[Welderhayden]

Hi all,

Ive got trouble at work trying to repair a water cooled panel structure that transports off gases from the electric arc steelmaking process. Current consus is to grind out as best you can and weld with 7016 rods but within 3 days the repairs are cracked through the centre again, never in the parent metal. So my question is, has anyone got experience using 312 stainless to repair cracks in a heavy industrial setting such as steelmaking? My only thought behind it is the high elongation % and tensile strength... Any help greatly appreciated

[Coldman]

What parent metal are you trying to repair?


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[Welderhayden]

severely metal fatigued schedule 160 2- 1/2 inch pipe. Being on a EAF it is constantly heating and cooling " relatively speaking" so this is why we believe it eventually starts cracking. From new to the first time cracks appear is about 12-16 months of service life. (Ofcourse they are trying to squeeze more life out of them however possible)

[Coldman]

Grinding out as best you can may not be good enough in this instance. The repair needs to be a full penetration vee butt weld with reinforcement both inside and out. Your 7016 rods should do the job if used new out of the pack or out of an oven.
I suspect you don’t have full penetration in your repair leaving a linear defect inside which then continues to propagate the crack.


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[Welderhayden]

Unfortuneately even full pen vee butt welds havnt cut it for me

[Coldman]

It may be worthwhile also for xray or ultrasonic inspection of the zone to identify hidden cracks that may cause further failures


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[Welderhayden]

So you dont rate 312 stainless rods for repairs like this?

[Coldman]

312 does an amazing job but may not be of help if there are underlying defects present. Don’t mean to discourage you just caution to get all the facts and use the best procedures before relying on a miracle rod.
After all you haven’t given us details of your repair prep or procedure and no pics either so there is some guessing going on


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[Poland308]

Pre heat and post heat are important too. Especially on thick metal that’s heat stressed. You can get an inspection company to come and check things out with a mag flux check. It’s non destructive, fast, and will even show subsurface cracks.