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Calidad (Mechanical) (OP)
30 Sep 02 3:35
Due problems with our suppliers, I'm usign in a ASME Design Europeen (DIN Standards) and ASTM Materials. At this moment, I'm trying to use and analogue materials in ASTM for this Din Materials. (PED cathegory IV design)

I've checked in ASME section IId and Appendix 1 looks so usefull to find a solution, this appendix use two factors in order to determine allowable stress in several conditions (low temperature, below creep and over creep).These factor are called Rt y Ry, I can't understand how determine these values, this info is very confused, are there any sample to understand how obtained them?.

Ry = ratio of "average temperature dependent trend curve value of yield strength " to the room temperature yield strenght.

Rt = ratio of "average temperature dependent trend curve value of tensile strength " to the room temperature tensile strenght.

I know that ASME Codes supports any foreigner materials, which materials are to be supported now?

Your oppinion about this matter will be highly appreciated.

Best Regards

José Luis Gómez R.
Mechanical designer.
Amsterdam (Materials)
30 Sep 02 11:47
Dear Calidad,

As far i can understand is that your are not building a code stamped vessel. That give you some room to play with.
In case of a Non code item, it is possible to use DIN material when agreed with your client. You also mentioned the PED, within the PED you must have the approval of your Notified Body to use any material.
For Code stamped items it is possible to re certify material within the Code, see PG/UG 10. Tricky part are grain sizes. Within ASME Sec I & VIII div.I you can use European material according EN 10028-3, like P 275, 295 or P 395.

good luck,

Gert
Calidad (Mechanical) (OP)
30 Sep 02 12:28
Dear Gert:

Thank's for your promptly answer. Ped can authorize me to use this material using a particular appraisal of materials, that's correct.

But I refer to use of Din Mats using American Code, it is only to design (other jobs than PED's ones), the problem exist when I try to use properties analogues to establish allowable stress. For example, I'm using TTSt 35N , in Admerkblatt Code I will take Kvalues at 20 deg and after divided by 1.5 or 1.1 depending on design or testing condition. ASME Code has no an identical material, only simmilars ---> A-333 gr 1 or gr 6.

My particular job is to avoid to find an homologate material , only to use properties that permit me make calculations using St or Sy criteria as ADMerkblatter Rules.
At lower temperatures , Code is very clear because Rt and Ry not appear in the criteria but in the future if I have a job with the problems refered in table 1-100 ASME Section II App1 I would like to know how I can solve it.

Thanks again for your help.

José Luis Gómez R.  
prex (Structural)
1 Oct 02 2:43
As specified by Appendix 1 of ASME II D, simply take SYRY as equal to the yield strength at temperature (that you'll easily find for many DIN materials in their defining standards) and 1.1STRT as equal to the tensile strength at temperature (that is less easily available than yield).
This should sufficiently enlighten the meaning of those coeffs.

prex

http://www.xcalcs.com
Online tools for structural design

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