No Access to ASME Sec. 8, need Allowable Stresses... 5

[HarrisK]

Hi,

Just starting out as an Engineer... I don't have access to all ASME Sec 8 published to date and I needed allowable stresses for the following materials...

SA-516 Gr 70 built 1998 Temp. -20 to 100 F
SA-240 Gr 304 built 1993 Temp. -94 F
SA-516 Gr 70 built 1974 Temp. less than 150 F
SA-515 Gr 70 built 1974 Temp. between 110 to 230 F
SA-106 Gr B built 1998 Temp. 100 F

I'd really appreciate any help....
Thanks

 

[mengnr]

I think you need Section II, not Section VIII. Since I happen to be working with SA-240 / 304 now, I can tell you the allowable is 20 ksi from -20 to 100 F. The code does not go below -20 in the table.

 

[HarrisK]

Thanks mengnr, appriciate the help.... quick question though.... the code your referring to, when was it published ? .... I think I need the code published in 1992, or somewhere around that time, because thats when the vessel was built....

Once Again, Thanks

 

[curtis2004]

HarrisK,
Why (what purpose) do you need stress tables for material 1992 edition?
curtis

 

[Christine74]

From 1950 all the way to 1998 the allowable stress for both SA-515 Gr. 70 and SA-516 Gr. 70 was 17.5 ksi for temperatures up to 650°F.

-Christine

 

[mengnr]

That's the most recent version of the code. Sorry, can't help with the older ones.

 

[Christine74]

In the 1999 Addenda to Sect. IID, ASME changed from using a 4:1 design margin on the ultimate tensile strength to a 3.5:1 design margin, so the allowable stress for SA-516 Gr. 70 (70 ksi tensile strength) went from 17.5 (70/4) ksi in 1998 to 20.0 (70/3.5) ksi in 1999.

And prior to 1999, the allowable stress for SA-240 Gr. 304 at -20°F was 18.8 ksi, not 20.0 ksi.

-Christine

 

[HarrisK]

Thanks alot Christine74, that helps !

 

[HarrisK]

mengnr: No worries, appriciate the help.

 

[HarrisK]

curtis2004: To my understanding, SA metals in the US are made according to chemical compositions specified in the present ASME code, so if the metal was made a long time ago, they must have used the ASME code of that time.... and hence the allowable stresses would be different....

however, if the chemical compositions are the same, which seems to be the case for SA 516 Gr 70 at least, then the most recent ASME code will be correct as the only thing that changed was the design margin...

 

[JStephen]

Older allowable stresses are different due to differing design philosophy, not due to differing chemistry. While SA (and ASTM, etc) standards are updated from time to time, there are not usually significant changes in chemistry. If they change the chemistry much, you tend to get a new standard for the new material.

You didn't really say what your application is, but be aware that the ASME code not only gives allowable stresses, but specifies how those stresses are to be used. The calculated stresses actually used may be considerably higher or lower than the tabulated stresses based on the geometery and the application. Also, if you're evaluating existing vessels, there are other codes and standards applicable to them that may allow or restrict stresses at different levels from the design code.

 

[HarrisK]

JStephen: Thanks, that clears things out... The reason I needed those stress values is to evaluate pressure vessels currently in use... would other codes be applicable here ? If so, can you specify which ones, or do you need more informaiton ?

Thanks
Harris

 

[curtis2004]

HarrisK,
What would you like to do with the vessel(what is the task)?
curtis

 

[HarrisK]

cutis,

The vessel is currently being used at a natural gas purification plant, I need to det'm remaining life..

 

[JohnGP]

You probably should have these then:
API 510 Pressure Vessel Inspection Code: In-Service Inspection, Rating, Repair, and Alteration
API 579-1/ASME FFS-1 Fitness for Service

These reference others, but I would think they are the main men for your situation.

Cheers,
John

 

[curtis2004]

HarrisK,
ASME Section VIII, Div 1/2/3 are construction codes. They set rules for design and fabrication of pressure vessels. When vessel comply with the code it will have "U" stamp and once the vessel leaves fab shop there ends jurisdiction of the code, because as I mention it is construction code.
As mentioned by JohnGP you need API 579-1/ASME FFS-1 Fitness for Service in order to determine remaining life of the vessel. Other relevant section of the code for this would be Section V, NDE.
Regards,
curtis