ASME Codes for sizing a weld
ASME Codes for sizing a weld
(OP)
What would be the proper formulas to use for sizing a weld that would hold a branch connection. The main line is 10" schedule 40 with approximately 120psi air in it. We want to branch off with a 3" line. I know everyone is going to say use a weldolet, and that is more than likely the way we are going to go. It will be a 90 degree branch. I think ASME B31.1 is the code to use (I am not to familiar with the codes and do not have any of them).
But, I am a rookie engineer and I am interested in seeing some formulas and sizing a weld or welds.
Thank you for your help.
UncleSam
But, I am a rookie engineer and I am interested in seeing some formulas and sizing a weld or welds.
Thank you for your help.
UncleSam





RE: ASME Codes for sizing a weld
A compressed air system is nothing to fool around with because of the potential for harm. I would recommend you purchase a copy of ASME B31.1 Power Piping Code for your application. Section 104.3 of B31.1 "Intersections" will provide the information to engineer a 3" branch connection on the 10" main header. In addition, ASME B31.1 will provide guidance on approved material for fittings and post weld inspection requirements.
Please be aware that you should have a Welding Procedure Specification (WPS) and welder qualified to ASME Boiler and Pressure Vessel Code, Section IX if you are going to install the branch connection. If you hire a contractor, make sure that they have a National Board Certificate of Authorization to repair Boilers/Pressure Vessels. This way you have a contractor that knows what is required to perform this installation.
RE: ASME Codes for sizing a weld
Why do you advise ASME B31.1? Compressed air is not steam so why not use the appropriate standard i.e. ASME B31.1 - Process Piping.
RE: ASME Codes for sizing a weld
If you are referring to B31.3 Process Piping, B31.1 Power Piping includes water, steam, and gas piping systems. I am most familiar with B31.1 having spent a long time in Power Houses. Please read the Introduction, Section 100.1.2 and 122.8.3 of B31.1.
RE: ASME Codes for sizing a weld
RE: ASME Codes for sizing a weld
RE: ASME Codes for sizing a weld
In response to your original question,.....
With one exception, piping welds are not "sized" in the manner that structural welds are evaluated. Welds for piping are typically full penetration (develops full pipe strength of the section)or are generously sized fillet welds. The primary loading in most piping systems is pressure.
The exception is fabricated and pad reinforced "tees" at point of pipe intersection. These components are sized based on what is called the "area replacement technique". This technique uses the pressure loading on the joint to find the need for pad reinforcement.
I think that this answers you original question......
MJC
RE: ASME Codes for sizing a weld
a 3" on a 10" sch 40, is fully reinforced specially for compressed air.
It is good to rely in the Codes too.
A must here: a weld procedure to assure the soundness of the weld.
ER