be asked to weld a 40mm flange

[brendan h]

got a job coming up that will require me to weld a flange in position. ive been told the flange will be hard up against a wall and i probably wont be able to get to it from the outside (fillet weld side) the only way to weld it would be from the inside. To me this is going to be ok as it will seal? i have never welded a flange before and i do not doubt i can do it. my only concern is distortion? would i just put 4 tacks opposite eachother and weld a complete circle?

if it helps pipe is 40mm probably NB. i have not seen the job just been told it all. its a condensor line for a cooling tower so i am thinking probably 50psi max? will be seeing it next saturday preping eveything ready for whenever

 

[busa]

Use a weld neck flange instead of a slip flange ?

 

[Delgado]

If you cant use a different flange (as busa said) have a look on the otherside of the wall, being as its only 40mm tube, there should be a union, valve (or both) or something else that you could easily undo, pull the pipe through the wall a bit, weld it normally, and then put it back in position. Even if there is an elbow directly behind it on the other side of the wall, most people dont run pipes hard up against walls, so you should still be able to pull it through enough to weld it.

At any rate, If I were you, i'd take some large clamps, ratchet straps, stillsons ect... with me to the job, just in case.(and possibly an assistant)

hope it helps! (and sorry if it sounds obvious)

 

[brendan h]

am actualy a plumber,(Industrial) so I've got the gear for pipes. What we are doing,so I'm told, is replacing the lines with copper. I think the pipe may be coming out of the ground next to a wall.once again I will see it next week to confirm this. I know the best way to do it is from the outside but in this case I proably won't be able to get to it.

 

[Weldingartisan]

No problem with a bossed slip on flange (as opposed to a plate flange) even a PN6 or table D will not distort enough to prevent you making a joint. A weld neck is a good idea if you've got access round the butt. W/A

 

[penfold]

If it really is a condenser line, it'll have a vacuum on it, not positive pressure. Best to ask onsite if it's a potential issue.

 

[brendan h]

Aparently it's being pumped,henses the 50psi.

 

[busa]

Brendan.

If the line is only 1.5" NB running 50psi then a slip flange with a single pass on the inside will suffice. If you are that concerned about the job then why not tell them that you are a plumber, and that they should get a welder to do it.

 

[brendan h]

we can get a welder to do it.however i offered to do it as good practis. Like i said i can do it,i was just worryed about distortion and if welding the inside only is significant.