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? -- https://materials-welding.blogspot.com/ https://www.linkedin.com/groups/122787 --- You received this mess...
What API 650 is asking you to check API 650 limits local shape distortion at welds: Vertical seam → peaking (a local “kink”/step at the vertical joint) Horizontal seam → banding (a local “belt”/flat/step around the circumference at a horizontal joint) In both cases the maximum allowed deviation is 13 mm. A) How to verify peaking at a vertical weld (sweep board – 900 mm) Tools: 900 mm long curved sweep board (curved to the nominal tank radius) + feeler gauge / wedge gauge (or a dial gauge). Field method: Put the sweep board horizontally across the vertical weld seam so it spans ~450 mm each side of the weld (board centered on the weld). Hold it snug to the shell (usually you rotate/shift it slightly to ensure it’s seated properly). Measure the maximum ga...