Mismatch bores/ Wall thickness - Welding (EN and ASME)
Mismatch bores/ Wall thickness - Welding (EN and ASME)
(OP)
On a project, for economic reasons, we have pipe which has a thinner wall thickness than standard off the shelf fittings.
Before anyone says to match the wall thicknesses (in an ideal world) you may want to consider the vast range of pipe wall thicknesses available in the EN standards.
Could anyone tell me where I could find the maximum permissable difference in wall thicknesses allowable for welding, I'm aware we may need to grind away some of the material of the fittings.
I have access to most EN standards but only a few ASME standards.
Regards
Paul Hearn
Before anyone says to match the wall thicknesses (in an ideal world) you may want to consider the vast range of pipe wall thicknesses available in the EN standards.
Could anyone tell me where I could find the maximum permissable difference in wall thicknesses allowable for welding, I'm aware we may need to grind away some of the material of the fittings.
I have access to most EN standards but only a few ASME standards.
Regards
Paul Hearn





RE: Mismatch bores/ Wall thickness - Welding (EN and ASME)
while adhering to the applicable Code press/temp calcs for the thinner wall pipe, a tapered weld prep on the thicker fitting should get you there.
Steven C
Senior Member
ThirdPartyInspections.com
RE: Mismatch bores/ Wall thickness - Welding (EN and ASME)
3/16 inch is a typical limit of mismatch wall thicknesses. No standard I know of covers this, but I don't know all of them yet.
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RE: Mismatch bores/ Wall thickness - Welding (EN and ASME)
Steven C
Senior Member
ThirdPartyInspections.com
RE: Mismatch bores/ Wall thickness - Welding (EN and ASME)
3/16 is approximately 4.7 mm - can you recall where you got that figure from?
I can find an EN standard that indicates the mismatch of a circumference and alignment but doesn't mention anything about mismatch of wall thicknesses.
RE: Mismatch bores/ Wall thickness - Welding (EN and ASME)
Take a look at ASME B31.8, Appendix I
RE: Mismatch bores/ Wall thickness - Welding (EN and ASME)
RE: Mismatch bores/ Wall thickness - Welding (EN and ASME)
ASME B16.9 requires taper boring for any misalignment between fitting and pipe greater than 1.5mm. Although it seems that this is limited to fitting proof testing rigs.