SAMSON Type 3251 Globe Control Valve
Overview
The SAMSON Type 3251 is the globe valve at the heart of SAMSON’s Series 250, a control valve range intended for process engineering applications with high industrial requirements. It covers nominal sizes from DN 15 to DN 500, pressure ratings from PN 16 up to PN 400 and process temperatures from –196 °C to +550 °C, which places it a clear step above general-purpose valves in terms of pressure, temperature and material options. Combined with a SAMSON Type 3271 actuator it becomes the Type 3251-1 control valve; with a Type 3277 actuator for integral positioner attachment it becomes the Type 3251-7.
Seven Star LLC supplies the SAMSON Type 3251 to oil and gas, petrochemical, power and water projects throughout the Sultanate of Oman and the GCC. As a trusted supplier with engineering support in Muscat, we work with process engineers on valve sizing inputs, trim selection and actuator matching so the quoted assembly suits the real service conditions.
Operating Principle
In the SAMSON Type 3251, the medium flows through the valve in the direction indicated by the arrow on the body. A rise in signal pressure increases the force on the actuator diaphragm and compresses the springs. Depending on the selected direction of action, the actuator stem then retracts or extends, changing the position of the plug in the seat. The free flow area between plug and seat determines the flow rate through the valve and, with it, the downstream pressure p2.
When high pressures or differential pressures act on the plug, an optional pressure-balanced plug reduces the force the actuator must provide. Depending on how the springs are arranged in the Type 3271 or Type 3277 actuator, the valve takes one of two fail-safe positions on loss of air: actuator stem extends (fail-close), where the valve closes, or actuator stem retracts (fail-open), where the valve opens. Flow characteristics are equal percentage, linear or on/off, with a rangeability of 50:1.
Engineering Design of the SAMSON Type 3251
The body of the SAMSON Type 3251 is available in cast steel 1.0619, high-temperature cast steel 1.7357, cast stainless steel 1.4408 and special materials, while the Type 3251-AM variant uses additively manufactured stainless steel 1.4401/1.4404 for DN 15 to 80. End connections are flanges in all DIN EN versions or welding ends according to DIN EN 12627, and an ANSI version is described in data sheet T 8052. The plug can be metal-sealed, soft-sealed up to PN 40 or fitted with a high-performance metal seal, and low-noise plug designs are available.
For extreme temperatures or hazardous media, the valve can be fitted with an insulating section or a metal bellows seal; the bellows version includes a test connection to monitor the corrosion-resistant bellows. Noise can be reduced with flow divider ST 1 or AC-1/AC-3 trims, and a perforated plug, heating jacket and additional handwheel are also offered. The standard bonnet uses a PTFE V-ring packing for –10 to +220 °C or an adjustable high-temperature packing up to +350 °C, and optional RFID tags provide unique identification according to DIN SPEC 91406.
Key Features
The SAMSON Type 3251 offers a broad specification envelope for severe service:
- Nominal sizes from DN 15 to DN 500 with pressure ratings from PN 16 to PN 400.
- Temperature capability from –196 °C to +550 °C depending on body material and bonnet.
- Metal, soft and high-performance metal seat-plug seals, with leakage class IV, V or VI.
- Pressure-balanced plug option with PTFE or graphite seal ring for high differential pressures.
- Insulating section or metal bellows seal with test connection for cryogenic, hot or hazardous media.
- Noise-reducing flow divider, AC-1/AC-3 trims and perforated plug designs.
- Modular design that accepts positioners, limit switches and solenoid valves to IEC 60534-6-1 and NAMUR.
- Pneumatic operation with Type 3271 or Type 3277 actuators, and an electric Type 3251-2 version on request.
Industrial Applications
The SAMSON Type 3251 is specified in refineries, gas processing plants and petrochemical complexes for high-pressure letdown, hydrocarbon feed control, steam and condensate service and hot oil circuits. Its bellows seal and insulating section options suit cryogenic and toxic media, while the high pressure classes are relevant for boiler feedwater, high-pressure steam and injection systems in power generation.
In the Gulf region the SAMSON Type 3251 is also a candidate for desalination, district cooling and industrial utilities where long service life and tight shut-off matter. Seven Star LLC supports operators and EPC contractors in Muscat, Sohar and Salalah with documentation, material selection guidance and coordinated delivery of the valve, actuator and positioner as one assembly.
Technical Specifications
The SAMSON Type 3251 data below is summarized from SAMSON data sheet T 8051 EN (DIN version).
| Parameter | Specification |
|---|---|
| Model | SAMSON Type 3251 (Type 3251-1 / 3251-7 control valve) |
| Nominal size | DN 15 to 500 (Type 3251-AM: DN 15 to 80); ANSI version NPS per T 8052 |
| Pressure rating | PN 16 to 400 (DN 400: PN 16 to 63; DN 500: PN 16 to 40) |
| Temperature range | –196 to +550 °C depending on body material and bonnet |
| Body materials | Cast steel 1.0619, cast steel 1.7357, cast stainless steel 1.4408, special materials |
| End connections | DIN EN flanges; welding ends to DIN EN 12627 |
| Seat-plug seal | Metal, soft (up to PN 40), high-performance metal |
| Leakage class (DIN EN 60534-4) | IV (metal), V (high-performance metal), VI (soft seal) |
| Characteristic / rangeability | Equal percentage, linear, on/off / 50:1 |
| Packing | PTFE V-ring (–10 to +220 °C); high-temperature packing up to +350 °C |
| Options | Pressure balancing, bellows seal, insulating section, flow divider, heating jacket, RFID tag |
| Actuators | SAMSON Type 3271 or Type 3277 pneumatic actuator |
How to Order
For a formal RFQ on the SAMSON Type 3251, send Seven Star LLC your process data sheet with medium, flow rates, pressures, temperature and required leakage class. Our instrumentation division in Muscat can share the technical datasheet for download, confirm availability and lead time and quote complete assemblies including the SAMSON Type 3271 pneumatic actuator and the Samson 3730-3 HART positioner. For lower pressure duties, compare it with the SAMSON Type 3241 globe control valve. We deliver across Oman and the GCC with engineering support throughout the project.
Samson valve, actuator and positioner types
Samson builds a control valve from modules. The Type 3241 globe valve is the general-service body of Series 240, and the Type 3251 is the Series 250 body for higher pressure ratings. Either one is combined with a Type 3271 pneumatic diaphragm actuator or a Type 3277, whose yoke allows the positioner to be attached directly with a concealed travel linkage. The positioners listed are the Type 3725 and the Type 3730 family: the 3730-1 as the basic electropneumatic version, sold in its current generation as TROVIS 3730-1, and the 3730-3 with HART communication and valve diagnostics. Samson also makes PROFIBUS PA and FOUNDATION fieldbus variants in the same family, plus self-operated pressure and temperature regulators.Where Samson valves are used
Samson control valves throttle steam, gas and liquids in chemical and petrochemical units, refineries, gas processing, power stations, water and desalination plants, and food production. Many reach site as part of a skid or package, so the plant instrument team often meets them first when a positioner or actuator needs replacing. We supply these items to end users and contractors throughout the GCC.Ordering Samson parts: what we need
Every Samson device has a nameplate with the type, a configuration ID (Var-ID) and a serial number. A photo of that plate is the surest route to an exact match. Without it, please send:- Valve: type, DN or NPS, pressure rating, body and trim material, Kvs or Cv, plug and seat style, packing and bonnet type
- Actuator: type, effective area in cm², bench range, fail action and travel
- Positioner: full type code including Ex protection, communication and options such as limit switches or position transmitter
Browse Samson products by category: Control Valves, Valve Positioner, Valve Actuator.
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