Bevel End for Pipes & Fittings According to B16.25

Can you please reproduce those figures, or at least describe the geometry involved?

Dear Mr.Galala,

I have some query to ask -

Does it is important to mention every time "C" dimension calculated using B16.25(page-3 of 2003)in weld end preparation of two pipe spool even though pipe has same nominal OD and same nominal thickness and using fig.2a/2b.

C=A-OD tolerance-2*tmin-0.25.

Where,

A-Nominal outside diameter.

OD tolerance-undertolerance on OD(This value come from SA530 Table-1)

In case of A106 or A335 pipe above can be modified as-

C=A-0.79-2*tmin-0.25

C=A-0.79-2*0.875*tnominal-0.25

Here

tnominal=tmin/0.875.(12.5% mill undertolerance on pipe thickness)

For example -

Nominal OD-508mm

Nominal thicknes-S60(20.62mm)

So,C dimension

C=A-0.79-2*0.875*tnominal-0.25

C=508-0.79-2*0.875*20.62-0.25

C=470.875mm.

So,for higher thickness does we have mention mention "C" dimension rather than nominal inside diameter for every weld.

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Also,as per ASME B31.1,in case of inside thickness difference is greater than 2 mm internal trimming has to done.(explained below)

As per SA350 Table-1,(for 20" NPS pipe)

Over tolerance on OD,+3.2mm

undertolerance on OD,-0.8mm

and considering 12.5% under and over tolerance on pipe thickness,

SO,if we minus MAXIMUM INSIDE DIAMETER (mm) and MINIMUM INSIDE DIAMETER (mm),475.12-460.81=14.31mm,14.31/2=7.155 which is higher than 2mm (as per ASME31.1).In this case we have do trimming.

Conclusion

So,do we have to do trimming for each and every weld in case of higher pipe thickness as every time we will get inside thickness difference more than 2 mm and what dimension we will be showing on weld end preparation,either "C" dimension or "B"(nominal inside diameter) dimension from B16.25.

What is your explaination on this topic.