Is a 600# butt weld valve out of standard? 3

[OCANDOA]

We have found a 3/4" gate valve 600#, but some engineers suggest that this rating only applies for socket weld. We have also been told that this is out of standard.

Is this true?

Thanks for the input.

 

[JLSeagull]

ASME B16.9 applies to buttwelding fittings and B16.25 applies to buttwelding ends. Neither include valve information.

 

[JLSeagull]

MSS SP-72 is titled "BALL VALVES WITH FLANGED OR BUTT-WELDING
ENDS FOR GENERAL SERVICE". This kinda suggests that Buttweld end valves exist.

 

[Oldliar]

Check

http://www.bonneyforge.com.

You can get want you want; socket weld, screwed or butt weld in sizes from 1/4" to 2" (should cover your range). Body is 800# rated (rather normal for forged valves) but for your application you just state the schedule for your line and they'll make the bevel for you. If not, you grind it yourself. We use NR valves from Bonney Forge for 150# / 300# rated systems, however with socket weld. The valve body is rated 800#, however as it's SW it makes no different as the pipe is PE.

OL

 

[OCANDOA]

Thank you all for your comments...

To rephrase my question:
The valve specified is 3/4" Gate 600# with BW ends
The valve available is 3/4" Gate 800# with SW ends.

We have been considering the option suggested by Oldliar, to grind down the end. Our concern now is if the schedule of the valve will match the pipe.

Is there a specific reason to use a BW instead of a SW???

 

[abscott]

OCANDOA,
Industry practice is to use SW ends 1/2-2 inch body size and to move to the BW ends above 2 inch. In higher pressure classes such as 900-4500 there are occasions where customers specify BW ends in the small sizes.

A 3/4 in. BW gate valve sounds really unusual and I would question the person or agency that specified the valve. Sounds like a Typo to me.
Regards,
ABScott

 

[JimCasey]

>The valve specified is 3/4" Gate 600# with BW ends
The valve available is 3/4" Gate 800# with SW ends.<

Be careful. This is why I don't like to use the "#" designation because it is misleading and can get somebody hurt.

Class 800 is >Usually< a WOG rating: Water-Oil-Gas at ambient temp, pressure not to exceed 800 psi. I have not been able to relate this to a National standard, and apparently it is manufacturer-certified.

Class 600 refers to ASME B16.34, Titled "Valves Flanged, Threaded and Welded ends", and for each class and material there is a pressure/temperature relationship for which the valve is rated. Carbon Steel ASME Class 600 is good for 1480 psi at 100F.

If you take an 800WOG valve in place of an ANSI600 valve the 800 valve has a lower rating and may compromise the functionality of the installatiom-

 

[OCANDOA]

Jim, thank you for the observation.

The valve available is 3/4" API/ASME Class 800 and also meets the ASME B16.34.

ABScott, we also agree with you and find this unusual. This is also why we posted the question. We want to know if this is a typo or not.

The valve specified (3/4" ASME CL600) meets the design spec ISO 15761x and has been printed from a database of a known oil company. This same specification refers to a design Spec for Butt weld ends ASME B16.25. (Don't have it available for analysis)

Is there a section or a standard that can help us justify the use of a 3/4" CL800 SW over a 3/4CL600 BW?

Or will we have to find the exact same valve as the spec?

 

[abscott]

OCANDOA,
A butt weld is a "full penetration" joint and in larger sizes you can make a root pass and hold the joint together while the remaining passes are completed. As the pipe diameter and wall thickness decreases a butt weld joint becomes extremely difficult. In small piping the counterbore of the socket weld joint supports the small piping and a simple fillet weld is much easier to weld.

I have ASME B16.25, 1997, "ButtWelding Ends". The Scope reads: "This Standard covers the preparation of buttwelding ends of piping components to be joined into a system by welding" All the figures and dimensional tables start at 65DN (2 1/2 in.) and go up to 900DN (36 in.)

The fabrication codes (ASME B31 Series) generally carry the requirements for piping fabrication, including welded joints. ASME B31.1 Power Plant Piping in Part 4, "Selection and Limitation of Piping Joints" has sections that limit the use of socket weld joints to 2 in. and smaller piping. There is no restriction placed on the size of butt weld joints, however ASME B16.25 is referenced as the standard.
Hope this helps,
ABScott