rneill
Mechanical
- Jul 29, 2008
- 486
Has anyone looked at the flange rating table in Part 3 of ISO 15590 ...
Can anyone explain the high temperature ratings of Class 1500 and 2500 ...
Questions:
1. The 250 C rating (225 bar) of Class 1500 is higher than both the 175 and 200 C ratings which are 219 and 225 bar respectively.
2. The 200 C rating (365 bar) of Class 2500 is higher than the 175 C rating which is 341 bar.
3. If you calculate the temperature derating factor used, it varies significantly between pressure classes. For example, at 150 C, derating is as follows:
Class 150 - 96.9%
Class 300 - 96.4%
Class 600 - 96.6%
Class 900 - 96.7%
Class 1500 - 88.6%
Class 2500 - 88.5%
I assume that there is some problem with the ISO 15590 published ratings for Class 1500 and 2500 but a google search did not reveal any errata, or corrigendums and I was unable to find any mention of this issue?
I'm also curious that thru Class 900, the ratings are almost identical to MSS SP-44 except for the 200 C ratings which tend to be significantly different.
Can anyone explain the high temperature ratings of Class 1500 and 2500 ...
Questions:
1. The 250 C rating (225 bar) of Class 1500 is higher than both the 175 and 200 C ratings which are 219 and 225 bar respectively.
2. The 200 C rating (365 bar) of Class 2500 is higher than the 175 C rating which is 341 bar.
3. If you calculate the temperature derating factor used, it varies significantly between pressure classes. For example, at 150 C, derating is as follows:
Class 150 - 96.9%
Class 300 - 96.4%
Class 600 - 96.6%
Class 900 - 96.7%
Class 1500 - 88.6%
Class 2500 - 88.5%
I assume that there is some problem with the ISO 15590 published ratings for Class 1500 and 2500 but a google search did not reveal any errata, or corrigendums and I was unable to find any mention of this issue?
I'm also curious that thru Class 900, the ratings are almost identical to MSS SP-44 except for the 200 C ratings which tend to be significantly different.