e. (iii) Test liquid valves on room temperature
water and check for leakage. If the valve
is tight, testing is complete. If not, check
the valve leakage on elevated temperature
water between 201°F - 500ºF
(94°C - 260°C).
Note: No need to pop the valve on elevated
temperature water.
1.
Main Valve equipped with metal seats and air as
test media.
a. An initial leakage test of the Main Valve shall
be made using a piece of wet paper placed
over the outlet of the valve for one minute with
pressure held at 4% below valve set pressure
or 2 psig (0.14 barg), whichever is greater.
b. If leakage from Main Valve is indicated by a
bulging of the wet paper, the standard test
fixture (as described in 3.c shall be installed
on the outlet flange to determine the extent of
the leakage. The test fixture is to be connected
to the valve outlet in such a manner that no
leakage may occur in the connection.
c. Per API standard 527 (ANSI B147.1-72) a
standard test fixture consists of a piece of
tubing 5/16” OD (8 mm) x .032” (0.8 mm) wall,
where one end is joined to an adaptor on the
valve outlet and other end is immersed .500”
(12.7 mm) below the surface of a reservoir of
water.
D. Troubleshooting Leakage
1. To isolate leakage that may be coming from the
pilot, disconnect the pilot vent line (if applicable)
from the main base outlet and plug the main valve
outlet connection. If wet paper still bulges, then
leakage is occurring from main valve.
2. Leakage from main valve can come from either
the main valve seat, nozzle seal or dome seal. To
determine if the leakage is from either the main valve
seat or nozzle seal, the outlet must be filled to above
the seat line and checked for bubbles. If no bubbles
are present, then leakage is either coming from the
dome seal.
3.
The leakage rate shall be determined with the valve
mounted vertically and using a standard test fixture
as described in 3.c in Section XX.C. The leakage
rate in bubbles per minute shall be determined with
pressure held at 4% below valve set pressure or
2 psig (0.14 barg), whichever is greater. The test
pressure shall be applied for 1 minute for valves
of inlet sizes through 2” (50.8 mm); 2 minutes for
sizes 2.5” (63.5 mm), 3” (76.2 mm) & 4” (101.6 mm);
5 minutes for sizes 6” (152.4 mm) and 8” (203.2
mm).
4. The leakage rate in bubbles per minute shall not
exceed the values in Table 16.
Figure 68: with Optional Line Filter
Table 16: Leakage Rate
Set
Pressure
at 60°F
(15.6°C)
Effective Orifice
Sizes ≤ 0.307 in2
(1.981 cm2)
D & E Orifice Only
Effective Orifice
Sizes > 0.307 in2
(1.981 cm2)
F Orifice & Larger
Approximate
Leakage per 24
Hours
Approximate
Leakage per 24
Hours
psig barg
Bubbles
per
minute
Standard
Cubic
Feet
Bubbles
per
minute
Standard
Cubic
Feet
15-
1000
1.03-
68.95
40
0.60
20
0.30
1500 103.42
60
0.90
30
0.45
2000 137.90
80
1.20
40
0.60
2500 172.37
100
1.50
50
0.75
3000 206.84
100
1.50
60
0.90
4000 275.79
100
1.50
80
1.20
5000 344.74
100
1.50
100
1.50
6000 413.69
100
1.50
100
1.50
XX. Setting and Testing (Cont.)
78 |
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