Swagelok SS-1RM4 Needle Valve, 0.37 Cv, 1/4 in. MNPT

The Swagelok SS-1RM4 is built for direct installation into a female pipe port. Its ports are 1/4 in. male NPT, so the valve screws into a gauge tapping, a manifold or a vessel nozzle and acts as the throttling or shutoff point right at the source. It is a 316 stainless steel 1 series integral-bonnet needle valve with a regulating stem and a 0.172 in. orifice.

Technical specifications

Why male-by-male

Male NPT on both ends places the valve in line between two female ports, for instance between a process connection and a female-threaded transmitter or sample line. It eliminates the need for nipples and keeps the assembly short: the catalog lists overall dimensions in the 1.97 in. range for this valve. Thread sealant is needed on both tapered ends, and the valve body should be held with a wrench on the hex nearest the thread being tightened, never by the handle.

The 0.172 in. orifice gives a flow coefficient of 0.37. That is half the 0.73 of the 0.250 in. orifice version SS-1RF4, which makes SS-1RM4 the better choice when finer flow resolution is needed at low rates.

Materials and performance

Body, stem and gland are 316 stainless steel; the packing is two-piece chevron PFA held by disc springs under a packing nut. The live-loading reduces the need for adjustment, compensates for wear and cuts the operating torque. In the catalog, the pressure rating of 316 stainless valves is 5000 psig from -20 F to 100 F and 3435 psig at 450 F; the temperature limit follows the packing material as described in the options section.

Each valve is shell-tested and seat-tested with nitrogen at 1000 psig, with a seat leak limit of 0.1 std cm3/min. The Swagelok data page lists low-emissions certification.

Selection and handling

Pick SS-1RM4 where the port is female NPT and the line is gas or clean liquid. If the line is tube, use SS-1RS4 with Swagelok tube-fitting ends; if the port is male, use the female version SS-1RF4. Soft-seat stems with PCTFE tips and vee stems are available in the catalog for bubble-tight or higher-rated duty, but those are different part numbers. Note that the catalog limits PCTFE stem tips to 200 F.

Install with the flow in either direction, depressurise the line before changing packing, and avoid using the valve as an isolation point in safety-critical service unless your system design allows it.

Typical applications for a male NPT needle valve

The SS-1RM4 is most often used as a root or instrument valve threaded straight into a process tapping. Common positions include the isolation point under a pressure gauge, the inlet to a pressure transmitter or switch, a sample take-off on a vessel or pipeline, and a purge or bleed point on an analyser line. Because the regulating stem gives fine control, it is also used to throttle small gas flows, for example on instrument air, nitrogen blanketing or calibration gas supplies, where a ball valve would be too coarse.

In oil and gas, water treatment, desalination and chemical plants across Oman, the same small-bore valve can appear many times on one skid. Standardising on one part number across those positions simplifies spares and makes field replacement quicker.

Choosing between regulating and shutoff duty

The regulating stem is intended for metering and flow adjustment. If the main requirement is repeated tight shutoff, review the soft-seat and vee-stem options in the catalog as separate part numbers, and remember the lower temperature limit stated for PCTFE tips. For applications that need both fine adjustment and positive isolation, many designers place the needle valve downstream of a dedicated isolation valve so that the metering setting is not disturbed each time the line is closed.

Installation practice

Before installation, check that the female port is clean, undamaged and of the correct NPT size. Apply thread sealant to the male threads only, keeping it away from the first thread so that it does not enter the flow path. Tighten with a wrench on the body hex, not the knob, and position the valve so that the handle can be reached and turned without tools. Open and close the valve gently; the regulating stem does not need heavy force to close, and overtightening can damage the stem tip and seat. After pressurising, check the threaded joints and the packing area for leakage, and adjust the packing nut only as described in the catalog.

Where the valve supports the weight of an instrument, consider whether vibration from pumps or compressors could load the threaded joint, and provide independent support for heavier instruments where needed.

Service conditions in Oman and the GCC

The 316 stainless steel body suits coastal and offshore-adjacent sites where carbon steel or brass would corrode in salt-laden air. High ambient temperatures in summer and direct sun on exposed instrument racks raise the metal temperature of the valve, so the pressure-temperature data in the catalog should be read for the actual operating condition rather than room temperature. Dust and sand can collect on exposed stems and threads, so keep the valve clean, avoid operating it with grit on the stem, and check the packing during routine instrument inspections.

Documents and quotation

For the full data, download the Swagelok integral-bonnet needle valves O, 1, 18, 20 and 26 series catalog MS-01-164 (EN) attached here. Quotation requests for SS-1RM4 are matched to the exact order code, so include the quantity and any option designator. We are an independent supplier based in Muscat.

Check the code, size and end connection against the catalog table before purchase, since variants with similar numbers exist. Related items: product category.