Bar Material

[steris]

Hi All,

We are working on a design for a Section VIII div 1 vessel that will need to have stiffening bars welded to a flat head in order achieve the desired working pressure. I am trying to source a bar specification that is available in square/rectangular shapes and cold rolled. Ideally, I would like to use A-108-1018 because it has the mechanical properties needed, is P1 (which is required), is available as cold rolled (which our welders prefer to hot rolled b/c there is no layer of mill scale), and is inexpensive. Here is the issue I am running into - QW-422 lists A-108-1018 as a weldable P1 material in bar form however UCS-23 does not list that as an allowable specification for a Section VIII pressure part. My questions are:

1) Is there a material specification I should look at that would allow 1018 CW bar to be welded onto a Section VIII vessel as a pressure part?
2) Aside from cutting out bar from plate or using A-36, are there any other bar specifications that would be appropriate for this application?

Thanks for the help!

-Steris

 

[GenB]

Yes there are other approved bars look in sect D for specs and allowed materials' why not A36 in lieu of 1018? Cold rolled is not even allowed.

 

[SnTMan]

What's wrong with SA-36? Widely availabe, widely used.

Regards,

Mike

 

[steris]

Hi GenB - Thanks for the info! I actually did not realize that cold rolled was not allowed. Is this because of the effects welding would have on it's mechanical properties? Is there a reference to this or is this "just known"?

The welders had asked me to look at grades other than SA-36 mainly because we grind off all of the mill scale prior to welding and this takes a significant amount of time/effort. The hope was that if we went to a cold rolled spec, the mill scale would not be present and weld prep would be much quicker. We currently use SA-36 for this application - I was just exploring other alternatives that may be appropriate.

 

[SnTMan]

steris, your alternative is to get out Sec II, Part D, see what bar specs are permitted, consult those specs, and pick one.

Regards,

Mike

 

[fegenbush]

steris,

In my opinion, a proper weld procedure will always require the base metal be cleaned prior to welding. In the case of HRAP (Hot Rolled And Pickled) plate and shape, this involves grinding or blasting of the mill scale. However, cold rolled steel is not free from surface contamination, and must also be cleaned. Often there is oil present to prevent surface rust from forming.

It is permissible to use cold rolled steel so long as the steel meets the required ASME specifications (see ASME SA-1008)

If removal of mill scale is an economic concern and your facility does not perform sufficient quantity to justify an in-house blasting operation, consider sending the raw materials to a contractor specializing in such services. The cost can be quite competitive.