API 653 Chap 10 - Tank Reconstruction

Question 1

Bottom plates to be reused should be cut by? (2)

Answer 1

1. cut by deseaming of lapwelds; or
2. by cutting alongside of the remaining welds at a minimum of 2 in. away from existing welds, except where cuts cross existing weld seams

Question 2

Tank shell plates may be dismantled using one of the following methods or a combination thereof (3)

Answer 2

a) Any shell ring may be dismantled by cutting out existing weld seams andthe heat affected zone (HAZ) of the weld. For the purpose of this method,
the minimum HAZ to be removed will be ½ of the weld metal width or ¼ in.,
whichever is less, on both sides of the weld seam.
b) Any shell ring ½ in. thick or thinner may be dismantled by cutting through the weld without removing the HAZ.
c) Shell rings may be dismantled by cutting vertical and/or horizontal cuts through the shell a minimum of 6 in. away from existing welds, except
where cuts cross existing welds.

Question 3

Roof plates shall be cut by (2)

Answer 3

(1) deseaming of lap welds, or
(2) by cutting alongside of the remaining welds at a minimum of 2 in. away from existing welds, except where cuts cross existing welds. (not cutting through the weld)

Question 4

Weld spacing have to be maintained with a minimum of….. on vertical joints?

Answer 4

5t

Question 5

When should welding not be performed? (4).

Answer 5

1. wet from rain, snow or ice
2. high winds
3. when base metal is less than 0F
4. 0-32F or thickness >1”, base metal should be warm to hand (140F)

Question 6

what kind welding temperature needed for over 1.5” thick ?

Answer 6

Preheat temperature&raquo_space; 200F

Question 7

When should tack weld be remove ?

Answer 7

when welded manually

Question 8

When should tack weld not be removed?

Answer 8

when they are welded by submerged arc

Question 9

when to use low hydrogen electrodes?

Answer 9

1. T&raquo_space; 1/2” Group 1-3

2. Group IV-VI (all)

Question 10

When % is misalignment allowed in shells in vertical joints?

Answer 10

1. T > 5/8” shall not exceed 10% of thickness , with max 1/8”
2. T < 5/8” not exceed 1/16”

Question 11

When % is misalignment allowed in shells in horizontal joints?

Answer 11

1. T > 5/8” shall not exceed 20% of thickness , with max 1/8”
2. T < 5/8” not exceed 1/16”

Question 12

Max out of plumpness of the top of the shell relative to bottom?

Answer 12

Shall not exceed 1/100 of the tank height , max 5 in

Question 13

Peaking (V) and banding (H) should not exceed what?

Answer 13

1/2” / 1”