grinding of socket welded stainless pipe joint
grinding of socket welded stainless pipe joint
(OP)
I have recently observed some 1" schedule 80 socket welded joints that were ground in order to "dress up" the weld. In the process, both the pipe and fitting were ground. Question: Is there any code requirement that specifically prohibits or limits the grinding of stainless pipes, welds, and/or fittings? Is the ASTM A312/A312M allowable wall thickness tolerance (12.5%) applicable?





RE: grinding of socket welded stainless pipe joint
What the shape of the grind cuts are: Some will threaten pipe integrity. Some - most actually that shallow or incidental and with non-sharp edges - will not matter.
EVERY pipe can be ground during and before welding to provide a clean surface!
RE: grinding of socket welded stainless pipe joint
RE: grinding of socket welded stainless pipe joint
Absolutely. If the 12½% is not violated, you are done - accept the prep & fitup. If the welder got carried away and went below that limit, the overground area can be welded up to nominal wall thickness. [you are already going to weld]. If you decide to calculate the Minimum Wall [vs. 12½% less than nominal], you have to take into account the bending stresses and tension [pipe span is in tension]. Not a trivial calculation.
RE: grinding of socket welded stainless pipe joint
As an ex pipe welder and welding inspector I get highly suspicious when I see stainless steel welds that have been ground.
What may look perfectly acceptable to the naked eye may look a bit different once tested.
Cheers,
DD
RE: grinding of socket welded stainless pipe joint
As far as your question: yes, there will be an inspection code.
All codes allow levels of grinding and undercut.
But which code is applicable for your situation: ASME B31.1, B31.3, API 1104, or one of the AWS codes? Let me know and I will share a copy with you, if needed.
RE: grinding of socket welded stainless pipe joint
If it's grinding at the toe, it might be standard practice to increase fatigue life. If it's grinding at the throat, it should be checked against required fillet profile to make sure you have enough throat.