ASEPCO Support Knowledge Base 2 :: What are the Pressure Ratings for End Connections and Diaphragm Clamps?

What are the Pressure Ratings for End Connections and Diaphragm Clamps?

ASEPCO Radial Diaphragm Valves are designed for a working pressure of 250 PSI in all sizes.
You have asked for a temperature rating 300° F. As far as the effect of temperature on 316L stainless steel bodies we would not downgrade the pressure rating below 250 PSI.
As for the diaphragm and pressure seal o-rings there are some cleaning or flow products, which may give a reduced service life at 300° F. Again, we would not make a blanket pressure downgrade below 250 PSI for the valve bodies. This is a matter for consultation with ASEPCO regarding the time of exposure and the solvents present in the flow medium, or in the cleaning agents used.
Standard ASEPCO valves are supplied with TC clamps of cast 304 stainless steel with one bolt hand tightened, and one hinge pin.

The pressure ratings for this type of clamp are as follows, as rated by the clamp manufacturer:

		** Pressure Rating for End Connection		Pressure Rating for Diaphragm Clamp
Valve Size	Diaphragm Clamp Size	Max Pressure at 70° F	Max Pressure at 250° F	Max Pressure at 70° F	Max Pressure at 250° F
.5 & .75	1.5	1500 PSI	1200 PSI	500 PSI	250 PSI
1	2.5	500 PSI	250 PSI	400 PSI	200 PSI
1.5	4	500 PSI	250 PSI	200 PSI	125 PSI
2	4	450 PSI	250 PSI	200 PSI	125 PSI
3	4	350 PSI	150 PSI	200 PSI	125 PSI
4	6	200 PSI	125 PSI	150 PSI	75 PSI

** Line Clamp is supplied by user

Infrequently a customer inquires whether he can be given our full 250 PSI design pressure rating in the larger valve sizes where the single bolt, single hinge pin is usually employed as the diaphragm clamp. We advise that upon request we will ship the valves with the two-bolt high pressure clamp installed as the diaphragm clamp.

This provides the following pressure ratings, as rated by the clamp manufacturer:

		Pressure Rating for End Connection		Pressure Rating for Diaphragm Clamp
Valve Size	Diaphragm Clamp Size	Max Pressure at 70° F	Max Pressure at 250° F	Max Pressure at 70° F	Max Pressure at 250° F
.5 & .75	1.5	Use One-Bolt 1500 PSI	1200 PSI	Use One-Bolt 500 PSI	250 PSI
1	2.5	Use One-Bolt 500 PSI	250 PSI	Use Two-Bolt 720 PSI	660 PSI
1.5	4	Use One-Bolt 500 PSI	250 PSI	Use Two-Bolt 570 PSI	525 PSI
2	4	Use One-Bolt 450 PSI	250 PSI	Use Two-Bolt 570 PSI	525 PSI
3	4	Use Two-Bolt 600 PSI	550 PSI	Use Two-Bolt 570 PSI	525 PSI
4	6	Two-Bolt Clamps subject to special inquiry

ASEPCO does not advise routine use of two-bolt clamps in order to meet a standardized pressure rating. The one-bolt, one pin design has been employed as the standard diaphragm clamp for valves rated to 250 PSI based on our laboratory testing at pressures well above 250 PSI. It should be noted that the ASEPCO diaphragm clamping design is inherently more rigid and free from twisting distortion than the TC Clamp on end connections, or piping joints in general.
The one-bolt, one-pin clamp is widely used in our customers plants for many services. This results in a users familiarity with the effort needed to obtain a tight joint. When properly tightened, ASEPCO finds that these clamps provide satisfactory sealing service, for the full 250 PSI ASEPCO rating.