Anderson Greenwood Series 800 High Pressure Modulating Pilot Operated Relief Valve

Overview

The Anderson Greenwood Series 800 is Emerson’s high pressure member of the Anderson Greenwood pilot operated relief valve family. Its non-flowing, modulating pilot can be set from 1,481 to 6,170 psig (102.13 to 425.52 barg), with pressures up to 7,600 psig (524 barg) available on request, on ANSI Class 900 to 2500 inlets. Emerson calls it the most advanced design in its pilot operated range: pilot and main valve stay tight up to 98 percent of set pressure, and the main valve lifts only in proportion to the relief demand. The Anderson Greenwood Series 800 can be used on liquids, gases and mixed phase fluids, including dirty and wet services, and Emerson notes that its pilot trim gives stable lift even on hard, liquid filled systems.

Seven Star LLC supplies the Anderson Greenwood Series 800 to operators of high pressure wells, gas injection and gas lift systems, high pressure pump discharges and pipeline facilities in the Sultanate of Oman and across the GCC. Our Muscat team supports selection, documentation and spare soft goods, and we provide model selection support from Muscat.

Working Principle of the Anderson Greenwood Series 800

At zero system pressure the pilot inlet seat is open and the outlet seat closed. Process pressure enters the pilot through a filter screen, travels through the feedback piston and past the inlet seat into the main valve dome, where it holds the piston on its seat. In the Anderson Greenwood Series 800 the sensing element is an O-ring sense seal rather than a diaphragm, which suits the very high set pressures. As pressure approaches set, it pushes the sense seal and feedback piston upward until the inlet seat closes; with the outlet seat also closed, dome pressure is trapped and there is no pilot flow at any stable inlet pressure.

A small further increase in pressure opens the outlet seat and partly vents the dome. The lower dome pressure acts on the unbalanced feedback piston, reducing its lift and tending to lock in the new dome pressure. Above set pressure, the spool and feedback piston combination moves back and forth to raise or lower dome pressure, positioning the main valve piston at exactly the lift that keeps system pressure constant at the required flow; full lift is reached with relatively little overpressure. When pressure decays below set, the feedback piston opens the inlet seat, the dome repressurises and the valve closes. Pilot exhaust is routed to the main valve outlet.

Design Advantages at High Pressure

Emerson’s datasheet compares pilot operated and spring loaded valves of the same size. For a 4P6 valve, the maximum set pressure listed for a direct spring operated valve is 1000 psig (69 barg), while the Anderson Greenwood pilot operated valve reaches 3705 psig (255.5 barg) and above; for a 3K4 valve the figures are 2220 psig against 3705 psig. Because no spring holds the seat closed, the pilot valve is shorter and lighter, and the datasheet cites height savings of around 40% and weight savings of up to 45% on selected sizes. In a high pressure service these savings make the Anderson Greenwood Series 800 easier to install and support, especially offshore and on compact skids.

The balanced main valve of the Anderson Greenwood Series 800 is not affected by back pressure, so there is no bellows to fail, and soft seats reseal tightly after each relief cycle. Main valve nozzles can be replaced in the field, and lettered orifice valves follow API 526 dimensions, with API 526 direct spring center-to-face dimensions available to replace an existing spring valve without piping changes.

Key Features

The Emerson datasheet lists these features for the Anderson Greenwood Series 800:

• Total valve tightness to 98% of set pressure, so the system can operate close to set without leakage.
• Modulating action that relieves only the required flow, reducing product loss, emissions and noise.
• Balanced design with lift unaffected by back pressure.
• Field test capability with set point indication, allowing in-service checks without an isolation block valve.
• Non-flowing pilot that minimises entry of dirt and hydrate formation in dirty or wet service.
• Rugged bracket pilot mounting and a single, accurate set pressure adjustment.
• ASME Section VIII and XIII (UV designator) code stamp for gas and liquid service and CE mark to PED 2014/68/EU.
• Full nozzle main valve available as an option.

Industrial Applications

Typical duties for the Anderson Greenwood Series 800 are found wherever set pressures exceed the reach of the Series 400: wellhead and flowline protection, high pressure separators, gas injection and reinjection compressors, water injection and pipeline pump discharges, and chemical injection packages. Oman’s enhanced oil recovery projects, sour gas developments and high pressure gas fields all contain relief cases in the Class 900 to 2500 range where modulating action limits flaring.

Seven Star LLC supplies the Anderson Greenwood Series 800 and replacement soft goods for these applications to operators and contractors in Muscat, Sohar, Duqm and Salalah and throughout the GCC.

Accessories and Materials

Optional accessories for the Anderson Greenwood Series 800 include a field test connection with indicator, backflow preventer, pilot supply filter, pressure spike snubber for gas, remote pressure sense connection, remote valve lift indicator, manual unloader, pilot lift lever, remote unloader and NACE trim (MR0175/ISO 15156:2002, which the ordering guide lists as standard for this series). Anderson Greenwood Series 800 main valve material codes include CS body with SS trim, stainless steel, low temperature CS, duplex and super duplex.

Selection Notes (General)

The following is general guidance rather than manufacturer data. Confirm the set pressure and inlet rating, calculate the orifice area for each relief case, and remember that the Series 800 is offered from 1 in. x 2 in. to 4 in. x 6 in. with orifices up to 9.489 in2, so very large capacities may need multiple valves. For any Anderson Greenwood Series 800, select soft goods to suit the fluid, temperature and any explosive decompression risk in high pressure gas.

Technical Specifications

Main data for the Anderson Greenwood Series 800 from Emerson datasheet VCTDS-00543:

How to Order

To receive a quotation for the Anderson Greenwood Series 800, send Seven Star LLC the fluid, relieving capacity, set and back pressures, temperature, inlet and outlet ratings and any NACE or material requirements. The Emerson datasheet is available for download on this page. For other relief duties, see the Anderson Greenwood Series 90/9000 relief valve, the LESER Type 457/458 high pressure safety valve and the Crosby JBS-E SIL 3 capable relief valve. Seven Star LLC provides model selection support from Muscat for customers in Oman and the GCC.