

15. 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. 6 inches. 7.3.1.6

16. The maximum vertical and horizontal dimension of a lapped patch repair plate is:

48 and 72 respectively. 7.3.1.7

17. The minimum lapped patch repair plate dimension is:

6 inches. 7.3.1.7

18. An owner-user wants to put a NPS 8 shell opening (nozzle) in an AST shell, within a lapped patch shell repair. Per API 653 is this acceptable?

Not acceptable. 7.3.1.8

19. Prior to application of a lapped patch shell repair, the areas to be welded shall be _______ for plate defects and remaining thicknesses. UTd. 7.3.1.9

20. An inspector finds a 36 by 48 lapped repair patch that has a thin area near its center. The owner-user asks that a lapped repair plate be installed. This installation:

Is not permitted according to API 653. 7.3.1.10

21. What is the minimum hole diameter caused by the removal of an existing shell opening that may be repaired by a lapped repair plate? 2 inches. 7.3.2.1

22. 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?

0.7 7.3.2.3

23. Calculation

24. 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?

0.35 7.3.3.125. Calculation

26. The area of metal on the tank shell that has thinned and been repaired by using a lapped patch:

Shall not be considered as effective in carrying the calculated service or hydrotest loads. 7.3.3.3

27. Lapped patch repair plates may be used to repair small shell cracks. 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:

0.35 7.3.4.228. 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? & 3/16 7.3.4.3

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