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[MW:36060] Peaking & Banding Inspection API 650 Tanks

By Materials & Welding

As per API 650, local deviations from the theoretical shape (for example, weld discontinuities and flat spots) shall be limited as follows:

a) Deviations (peaking) at vertical weld joints shall not exceed 13 mm (1/2 in.). Peaking at vertical weld joints shall be determined using a horizontal sweep board 900 mm (36 in.) long. The sweep board shall be made to the nominal radius of the tank.

b) Deviations (banding) at horizontal weld joints shall not exceed 13 mm (1/2 in.). Banding at horizontal weld joints shall be determined using a straight-edge vertical sweep board 900 mm (36 in.) long.

How is this value verified at site? For example, at a vertical joint, if one side shows 6 mm and the other side shows 7 mm, is it acceptable? Or should the average be considered? Also, how can we determine whether the deviation is negative (-) or positive (+)? Can anyone please explain?

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