fyi,
also studs in unified and rolled alloys books, are 1/4" shorter than in
Megysy and Crane.
I forget What NAVCO said.
annoying, i agree about less information provided.
but the principle of bolting the joint is the endeavour to roughly balance
the loads each side of the joint between the body and the bolt. this is
oversimplistic because there are all the other forces eg. separating and
friction forces. However bolts straight through defeats the "net balanced
force" principle. eg the back side of the flange joint would have no
opposing force
so the gasket/joint would never seat.
the nut on the backside has to be able to stretch the stub/bolt . With a
stud right through this couldnt happen, and the force would all be on one
side only as Steve said, putting the body in compression at both ends.
I think this fundamental issue got overlooked in the suggestions/discussions.
> 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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Received on Sat May 28 20:06:00 2005
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