Final answer:
The company employing the welder is typically responsible for ensuring that welders identification cards or copies are available as proof of valid qualification. The employer maintains this as part of compliance measures, with the support of the welding supervisor.
Step-by-step explanation:
In the context of professional welding, the responsibility for ensuring that welders identification cards or copies thereof are available as proof of a welder's valid qualification typically falls on the company employing the welder. The company must maintain records that show all of their welders have the appropriate qualifications to meet job specifications and regulatory requirements. This is not only a matter of ensuring quality and safety in welded products but also a compliance matter to prevent legal and financial liabilities.
While the welder themselves must ensure they are qualified for the tasks they perform, the overarching responsibility for record-keeping and validation often rests with the employer. In collaboration, the welding supervisor may assist in this process, as they oversee the work and can keep track of the welders' qualifications and their expiration dates.