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learner08 (Mechanical) (OP)
11 Oct 06 23:51
Would appreciate anyone's help.  Thanks in advance.

If a valve is supposed to be say Class 800,  what does it mean?  I am sure it is related to pressure and temperature but do not know the exact meaning.

Also if I have a valve with known capability to handle a known pressure and temperature,  how do I know what Class it is?

I guess both questions are related .....
Helpful Member!(2)  FIF99 (Materials)
12 Oct 06 2:34
Hi,

It's listed in the API 602. Per grade of materials are maximum allowable design pressures presented at different temperature levels.
Class 800 is applicable for Socket weld or Threaded end valves.

Success.
Regards, FKE
Helpful Member!  BigInch (Petroleum)
12 Oct 06 6:22
A <WOG> 800 is a working pressure rating, not a class.

A valve that has a WP rating, a working pressure rating, might not have a ANSI class designation.  ANSI class designations apply to flanges (and flanges on valves), and are sometimes applied to compatible weld end valves (where basically the flanges are not welded on to the valve body).

For a definition of WOG (water, oil, gas pressure withstanding capability and is not related to fluid compatibility), see here,

http://www.nibco.com/showFile.do?fileId=1336

BigInchworm-born in the trenches.
http://virtualpipeline.spaces.msn.com

pipe15 (Mechanical)
12 Oct 06 6:59
flanges and valves are rated by class.  most people will say that a flange or valve is a 600#, 800#, 1500# etc.  this is not quite right.  the word 'pound' sould not be used in the description.  the proper term is 'class' as you mentioned in your original post.  one source for the temp/pressure limits for flanges and valves is B16.5 and B16.34 respectively.  a pressure/temp example for a class 600 A105 flange from B16.5 show that at 200 degrees, the allowable working pressure is 1360 psig, but at 650 degrees the allowable working pressure drops to 1100 psig.
hope this helps
mark
Ashereng (Petroleum)
12 Oct 06 14:32
I have also heard of Class 800. I can not recall the particulars, although FKE's indication that they are for threaded ends or butt weld seems right.

For WOG valves, typically, we use WOG 2000# and up. I don't recall seeing a WOG 800#, not to say they don't exist.

"Do not worry about your problems with mathematics, I assure you mine are far greater."   
Albert Einstein
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Cockroach (Mechanical)
12 Oct 06 15:58
The proper ANSI Class rating would be 900, not 800.  You can use API 6D Table 2.1 for maximum operating pressure and temperature class for all the ANSI Class ratings.

Kenneth J Hueston, PEng
Principal
Sturni-Hueston Engineering Inc
Edmonton, Alberta Canada

JLSeagull (Electrical)
12 Oct 06 16:32
API Spec 6D 2002 refers to ASME B16.34 for rating tables by material groups.  No table 2.1 exists.  

API STD 602 indicates that "Class 800 is not a listed class designation, but is an intermediate class number widely used for socketwelding and threaded end compact valves."  Also "This International Standard is applicable to valve end flanges in accordance with ASME B 16.5 and valve body ends having tapered pipe threads to ISO 7-1 or ASME B 1.20.1. It is applicable to extended body construction in sizes and pressure designations of Class 800 and Class 1500, and to bellows and bellows assembly construction as may be adaptable to gate or globe valves in sizes. It
covers bellows stem seal type testing requirements."
Ashereng (Petroleum)
12 Oct 06 18:05
ANSI/ASME B16.1-1989 Class 800

Didn't this exist?

"Do not worry about your problems with mathematics, I assure you mine are far greater."   
Albert Einstein
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Ashereng (Petroleum)
12 Oct 06 18:09
I have done a quick google, and Flowserve makes an ANSI Class 800 valve.

They are welded and threaded ends, as per FKE.

http://www.flowserve.com/vgnfiles/Files/Literature/Products/Flowcontrol/Vogt/VVABR0003.pdf#search=%22ansi%20class%20800%22

"Do not worry about your problems with mathematics, I assure you mine are far greater."   
Albert Einstein
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ytse (Mechanical)
12 Oct 06 22:06
Class 800 valves are covered in API 602.

Section 1 of API 602 stated "Class 800 is not a listed class designation, but is an intermediate class number widely used for socketwelding and threaded end compact valves."

Section 4 of API 602 stated:

4.1.2 Interpolated ratings
Pressure/temperature ratings for Class 800 shall be determined by the equation: P8 = 1/3 P6 + 2/3 P9
where
P8 is the pressure at the specified temperature, expressed in bar3, for Class 800 rounded to the nearest
(10 kpa);
P6 is the listed pressure, at the specified temperature, for Class 600, expressed in bar;
P9 is the listed pressure, at the specified temperature, for Class 9004, expressed in bar.
vpl (Nuclear)
13 Oct 06 7:58
In reading the responses to this thread it seems there are two different "meanings" for Class 800 -- dependent on what the governing industry standard is (API or ANSI).  Since learner08 didn't specify his application, both sets of answers are reasonable.  However, he needs to be sure that he is using the correct standard for his industry and application.

Patricia Lougheed

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JLSeagull (Electrical)
13 Oct 06 12:24
Perhaps once true but the standards are being coordinated among US clubs and overseas clubs too.  API refers to ASME.
Cockroach (Mechanical)
14 Oct 06 14:31
Yeah, I agree VPL, perhaps there are multi-specifications.  I refer to CSA Z245.15 which references the valve ANSI Classes to the API specification.

Sounds like ANSI Class 800 is socketweld and the likes.

Kenneth J Hueston, PEng
Principal
Sturni-Hueston Engineering Inc
Edmonton, Alberta Canada

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