Valve material - A350-LF2 1

[tomconway]

Can you use the code Temperature / pressure limits for valves manufactured from the above material if the valves are actually machined out of a solid forged bar?
This case is a 4"NB 1500# flanged valve.
My valve supplier state that it is acceptable?

 

[reverman]

Seems like an expensive method in making a valve but as long as it meets all the critical dimensions and materials (E-E, wall thickness, flange dimensions) I don't see any reason it would not be acceptable.

 

[SJones]

You can use the ratings but, as an aside, ASTM A961 does prohibit the machining of flanges from bar.

Steve Jones
Materials & Corrosion Engineer

http://www.linkedin.com/pub/8/83b/b04

 

[JLSeagull]

That is interesting. In 1996 I bought a specially control valve fabricated from billet with a flange face machined into each end for connection via cap screws. I don't have a copy of ASTM A 961 or ASME SA 961.

 

[reverman]

This may be a suspect loophole but A961 says "flanges, elbows, return bends, tees, and header tees shall not be machined from bar"

It does allow other hollow cylindrical parts up to 4" to be machined from bar provided the axial length is parallel to the metal flow lines.

One could argue a valve body is a hollow cylindrical part thus you could use bar for up to 4" sizes. I'm not sure I'm very comfortable with the argument, but if the situation is desperate with some calculations and agreement with the customer you may be able to make the case in using the bar material.

 

[tomconway]

I agree with reverman that this maybe a loop hole and will insist on valves with forged bodies.
As a ASME member working in the UK OIL and GAS offshore maintenance and modifications sector there is always pressure to accept alternatives that reduce the delivery times. I need to produce justification not to accept alternative to accepted practice.

 

[valvit]

ASME VIII Section 1, ASTM A182, ASTM A105 and ASTM A350 all prohibit flanges and flanged components of all types from being manufactured from bar stock.

 

[bj45]

Justification? P/T limits per B16.34 does not restrict mfg practice. It just calls A350-LF2.

 

[tomconway]

Thank you Valvit and bj45 for confirming that the code is not clear on this subject as we have heard both these interpretation previously.
My own view is that while is may possible be in accordance with the code it is certainly not in accordance with the spirit of the code. I will continue to err on the side of caution and reject valves manufactured out of bar stock
.

 

[rmw]

The "spirit of the code"?????? Either it meets the code or it doesn't. Codes are very specific documents written in black and white to keep "spirits" from governing how we build things.

Imagine yourself in a court of law telling a jury in a serious injury case that your interpretation of the code was that the "spirit was...."

Maybe I have just got a burr under my saddle here, but once you start making decisions based on the "spirit" of something, then you can decide just about what you want to.

You could just as well accept the valves if the "spirit" so moved you.

We are not Lawyers here - we are engineers. We deal in facts.

I'm done ranting now.

rmw

 

[tomconway]

OK cowboy
You can read valvit and bj45 replies.
you call it?
Do we allow Bar stock forged material to be machined to produce a Flanged Ball valve.
WHICH PART OF THE CODE ARE YOU GOING TO IGNORE

 

[rmw]

The spirit part.

What is the code that governs the ultimate use of this valve? Valvit quotes from Section VIII Div I which is a pressure vessel code. Are you using this valve inside the pressure boundary (code jurisdiction) of a pressure vessel? Or is it for a piping application? And if yes, which piping code governs?

Consider for example a bolting situation I recently encountered. When designing a pressure vessel for service below 20F, I can use the bolting that the BPV code allows which is 193 B7 (down to some temp limit). For the same ambient conditions at the same plant, the piping connected to that very same PV is governed by B31.1 which drives me to a different fastener material for temps lower than 20F - A320. Strange, but true.

I can't design my piping bolting for temps between 20F and 40F with 193 B7 fasteners and tell the head engineer "well, since the BPV code allows me to use that material below between 20F and 40F, the 'spirit' of the code allows me to do it on the piping." I have to use the material dictated by the code that governs where the flange is which means that I have two different boltling materials within sight of each other, literally. But the applicable code is satisfied in both cases.

So, first, let's determine which code governs your application and then delve into that particular code for the correct answer to your question.

rmw