How to calculate weld reinforcement for branch fitting?

As an engineer you should straight forward reject the half coupling.Only allow weld-o-let for a branch connection.Use ASME Code B31.3 for further support your decision.

1. I prefer to use Reducing Tee 4"x1.5" NPS, or at least Weldolet 4"/1.5" NPS (if it is available). Otherwise:

2. You can make an appropriate curvature for that half coupling 1.5" NPS to match with the curvature of the main run 4" NPS, to be beveled and butt-welded and add a fillet weld with a leg not more than the thinner of welded thicknesses. Or

3. If it is possible, you can use the half coupling to be welded as "set in" not "set on", and in this case the hole in pipe can be beveled to be butt-welded followed by a fillet weld around the half coupling with the same leg as in "2".

Note: For all prescribed cases and as you use standard fittings with appropriate dimensions/schedules/ratings/classes, no need to proceed any calculations.

First of all you can buy real nice weld on branch fittings you can weld on in one pass or cut the pipe or coupling with two cuts 45degree or 60 degree what ever fits better to get the branch closer to the pipe to maybe two passses we used this in the race car years ago

Mike

Thank you for every answer.

In this project ,I can't reject these fittings because of time schedule.

One point, that make me doubt, is calculation method for weld reinforcement. I can't find any document that refered calculated method. Normally, if we weld full penetration , it will be safe. Interesting thing is if we cannot do it, what solution shall be applied?

Now , I have two choises

1 Full penetration: I have to discuss with the authorized person in project for approved such a defect.

2 Not full penetration: Find some document that sound for proving size and shape of reinforcement.I would like to find some clue ,if anyone have it please tell me more.

Thanks you sir,

Chalermphol C. Thailand

Please look into ASME B31.3, paragraph 328.5.4 - particularly Fig 328.5.4D.

I think you are over killing on the amount of weld and this will cause distortion. Half couplings work great on lower pressure(below 150 psi) branch connections especially on stainless steel pipe because it draws or distorts more. When people tell you to not use a half coupling for a branch connection it is incorrect that is what they are made for. Please keep in mind that half couplings are not made for steam and other higher pressure services but more for fire protection, water, air etc. I have been welding both half couplings and weldolets on for near 30 years and I one thing I know for sure is that welders nearly always put way to much weld on them. I will garantee that if you fully weld on a threadolet on stainless steel you probably won't draw the threads on the threadolet but you will draw the header so badly that that it could be ruined. I agree with Ashim (as always and he gets my GA) on the points he made about the installation procedures. I always install half couplings in a "saddle in" technique as opposed to a "saddle on" technique to reduce distortion.

pipewelder,

just replied one in section weldolet welding. most of the time the design engineering mis- interpretes the definition of groove. also they miss to visit the section of un- listed fittings of asme b31.3 where on the welding thickness, the code recommends to interpolate.

ciao

ashbandy

See ASME B31.3

APPENDIX H

SAMPLE CALCULATIONS FOR BRANCHREINFORCEMENT

I think it is helpful

Regards

Refer ASME B 31.3.Check the header pipe cut-out(May be this is the reason for overwelding).you can go for 4" X 1.5" TEE OR WELDOLET for SS.