Masoneilan 525 Double-Seated Pressure Reducing Regulator
Overview
The Masoneilan 525 is the pressure reducing model of the 525/526 double-seated regulator pair from Baker Hughes. In the numbering system the first digit 5 is the regulator type, the second digit 2 is the double-seated body and the third digit 5 marks reducing service, so the Masoneilan 525 holds a steady pressure downstream of itself while the supply pressure and the demand change. Its high-capacity globe body, top and bottom guided plug and 10900 spring-diaphragm actuator are chosen for steam let-down stations, boiler feed and process water lines, and gas headers that need rated Cv anywhere from 3.6 to 125.
Seven Star LLC, a trusted supplier of Masoneilan products for Oman and the GCC, handles Masoneilan 525 enquiries from utilities managers, EPC contractors and plant maintenance teams. From Muscat our instrumentation specialists match body size, trim number, actuator case and spring range to your steam, gas or water data, and attach the Baker Hughes technical specification and instruction manual to each quotation. The 525-50 differential model and the extension bonnet (EB) for hot service share the same documents.
Reducing Operation of the Masoneilan 525
The Masoneilan 525 is a direct-operated regulator that controls the downstream pressure. The controlled pressure is piped from a point six to ten feet from the regulator, or from the discharge line near the pump on pump pressure applications, to the 1/2 inch NPT connection in the diaphragm case. A gauge and a needle valve go into that line, and the needle valve also serves as a choke against cycling from pump pulsation. The actuator spring holds the plug open; when downstream pressure rises above the set point the diaphragm pushes the plug toward its seats and throttles the flow, and when the downstream pressure falls the spring opens the plug again.
The set pressure is chosen at the factory, or if none is specified it is left at the bottom of the range shown on the serial plate. To raise it the adjusting screw is turned clockwise to compress the spring, and counter-clockwise to lower it. During start-up the outlet stop valve is opened first and the inlet stop valve is opened partly so that pressure builds slowly while the setting is checked on the gauge. On steam service the Masoneilan 525 is mounted with the diaphragm actuator below the body so that a water seal protects the diaphragm, and a three-valve bypass is recommended so that the regulator can be removed without interrupting the line.
Engineering Design of the Masoneilan 525
The Masoneilan 525 uses a contoured disc plug with an upper and a lower threaded seat ring. The two seats are balanced by the guide bushings in the bonnet and the blind head, so the plug is supported at both ends, which gives it stability against side loads. Standard shutoff is Class II leakage. The plug and seat rings are 316 stainless steel, with a hardfaced 316 option, and the bonnet has carbon-core PTFE jacketed packing with an optional lantern ring for a leak detection or lubricator connection. The bonnet is fastened with body studs and a spiral-wound 316L and graphite gasket that must be replaced at every overhaul.
A feature specific to the reducing model is the maintenance route: the manual describes removing the bonnet together with the plug stem and plug as one unit from the top of the body, and then inspecting the bushing, plug and seat rings. Plug and stem are pinned together, and if a plug is replaced the stem should be replaced as well, because the original pin hole does not give the correct fit. The manual shows the pin hole sizes for stems of 1/2, 5/8, 3/4 and 1 inch.
Key Features
The following points explain why the Masoneilan 525 is specified for reducing duty:
- Double-seated, top and bottom guided plug gives a large flow capacity through a compact body.
- Rated Cv values of 3.6 to 125 are available in seven body sizes from 3/4 to 4 inch.
- Full-area and reduced-capacity (0.4 factor) trims allow the regulator to be matched to the flow.
- Actuator spring ranges from 0.5-2 psi to 400-750 psi cover low-pressure air to high-pressure steam let-down.
- An extension bonnet keeps the diaphragm cooler on service above 450°F (232°C).
- Threaded or socket weld ends in sizes up to 2 inch, and flanged ends in ASME 150, 300 and 600 or equivalent PN ratings.
- Lapping and pinning procedures in the manual allow the seats to be reconditioned in a workshop.
- The estimated useful life is more than 25 years with annual inspection.
Industrial Applications
The Masoneilan 525 is typically fitted on steam header let-down to process users, on compressed air and nitrogen headers, on pump discharge and boiler feed lines that need a constant pressure, and on lube oil or fuel oil circuits. In Oman these needs are present at district cooling plants and hospitals in Muscat, desalination and power plants on the Batinah coast, refineries and the manufacturing zones of Sohar and Salalah, where a self-acting regulator with a simple maintenance routine is a sound alternative to a full control valve loop.
In Oman and the GCC, Seven Star LLC supplies the Masoneilan 525 with the 525/526 family page and the Masoneilan 10000 Series double port valve for instrumented control. When a back-pressure duty is needed on the same body we can supply the 526 version, and the two share spare parts such as seat rings, packing and gaskets.
Technical Specifications
The tables below collect data of the Masoneilan 525 from the 525/526 technical specification. Please consult the datasheet for the complete capacity and sizing tables.
| Parameter | Specification |
|---|---|
| Model | Masoneilan 525 pressure reducing (525-50 differential reducing; EB extended bonnet option) |
| Service | Steam, gas, liquids |
| Body | Double-seated high-capacity globe; plug guided at top and bottom |
| Characteristic and trim | Quick-opening disc plug on threaded seat rings; full area or reduced-capacity trim |
| Flanges | Flanged ASME 150, 300 or 600, with ISO PN 20/50/100 or EN PN 16/25/40 equivalents |
| Threaded and socket weld | Sizes up to 2 inch |
| Actuator | 10900 Series spring-diaphragm |
| Seat leakage | Class II (manual) |
Rated Cv, face to face and weight by body size
| Size | Rated Cv options | Face to face, Class 150 RF | Body weight, threaded / Class 150 flanged |
|---|---|---|---|
| 3/4 in. (20 mm) | 3.6, 6 | 7.25 in. (184 mm) | 18 / 36 kg |
| 1 in. (25 mm) | 3.6, 6, 9 | 7.25 in. (184 mm) | 20 / 39 kg |
| 1-1/2 in. (40 mm) | 8.4, 14, 21 | 8.75 in. (222 mm) | 20 / 48 kg |
| 2 in. (50 mm) | 14.4, 21, 36 | 10.00 in. (254 mm) | 23 / 68 kg |
| 2-1/2 in. (65 mm) | 21, 36, 54 | 10.87 in. (276 mm) | – / 79 kg |
| 3 in. (80 mm) | 30, 54, 75 | 11.75 in. (298 mm) | 50 / 111 kg |
| 4 in. (100 mm) | 50, 75, 125 | 13.88 in. (353 mm) | 87 / 138 kg |
Saturated steam capacity of the Masoneilan 525 at 50 psig inlet and 30 psig outlet is 605 lb/hr with Cv 6, 2100 lb/hr with Cv 21 and 12500 lb/hr with Cv 125, and at 100 psig inlet and 60 psig outlet it is 1100, 3850 and 23000 lb/hr for the same Cv values. With the 3-1/2 inch actuator in the 150-450, 150-300 or 400-750 psi ranges the Cv is limited to 60 percent of the nominal value.
Related Masoneilan regulators include the Masoneilan 526 back pressure regulator, Masoneilan 525-526 Series family page and Masoneilan 535H pressure reducing regulator.
Request a Quote for Masoneilan 525
Send your RFQ for the Masoneilan 525 to the Seven Star LLC instrumentation division in Muscat, quoting fluid, inlet pressure, outlet set point, flow, body size and end connection. We return a confirmed Cv, actuator and spring range, the stock position in our regional warehouse, and the Masoneilan 525 datasheet and instruction manual from Baker Hughes, which can also be downloaded from this page. Seven Star LLC acts as a trusted supplier of Masoneilan products across Oman and the GCC.
Masoneilan control valves and actuator series
The globe valve listing centers on the 21000 series, including the cryogenic version with extension bonnet, and the 41005 cage-guided series in high pressure, API 6A and VRT anti-cavitation executions. The 80385 and 80386 are three-way combining and diverting valves. Rotary products include the 35002 Camflex II and the 37002 MiniTork II butterfly control valve. Actuators cover spring-diaphragm, cylinder and rack-and-pinion designs, among them the 5A cylinder actuator for Camflex II. Masoneilan also makes pressure regulators, SVI digital valve positioners and displacer-type level instruments, and offers Lo-dB trim for noise control.Where Masoneilan valves are used
Throttling duty on steam, hydrocarbons, gas and water is the daily work of these valves: feedwater and steam conditioning in power plants, separator and compressor loops in gas processing, high pressure drop letdown, cryogenic service in LNG and air separation, and general flow, pressure and level control in refineries and chemical plants.Ordering Masoneilan valves and spare parts: what we need
For spare parts the serial number is decisive, since the factory record behind it lists trim, materials and actuator. Send a clear nameplate photo with serial number, model number, size and pressure class. For a new valve add the process data: fluid, inlet and outlet pressure, temperature, minimum, normal and maximum flow, required leakage class, fail position, air supply and control signal.Browse Masoneilan products by category: Control Valves, Valve Actuator, Regulators, Valve Positioner, Level Transmitter.
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