Automatic welding machine for welding Nozzle to shell (Vessel in Vertical Position) 2

[Mateeng]

H Welding Folks,
Does anybody know any automatic welding machine vendor can perform nozzle to shell welding in position?
Actually there is CS vessel with nozzle to be removed and re-welded. This shall be done on in service vessel during turnover. The vessel is in vertical position and Nozzle to be welded to shell body. SAW process is not a recognized welding process. I'm thinking of automated GTAW, GMAW or FCAW. Any thoughts?

 

[DekDee]

Why do you want automated ?

 

[Mateeng]

Nozzle to shell weld (shell in vertical position).

 

Need more info - material, configuration, diameter, thickness.
Why do you insist on automatic?
One thing I can tell you in advance is that you just don't buy an automatic welder off the shelf and put it to work on a pressure boundary weld. Even bringing in a vendor can be fraught; I have seen a few disasters with that.

"Everyone is entitled to their own opinions, but they are not entitled to their own facts."

 

[dhengr]

Mateeng:
You probably aren’t going to automate that welding operation. For starters you’ve got three or four different welding positions around the nozzle when the vessel is standing vert. and the nozzle is horiz. And, while a good welder can deal with that, I’m not sure than any simple automation equipment can deal with that changing condition. If the welding was all downhand and following a nice nozzle surface, that would be an easy one to automate.

 

A human remains the most sophisticated adaptive welding machine ever devised.
(With the proviso that he/she turns up to work awake, sober, etc.)

"Everyone is entitled to their own opinions, but they are not entitled to their own facts."

 

[weldstan]

Contact some of the automatic welding manufacturers like Liburdi Dimetrics, Arc Machines, etc. Much money and time will be spent in developing the welding parameters for making the automatic weld, assuming there is a system available. Performing the work manually will be the cheapest and fastest method.

 

weldstan, you are right on.
I would add that 'automatic doesn't automatically mean automatic' if you get my drift (it's one of my rules for living as a WE).
Be aware these companies will rarely admit that manual welding might be a better approach. (Cf my comment of 30 Jul 18.)

"Everyone is entitled to their own opinions, but they are not entitled to their own facts."

 

[weldstan]

My former company performed hundreds of nozzle replacement repairs on vessels, both vertical and horizontal. Every one was done manually, sometimes with special techniques developed by me to limit distortion or limit heat input when welding on pressurized, in service vessels.

 

[Mateeng]

Dear Folks,
Thanks for all great responds.
The reason we approached automatic welding is we have to keep the interpass temperature not less than 500 C to avoid the PWHT as per weld engineer instruction. Manual welding facing 500 C is not easy for welders. We are looking to take the advantage of the Automatic welding machine to have less exposure for welder.
The subject is still under consideration by Client and Engineer.
Any suggestion rather than Automatic welding machine?
I will try to approach Liburdi Dimetrics and Arc Machines.
Regards

 

[DekDee]

Mateeng,
Find yourself a new Welding Engineer.
You have been given ridiculous advice and it could cost you big money.
Good luck.

 

[CWEng]

Usual preheat to avoid PWHT (for certain thicknesses) on carbon steel is 93C (200F) (for ASME Section VIII). Are you sure there wasn't a decimal place or conversion error. Otherwise, DekDee is correct.

 

[weldstan]

Your Welding Engineer is wrong. See NBIC Method 1 Alternatives to PWHT. His minimum interpass temp will lead to reduced strength and toughness in the weld.

 

500°C or 500°F?
I don't even know how you manage 500°C on a vessel.
Even 500°F is extreme.
Find a new welding engineer.
Wait ... are you and he possibly the same person?

"Everyone is entitled to their own opinions, but they are not entitled to their own facts."

 

[Mateeng]

Accept my apology. I did double check and the correct preheat is 500 F. It looks like there was a mistake in temperature unit.
It is much better condition 500 F compare to 500 C for manual welding. Now we should see how we can accommodate the welder to work with 500 F min preheat.
Any suggestion to help the welder welding in more comfortable situation.

 

[dhengr]

Buy 48” long welding rods.

 

[weldstan]

Preheat to 250 F with heating pads. But again do review Method 1 and adhere to it. That's all you need to do.

 

[Mateeng]

Thanks all for input to subject.