Swagelok 50 Series Lift Check Valve, 316 SS, to 900 F

Swagelok 50 series lift check valve for high-temperature and high-pressure lines

The Swagelok 50 series is a lift check valve that stops reverse flow in gas or liquid lines up to 6,000 psig (413 bar) and up to 900 °F (482 °C). It has no spring and no elastomer: a metal poppet is lifted by forward flow and drops back onto a metal seat under gravity and reverse pressure. That makes it a very different product from the spring-loaded poppet check valves of the C, CP and CH series that are already listed on this site, and it is selected specifically where temperatures are too high for seals or where an elastomer-free path is required. Seven Star LLC supplies Swagelok 50 series check valves in Oman and the GCC as an independent supplier in Muscat.

Three body sizes carry the 50 series name: the 53, 56 and 58. They share the same construction and differ in orifice and flow capacity, matched to 1/4, 3/8 and 1/2 or 3/4 in. connections.

Working principle and installation orientation of the 50 series

Forward flow pushes the poppet up off the orifice and the valve opens. When the flow stops or reverses, gravity and the reverse pressure return the poppet to the seat and the valve closes. Because nothing holds the poppet down except its own weight and reverse pressure, the valve is described as gravity assisted, and the catalog requires it to be mounted horizontally with the bonnet nut on top. In a vertical line the valve will not seat reliably and should not be used.

The union-bonnet design allows the bonnet to be removed for inspection without taking the body out of the line, and the compact size suits instrument and sampling pipework. Reverse leakage is expressed through the reverse flow coefficient, which the catalog gives as less than 0.1 percent of the forward coefficient, so this is a flow-limiting check rather than a bubble-tight shutoff.

• Rugged all-stainless construction.
• No springs or elastomers to age, relax or swell in hot service.
• Compact body and union bonnet.
• Not suitable for vertical mounting or for service that needs positive shutoff.

Pressure-temperature ratings of the 50 series

The ratings follow ASME class 2500 for 316 SS. The catalog table shows how working pressure decreases with temperature.

Valves with tube fitting ends are further limited by the tube pressure ratings in the Swagelok tubing data catalog, so the system rating is the lowest of the valve, tube and fitting ratings.

Models, sizes and ordering numbers

Other combinations include 6 mm metric tube fittings, 1/8 in. female NPT, mixed tube fitting and female NPT, and tube socket weld or pipe butt weld ends. The length of a 53 series valve with 1/4 in. tube fittings is 2.40 in. (61.0 mm).

Special options: sour gas and special cleaning

For sour gas service the 50 series check valves can be supplied with materials selected in accordance with NACE MR0175 / ISO 15156, in which the poppet is alloy 400 (ASTM B164) and the other materials are unchanged. The rated pressure at 70 °F for this option is 6,000 psig (413 bar). For oxygen or other cleanliness-critical services, adding -SC11 to the ordering number requests special cleaning and packaging to ASTM G93 Level C, whereas standard cleaning follows the Swagelok SC-10 specification. Many valve bodies are also available in other alloys on request.

Applications of the 50 series in Oman and the GCC

A metal-seated check with a 900 °F limit is useful on hot sample lines, steam-sampling and boiler instrumentation in power stations, hot gas lines at gas processing plants, and heat-transfer oil or utility lines in petrochemical complexes. In refineries it protects analyzer sample systems from back-flow of process fluid. Its absence of elastomers also suits hydrogen and aggressive hydrocarbon services where seals swell or degrade, and sour gas service where the NACE option is requested.

In a desert climate, the valve’s all-metal construction is not affected by high ambient temperatures or sun loading, but make sure that the installation is horizontal because skid piping that changes elevation can easily put the valve into a vertical position by mistake.

Selection checklist for a 50 series check valve

• Fluid, temperature and maximum pressure, including peaks.
• Series size from the required flow: Cv of 0.30, 0.64 or 2.20.
• End connection type and size.
• Orientation: it must be horizontal, bonnet nut on top.
• Sour gas requirement, and special cleaning needs.
• Acceptable reverse leakage, remembering it is not a bubble-tight valve.

If a spring-assisted check valve is acceptable, the C, CP and CH poppet check valves are the alternative and may be oriented in any direction, within their temperature limits.

Information to send with a 50 series RFQ

• Medium, flow, pressure and temperature.
• Connection type and size.
• Sour gas or special cleaning options.
• Quantity and delivery site.

Documents and quotation

The Swagelok lift check valve catalog for the 50 series is attached to this page. Send your service data and we will confirm the ordering number and available documents.