You need to review the ASTM A513 standard to see what you are dealing with.

The standard allows for the use of anything from a low carbon steel to an alloy steel with tensile strengths ranging from 32 ksi up to 105 ksi depending on the base metal alloy and the state of heat treatment.

The diameter can be as small as 1/2 inch or as large as 15 inch and the wall thickness can range from 0.035 inch to 0.650 inch.

This appears to be a "catch all" specification for a wide range of mechanical tubing where the mechanical properties are specified as supplementary requirements, i.e., they only have to be met if the customer specifies the material, alloy chemistry, heat treatment, etc. It is for that reason that it is most likely not included in AWS D1.1 as a prequalified base metal. The alloy chemistry can vary from that of AISI 1008 to 4140 and a few other NiCrMo varieties thrown in for good measure. Even if you order the material as low carbon steel, the vendor can provide you with alloys of varying carbon content from 0.05% to 0.25% with varying mechanical properties.

If you narrow the purchasing requirements to specific alloy chemistry, state of heat treatment, hot or cold formed, and a minimum/maximum range of the mechanical properties you could qualify the procedure based on the new purchasing requirements. Without the supplementary requirements, you have no reasonable idea of what you are being supplied with by your vendor.

Your first step to finding a solution is to purchase a copy of the ASTM standard, get together with your engineering and purchasing people to find out what is being purchased, and how it is being specified. I would also check to see how your receiving inspection people are checking the material for conformance to the purchasing requirements. 

Once you nail down the alloy and the required mechanical properties of the material used to fabricate the welded pipe, you can qualify the procedure using the same alloy in plate form subject to the same heat treatment, etc. However, there is a catch! You would have to make sure the purchase orders include all the required information for the plate material you use to qualify the procedure and then use the same requirements when purchasing the tube material. Your welding procedure would not include a wide range of materials used for the fabricated welded pipe because the materials used are based on AISI requirements (no mechanical properties specified).

None of this is going to make you popular with the purchasing department because you will no doubt quadruple the cost of the mechanical tubing and you will have a short list of vendors that can provide the material you require.

Best regards -  Al

Logan,

First, look at Clause 1.2 in D1.1. (Second sentence) "The code may be suitable to govern structural fabrications outside the scope of the intended purpose.  However, the Engineer should evaluate such suitability," 

Second, second paragraph of D1.3 Clause 1.1 "When used in conjunction with AWS D1.1"

There is a merging of the two on items that need to be addressed by the Engineer.  D1.3 is intended mainly to address the matter of thinner materials that also need to be handled within the scope of D1.1.

Your main problem will be in addressing the composition of the material in use as Al went into.

From there, you should be able to address a blending of the codes with the approval of an Engineer to deal with the thickness issue.  BUT, the bottom line is that the customer or his representative (an Engineer) will be calling out the specs for any one particular job.  The next job may get called out differently. 

To have something in place so you can say your shop fabricator/welders are qualified to weld the rails would be a judgment call by your company.  I would qualify my people to some of the pipe tests from D1.1 as well as having some qualifications to D1.3.  When the customer specifies that those are not good enough you will have to develope a procedure that satisfies them.  Then, get your people qualified to THAT procedure. 

When dealing with railing, most of my customers have always been satisfied with ANY D1.1 certification.  Most of your print General Notes sections are only going to specify that 'all welders are currently qualified to AWS D1.1'.  And most inspections notes make the same condition, 'Inspections to be done to AWS D1.1'.  This is not always the case, but most of the time.

This is one of those items that falls between some of the cracks depending upon how different engineers look at rails.  Each job will present it's own conditions as to how they will be fabricated.  Exact usage of the rails will also effect how they are handled: barriers around a parking lot, fall protection, industrial, residential, etc.

Have a Great Day,  Brent

Agreeing completely with Al and Brent.  But I'll throw something else in the pot as well.  Have you considered B2.1 as a controlling specification for the qualification of your WPS?  After all, that's what B2.1 was written for.  One consistent rule in all qualifications is to run e sufficient quantity of coupons to obtain the required number of test specimens.  In the case of the varying chemistry of A513 steels, the first step would be to determine what size, type and grade will be used in production.  Obtain some of that same material (preferably from the same heat as the production material itself) and use it to qualify your procedures.  If I were doing this, I would definitely have the engineer specify type and grade of steel.  As Al indicated, you can't do much without that.  Good luck.