The first question I have for you is, "What is the application?"

A53 pipe, when used in high temperature applications, are subject to graphitization when subjected to high temperature for long periods of time. For those applications, ASTM A106 Seamless CMn steel pipe is a better choice.

If the pipe is a structural member, subject to tension, seam welded pipe may by appropriate and there is no need to purchase the higher priced seamless pipe.

Any purchase order, for any material, should list the requirement in explicit detail. For instance, if seamless pipe is required, then the PO must specify "seamless only." If the purchaser requires material test reports for the actual product shipped, then the PO should include a requirement for Certified Material Test Reports. You only get what you pay for and then only when you are willing to enforce the contract requirements by independent testing. That being the case, the PO should also state what measures the purchaser is willing to take to enforce the requirements of the purchase order, i.e., independent material testing on a random sampling and refusal to pay for materials not in compliance with the PO requirements.

Al the bells and whistles will do little good if the purchaser orders the materials and has a production schedule that doesn't allow time for the independent testing and perhaps recognize the need to reject the material received. In short, it pays to purchase materials from reputable vendors.

Best regards - Al