Need more on D1.1 prequalified materials

Date 02-12-2002 14:39

All of the specifications that you reference are for mechanical tubing. As such there is no tensile strength, yield strength, and impact property requirements specified. The specifications you list are basically just a chemistry specification.
When you talk about D1.1 you are talking materials used to support calculated design loads. How you design anything when you have no minimum specified yield strength or tensile strength? The only time I have seen the type of material that you listed used in structural applications was when we stuck em in the ground, filled them with concrete and used them as pipe bollards to protect a loading dock.
I do not believe that you will ever see your tubing specifications used for prequalified welding procedures. Along with joint design, you need to match filler metal to base metal, how do you do that when you don't even know the minimum specified strength of the materials?

By kpauley (*)

Date 02-12-2002 16:20

Thank-you, Mr. Johnson, my sentiments exactly!

By Marv Date 02-13-2002 04:23

Hold on! A106 is not mechanical tubing and besides, I have a reference book right in front of me that lists the Ultimate Tensile for A513 @ 70K and yield @ 60K. Typical mechanical properties can be obtained for practically all commercial types and grades of steel. I'm not a structural engineer, I just have the privilage of coming up with welding procedures for various applications where structural engineers have already decided on material types and grades without consideration of welding and have plugged in the generic phrase "All welding to conform to AWS D1.1, latest edition". Reading the descriptions out of a steel supply reference book of the various materials that I listed repeatedly states "structural" application. By the way, I think you could find something cheaper to make bollards out of. (I get the point) Thanks for your input. I agree with the fact that these materials will most likely not be considered for prequalified status. It's PQR time.

By DGXL

Date 02-13-2002 16:43

Marv,
I noticed the ASTM specifications in your post and looked these up in my ASTM standards. The A106 and 513 standards are not listed under structural-steels. These are listed in two different ASTM volumes (01.04 for structural steel and 01.01 for steel pipe, tube and fittings). The above standards are not classified as structural by ASTM regardless of the yeild/tensile values.

Dimensional properties may vary as well (i.e: the radii of corners on square/rectangle shapes) compared to those of non-structurally approved materials. The elasitc/plastic behavior, brittle fracture concerns due to manufacturing processes, all of these may affect the performance of the material. I do know many materials with the same tensile/yeild propeties do not perform identically.

I also had a client who used some "non-standard" structural materials (and weld configurations) and I was constantly qualifying welders and procedures to AWS B2.1-XX. I didn't mind as it was always a learning experience for myself and others. This specification was very handy for these types of welds and materials.

With regards to your original post, I don't know why more materials are not specified. Availability and cost may be other factors as to what is prequalified and what is not.

By Marv Date 02-13-2002 20:24

Thank you all for your response. I have enough information to satisfy my situation at hand. All the information was helpful especially the last post. This is the first time (over the last few days) I've used this forum and I find the results positive. If there is any one thing that those of us in the welding industry can agree upon is the fact that welding is much more complex than those on the outside can imagine. I've been involved in welding for over 30 years in one capacity or another and obviously I don't have all the answers. Thank you all for your help. I'll be around until the "new" wears off.

By R. Johnson (**)

Date 02-14-2002 22:35

ASTM A512 MT1010, ASTM A513 MT1020, ASTM A519 Gr 1018 and ASTM A120
These are the specifications that you had posted in your February 7th post. I found no reference to A106 and as such my comments were not directed to that specification. As for A513 the only time you have tensile strength and hardness specified is when you specify supplemental requirement S5 in your purchase order and MT1020 shows an ultimate tensile strength of 52 ksi with an elongation of 12% and a yield strength of 38. Of course I am looking at ASTM A513-97a which might not be the latest revision.

By Marv Date 02-15-2002 05:32

You're right. I got my 120 and 106 confused along with everything else. I have taken all of the feedback and passed it along to my good friends in the structural engineering and design department now we can move on to the next problem. Thanks again for the feedback. By the way for the rest of the story...The A513 (1-1/2 x 1/4 wall, [approx.]) was welded into a piece of A500 (1/4 x 2 x 6) tubing for the primary purpose of providing a sleeve for a 1" dia. bolt, and also providing a hinge point. The material selection was based solely on convenience of size since it could be cut to length and welded in without machining providing an adequate fit. Everything else on the whole part was designed with prequalified materials and things were ok until an observant QA guy picked up on the A513 in the materials block. Now you all know how this came about. It was debated as to whether or not the part had any real "structural" purpose. However, since it was welded in and became part of the structure; the QA guy was right and we had made a mistake. We have replaced the "sleeve" with some "prequalified" material that has been machined to size.