Min Wall pipe bevel "C" Dimension 1

[dahar]

When calculating the "C" dim using B16.25 it talks about nominal pipe only and the formula listed is C=A-.031-1.75t-.01(in.). However, I have found that PFI also gives the same formula for nominal pipe but has also given a formula for min. wall pipe (A335, A106,A312) as C-A-.041-2tm (in.) This seems to be correct for min wall pipe. Can anyone help me here?

 

[metengr]

The information is all there in B16.25. Under Section 4;

EQ 1: C = A - OD tolerance - 2 X Tmin – 0.010 (US customary units)

A = specified outside pipe diameter at welding prep
OD tolerance = under tolerance on the pipe OD from the applicable pipe specification

Tmin = thickness - manufacturing tolerance for pipe wall thickness based on applicable pipe specification

0.010 = plus machining tolerance on Bore C dimension


Based on tolerances specific to ASTM A106, A335 pipe;

EQ 2: C = A - 0.031 - 2 X 0.875 Tmin - 0.010 (US customary units)


The difference between these equations is that equation (2) accounts for pipe tolerance specific to the referenced ASTM Pipe Specifications with an under-tolerance of 12.5% on wall thickness.

 

[dahar]

Thanks Meteng,

I'm looking at the ASME B16.25-1997 version and Section 4 only has one equation. Are you looking at a later edition that shows eq.1 & eq.2 you have shown.

 

[metengr]

yes, 2003 edition.