WPS and SA-193 B-7 Bolt weled to shell plate 1

[charpyboy50]

SA 193 is not list in Section IX.Does a seperate PQR need tobe generated,or is there another bar stock material per section II part(A) which i can certified with a different P# provided code cal are acceptable.

 

[metengr]

charpyboy50;
That is right, it is not listed because it is not recommended to be welded.

 

[CodeRef]

SA-193 Grade B7 has carbon content greater than that allowed by UCS(5)(c) which states the following:

(c) Carbon or low alloy steel having a carbon content
of more than 0.35% by heat analysis shall not be used in
welded construction or be shaped by oxygen cutting.

SA-193 specification allows the carbon content to be in the range of 0.37% to 0.49% therefore, not acceptble for welded construction.

There are three kinds of people in this world; those who can Google and those who can't.

 

[metengr]

I am going to dive into this a little deeper. There is really more to this than just the general blanket statement in Section VIII, Div 1, UCS 5(c) as mentioned by CodeJackal.

Actually, when you read all of the Notes in Table I of the ASME SA 193 specification, Grades B7 and B7M material can technically vary down in 0.35% or even 0.28% respectively, a leaner carbon version of 41XX if you will, because of the second column in Table 1, which is the Product variation by over and under the specified range (0.02%), and bar size, if the tensile properties meet Table 2 requirements (see Note 4). If you review ASME Section II, Part D, Table 3 you will notice there is no Note W1 for Grade B7 or even Grade B7M for this very reason.

4140 alloy (UNS G41400) steel is not permitted to be welded, brazed or subject to thermal cutting based on Section II, Part D, Table 3, Note W1, for SA 574 bolting material. This applies across the Code book sections that reference Table 3 Bolting material in Section II, Part D. The UNS G41400 steel can indeed fall under Grade B7, and UCS-5 (c) would be applicable like using Note W1.

So, what does this mean, well if you have a version of SA 193 Grade B7 or B7M that is lighter in carbon content than 0.35% and can meet the strength requirements in Table 2, yes, you can weld this material. However, as I stated above I used the words "NOT RECOMMENDED" because of good engineering practice. The heat from welding will alter the original mechanical properties for this bolting material.

 

[CodeRef]

metengr,

That is a good detailed explanation. I had not thought to look at Table 3 of Section II Part D and tie it to Note W1. I will have to keep that in mind.

I did notice that the product variation of +/- 0.02% was for "product analysis" and not "heat analysis", which leads to the following question and answer:

Q. When would a VIII-1 Certificate Holder perform product analysis on bolts/studs or nuts?
A. When they are welding to it, or if it is raw material that is not supplied in product form to a bolting/stud or nut specification.

Do you agree?

I am not familiar with any Bolts/Studs or Nuts that would inherently have low carbon content in the range below 0.35% carbon by "heat analysis".

If there is, then we can answer charpyboys next question.

Am I correct to say that high carbon content (typically above 0.35%) for Bolts/Studs and Nuts is directly proportional to their desired high tensile strength?




There are three kinds of people in this world; those who can Google and those who can't.

 

[metengr]

CodeJackal;

Q. When would a VIII-1 Certificate Holder perform product analysis on bolts/studs or nuts?
A. When they are welding to it, or if it is raw material that is not supplied in product form to a bolting/stud or nut specification.

Do you agree?

Yes

Am I correct to say that high carbon content (typically above 0.35%) for Bolts/Studs and Nuts is directly proportional to their desired high tensile strength?

Yes