Flowserve V-376 R4 Edward Valves Manual de usuario descargar pdf (Pagina 10)

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Flow Control Division

Edward Valves

WARNING

Edward valves are not provided with a pres-

sure relief device. A pressure relief device

must be provided elsewhere in the piping

system to prevent the piping system pressure

from exceeding the maximum rated pressure

of the valve.

PIPING SUPPORT

Piping should be supported sufficiently to

preclude excessive end loads on the valve.

VALVE INSTALLATION GUIDELINES

Except as noted below, Edward stop valves

and stop-check or check valves with springs

can be installed in any position. Installed

positions with the valve cover or bonnet

below horizontal, where dirt and scale can

accumulate in the valve neck, should be

avoided.

For optimum performance, the orientation

limits shown in Figures 1 and 2 should

be observed even for spring-loaded

check valves.

The orientation limits shown in Figures 1

and 2 must not be exceeded for Edward

stop-check valves and check valves with-

out springs. The limitations given for line

inclination and bonnet roll angle should

not be combined.

All check and stop-check valves should be

installed with 10 or more diameters

of straight pipe upstream of the valve

to minimize flow disturbances. For addi-

tional information, refer to the “Technical”

section of the Edward Valves Catalog,

Publication No. EV-100.

SEAT AND DISK JOINT LEAKS

A leak existing between the seat and disk of

a closed valve might be indicated by one of

the following: a definite pressure loss in the

high-pressure side of the valve; continued

flow through an inspection drain on the low-

pressure side; or, in hot water or steam lines,

a downstream pipe that remains hot beyond

the usual length of time and conductivity

range.

Such a leak may be the result of closing on

dirt, scale or other foreign matter in the line.

It may also develop because of the operator’s

failure to close the valve tightly. An increased

velocity is imparted to a flow forced through

a very small opening. This increased velocity

subsequently gives rise to the “cutting” of

both disk and seat, particularly by particles

of line scale or rust in suspension or normal

solids in solution. In spite of the fact that the

hard-surfaced material on the seat and disk is

corrosion- and erosion-resistant, grooves, pit

marks, or other surface irregularities may be

formed on the seat and disk joint surfaces

when the disk is closed against a foreign

body on the seat. This sometimes occurs dur-

ing the initial start-up of a piping system.

Leakage of steam through a valve that is

badly steam-cut has a whistling or sonorous

sound. If the valve is only slightly steam-cut,

however, leakage is identified by subdued

gurgling or weak popping sounds. These

sounds can be heard through a stethoscope

or by placing one end of a stick against the

valve body while holding the other end

between the teeth, with hands over the ears.

General Information

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