Flange

Is it possible to weld Cl125 FF flange with Cl150 WN FF flange & why ?
This type of arrangement is generally in case of threaded pipe. Pl. give info regarding this.

Thanks
sachin

Sorry for the previous post. Actually I was asking whether it is possible to bolt Cl 125 FF Gate Valve with Cl 150 WN FF flange .
Gate Valve : 8” - Gate, CL125, FF, DI body, OS&Y, Bronze trim,
Resilient St, UL/FM, HW
Service : Fire water
Pipe MOC : A53-B-E,ERW,Std.Wt.,BBE
Piping Spec : Threaded ( small bore pipe is threaded )
Corrosion All : 0.063”
Dgn Pr. & T : 200 psig & 150 F
Insulation : No

I have seen Cl 125 valve in threaded spec .Also tell whether it is more preferable to use Cl 125 FF Gate valve than Cl 150 RF type gate valve
As per my understanding we should go with RF type as these are more
common , leakproof in nature , etc.

Thanks for valuable info .

If the spec calls for a Cl 125 FF Gate Valve, then use a Cl 125 FF flange.

If the spec calls for a Cl 150 RF Gate Valve, then use a Cl 150 RF flange.

The flange must be appropriate to the valve end, if 150 RF - 150 RF etc.

Actually, the bolt dimensions (BC and diameter) are equal between the two flange classes in 8". The most important issue is that both flanges need to be FF. As long as the valve manufacturer's bolt torque requirements are met, the suggested arrangement should work fine.
RF to FF arrangements can cause gasket problems and cracking of the DI or CI FF flange, since RF flanges are typically steel.

Tim Storey

IF "CI" means "Cast Iron" you wouldn't be welding anything! Cast iron is one of those materials that is both a god send and a curse! It is easy to machine, stands up to corrosion, and is cheap (compared to steels). BUT is a "bear" to weld on and should only be attempted in a suitable shop or by expensive experts with appropriate equipment. Normally you'll see cast iron with threaded ends and fittings or with cast on flanges. The 125# rating does have the same dimensions as a 150# rating, which allows bolt up, but CI 125# flange is always flat faced and if used with a 150# flange there is a good chance that the flat faced cast iron flange can be broken when mated up to the raised face 150# flange! REAL bad news if this cast iron flange is on a pump or other expensive piece of equipment! Normal design would require the raise face on the steel flange to be machined off to a flat face configuration, then bolting up to CI 125# is not a problem. …Good Luck!