# 150 Flanges

[99491]

Dear All,

Should be a simple one.

Can someone please tell me what the 150/300..etc denotes in a ANSI B16.5 Flange. ie class 150.

Thanks

 

[JLSeagull]

WAG
Perhaps some wafer valves designed to install between flanges are machined to fit either Class 150 or Class 300 facings.

 

[btrueblood]

Class roughly corresponds to the pressure limit for steam, if wrought mild steel is assumed to be the material. It really only defines the bolt pattern, face design, and flange thickness now, although it is still true that a higher class number will withstand higher pressures.

 

[JLSeagull]

Sorry for the confusion. Trueblood's response is on track for the rough correlation between the pressure rating in psig with flange class at the saturated steam temperature for steel. My response considered having found a connection that was marked Class 150/300.

 

[gouveia]

A fitting designation as Class 125 denotes the following:
1. Use with steam pressure is not in excess of 125 pounds.
2. Use with water when pressure is not in excess of 175 pounds.
3. Fittings are made of cast iron.

A fitting designation as Class 250 denotes the following:
1. Use with steam pressure is not in excess of 250 pounds.
2. Use with water when pressure is not in excess of 400 pounds.
3. Fittings are made of cast iron.


A fitting designation as Class 150 denotes the following:
1. Use with steam pressure is not in excess of 150 pounds.
2. Use with water when pressure is not in excess of 300 pounds.
3. Fittings are made of Malleable iron.

 

[texasvalve]

ANSI Classs 150 flanges are rated to 280 psi water pressure at ambient temp & 300 ANSI are rated to 740 psi water. They are correct tht the 150 & 300 designations are for steam applications. THe ASME steam tables do a good job with this. Crane Vavles Flow of Fluids has a lot of good info on this. Look at the Brown Bookstore online.