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Brand
Anderson Greenwood
Anderson Greenwood is the Houston-born brand that brought pilot-operated pressure relief valves to the oil industry. It was founded in 1947 and today belongs to Emerson, together with Crosby, as part of its pressure relief valve range. Seven Star LLC is an independent supplier in Muscat. We source Anderson Greenwood pilot-operated relief valves, pilots, soft goods kits and spares for plants in Oman and the GCC, against the valve’s full model number and nameplate data.
Read the full brand profile- 4 products
- 1 category
Brand profile
About Anderson Greenwood
- Founded
- 1947
- Speciality
- Pressure relief valves
- Listed with us
- 4 products
Anderson Greenwood products by category
Anderson Greenwood is the Houston-born brand that brought pilot-operated pressure relief valves to the oil industry. It was founded in 1947 and today belongs to Emerson, together with Crosby, as part of its pressure relief valve range.
Seven Star LLC is an independent supplier in Muscat. We source Anderson Greenwood pilot-operated relief valves, pilots, soft goods kits and spares for plants in Oman and the GCC, against the valve’s full model number and nameplate data.
Anderson Greenwood company profile
| Established | 1947, Houston, Texas, USA, by Ben Anderson, Marvin Greenwood and Lomis Slaughter Jr. |
|---|---|
| Known for | Pilot-operated safety relief valves, developed in the late 1950s and sold to the oil industry from the early 1960s |
| Ownership history | Keystone International (1986), merged with Crosby. Tyco Flow Control (1997), then Pentair (2012). Emerson since 2017. |
| Product families | Pilot-operated pressure relief valves (pop action and modulating), low-pressure and tank relief valves, instrument valves and manifolds |
| Industries | Oil and gas production, gas processing, pipelines, refining, petrochemical, LNG and power |
Milestones
- 1947: Ben Anderson, Marvin Greenwood and Lomis Slaughter Jr. found the company in Houston.
- Late 1950s: Pilot-operated safety relief valves are developed, and sold to the oil industry from the early 1960s.
- 1986: Keystone International acquires the company; it is later combined with Crosby.
- 1997: Becomes part of Tyco Flow Control.
- 2012: Pentair takes over Tyco's flow control business.
- 2017: Anderson Greenwood becomes an Emerson brand.
Anderson Greenwood relief valve series
| Series | Type | Key features |
|---|---|---|
| Series 200 | Pop action pilot-operated safety valve | Full lift at set pressure with no main valve throttling, which helps prevent freeze-ups in cryogenic and refrigerant service |
| Series 400 | Modulating pilot-operated relief valve | Opens only as far as needed to relieve the overpressure, which cuts product loss on each relief event |
| Series 800 | High-pressure modulating pilot-operated relief valve | For high-pressure gas and liquid service |
| Series 90/9000 | Pressure relief valve | Pilot-operated relief for process and storage applications |
In a pilot-operated valve, system pressure holds the main valve closed and a small pilot decides when to open it. The seat stays tight up to set pressure, so the valve can run closer to set pressure than a spring valve. Because the design is balanced, back pressure does not change the lift. Soft seats give bubble-tight shut-off, and metal seats are used for high-temperature service. API 526 centre-to-face dimensions are available for the Series 200, 400, 500 and 800, so these valves can replace a spring-loaded valve without piping changes.
Where Anderson Greenwood valves are used
In Oman and the GCC, Anderson Greenwood pilot-operated valves protect separators, compressor stations, pipelines, gas plant vessels, LNG and refrigeration systems and storage tanks. Plants mostly order like-for-like replacements, pilots and soft goods kits for planned recertification.
Ordering: what we need
Send the full model number from the nameplate, the set pressure, inlet and outlet size and rating, the orifice, the body, trim and seat materials, the service fluid and temperature, the back pressure, and whether the valve needs a field test connection, a backflow preventer or a remote sense line. For a soft goods kit, the model number and serial number are usually enough.
Facts checked against Emerson Anderson Greenwood product pages and published company history, October 2026.
Request a Quote for Anderson Greenwood Products
Looking for Anderson Greenwood parts not listed here, or pricing for a project? Send us the part numbers and quantities. Seven Star LLC sources genuine Anderson Greenwood products for customers across Oman and the GCC and replies with a formal quotation.
- Genuine OEM products
- Supply across Oman & the GCC
- Formal quotation from our sales team
Free, no-obligation quotation · takes about 1 minute
Other enquiries: [email protected] · WhatsApp
FAQ
Questions about Anderson Greenwood
Common questions about Anderson Greenwood equipment, part numbers and supply to Oman and the GCC.
01How do I identify an Anderson Greenwood Series 90 or 9000 valve from its nameplate?
The nameplate carries the model number, serial number, set pressure, orifice or size and the capacity. The model number encodes the series, pilot type, connection sizes and materials, so please send it complete, or send a clear nameplate photo. With the serial number the manufacturer can trace the original build, which is the safest basis for a like-for-like replacement or a soft goods kit.
02Where are Series 90/9000 pilot-operated valves normally used?
They are low-pressure pilot-operated relief valves, so the typical duty is tank and vessel protection: low-pressure storage tanks, vessels and low-pressure piping systems. A pilot-operated design stays tight close to set pressure, which reduces product loss compared with a weight-loaded vent. Suitability for your case must be checked against the manufacturer's sizing data.
03Who owns Anderson Greenwood today?
Anderson Greenwood was established in 1947 in Houston, Texas, by Ben Anderson, Marvin Greenwood and Lomis Slaughter Jr. It passed through Keystone International, Tyco Flow Control and Pentair, and has been part of Emerson since 2017.
04Is Seven Star LLC a distributor of Anderson Greenwood?
No. Seven Star LLC is an independent supplier and is not an authorized distributor or agent of Anderson Greenwood. We source Anderson Greenwood valves and parts through commercial channels, check the model number against the manufacturer's documentation, and provide the manufacturer's datasheet and the certificates the manufacturer issues with the order, on request.
05What should I send to get a quotation for an Anderson Greenwood relief valve?
Send the model and serial number, set pressure and vacuum setting, fluid and relieving temperature, required capacity, back pressure, inlet and outlet size and flange rating, materials, and the design code. If you only need spare parts, the serial number and a list of the parts or kit are enough for us to check the correct items with the manufacturer's documents.