Ball Valve Body Material 1

[jsn1980]

LPG piping design temperature -45 deg c to 50 deg c and design pressure 40kg/cm2 g
And material for this line is A333-6 SEAMLESS

Valve vendor want to supply
Ball Valve Body material ASTM A351 Gr.CF8M can use instead of A 352 Gr.LCB
Ball Valve Body material ASTM A182 Gr.F316 can use instead of A 350 Gr.LF2

It is acceptable or not.
what is advantage and disadvantage?

 

[Ripz]

You original specs are carbon steel materials which undergo impact testing to prove that they do not suffer excessive loss of toughness which can result in brittle fracture. These are usually required for low temperature applications, as your service is at -45 deg C.

The vendor specifications are for 316 Stainless Steel bodies, which are usually not susceptible to brittle fracture, thus are not required to be impact tested.

Your advantages are less change of brittle fracture and also minimal corrosion.

Your disadvantages would be the increased cost of the valve and the introduction of dissimilar metal contact surfaces which may be a point of galvanic corrosion.

 

[bcd]

If your supplier sells teh stainless steel at the same price as the LCB or LF2, then that is very good for you.

There is a slight reduction in pressure rating for the stainless steel, but it is ususally insignificant.

Chances are the supplier has the stainless steel material on the shelf and can deliver much quicker than if they have to order LCB or LF2 castings from a foundry. So I expect you will see a shorter delivery time.

This material substitution is common and is normally OK. The LCB abd LF2 valves most likely have stainless steel trim inside so material compatibility should not be a problem.

 

[jsn1980]

Dear RipZ

For dissimilar metal contact surfaces which may be a point of galvanic corrosion.

To avoid Galvanic corrosion pikotek gasket can use known (to isolate two dissimilar contact surface)


Thanks