Hot Tap Calculation
Hot Tap Calculation
(OP)
I am working on an external pressure calculation for a hot tap. The equation is from ASME Sec. VIII, Div. 1, UG-28. Ultimately, I need to get factor B from figure CS-2 in Sec. II, Part D, pg. 797. To get factor B I first need Factor A from figure G on pg. 795. To get factor A I have to enter the figure with a value for L/Do and Do/t. The intersection of these two values falls off the lower right side of the figure. I can't get an A factor from the tables either because extrapolation is not allowed.
Has anyone encountered this before? What do I do? My supervisor checked my work and is having the same issue.
Has anyone encountered this before? What do I do? My supervisor checked my work and is having the same issue.





RE: Hot Tap Calculation
Regards,
Mike
RE: Hot Tap Calculation
L=1.4375 in
Do=16 in
t=.373 in - thickness is from client UT readings
L/Do = .0898
Do/t = 42.895
RE: Hot Tap Calculation
Regards,
Justin
RE: Hot Tap Calculation
RE: Hot Tap Calculation
Regards,
Mike
RE: Hot Tap Calculation
Regards,
Justin
RE: Hot Tap Calculation
Regards,
Mike
RE: Hot Tap Calculation
You have a NPS 1 'olet on an NPS 16 Std. weight pipe. You plan to hydrotest the 'olet and valve (and hot tap cutting machine). You are concerned about external pressure over the perhaps 1.5" diameter area on the NPS 16 pipe collapsing it.
Is that correct?
RE: Hot Tap Calculation
That is what the calculation is for, you are correct. We did a 2" tap on the same header on a separate project. So we know that is safe to perform the tap with a 1" sockolet due to the smaller hole. We just have to provide supporting documentation for the client's records. We just used A = 0.1. Which gave us a B factor of 18000. I think the pressure came out to be about 550 psig. Thanks for the assisstance.
Regards,
justin