welding a stainless steel pipe to another

[mi3gto]

Folks I want to have a 316 ss pipe joined to another with as strong a join as I can get. I have access to a very experienced TIG welder but want to ask.

I want to socket the lower tube so that the upper tube fits inside for a few inches. The resultant joint is then to be welded, closing the joint which will then be polished.

What is the best way to produce a socket in the SS tube? one tube is 38.1 OD (male paart) the other (female part) will probably be 42.164mm OD x2.77mm Wall. This gives an ID of 36.624mm. or swap the male - female config so that the male fits inside the 38.1 tube with a flare to suit sizes available?

Any ideas or suggestions welcome. George

 

[Shox Dr]

The outer tubes need to be crossdriled 8-10mm so they can be plugged weld and tied into the inner tube.

 

[hotrodder]

What's the part for? How will it be loaded? A belt and braces approach with the joint won't necessarily make the part stronger

Depending on the tooling available and the wall thicknesses can flare the smaller tube or machine either of 'em. Kit that'll flare ~3mm stainless tube nicely ain't the cheapest, especially if you want a few inches of overlap. If you don't want to machine the tube/the lengths are too long to make it pratical etc then could machine a concentric reducer that sleeves both sections. Presumably nothing is flowing through the tube as the step/crevices might be an issue?

 

[Shox Dr]

der misread that

 

[mi3gto]

part is a A frame off a RIB. Possible that a sleeve might be a better approach? The area will be braced as well and no requirement for towing as it is for nav lights and antenna only. The existing frame is to wide so I need to step it at the base to fit between the tubes. I may even make the base step hinged so that the frame can be lowered.

If I go with a sleeve, should I weld the two tubes together, grind flat then slide the sleeve over the join and weld that at both ends? If I go the hinged route the tube from both the upper and lower part will be welded to a flat plate that is hinged. I have a pic somewhere showing just this.

g

 

[hotrodder]

I can't picture it properly but as Shox said plug (rosette) welds would typically also be used with a sleeved joint to properly tie everything together. Pic of best practice for an inside sleeve in this thread... http://www.mig-welding.co.uk/forum/showthread.php?t=25879&highlight=sleeve and an outside sleeve...



Yep, with an outside sleeve you'd cut, weld and then add the sleeve.

 

[Shox Dr]

I've never noticed on those diagrams it says rosettes don't need to be used if the sleeve is a tight fit.

 

[hotrodder]

Me neither although i'd say the line between tight enough to skip the plugs welds and being sooo tight you spend 1/2 hour swearing at the thing is a pretty fine one? I've just noticed that the rosettes are called out as 1/4 of the tube diameter! Fine with small diameter tube, perhaps a bit of overkill once you get upto 40 odd mm OD

 

[Shox Dr]

I not used over 10mm which just happens to be a 1/4 of 40mm, and never had a problem but then I don;t think Ive sleeved anything over that

 

[hotrodder]

Yeah, dunno what was going through my head when i wrote that for some reason i was picturing a huge hole. Must have done something daft like confusing 1/4s with 1/2s or just lost the plot