Weldable Primer

Date 09-09-2011 17:15

Hi,
I had the chance to read lots of previous postings on this subject, so I do realize that it is a very touchy subject...
The situation: we are receiving for many years parts from China that are protected against corrosion with a "weldable primer". The welders performing work with these parts have to use proper breathing equipment to protect themselves.
The problem: currently we are investigating alternative suppliers, and they are offering alternative "weldable primers" instead the currently used and proven.
The questions:
1. Are there any standards, codes that regulate these "weldable primers"?
2. How can we ensure that the supplied "weldable primers" are really what they supposed to be?
3. Is there any "base line" requirement or method to allow for comparison and decision making: Yes / No?

The bottom line is how can we ensure that the protective primer is really weldable?

Thank you in advance,
George

By Lawrence (*****)

Date 09-09-2011 18:03

Not speaking about compliance here... Just your bottom line question. Others will be able to fill in on compliance.

"The bottom line is how can we ensure that the protective primer is really weldable?"

Run a PQR/s with the primer/s in question.

Same brand/s of primer

Same thickness of application.

The PQR will tell you if the primer is weldabe.

By G.S.Crisi (****)

Date 09-09-2011 18:15

May I ask a curious question? What's a "weldable primer"?
For me, the word "primer" designates a paint, usually but not always zinc rich, that's applied to a steel surface to prevent it from rusting until the final paint is applied.
Giovanni S. Crisi
Sao Paulo - Brazil

By George

Date 09-09-2011 19:09

Hi Giovanni,

As I understand it, the basic idea is to "leave" the primer as is (meaning not to perform any additional cleaning operation) on the item, and just weld the other part directly to it, without having any defects (cracks, porosity, etc.).
3M has a primer called "Mar-Hyde Weld-Thru Primer", so this is the only reference that I have at this point...

Regards,
George

By defaced (**)

Date 09-09-2011 21:20

Yep. It's used alot in ship yards where plate is cut and may sit on a hardstand for a while before being welded. Between cutting and welding, the plates are covered with "weldable" primer so to prevent rust. "Weldable" is in quotation marks because alot of guys who have worked with the stuff don't consider it weldable.

By 99205

Date 09-09-2011 18:33

I think the EPA-VOC Standards would regulate that type of stuff. I've used this before and it is pretty good. http://www.eastwood.com/bloxide-weldable-primer-gallon.html?srccode=ga110030

By George

Date 09-09-2011 19:10

Thank you all for your comments and suggestions.

Best regards,
George

By 803056

Date 09-09-2011 20:37 Edited 09-10-2011 10:13

You might want to read AWS D3.9 Specification for Classification of Weld-through Paint Primers.

I have a very low opinion on the entire document. It rings as true as buying a Rolex watch from a street vendor.

“Hey buddy; you want a buy a watch?” However, in this case it is more like, “Hey buddy, you want buy some weldable paint primer? Guaranteed not to poison your welders.”

Weldable or not, here’s some reading material you might want to look over. Just because you can weld over the paint doesn’t mean it is a good idea to do so. The welder’s health must be considered and if you are getting painted materials from China, there is a good bet there are some heavy metals used in the pigment.

http://www.oshainfo.gatech.edu/welding-general.pdf

http://www.cpwr.com/hazpdfs/kfwelding.pdf

http://www.lhsfna.org/index.cfm?objectID=5CE2DA3D-D56F-E6FA-9C537BAF0D35BC04

Al

By joe pirie (***)

Date 09-10-2011 10:57

I believe AWSD1.1 calls for the steel to be welded to be free from rust,scale grease, oil, paint etc.
as far as im concerned the shop i m working at can put on all THE WELDABLE PRIMER they want
for field connections as specified on the approved plans. If im in the field the welders will be cleaning all this crap off
prior to welding . The shop im currently in uses a spray can that says weldable primer on it and its quite expensive
once dry it looks like gray primer out of a 99 cent spray can. out in the field how do you know what they sprayed
it with?

By 803056

Date 09-10-2011 12:00

Hello Joe;

I understand where you are coming from Joe. There are no cleaning requirements in D1.1-2010, Clause 3. However, Clause 5.15 contains language that allows a thin rust-inhibitive coating (primer paint?).

My position is that while Clause 5.15 permits the primer, it isn't necessarily prequalified just because Clause 5 permits it. A good example of a similar situation permitted by Clause 5, but where the requirements of prequalification are not met would be for groove welds made with backing. Clause 5.10 allows for the use of copper, flux, glass tape, ceramic, or steel backing, but only the use of steel backing is prequalified (ref. 3. 13.3). If the contractor wishs to qualify the procedure with the primer intact, he is free to do so. If the procedure passes, he is free to use the primer that will be welded in production.

Best regards - Al

By George

Date 09-13-2011 18:56

Hi Al,

Thank you very much for all these additional materials.
Best regards,
George

By jrw159

Date 09-11-2011 15:59

George,
Here is a thread you may find interesting.

http://www.aws.org/cgi-bin/mwf/topic_show.pl?pid=152311;hl=welding%20fume%20analysis

jrw159

By joe pirie (***)

Date 09-11-2011 18:28

i only have the 2008 edition of d1.1 thankyou for setting me straight joe

By George

Date 09-13-2011 18:53

Thank you very much!