If you decide to do this, how would you know for certain what pipe you are actually dealing with ("ostensibly grade 40 and 80")?

Well, I am assuming at this point that they have some type of bill of lading or certification from the seller. They have worked with other structural engineers. One has retired. His general notes, which I saw on several of his projects for them, state the pipe spec - grade, type, yield, and I am assuming that he did not make that up, but had documentation that I would have access to, should I decide to go forward. I suppose one could make the argument that if the pipe is spec'cd on the drawing it is the fabricator who is responsible for meeting the spec, but I tend to believe this is analysis rather than design, and if I cannot determine what the materials they are using are, then I will have to decline to be involved. Although I am certain that the design of the TRUSS is feasible and reasonable, I am less sure that the processas and materials are verifiable. But on the other hand if I turn him down, I want to be able to tell him why as well, for his sake if not for mine. Not that he will listen.

When you state grade 40 and 80, are you referring to schedule 40 and 80?

I would not stamp anything salvaged, as a permanent structure.  Then the audacity for someone to ask you to provide calculations, obviously they have no idea where to draw the line.  What happens when it falls down due to some unforeseen reason? Do you think he or the insurance companies involved will be on your side?  You put a lot of trust in this scrap metal.

Just my humble two cents worth.

Regards

VOD

When welding this pipe, toxic fumes may become present. This may be in violation of OSHA or the EPA. Testing should be done prior to use and especially welding to protect the health workers.

Actually, after contacting the AISC tip line, and finding out that there are indeed test proceedures to determine the quality and suitability of the pipe that COULD be done, and a lot of consideration about the lack of understanding by the potential client about the requirements of the code and materials handling and what the drawings would really mean, and his insistence on providing his potential client with half a job, I declined the contract by overpricing my services and stating that we did not feel that our requirements for testing and quality control woud meet his needs...never heard back. And am just as glad. But I am getting awful tired of turning down jobs that just should not even cme up. AISC by the way did have some good info should anyone else ever run into this or a similar issue.The statement theymade to me is that this type ofg material is NOT typically "scrap metal", and often has not ever been used for anything. If it has been used to transport product, it must be cleaned and the  fume and welding quality are major issues. And believe me everything about this operation appeared to me to be in violation of EPA, OSHA, AISC, AWS and any other agency you can think of. I did not have a lot of trust in a contractor who was flying by the seat of his pants and wanted to fly by the seat of mine. But thanks for your input and consideration.

All:   

Been there, done that.  Not uncommon!  Consider more than wall thickness (S/40 or S/80 or whatever).  Much production tubing / pipe has experienced some small amount of corrosion, internal & external; thus, use thinist recorded, or require UT testing and rejection of anything below a threshold value.  Consider grade too; if unknown, either have it tested or assume lowest available (Grade A if line pipe, or J-55 if downhole tubing).  Consider wind loading per ASCE 7-98.  Though one can calculate forces and moments and shears, etc., do not forget to consider wind bracing, both while structure is being built and during use.