Cold Metal Transfer (CMT) Welding in ASME Pressure Vessel 1

[IdanPV]

Hello all,

I need your assist with obtaining some information regarding CMT welding for ASME VIII-1 pressure vessel.
The vessel is 2mm in thickness and the joint design is groove weld.

Although the CMT process is just a controlled GMAW process, I wanted to make sure I am not missing something, as I didn't find any information regarding this process in ASME Section IX.
I've tried to find interpretation regarding this issue, but I didn't find any.

1. Is there anything unique regarding the tests and examination needed for this process?
2. Are there any restrictions in the Code for this kind of process for pressure vessels?

Your help will be much appreciated.

 

[XL83NL]

You're surely looking at the limits of UG-16, let alone UG-45. Your vessel doesn't have any nozzle?

Huub
- You never get what you expect, you only get what you inspect.

 

[IdanPV]

Hi XL83NL,
Thanks for your comment,

Per UG-16(b) - the minimum thickness shall be 1.5mm (exclusive of any corrosion allowance).
- Since the design pressure is very low, and the vessel radius is small, the minimum required thickness per UG-27 is less than 0.8mm.
- RAW Material is SA240-316L.
- Non-corrosive service.
I don't see any problem with UG-16.

Nozzles welds are per Figure UW-16.2 and nozzles thickness is determined by Table UW-16.1.

As I wrote, I am asking about groove welds only.

 

Although the CMT process is just a controlled GMAW process, I wanted to make sure I am not missing something

You're missing the heat. Heat is necessary for arc welding, and personally I like all my arcs to be hot.
CMT is up there with T.I.M.E. gas and recycled flux as goofy marketing concepts.

Know what you are buying. Fronius tries to do mechanically (think 'wear out') what Lincoln STT and Miller RMD do electronically and IMO better.

ASME Section IX should consider this as short-circuiting arc transfer mode, which is addressed by several essential and non-essential variables, the primary one affecting base metal thickness limits. Otherwise Code does not tell you what process to use, and the qualifications (procedure and performance) are not subject to any special tests.

Since this appears to be a FOAK, some rudimentary weld development work and welder training is advised.

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

 

[IdanPV]

Hi, ironic metallurgist,

That was a great post, thank you.

Can you please share more information regarding those sentences:
"CMT is up there with T.I.M.E. gas and recycled flux as goofy marketing concepts."

"Fronius tries to do mechanically (think 'wear out') what Lincoln STT and Miller RMD do electronically and IMO better."

Any of you has an experience using CMT welding in the pressure vessels industry?