Steel structures in Canada are usually NOT welded in accordance with ASME IX with NDT to ASME V. Structures, whether they are used in buildings or as non-building structures (that's what we'd typically consider a "skid" to be, if it has grating and guardrail or handrail), are usually welded and inspected in accordance with the requirements of the Canadian Welding Bureau (CWB) and the associated CSA standards.
The client listed CSA in their list of "relevant standards". They are a client who is buying both design AND fabrication services by the sound of it. They are not, or should not be, expected to be knowledgeable enough when ordering something like this to identify just exactly WHICH rules, codes and standards apply to that structure in their jurisdiction. If this project is going to be installed in Canada, and especially if it will support people above grade or support things that, should they fall, might kill or injure people at grade, you're on the hook to get your company and its welders into compliance with CSA W47.1. Merely having welders and procedures qualified under ASME IX is insufficient, though it will be a good start for sure.
In some instances, compliance with AWS D1.1 may be acceptable, but there may be additional requirements for inspections etc. required by the Canadian jurisdiction. I've never bought a non-building structure for a Canadian installation fabricated outside Canada, so I just don't know- others may chime in.