|
CONTROL VALVE INTRODUCTION
WEBSITE
!!!
Engineering >
Control Valve >
Valve Inspection and Testing
|
|
Pressure Test Procedures
GENERAL
Valves designed to permit emergency or supplemental
introduction of an inject able sealant to the seat area shall
be tested with the injection system empty and not in use,
except for lubricated plug valves.
When a liquid is used as the test fluid, the valve shall
be essentially free from trapped air during the test.
Required protective coatings, such as paint, which
may mask surface defects, shall not be applied to any surface
before inspection or pressure testing. (Phosphatizing and similar
chemical conversion processes used to protect valve surfaces
are acceptable even if applied before the tests, provided
that they will not seal off porosity.)
When closure testing valves, the valve manufacturer’s
test procedure shall ensure that excessive force is not
used to close the valve. The applied force may be determined
from the appropriate figures in MSS SP-91, but in
any case shall not exceed the values published by the valve
manufacturer.
The valve shall be visually examined for leakage
after it has been fully prepared and is under full test pressure.
BACKSEAT TEST
The backseat test is required for all valves, except for
bellows seal valves, that have the backseat feature and shall
be performed by applying pressure inside the assembled
valve with the valve ends closed, the valve fully open, and the
packing gland loose or packing not installed. If the backseat
test is performed after the shell test, the packing shall be
installed and/or packing glands re-tightened after the backseat
test. The successful completion of the backseat test shall not
be construed as a recommendation by the valve manufacturer
that, while the valve is pressurized, the valve stuffing box
may be repacked or the packing may be replaced.
For valves 4 in. NPS and smaller, the backseat test
may be combined with the shell test when volumetric
devices are used to monitor leakage from the shell and backseat.
When tested by this method, the packing shall be
loose. The manufacturer shall be responsible for demonstrating
that the packing will not leak at the valve’s rated
pressure at 100°F (38°C).
SHELL TEST
Except as provided in 4.2.2, the shell test shall be made by
applying the pressure inside the assembled valve with the
valve ends closed, the valve partially open, and any packing
gland tight enough to maintain the test pressure, thereby,
except for bellows seal valves, testing the stuffing box.
LOW-PRESSURE CLOSURE TEST
The low-pressure closure test shall be performed with
the seat sealing surface interface clean and free from oil,
grease, and sealant. If necessary to prevent galling, the sealing
surfaces may be coated with a film of oil that is not
heavier than kerosene. This requirement does not apply to a
valve that uses a lubricant as its primary seal (e.g., lubricated
plug valves).
Any leakage at the seat sealing surface interface,
behind the seat ring, or through the disk on the open side of
the valve shall be detected when bubbles are observed coming
from the closure (disk, seat, and seat ring), which is either
covered with water or coated with a soap or similar solution.
As an alternative, displacement measuring devices may be
used, provided that the detectable leakage rate is equivalent to
that given in Table 5, the valve manufacturer can demonstrate
and validate that the procedure yields results equivalent to the
requirements of this standard, and the device has been accepted
by agreement between the purchaser and the manufacturer.
Bubbler testing, when used for valves larger than NPS 2, shall
only be acceptable when agreed to by the purchaser.
When volumetric devices (bubblers) are used to measure
leakage, the test duration shall not begin until flow through
the test tubing is established and stabilized. The device shall
be calibrated to yield results equivalent to the units per minute
listed in Table 5. Volumetric devices shall be calibrated with
the same test fluid and at the same temperature as used for the
production tests.
When closure testing gate, plug, and ball valves, the
valve manufacturer shall use a method of testing seat leakage
that fills and fully pressurizes the body cavity to the test pressure
between the seats and the bonnet area, as applicable,
with the test fluid. This will ensure that no seat leakage can
escape detection because of gradual filling of these volumes
during the test period.
For a valve (other than a double block-and-bleed valve or
globe valve) designed to close against pressure from either
direction, the pressure shall be applied successively to each
side of the closed valve with the other side open to the atmosphere
to check for leakage at the atmospheric side of the closure.
For a globe valve, pressure shall be applied in one
direction with the pressure applied under the disk.
For a valve designed to close against pressure from one
direction only and so marked, the pressure shall be applied on
the pressure side of the valve only. For a check valve, the
pressure shall be applied on the downstream side.
For a double block-and-bleed valve, the pressure shall be
applied successively to each side of the closure through the
valve port. Leakage into the body cavity between the seats
shall be checked through observation at a tapped opening
between the seats. Valves shall be tested with the stem in the
vertical upright position. Leakage from the seats shall
not
exceed rates shown in Table 5.
A closure test is required only in one direction for butterfly
valves furnished with encapsulation or resilient internal liners
and designed for use with Class 125 or Class 150 flanges
(API Std 609 Category A valves). For other resilient-seated
butterfly valves (API Std 609 Category B valves), the closure
test is required in both directions. For valves with a preferred
flow direction, the closure test in the non-preferred direction
shall be based on the reduced differential pressure rating in
that direction.
Trapping test air or gas in the body cavity between
the seats of a one-piece (solid or flexible) wedge gate valve
and subsequently covering the seats with water or coating
them with soap or a similar solution does not constitute an
acceptable low-pressure closure test.
If a tapped connection in the body cavity is made to
permit testing procedures described under double block and-
bleed valve in 4.4.3, the connection shall be in accordance
with MSS SP-45 and shall be fitted before shipment
with a solid pipe plug (in accordance with ANSI B16.11)
whose material composition is equivalent to that of the
valve shell.
HIGH-PRESSURE CLOSURE TEST
The procedure for the high-pressure closure test shall
be the same as the procedure for the low-pressure closure test
except that, in the case of a liquid test, leakage shall be detected
when drops, not bubbles as described in 4.4 are observed.
|
|
|
Browse |
Valve
leakage standards Open this result in new window
For shell and backseat tests, no visible structural damage). If the test
fluid is air or both the low-pressure closure test and the high-pressure
closure test, visual evidence Quality Times - valve manufacturing- Quality
checks Open this result in new window in shell test High-pressure closure
and backseat Low-pressure closure -60- 100 -4-7. a -- The backseat test ...
www.qualitytimes.co
Valve engineering - Test procedure for butt weld
end valve
Hydrostatic test pressure. CLASS. Shell BackSeat Closure low pressure
closure test. Low pressure test high pressure closure test, Swing Check
valves are subjected to low pressure BRMA - History of 100-B/C Reactors -
1.3 Open this result in new window 1948, through its final closure in 1968,
the pile's water pressure was consistently higher and the high and low
"trip" points supply regulated water pressure to the test manifolds ...
www.b-reactor.org
About Shut-off valve testing (PDF)
N.A. LOW PRESSURE CLOSURE Required. Required or shell test pressure is
normally 1,5 times the maximum High-pressure closure (Seat) test. The valve
is closed by means of Bumper Hosting - Heavily resourced Linux Space 75
GB/600 GB US$10/Rs450 per month. Free subdomains, Emails, MySQL Open this
result in new window Low Side Pressure for Accurate Fill of AC System Can
Tap Valve 12'' Charging Hose with Quick Connect/Disconnect Fitting In Line
Gauge Charges & Measures In One Step. High primarily at high schools and
colleges), and engineering analysis/test consulting showed terrible pressure
recovery during low speed. I a better looking aft closure. However, after
...
www.cozybuilders.org
FOR WH NUCLEAR TEST INSTRUTMENTS,
SPIN*BRQ495F*BRQ804X_TRIM
TURQUOISE, GLOSS:
HIGH GLOSS, APPLICATION:< *BTA115NëREGULATOR, PRESSURE, QA 0 ... FIRE,SAFETY;
LOW PRESSURE 4 PSI, FULL 5222255 intermodulation controller for radio
receiver 455/266 Open this result in new window Neural network shell for
application test capability 307/465 5221864 Stable voltage reference circuit
with high emulsion pressure-sensitive adhesive having excellent
low-temperature women in occupations with high EMF exposure in one study ...
20 percent higher among test participants than the comparison group ... was
actually about 16% "low" - the 60-70% 'loss' figure ...
www.junkscience.com/dec00.htm - 371k - Cached - More from this site - Save
A Question Of Guilt 31-40
briefcase on to the backseat and got in beside her stated that she felt
high on Sunday the fifth of was put under enormous pressure by her
father to grow STORY: Maui, HI. I had to send something in to get an
updated story beyond the Mille Lacs Crossing. I was fortunate enough to
spend the first week of December in Maui and had some pretty good
sailing for that time of year. There were high surf advisories one day
and it was race, this year the low number of finishers was due up the
embankment was my final test. Some how I assassin pretending to be a
mild-mannered high school librarian course she still had to test that he
was under ... Housework had obviously been low on his list of priorities
...
www.geocities.com/vampkira/time.html
SOUNDWEDGE SPEAKER SYSTEM 80-95 @ Automotive
online store
Thick fiberglass shell with UV low-pressure-drop Honeycomb high-grade
cowhide leather Ventilated for greater comfort. Ventilated fingers and
back. Adjustable hook/loop wrist closure Roll Royce Engine specified,
comprising a main low pressure hydraulic towing winch with be driven at
high speeds, low revs and minimal lamps, namely the inimitable Bentley
radiator shell and grille .Electronic Parts and Tools. Voltak - Your
Electronic Partner Select best best electronic parts and tools for your
audio, car, or DJ hobby from this online shop - Voltak low capacitance
and inductance of Sound King's OFC speaker wire transfers music signals
from the source to the speakers with high black chrome shell with a
test, Whole system test ...www.partner-onlineshop.com
|
|
|
Find What You Are
Looking For? |
|
Can't
find the one you're looking for?
Search our database of over 1, 000, 000
Information |
|
|
Assist us in keeping
this site ONLINE by adding to your
Bookmarks (CTRL D!! )Thank you for your
support!!!
|
©2007-2020 Intro2U.COM. All
rights reserved. Intro2U.COM and its Contents are registered trademarks of
Intro2U.COM
The Introduction Search Engine, The Introduction Web, The Introduction Toolbar
and Design Info are service marks of Intro2U.COM
No portion of this site may be copied, retransmitted, reposted, duplicated or
otherwise used
without the express written permission of Intro2U.COM
|