CuMo
Mechanical
- May 1, 2007
- 146
Hi guys
I need to reed this forum more often as there is such tremendous amount of useful information for the designer but there I am - still not created a habit as I'm too tired to read it after work.
Anyway.
I was designing a flange today and due to the size of the bolts I went to read Mandatory Appendix 2 of ASME VIII-1 2-2 (e).
(e) Bolts, studs, nuts, and washers shall comply with the
requirements in this Division. It is recommended that
bolts and studs have a nominal diameter of not less than
1/2
in. (13 mm). If bolts or studs smaller than 1/2 in.
(13 mm) are used, ferrous bolting material shall be of alloy
steel.
Having A193-B8 S30400 bolts into the configuration I decided to go and read ASME SA-193 spec and double check what's written in it.
I had the same confusion some time ago but didn't have time to investigate. Also I have studied materials in university but in a country much closer to the Soviet union than USA, well of course in a different language so I can't get the right feeling of what the text implies here:
This specification covers alloy and stainless steel
bolting material for pressure vessels, valves, flanges, and
fittings for high temperature or high pressure service, or
other special purpose applications.
Why the code makes difference between alloy and stainless steels? Aren't stainless steels alloys themselves?
Where does the code tell the difference between one and another?
Reading this:
3.3 Stainless steels: The addition of more than about 12% Cr renders a steel 'stainless' or corrosion resistant because of a passive layer of chromium oxide Cr2O3 on the surface. Steels containing large amounts of Cr are ferritic, as Cr is a ferrite stabiliser. Stainless steels can be classified into three main types.
Does the ASME BPV code use the same method to differentiate between alloy steel and stainless steel or is there a different criteria?
I could've posted this into the material sub forum but being ASME VIII design I found it more appropriate to post here.
Any info on the subject would be helpful!
Thanks!
I need to reed this forum more often as there is such tremendous amount of useful information for the designer but there I am - still not created a habit as I'm too tired to read it after work.
Anyway.
I was designing a flange today and due to the size of the bolts I went to read Mandatory Appendix 2 of ASME VIII-1 2-2 (e).
(e) Bolts, studs, nuts, and washers shall comply with the
requirements in this Division. It is recommended that
bolts and studs have a nominal diameter of not less than
1/2
in. (13 mm). If bolts or studs smaller than 1/2 in.
(13 mm) are used, ferrous bolting material shall be of alloy
steel.
Having A193-B8 S30400 bolts into the configuration I decided to go and read ASME SA-193 spec and double check what's written in it.
I had the same confusion some time ago but didn't have time to investigate. Also I have studied materials in university but in a country much closer to the Soviet union than USA, well of course in a different language so I can't get the right feeling of what the text implies here:
This specification covers alloy and stainless steel
bolting material for pressure vessels, valves, flanges, and
fittings for high temperature or high pressure service, or
other special purpose applications.
Why the code makes difference between alloy and stainless steels? Aren't stainless steels alloys themselves?
Where does the code tell the difference between one and another?
Reading this:
3.3 Stainless steels: The addition of more than about 12% Cr renders a steel 'stainless' or corrosion resistant because of a passive layer of chromium oxide Cr2O3 on the surface. Steels containing large amounts of Cr are ferritic, as Cr is a ferrite stabiliser. Stainless steels can be classified into three main types.
Does the ASME BPV code use the same method to differentiate between alloy steel and stainless steel or is there a different criteria?
I could've posted this into the material sub forum but being ASME VIII design I found it more appropriate to post here.
Any info on the subject would be helpful!
Thanks!
![[glasses]](/data/assets/smilies/glasses.gif "[glasses] [glasses]")