Brand: Swagelok

Swagelok SS-4R3A5-RT Proportional Relief Valve, 1/4 in. ISO

Name: Swagelok SS-4R3A5-RT Relief Valve 1/4 in. ISO | Seven Star
Brand: Swagelok
SKU: SS-4R3A5-RT

Description

The Swagelok SS-4R3A5-RT is the ISO-thread version of the R3A high-pressure proportional relief valve. It has a 1/4 in. male ISO tapered inlet thread and a 1/4 in. female ISO tapered outlet thread, for equipment in markets and plants that use ISO 7/1 (BSPT-type) tapered pipe threads rather than NPT. NPT and ISO tapered threads look alike but do not mate correctly, which is why Swagelok lists a separate RT code.

Technical specifications

Parameter	Specification
Part number	SS-4R3A5-RT
Description	High-pressure proportional relief valve, no handle
Series	R3A
Body material	316 stainless steel
Connections	Inlet 1/4 in. male ISO tapered; outlet 1/4 in. female ISO tapered
Thread standards	ISO 7/1, BS EN 10226-1, DIN 2999, JIS B0203 (catalog footnote)
Set pressure range	50 to 6000 psig (3.4 to 413 bar), by spring selection
Working pressure at 100 F	6000 psig (413 bar) inlet; 1500 psig (103 bar) outlet
Seal material	Fluorocarbon FKM
Height	3.89 in. (98.8 mm), per catalog table
Cleaning	Standard cleaning and packaging SC-10

Why an RT version exists

The catalog adds a footnote to the ISO-threaded entries pointing to the specifications ISO 7/1, BS EN 10226-1, DIN 2999 and JIS B0203. Those are the tapered pipe threads used on equipment outside North America. An NPT thread has a 60 degree flank angle and an ISO 7/1 thread 55 degrees, so mixing them can leak or damage the threads. If your port is marked R, Rc, Rp or BSPT, order the RT code instead of SS-4R3A5.

Confirm the thread standard on your equipment drawing before ordering, since NPT and ISO parts are not interchangeable.

Relief performance

Performance is the same as the NPT valve: a spring selected for the set pressure range, a cap label showing the range, a lock nut and lock wire hole to fix the setting, and a quad seal to prevent leakage around the stem during relief. Set pressure repeats within plus or minus 3 psig or 5 percent, whichever is larger, at room temperature, and the valve opens gradually with a proportional action rather than a pop.

The catalog says each R series valve is tested for set and resealing performance and cleaned to SC-10.

Limits and ordering

This is a proportional relief valve, not a code safety valve, and it is not a safety accessory under the Pressure Equipment Directive; the catalog states this clearly. Provide the set pressure, fluid, temperature and thread standard with the inquiry. The related codes are SS-4R3A5 (NPT) and SS-4R3A1 (male NPT by tube fitting).

Seal materials other than FKM have their own temperature and maximum-set-pressure limits in the catalog.

Documents and quotation

Source document: Swagelok proportional relief valves R series catalog MS-01-141 (EN), attached for download, which carries the tables this summary draws on. To get a quote for SS-4R3A5-RT, reply with the quantity and options, and we will check the code against the document first. Seven Star LLC is an independent supplier in Muscat.

We recommend confirming the exact size, thread or flange standard and material with the attached document before placing an order. Related items: product category.

Datasheets & Documents

Catalog Swagelok proportional relief valves R series catalog MS-01-141 (EN) Download

Reviews (0)

Reviews

There are no reviews yet.

How would you rate this product?

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.

FAQ

Questions about the Swagelok SS-4R3A5-RT Proportional Relief Valve, 1/4

Answers from our engineering team on installation, compatibility and integration.

01What does RT mean in the code?

It marks ISO tapered pipe threads instead of NPT.

02What are the end connections?

1/4 in. male ISO tapered inlet and 1/4 in. female ISO tapered outlet.

03What is the set pressure range?

50 to 6000 psig (3.4 to 413 bar) by spring selection.

04Is it a safety valve?

No. It is a proportional relief valve, not ASME or PED certified.

05Can I use NPT parts with it?

No. NPT and ISO tapered threads are not interchangeable.