Ball valve pressure rating

[sree60]

Hi members

In one of the applications we have specified the ball valve 1 in size SS316 as 150# rating. On the valve body 5000psi rating is embossed.
Are the two pressure equivalent? how do we correlate the two?

regards
sree

 

[unclesyd]

Looks like you may have a high pressure valve in a low pressure service. This situation is OK for most applications unless the high pressure valve doesn't function well at low pressures.

Comeback with exactly what you called out for the valve and the service it will be used in, temperature and pressure.

If you can give us all the information on the valve.

 

[jsummerfield]

The ASME B16.5 flange class 150 has no # and no obvious relationship with 150. The pressure rating for a class 150 flange also varies by metalurgy. A class 600 stainless steel valve is not suitable for 1480 psig at 100 degree F like the class 600 carbon steel valve. Often small valves have other ratings. Except for the connection, a Class 150 flanged valve body may also be available for 800 psi socket weld applications. A 5000 psi body rating would exceed the pressure requirements associated with a class 150 flange. This is common for stainless steel instrument valves.

John

 

[cktayum]

There should be a table to convert flange class rating to psig, and this is different for different material. As i remember, for SS316, flange class 150 should be around 300 to 400 psig (I don't remember the exact value, I can try to check it out) and this is much lower than your valve body rating.

my opinion is that, you may double check on your system requirement, and see whether do you really need 5000psig, if you need 5000psig, then i suggest you change your flange class to higher class, may be class 2500, or may be you can change to a NPT thread, an 1" female NPT thread will have rating to 4400psig for SS316.

Another option is may be you can use a double ferrule compression end connection by using a SS tubing, an 1" OD SS316L tubing with 0.12" wall thickness can stand up to 4700psig. fitting like Swagelok, can stand pressure as high as the tubing rating.

 

[jsummerfield]

B16.5 has tables with temperatures and pressures for flange classes and material groups. Table 2-1/1 applies to A105, A350, A216, A515, A516. Class 150 is good to 19.6 bar up to 38 degree C. Table 2-2.3 applies to A182 Gr F316L/F304L and A240 Gr 316L and 304L. Class 150 is good to 15.9 bar up to 38 degree C.

If you are a psi type person think of one bar as about one atmosphere instead of the precise conversion. I don't think that Class 150 quite makes 300 psig in any material. If I buy a 1/2-inch Whitey Valve or Swagelok fitting for a class 150 system the valve would be rated much higher, perhaps 5000 psig. However, if I buy a 3/4-inch line class ball valve from Bonney Forge it may only be rated 800 psig. The eight-inch class 150 ball valve is likely rated something under 300 psig.

John

 

[JimCasey]

Class 150 is rated for 285 psi at 100F in most materials.
Without straining too hard, you can find an excerpt from ANSI (Now ASME) B16.5 or B16.34 in the technical section of most pipe-valve-fittings catalogs. Or maybe your company actually has a copy of the standard in the Engineering library. Both standards have charts of rated pressures of various ferrous materials at a range of tempreatures.

As pointed out in an earlier post: A 5000 psi ball valve >may< have really hard seats that require more than class 150 pressures to seal tightly. But at least the seats won't extrude at 5000 psi.