flanges

[cme]

What flange would be mated with a stop/check valve (say Crane model 30E) which is rated for 250 lbs? Does a 250 lb valve have 300 lb flanged ends? I can only find threaded cast iron companion flanges that are rated for 250 lbs. I would think the flange needs to be steel so it can be welded to the adjacent pipe.

 

[TBP]

Dimensionally, Class 250 CI, and Class 300 CS are the same. They would be matched as you stated.

Class 125 CI and Class 150 CS are also dimensionally the same. The difference here, is that when joining these two kinds of flanges, the raised face on the 150 must be removed and a full face gasket used. This prevents the relatively thin & brittle CI flange from being "sprung" into a gap when the bolts are being tightened. There are also fastener consideration for all of these flanges, if they are being installed in an application that falls under ASME B31.1. I would urge you to be cautious here. Quite a code labyrinth for the un-initiated.

 

[cme]

This is what my spec reads:

B. Flanges - Faced true, flat face or raised face type as indicated, welding type for welded lines, screwed type for threaded lines, pressure rating as required by service per ASME B16.5, B31.1 and B31.9. Flanges shall be flat or raised face type to match and be compatible with flange construction at equipment and valves.
1. Threaded lines - ASME B16.1 with ASME B1.20.1 threads, face and pressure rating per service per ASME requirements, screwed ends.
2. Welded lines - ASME B16.5, face and pressure rating per service per ASME requirements, forged steel, slip-on welding (front and back) type. Utilize ASME B16.5, forged steel, welding neck type for high pressure steam (above 99 psig) and high temperature hot water service; both with pressure rating per service per ASME requirements.
3. Flange hardware - ASTM A307, carbon steel, threaded bolts and nuts, Grade A for steel flanges, Grade B for cast iron flanges.

Any input?

 

[TBP]

The important thing is to comply with the codes & regulations as they apply in your jurisdiction. (Lots of local spins on this stuff.)

An aspect that frequently slips through the cracks is having someone competent actually CHECK that the material and method of constuction specified is actually happening out in the field. This function either doesn't get done at all, or is considered so minor that it's delegated to some kid just out of school, or a middle-aged dud. "Give it to old Charlie - surely he can't screw THIS ONE up." Wanna bet? I've seen lots of jobs that were just one big adventure in "corner cutting", because the contractor KNEW that nobody was going to check up on him.