Pipeline valve for higher pipe meterial yield strength

[if7005]

I have a problem for ball valve material selection for B31.8 pipeline.
Piping material use API 5L X70 ( SMYS=70 psi ), but valve material A105 with lower yield strength ( 36 psi).
Valve shall be full bore opening, but it seems not possible because the valve will be thicker (different ID) cause with lower strength.
1.Can the valve body manufactured with same pipe ID, wherefore OD enlarged.
2.What kind of common valve material should be used other than A105 to match the ID of pipe X70 ?

 

[BigInch]

You need to do two things, match the diameters and match the steel for ease of welding. A106 won't weld nicely to X60+. Use a transition piece of X52 with an intermediate thickness. That can provide a transition steel for welding too and adjoining walls should not have a difference greater than 3/16". If they do, they need to be bored down to that or less. The thinest part of any wall after counterboring must at least hold the design pressure.

We will design everything from now on using only S.I. units ... except for the pipe diameter. Unk. British engineer

 

[if7005]

BigInch,
You mean different ID (inner diameter) between valve and pipe still accepted, but is it any effect during pigging i.e pig may stuck around bottle-necking ?

 

[BigInch]

There's only one company in the whole world that for some reason believes you can't have different IDs due to pig running. They pay for that misconception 1000 times over every day.

Its good that you're thinking about how you will operate this pipeline. In the heaviest of wall thickness possibilities you might run into some problems with some kinds of pigs, so check with your pig supplier, if you have any doubts about that. It is usually not something you need to consider, unless you have wall thicknesses very much greater than the norm.

We will design everything from now on using only S.I. units ... except for the pipe diameter. Unk. British engineer

 

[if7005]

BigInch,
Pipe thickness = 12.7 mm w y.strength 65 psia
Valve A 105 yield strength 36 psia.
Valve thickness approx. ( 65/36 )x 12.7 = 23 mm

 

[BigInch]

Check the stress on a transition of 18 mm wt, X52. If that's OK for stress, then just make sure your valve is full bore and I'd say you're good for pigs. You wouldn't even need counterbores.

We will design everything from now on using only S.I. units ... except for the pipe diameter. Unk. British engineer

 

[if7005]

Thanks BigInch,
I think it's big idea to insert a transition-piece. Fortunately the line is not to be pig able, so it doesn't matter to make different id.

 

[BigInch]

Be sure to specify the pipeline's design pressure.

We will design everything from now on using only S.I. units ... except for the pipe diameter. Unk. British engineer