RE: Bolting and Valve Length Question

From: <Steve>
Date: Fri May 27 2005 - 19:05:00 EDT

Hi Paul
The length of a 12" 600# butt weld flange is about 6". You have two of these as part of the valve, so the valve " true body" length will be 33-12 = 21" (most flanged valves are actually buttweld valves with weldneck flanges attached. The exit neck of the valve will be around 3.5" each side, leaving the 14" for the leaf, seal and bonnet assembly. On higher pressure valves, the bonnet tends to be circular and must be larger than the valve bore to let the gate be removed. Next size up is 14", and there you have it; 12" for flanges + 7" for inlet outlet ports+ 14" for bonnet = 33".
There are almost certainly shorter valves of a unitized construction available, but 33" seems a good length for layout.

Through studs would almost certainly foul the bulge where the gate is housed, plus, even if you could you would be putting the valve body in compression.

Don't know why manufacturers provide less information than they used to, but I expect it has something to do with lawyers.

Cheers

Steve

-----Original Message-----
From: PipingDesign@yahoogroups.com [mailto:PipingDesign@yahoogroups.com] On Behalf Of Paul Bowers
Sent: Saturday, May 28, 2005 10:25 AM
To: PipingDesign@yahoogroups.com
Subject: [PipingDesign] Bolting and Valve Length Question

I've enjoyed the recent bolting discussion, so I post this:

A 12"-600# gate valve is 33" from flange face to flange face (not including the 1/4" raised faces, presumably). Does anyone know why this dimension is as large as it is?

<mumble>cast steel, longitude, twisting, etc.</mumble>

Can 16 (of 20 total) 1.125" diameter, 36" long studbolts be passed straight through to the other flange without interfering with the valve body?

I seem to remember that wafer valve manufacturers used to publish bolting requirements, I.E., "you need X studs/machine bolts plus Y cap screws to install this valve" but lately I see that most isometrics (CAD

or not) leave the bolting up to the contractor. Is this because of misunderstanding on the part of the designers and resulting field screw-ups?

Paul

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