Pressure Vessel 2-1/4 Cr 1 Mo Clad w/ 321ss welding issues

[akvtech]

A vendor declined to bid on 2-1/4 Cr vessel because they say they've had too many cracking issues in the past. Does anyone have experience with this material 1" to 3" thick? Issues such as weldability, cracking, HIC, delayed HIC, Pre-heat sensitivity, PWHT issues etc... If so what was your key to success or solving any cracking issues?
The vessel in question would be 1-3/4"thick clad with 321ss.
Thanks

 

[Duwe6]

Some of the problem could be HIC, but most of the vendor's problem is almost certainly preheat - interpass - delay of PWHT issues.

2¼ Cr is welded regularly and reliaby by good vessel shops. The preheat HAS to be maintained throughout the making of each weld, or a 1-hour oer inch H2 bakeout at 600°F has to be performed prior to allowing it to cool down to room temp. The simple solution is to use a PWHT company to supply the preheat, using their thermocouples to control max interpass temperature as needed. And weld each joint around-the-clock from start to finish.

Using a oxy-fuel 'rosebud' torch for preheat, applying a half-hearted preheat, and taking a long lunch prior to having deposited at least 1/2-inch *thickness* of weld will guarantee you severe cracking issues.

 

[akvtech]

Thanks Duwe6...they have to use gas manifolds when using SAW on large vessels. My guess is they don't want the headache of strict pre-heat controls

 

[Guest102023]

All good points made by Duwe6.

I would only add that electric resistance preheating should not just be recommended, but mandatory. Consider radiant gas heaters for really thick sections (>3").