It has absolutly nothing to do with the requirments in Canada and has everything to do with the requirments in your purchase order and contract.. It's really that simple.
If you don't agree upon a requirement as the OEM or their representative, the buck for poor workmanship will probably fall on your doorstep.
As already mentioned... The disturbing responses you recieved from the contractor are probably exactly the same disturbing response you would get from an American contractor if you did not settle on a quality program and requiremts at the outset of your dealings.
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Discovering your own quality requirements and those written into your purchase order and contract doccumentation is the very first step you need to take... You can offer no righteous criticisim without a written level of quality and inspection expectations.
I know this sounds harsh... But it is beginning to sound like you are simply getting the usual response from the low bidder.
Edit: You might want to look specifically in your contract for language referring to
AWS D15.1 Railroad Welding Specification for Cars and Locomotiveshttp://pubs.aws.org/download/previews/Pages%20from%20D15.1-D15.1M-2012.pdfThis may also help... But if your product line is delivered to the U.S. it's doubtful
http://eng.cwbgroup.org/Documents/0350e-ApplicationForCertificationtoW1781.pdfEdit Edit:
The attached form is a copy from the CWB website.. Also might be useful in future bid work