Plasma Arc Welding defects on weld line in stainless steel pipe

[Leo96]

Hi all, I am currently using a plasma welder with 96%Ar+4%H2 penetration gas, 100%Ar shielding gas and 100% N2 purging gas. My welder power was set to 351Amp, 29.4V with a welding nozzle 4.0mm.

And I noticed there are small lumps in wavy pattern on my weld line.

Can someone give me some advice whether this is due to purging gas or any other factor ?

Thanks guys.

 

[voipio]

Difficult to tell. Is the process manual or automatic? It looks automatic, but worth confirming. What is the welder being used, pipe thickness, surface preparation, steel grade, initial gap size, filler material? Some "before" pics would also be helpful.

 

[voipio]

First thoughts, based on the images, are that there is considerable material being expelled from the joint, and depositing on the surrounding internal wall of the pipe. This would suggest that the welder plasma velocity was too high, so gas pressure may be too high and/or the nozzle being used is too small. Double check the recommended parameters for the particular process, and ensure that the gas pressure gauges are reading correctly.