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Brand: Swagelok
Swagelok SS-4R3A5 Proportional Relief Valve, MNPT x FNPT
Description
The Swagelok SS-4R3A5 is the all-NPT member of the R3A high-pressure proportional relief valve range, with a 1/4 in. male NPT inlet and a 1/4 in. female NPT outlet. That makes it the simplest relief fitting to thread into an NPT port and pipe the discharge away, with no tube fitting involved. Like the rest of the R3A family it covers set pressures from 50 to 6000 psig (3.4 to 413 bar) and is built from 316 stainless steel with an FKM seal.
Technical specifications
| Parameter | Specification |
|---|---|
| Part number | SS-4R3A5 |
| Description | High-pressure proportional relief valve, no handle |
| Series | R3A |
| Body material | 316 stainless steel |
| Connections | Inlet 1/4 in. male NPT; outlet 1/4 in. female NPT |
| Set pressure range | 50 to 6000 psig (3.4 to 413 bar), by spring selection |
| Inlet working pressure | 6000 psig (413 bar); up to 8000 psig (551 bar) during relief |
| Outlet working pressure | 1500 psig (103 bar) |
| Seal material | Fluorocarbon FKM |
| Service class | High pressure |
| Height | 3.89 in. (98.8 mm), per catalog table |
| Testing | Each valve tested for set and resealing performance |
| Cleaning | Standard cleaning and packaging SC-10 |
NPT in, NPT out
The NPT outlet is the main difference from the SS-4R3A1. A female NPT outlet takes a pipe nipple or a hose adapter, so relieved gas or liquid can be routed to a vent line, a collection vessel or a drain with standard fittings. An ISO threaded version, SS-4R3A5-RT, is listed for markets that use ISO 7/1 threads. Tapered NPT threads need thread sealant and are not interchangeable with ISO threads, so check your port standard.
Because the thread, not a nut, positions the valve, orient it with the cap accessible before final tightening.
Performance in service
Each R series valve is tested for set and resealing performance. For R3A valves with a set pressure of 100 to 200 psig the minimum resealing pressure is 50 percent of the set pressure, and for 850 to 1000 psig it is 84 percent, which tells you how far pressure must fall before the valve shuts again. Maximum set pressure depends on the seal material and temperature, from 6000 psig for FKM at moderate temperature to about 4660 psig at 275 F.
The valve has a lock nut and lock wire hole to keep the cap position, and a polyester label identifies the set pressure range of the installed spring.
Selecting and ordering
Provide the set pressure, fluid, temperature and back pressure with your inquiry, because the spring, seal and cap label depend on them. For a low-pressure application below about 225 psig the RL3 series is the better match, while the 1/2 in. R4 series offers a larger orifice. Remember that the R series is a proportional relief valve, not a code-stamped safety valve.
We supply Swagelok items as an independent supplier in Muscat and quote against the exact order code.
Documents and quotation
The attached Swagelok proportional relief valves R series catalog MS-01-141 (EN) is the reference for every value on this page. Seven Star LLC, an independent supplier in Muscat, quotes SS-4R3A5 against the exact code; please add the quantity and any special requirement.
Before ordering, please confirm the part number, size and connection against the attached document, as nearby codes differ by one character. Related items: product category.
Datasheets & Documents
- Catalog Swagelok proportional relief valves R series catalog MS-01-141 (EN) Download
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About brand
Swagelok is the American maker of tube fittings and small-bore valves, best known for its two-ferrule compression tube fitting. Fred A. Lennon and Cullen B. Crawford founded it in Cleveland, Ohio, in July 1947 as Crawford Fitting Company to make that fitting. Lennon bought the whole business and the patent in 1948, and the company has been based in Solon, Ohio, since the mid-1960s.
Seven Star LLC is an independent supplier in Muscat. We list Swagelok tube fittings, needle, ball, check, relief and metering valves, filters, regulators and sample cylinders, and supply them for instrument tubing and analyser systems in Oman and the GCC by exact part number.
Swagelok company profile
| Established | July 1947, Cleveland, Ohio, as Crawford Fitting Company |
|---|---|
| Founders | Fred A. Lennon and Cullen B. Crawford; Lennon bought out Crawford in 1948 |
| Headquarters | Solon, Ohio, since the mid-1960s |
| Product families | Tube fittings and adapters, face seal fittings, needle, ball, plug, check, relief and diaphragm valves, filters, regulators, quick-connects, sample cylinders and hoses |
Milestones
- 1947: Fred A. Lennon and Cullen B. Crawford found Crawford Fitting Company in Cleveland in July.
- 1948: Lennon buys out Crawford.
- Mid-1960s: Headquarters move to Solon, Ohio.
Swagelok products we list
| Family | Models | Typical use |
|---|---|---|
| Tube fittings | Overview, SS-810-6 union, SS-810-3 tee, SS-810-9 elbow, SS-810-4 cross, SS-810-1-8 male connector, SS-810-7-8 female connector, SS-810-61 bulkhead, SS-12M0-6 metric union, VCR face seal | Leak-tight connections on instrument and process tubing |
| Needle and metering valves | SS-1RS4, SS-1RF4, SS-18RF6, SS-6NBS6, SS-20VS4, SS-4MG | Isolation and fine flow adjustment on instrument lines and sample systems |
| Ball and plug valves | 40G, 40GX 3-way, 60 Series, 83 Series, P4T plug | Quick quarter-turn shut-off and switching |
| Check, relief and sealed valves | SS-4C-1, CH, R3A, RL3, SS-4BK bellows, SS-DLS4 diaphragm | Backflow prevention, overpressure relief and leak-free sealing for toxic or high-purity media |
| Filters, regulators, sampling | SS-4F-2, SS-4TF-7, KPR regulator, sample cylinders, QC quick-connects | Analyser sample conditioning and gas or liquid sampling |
A Swagelok part number can be read directly. In SS-810-6, "SS" is 316 stainless steel, "810" means a 1/2 in. tube fitting (8 sixteenths of an inch, 10 series), and "-6" is a union. A suffix such as "-8" adds a 1/2 in. NPT end, and "M0" marks metric tube, as in SS-12M0-6 for 12 mm. Tube fittings must be made up the same way every time: finger-tight, then 1 1/4 turns for most sizes. A gap inspection gauge confirms the fitting has been pulled up.
Where Swagelok products are used
In Oman and the GCC, Swagelok fittings and valves are used on instrument impulse lines, analyser sample systems, hydraulic and pneumatic control tubing, chemical injection and gas sampling in oil and gas, refining, petrochemical, power and laboratory installations.
Ordering Swagelok products: what we need
Send the full Swagelok part number (for example SS-810-6 or SS-1RS4), the material, and the tube size in inches or millimetres. For valves, add the end connections and any options. For sample cylinders, add the volume, pressure rating and end configuration.
Facts checked against Swagelok company history, October 2026.
Browse Swagelok products by category: Pipes & Fittings, Regulators, Fittings & Valves.
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Frequently Asked Questions
What are the end connections of SS-4R3A5?
1/4 in. male NPT inlet and 1/4 in. female NPT outlet.
What is the set pressure range?
50 to 6000 psig (3.4 to 413 bar), set by the chosen spring.
Is it ASME certified?
No. The catalog says R series valves are not ASME or PED safety devices.
Is an ISO thread version available?
Yes, SS-4R3A5-RT has ISO threaded connections.
How is resealing defined?
Resealing pressure is the upstream pressure at which flow stops, always below the set pressure.
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