Weldable primer?

[ted655]

Is there a primer for unprotected (no shelter, outside construction,& storage) steel? Something that can be welded over as work progresses. Thanks

[Bergalia]

From my limited experience, I'd say NO. Not if you want a good clean weld. Any impurity affects the quality and soundness of the fusion. But a few passes with an angle grinder should remove any trace of rust.
But check out MikeJohns' note on alaskatrawler under Metal Boat Building. He sounds a sensible chap - even though he's gone for steel rather than timber...

[ted655]

While reading a Bruce Roberts page on steel fab, it was briefly mentioned his kits came with primered pcs that could be directly welded. I thought maybe there was something new. I was taught also, about weld purity. If ever you don't want a pinhole, it is in a hull weld!

[D'ARTOIS]

Yes there are so called "weldingprimers" that are used by the steelsheet suppliers in order to prevent untimely rust and also simplifying welding. Another advantage is that those sheets are already shotblasted and the mill scale is already removed.
You can work your sheets now at all ease, the sheets are no subject to corrosion as long as the weldingprimer is not damaged.
All professional shipyards are using these pre-treated sheets.

[ted655]

Is there a name by which it is known or does each supplier have its own version? What about shapes & flat stock? Thanks

[alaskatrawler]

The weld through primer I am most familiar with is by international coatings it is called Nippe Ceramo. It is grey and goes on very thin it has only a small amount of zinc and with a proper coat will not bloom rust for about 6 months providing the coating is not damaged.

[ted655]

OK! Thanks.

[alaskatrawler]

The product # is Interplate 937 Nippe Ceramo.

[Kythoni]

another product, which i have used to great result is "Sigmaweld MC". It can be overcoated and really seems to work. This is the stuff that Bruce Roberts uses for his kits, in his case it is applied at the mill.

Give me a PM if you want more details.

Cheers

PS Its also Lloyds approved for shipbuilding and a specific marine product.

[ted655]

I had trouble loading their data sheets. Can you tell me, is this also a 2 part primer? Thanks

[Kythoni]

Yes, it is. Datasheet attached.

[boltonprofiles]

Hello Ted,

This reply may be a bit late but I just thought I would let you know what we did for a customer of ours from Guilford, UK.
We completed another Bruce Roberts Design kit, a Spray 460c, cut from quality British Steel which was completely untreated at this stage.
We then had all the pieces, the complete kit, shotblasted and primed with weld through primer which I can supply the name of if you still need it. This primer is used I believe by Corus, British Steel in the same application. This of course meant that the profiles were all sealed - edges and all.
I do not know technically how this will affect the welds but it worked for him.

Don't forget using this method obviously means that each profile will not be individually marked as it is not practical to do so.

I would ask Bergalia who replied to your thread as well or WynandN who obviously know their technical stuff.

http://www.boltonprofiles.com
Paul.

[ted655]

Thank you very much/ Ted

[boltonprofiles]

Hello Ted,

Again, probably too late for you, but paint supplier we use who is worldwide is Leigh's Paints, Tower Works, Kestor Street, Bolton. BL22AL.
We use the Metaguard two pack epoxy weld through primers in red/grey.
Their website - http://www.wjleigh.co.uk

[boltonprofiles]

Try http://www.wjleigh.co.uk or http://www.sigmacoatings.com