Welding stainless exhaust pipe

[johnc]

I 've had to make up an exhaust for my resto project and have 'slid'sections of smaller/larger diameter pipes together and clamped them but cannot get a gas tight seal.
I have a Clarke Pro90 MIG and wonder if is it possible to form welded joints with this,bearing in mind it is only to form a seal and not for actually joining the pipes together.If it is possible what gas and wire would I need?
Thanks
Johnc

 

[mike 109444]

Hi johnc If you tried to weld it just "to form a seal" you are going to have a hard time of it! Thoes that have tried to weld up or make up an exhaust by welding usually have the problem after of pin holes causing leaks. Why dont you use some exhaust paste when assembling? I have found GumGum exhaust paste to work well and when I have welded an exhaust I usually water some down to a thin/watery liquid and brush it into the welds, which once dry usually fills any pin holes/gaps.

 

[johnc]

Hi Mike,
Thanks for the reply.I've used assembly paste (Holts) without success but as the weld option looks doubtful I guess I'll dismantle it again and try with more paste.I wonder if diluting a bit may help to enable it to 'flow' into the tight joint may be worth a try.
Regards
John

 

[wheresmejumper]

is there an obvious difference in the size of the sections?

 

[Wozzaaah]

Is it proper exhaust tube you're using? I take it you've cut slots in it so the clamps can work?

 

[wheresmejumper]

the same section and exhaust expanders would be an easy option

 

[johnc]

SS Welding

The components are proper exhaust pipe and the fit is very tight one into the other.I have cut slots to help form a 'clamp'effect when the U clamps are tightened but this has not been sufficient to seal the joints.

 

[justmental]

plug a pit of exhaust paste in there it will soon seal its self up when carbon forms on the inside.
i have worked for over 20 years in exhaust centre's even having to make a few when they where not available.

 

[Wozzaaah]

What type of clamps are you using and where are you placing them on the slots? If you don't put them in the correct place they will often blow.

 

[johnc]

I have considered all yourcomments and also looked on another welding forum and find a variety of opinions,some of which suggest there is no real problem MIGing with m.s. wire.So I thought I'd do a trial on a couple of offcuts of pipe and find that whilst the welds may not be pretty the result is acceptable to me.I'm going to do the sleeve jointing with welds to form a seal and assemble with jointing paste for good measure.
Thanks all.
John

 

[althemusicwizard]

Hey John,

I'm about to tackle a similar thing with my motorhome exhaust....don't suppose you're anywhere near Manchester are you?

Have you posted any pics of the repair anywhere?

Cheers
Al