Need to Weld Together 2 Pieces of Piping 2

[MechEng176]

Hi,

I'm working on a project where the customer doesn't want any NPT connections at all so I have to change over all of my adapters to one piece units.

So before I had a 6'' 600# raised face (RF) flange tapped to 3'' NPT, in that I put a 3'' NPT nipple, and on the nipple I put a 3'' hammer union adapter. Now I'm getting a 6inch to 3 inch, RF, weld neck, standard reducing flange made of A105N. But the weld neck hammer unions adapters I have have an XXH wall thickness. Is it not possible to butt weld the 6x3 600# reducing flange I have to the XXH hammer union adapters because the wall thicknesses are different? Also, I have a welding company in place to weld together my pieces, but what information do they need from me to weld them together.

Thanks!



Hammer Union Hard Pipe

https://www.google.ca/search?q=hamm...ASG34HoAg&ved=0CDcQsAQ&biw=1366&bih=667&dpr=1

 

[BigInch]

What's the wall thickness of the 3" reducer's end?
Welding ends should not differ in thickness by more than 3/16", or you will need to put a short pipe with an intermediate wall thickness in between. The pipe can be taper bored if necessary.

They will need the welding design code reference, such as B31.4 or B31.8 with API 1104, or ASME BVP for example. Check your piping design code to see what welding design specs are referenced.

I hate Windowz 8!!!!

 

[MechEng176]

I'll have to confirm the wall thicknesses and look into it the possibility of welding them together. I'll probably just end up getting everything XXH so I don't have to bother with another pipe in between to weld and that everything is XXH (not needed for this temporary application but nice regardless). Thanks!

 

[BigInch]

Make that 3/32"
Sorry, but I have a hard time thinking (or not thinking) in 1/32"s.

I hate Windowz 8!!!!

 

[MechEng176]

I was looking up the wall thicknesses of schedule 160 vs XXH and they are more than 3/32 of an inch. So the only piece of pipe I can weld to a XXH pipe is another XXH pipe. Too bad that it wasn't 3/16 because then, if I wanted to, I could have welded a schedule 160 pipe to an XXH one since the difference is less than 3/16ths.

XXH to XXH it is then. Thanks.

 

[Duwe6]

"The pipe can be taper bored if necessary." As usual, Big Inch hit the target.

Just counterbore the XXH to match the other piece, and make sure that the machinist a) keeps the transition area far enough back from the weld cap that when X-rayed, it will not look like a weld 'feature'; and b) has a 3:1 or shallower taper in the transition area; and c) allows at least a small radius at the 'root' of the taper to avoide a stress concentration at the start of the taper.

 

[moltenmetal]

Duwe6 gives the correct advice for butt-welding pipe ends or fittings of differing wall thickness. Follow it carefully or you WILL fail a radiographic inspection!

 

[MechEng176]

Thanks guys, will definitely follow that advice if it comes to the point where I need a spool to go between the two pieces. I ordered both pieces as XXH wall so I shouldn't need to get a spool but now I know for next time.

 

[BigInch]

Probably not a bad solution. At least it's expedient.

And remember it is 3/32. it is 3/32. it is 3/32. it is 3/32.
That should help me remember too.

Learn from the mistakes of others. You don't have time to make them all yourself.