×
INTELLIGENT WORK FORUMS
FOR ENGINEERING PROFESSIONALS

Log In

Come Join Us!

Are you an
Engineering professional?
Join Eng-Tips Forums!
  • Talk With Other Members
  • Be Notified Of Responses
    To Your Posts
  • Keyword Search
  • One-Click Access To Your
    Favorite Forums
  • Automated Signatures
    On Your Posts
  • Best Of All, It's Free!
  • Students Click Here

*Eng-Tips's functionality depends on members receiving e-mail. By joining you are opting in to receive e-mail.

Posting Guidelines

Promoting, selling, recruiting, coursework and thesis posting is forbidden.

Students Click Here

Jobs

SA-182F316L low stress material

SA-182F316L low stress material

SA-182F316L low stress material

(OP)
While designing a kettle type heat exchanger, I am having a confusion if I should use low stress material for body body flange and tube sheet.
Also which are the scenario where low stress material should be used, I have read note G5, still having a curiosity to know in actual industry where low stress material is preferred and where high stress material can be used.

RE: SA-182F316L low stress material

Steve.sw90, generally lower allowables are used at gasketed joints. Body flanges, flat covers, tubesheets if gasketed, etc. Otherwise higher allowables are used.

Regards,

Mike

The problem with sloppy work is that the supply FAR EXCEEDS the demand

RE: SA-182F316L low stress material

(OP)
SnTMan, what if I go with higher allowable stress, is it a mandatory requirement for gasketed joint of a U-stamp vessel.

RE: SA-182F316L low stress material

(OP)
Also in that case I believe shell to which flange is welded should also be made low stress material for e.g. Sa-240 316L.
For me deformation in shell during operation could cause more damage to flange connection.

RE: SA-182F316L low stress material

Steve.sw90, use of lower allowables is not mandated by Sec VIII, Div. 1, as far as I know. It is fairly common for client specs to required it and I have seen a few that require use of lower allowables for all materials that have it, normally austenitic stainless.

Aside from client specs it is your choice what to use where, but use of lower allowables for flanges, etc. and higher allowables for everything else is very common.

I will add that if a gasketed joint leaks due to distortion of the members of the joint, you are done. Not repairable.

Regards,

Mike

The problem with sloppy work is that the supply FAR EXCEEDS the demand

RE: SA-182F316L low stress material

(OP)
In such case will it be ok to check for material with low stress at operating pressure and temperature, and high strength material used for design pressure and temperature.

RE: SA-182F316L low stress material

The thread title had me thinking that the OP is interpreting the "L" in "316L" as "low stress". I always thought the "L" refers to "lower carbon content" (which may result in lower mechanical strength). We used to specify the "L" grades only when needed for improved corrosion resistance?

Regarding the two lines with stress values per st/st grade (ASME II Part D tables): We used the lower values only where it is critical to minimize deflection (e.g. flanged/gasketed joints) or when specified by clients.

I find the last question by the OP an interesting one as I have not seen this approach before. It could result in a slight reduction in flange thickness? Whether or not it would be worth the risk of possible sealing issues during testing is debatable.

RE: SA-182F316L low stress material

(OP)
No confusion regarding L, it stands for low carbon content improving weld quality of SS.
anything above operating condition should be incidental, causing material exposed to higher tension for short period of time at certain operating temperature.

or else we can multiply operating condition with certain factor for eg. 1.25 or 1.15 and check design based on amplified values.

RE: SA-182F316L low stress material

Steve.sw90, aside from client specs, you are not mandated to use lower allowables. If you are feeling lucky, go for it.

As an alternate approach, why not used dual certified material, and then use the lower allowables of straight grade (non-L) material?

Regards,

Mike

The problem with sloppy work is that the supply FAR EXCEEDS the demand

RE: SA-182F316L low stress material

(OP)
Really Good Idea Mike, thank you.

RE: SA-182F316L low stress material

(OP)
Dear mike,

On further discussion regarding this with our AI, conclusion is as below,

These different stress values have been RECOMMENDED for SS materials where bending stresses are predominant.
I feel the manufacturer should have good knowledge and strong justification for use of higher allowable stress where bending stresses are governing. He may demonstrate this by performing alternate calculations.

Regards,
Stephen

Red Flag This Post

Please let us know here why this post is inappropriate. Reasons such as off-topic, duplicates, flames, illegal, vulgar, or students posting their homework.

Red Flag Submitted

Thank you for helping keep Eng-Tips Forums free from inappropriate posts.
The Eng-Tips staff will check this out and take appropriate action.

Reply To This Thread

Posting in the Eng-Tips forums is a member-only feature.

Click Here to join Eng-Tips and talk with other members!


Resources