Min pipe size to butt weld 2

[Krausen]

Hello Gentlemen,
I'm sure that has been addressed somewhere in the annals of eng-tips.com, but I couldn't locate a thread on it. I have a simple question - Can I expect a contractor to successfully butt weld 1" SCH 80 CS pipe?

I'm working for a client that allows this in their piping specs, but I hesitate because I've never seen this allowed by anyone else before. I always understood it to be bad practice to buttweld any piping less than 2" size under normal circumstances.

Thanks!

Tolerance is the virtue of the man without convictions -GK Chesterton

 

[pennpiper]

Krausen,
You wrote,
"Can I expect a contractor to successfully butt weld 1" SCH 80 CS pipe?"
I say Yes! It can be done, but.
It depends on the type of plant/System/Commodity/NDE Requirements.
I worked on a Plant that required butt welded pipe on all systems, large and small.
I also worked on a plant that required Butt welded joints on all size piping of SS systems.
-
Before I spent the time designing those systems I took a Welding Class where I did butt welding on 1" and 3/4" piping. I had to pass the NDE and destructive testing of all my welds.
-
It can be done, but the down side is the complexity in doing the actual weld of those sizes (in the shop or in the field) and the cost of the NDE that was required.


Sometimes its possible to do all the right things and still get bad results

 

[DGrayPPD]

What pennpiper said

Although it may not be as common, it can be done. During my days with a pipe fabrication shop we also had clients that required piping under 2" to be butt welded.

ASME B16.9 covers sizes all the way down to 1/2" NPS.

 

[MickMc]

Agree with both pennpiper & CPPD, I have seen it done on many projects with my previous being stipulated buttweld for all Process Service irrespective of size. In my early days as a pipefitter I have fabricated and tack welded small bore butt welded piping in preparation for welding.

 

[uaepiping]

Dear in my experience, I have seen even 1/2" butt welded piping.
Depends upon the requirements of the service?

 

[moltenmetal]

Can you successfully butt-weld 1" sch80 piping? Absolutely. Agood welder will do a good job butt welding small lines, with a little practice. If you want decent quality, the root must be done GTAW.

If it's carbon steel, is there a service where it makes sense to butt-weld carbon steel lines that small? Doubtful. The situations do exist, but they're rare. Generally everything 2" and smaller in carbon steel is socket welded. It's cheaper to do, and much more likely to be done right.

In corrosion resistant materials, butt welding at small linesizes is done to reduce the number of crevices and improve drainage to improve corrosion resistance. It also saves money on fittings- you don't want to buy huge hastelloy forged socket-welded tees and elbows for instance. There's a great deal less material in a butt welding tee or elbow. It's the same reason one uses lap joint flange construction in exotic materials.

 

[Gator]

Also for SS small bore cryogenic service. Buttwelded, bended pipe for flexibility and less cooldown mass.

 

[gwalkerb]

No problems with buttwelding at that size, we do it all the time at my shop. One of the biggest concerns when you get into small bore piping and buttwelding is heat deformation leading to alignment issues. But as long as your contractor has experience with this size, and good welding procedures, they shouldn't have any issue building your piping.

 

[KevinNZ]

Thin wall and small diameter may need a new PQR, WPS and/or WQR, check the qualified range.

 

[weldstan]

While not normally required, it can and has been done many times. For austenitic stainless pipe, orbital, autogenous welding systems are weld diameters < 1/4". We have routinely manually butt welded 1/2" diameter tube and pipe in the field.

 

[davefitz]

I agree with weldstan, orbital welders were designed specifically for this purpose ( I think it originated to address welding aircraft hydraulic tubing), and there recent upgraded to include solid state controls has expanded their applicability to more than small diameter /thin wall pipes and tubes. .

"...when logic, and proportion, have fallen, sloppy dead..." Grace Slick

 

[moltenmetal]

We orbitally weld tubing, i.e. autogenous welding without filler metal. Welding 1" sch80 is going to need filler metal- that's no longer orbital welding per se, and more automated GMAW welding. The machinery does exist, but outside of very large production environment it would never pay back against a manual welder with some skill.