WELDING PIPE TO FITTINGS

[valmeidan]

so I am welding a triclamp fitting onto a pipe. Now I was wondering, is it standard practice to fillet the edge of the pipe for welding the flat face of the ferrule? I guess in general when you weld pipe would you chamfer the edges around like this normally to do a bevel weld?

 

[valmeidan]

Heres anotehr pic

 

[moltenmetal]

OK, I was puzzled for a minute by your use of the word "fillet". What you meant to ask is if it is normal to bevel the end of a pipe when welding thin sections together, i.e. not pipe but tubing in this case.

Normally we do Tri-clamp fitting butt welds autogenously using an orbital (robotic) welder. The ends are prepared square, not bevelled, and the weld is completed without filler metal.

If you are welding with filler metal, you'd need to ask a welder which technique works best on thin sections like this. The issue isn't really how to get a decent weld, it's how to generate a weld which doesn't have an unacceptable surface finish on the ID such that you'll have to spend a lot of effort grinding and polishing the ID when you're done welding.

 

[EdStainless]

Generally at walls 0.065" and thinner I see people weld as MM described, square ends and autonomous.
At 0.083" and heavier I more often see a slight bevel and filler used.
An alternate to both is to use weld rings, but that is another issue all together.
But if this is for hygienic service then the real issue is the quality of the ID surface, you must have 100% uniform penetration with minimal excess metal.

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P.E. Metallurgy, Plymouth Tube

 

[valmeidan]

its actually pipe at .109 thick. The ends are machined ferrules. The reason I used pipe is because I am also welding some half couplings on the pipe down the run. So how in my case would I get "100% uniform penetration with minimal excess metal" ?

 

[valmeidan]

So here is a pic of the drawing

 

[EdStainless]

First I assume that you are using an semi-automatic orbital welder.
Practice. You need the right current and speed balanced with wire feed rate.
A skilled welder can probably develop a protocol with 5-6 practice runs. These can just be pipe to pipe.
Is this stainless steel?
What grade? Look very carefully at the CMTRs, variation in S will have a large impact on metal fluidity and may require some compensation.
Try autogenous welds first, they are much easier.

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P.E. Metallurgy, Plymouth Tube

 

[valmeidan]

I wouldnt be doing the welding, and it is stainless 304. I guess my question is would I still weld it like I've shown in the pic or face to face butt weld in this case, and if it's a butt weld, would there be a gap between the two parts so they can weld, I am not sure how this process works, but it would be made out of China so I cant just walk in and check, but I want the drawings as accurate as possible

 

[valmeidan]

I am assuming because its thicker wall that adding the chamfer would be ok?

 

[DekDee]

valmeidan,
"but it would be made out of China so I cant just walk in and check, but I want the drawings as accurate as possible"

I have spent the past 15 years working in Quality Control in Asia ( China, Thailand, Vietnam, Malaysia and the Phillipines)
and I know if people purchase things from Asia they are doing it because it is cheap but they don't realise unless you have expatriate supervision you have no idea what sort of quality you are going to get.
All the cost savings from fabricating in Asia are eaten up pretty quickly when you have major rework required in the country of destination (eg. Bay Bridge in California).
Get on a plane and make sure you are getting what you ordered,
Cheers,
DD