Differences between Yield Tensile & Max Allow Stress? 3

[MonicaLee]

Everyone, please do me one small favor. Can someone explain to me the following:

1) Is Minimum Yield (S) and Min. Tensile Strength meaning the Maximum psi on the deformation and ultimate strength of a material.
2) If I have ASTM A276 Min Tensile Strength is 80Kpsi and Min. Yield is 30Kpsi. To calculate the Maximum Allowable Stress level, do I use the Min. Yield or Min. Tensile.

I am sorry to ask this down-to-earth question but I need this be clear for understanding. Thank you for your time.

 

[SnTMan]

MonicaLee,

Whatever Code/Standard you are working to should have tabulated allowable tensiles as a function of temperature. These may be based on the minimum tensile or minimum yield, which are specified by the material spec, A276 in this case. These are ambient temp. values. You generally cannot get an allowable tensile directly from these values. For example see ASME Sec. II, Part D, Appendix A.

I know you are probably under the gun, but please take the time to determine whatever Code or standard you are working to and gain some familiarity with its rules.

If this is connected with your CRN's it will save time overall to submit calculations and so forth you can defend on a Code/standards basis.

Hope you find this useful.

 

[MonicaLee]

Thank you and yet another question referring to the last question. Should I use the Tensile or Yield for the Maximum Allowable Stress Value.

 

[metengr]

Here are the answers to your first question;
1. The minimum yield strength by definition, is the stress (measured load/original cross sectional area of the tensile specimen) where permanent deformation occurs during a tensile test. Permanent strain deformation can be established from tensile load versus deformation data using either 0.2% offset or by drop of the beam method.

The ultimate tensile strength is the highest stress prior to necking and failure during a tensile test. This stress is the maximum load/ original cross sectional area of the tensile specimen obtained from tensile load versus deformation data.


2. What is your application that requires you to calculate an allowable stress value? Material furnished under ASME SA 276 is not permitted for use in pressure boundary applications related to boilers and pressure vessels under the ASME Boiler and Pressure Vessel Code because it is not listed in Section II, Part D.
Allowable stress values can be calculated at your own risk using one or more methods - see Appendix 1 Table 1-100 in ASME Boiler and Pressure Vessel Code, Section II part D. Follow the rules for room temperature and above criteria for calculating allowable stress.

I have been noticing a pattern with your questions that is very disturbing. You should seek engineering expertise for these types of evaluations. This is not something that can be learned thru an engineering forum.

 

[EdStainless]

The reason to go to a code for this information is that the answer is yes, to all. Depending on the material, condition, temperature and application you may use the yield, or the tensile, or even creap data for setting the allowed stress.

= = = = = = = = = = = = = = = = = = = =
Corrosion never sleeps, but it can be managed.

http://www.trenttube.com/Trent/tech_form.htm

 

[MonicaLee]

Thank you so much guys. Have a wonderful day.

 

[vtpipeme]

Folks,

I have a question along the same line. We are cutting a plug for a vessel out of A-276 bar stock (316 SS), yet I can't find its allowable (or even yield) stresses in the ASME II tables. We're using it at 1200 F. Does anyone have any data on this? If so, from where?

Any direction is appreciated.

 

[SnTMan]

If you look at the top of the right hand page in Sec II, Part D you will see three column headings listing max allowable temperatures for Sec I, Sec III (I believe, don't have books available right now) and Sec VIII. If your material is not listed in Sec II, Part D or if you see NP in the column for the Section you are working to, the material is Not Permitted for use in that section, except as allowed by a Code Case.

It is important you be clear about which Code or Standard you are working to, and to make sure your material is permitted.

 

[TGS4]

If allowables aren't listed in ASME Section II, Part D, then the material is not permitted. Period. Try to find an acceptable/permitted material.

p.s. This would be a better question in a new topic. Hijacking threads like you have is not a good idea.