Reasons For Failure; Troubleshooting Leakage - Baker Hughes Consolidated 4900 Series Instruction Manual

XIX. Setting and Testing (Cont.)
D.3 Reasons for failure:
1. Any leakage from Pilot at 4% below valve set
pressure or 2 psig (0.14 psig), whichever is
greater. The 49MV22 and 49MV72 may have
50 bubbles per minute at 5% below the set
pressures at or above 2251 psig (155.2 barg)
and none at pressures below 2250 psig (155.1
barg).
2. Main Valve equipped with soft seats.
a. For Main Valve equipped with 49MV22 and
49MV72, no leakage (0 bpm) is acceptable at
5% below valve set pressure or 2 psig (0.14
barg), whichever is greater. For set pressures
2250 psig (155.1 barg) and above, 50 bpm is
acceptable for both Pilot and Main Valve.
b. For all other valve types, no leakage (0 bpm)
is acceptable at 4% below valve set pressure
or 2 psig (0.14 psig), whichever if greater.
3. 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 (Section XIX.D.3)
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.
Set Pressure at 60°F
(15.6°C)
psig barg
15-1000 1.03-68.95
1500 103.42
2000 137.90
2500 172.37
3000 206.84
4000 275.79
5000 344.74
6000 413.69
© 2020 Baker Hughes Company. All rights reserved.
Table 7: Standard Leakage Rates
Effective Orifice Sizes (0.307 in2 (1.981 cm2)
and Smaller) D and E Orifice Only
Leakage Rate (Bubbles
per minute)
40 0.60
60 0.90
80 1.20
100 1.50
100 1.50
100 1.50
100 1.50
100 1.50
c. Per API standard 527 (ANSI B147.1-72), a
standard test fixture consists of a piece of
tubing .313" OD (7.94 mm) x 0.032" (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.
E. 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 with water to above the seat line and
checked for bubbles. If no bubbles are present,
then leakage is 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 (Section XIX D.3).
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 in. 2
minutes for sizes 2.5" (63.50 mm), 3" (76.20 mm)
& 4" (101.60 mm) ; 5" (127.00 mm) minutes for
sizes 6" (152.40 mm) and 8" (203.20 mm).
4. The leakage rate in bubbles per minute shall not
exceed the Table 7 values.
Approximate Leakage per 24 Hours
Effective Orifice Sizes Larger than 0.307 in2
(1.981 cm2) F Orifice and Larger
Leakage Rate (Bubbles
ft m
3 3
per minute)
0.02
0.03
0.03
0.04
0.04
0.04
0.04
0.04
Consolidated 4900 MPV Series POSRV Manual
ft
3
20 0.30
30 0.45
40 0.60
50 0.75
60 0.90
80 1.20
100 1.50
100 1.50
m
3
0.01
0.01
0.02
0.02
0.03
0.03
0.04
0.04
| 67