Blue protective coating applied to pipe weld preps

[CMMehanicalWorks]

I am looking for the name of the blue protective coating that you apply to weld preps before welding to protect them. I ahve also seen it applied over the heat number stamps on piping as you cannot paint over these. I have googled the name "weld through primer" however the items are really only coming up for mig welding on car parts and they are spray cans. There must be some special type for applying to piping for the power industry. I have seen this used religiously by german piping companies however cannot seem to find the correct name or suppliers. Any help would be appreciated.

 

[CMMehanicalWorks]

I have attached an image of a pipe prep with the blue coating for anyone who is unsure what I am on about.

 

[IRstuff]

Are you sure it's not purple primer?

http://www.homedepot.com/p/Christy-...-for-PVC-CPVC-Case-of-24-RH-RHPP-HP/203597470

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[racookpe1978]

Almost certainly dye-chem blue:

Treat it like a laquer or enamel "temporary" varnish = OK for a short time to "sort of" delay - not even prevent rust, but only good for a few weeks indoors, 1-2 weeks outdoors. The solvent (remover) will remove the Dykem, but it WILL NOT "clean" the metal underneath adequately for welding. If you are going to weld (GTAW in particular) the prep area, you MUST grind the metal again just moments before welding. Never, of course, try to weld through the Dykem blue.

 

[racookpe1978]

IR stuff: That's a PVC product for gluing the plastic pipes.