Brand: Swagelok

Swagelok SS-4BG Bellows-Sealed Valve, 1/4 in. Tube Fitting

Name: Swagelok SS-4BG Bellows-Sealed Valve 1/4 in. | Seven Star
Brand: Swagelok
SKU: SS-4BG

Description

The Swagelok SS-4BG is a bellows-sealed valve from the B series. Instead of sealing the stem with packing, it uses a precision-formed metal bellows that isolates the process from the atmosphere, so there is no packing to leak or to adjust. This 316 stainless steel version has 1/4 in. Swagelok tube fitting ends, a non-rotating spherical metal stem tip and a gasketed body-to-bellows seal, and it handles up to 1000 psig at room temperature and up to 600 F.

Technical specifications

Parameter	Specification
Part number	SS-4BG
Description	Bellows-sealed valve, gasketed, spherical stem tip, straight pattern
Body material	316 stainless steel
Bellows material	321 stainless steel
Connections	1/4 in. Swagelok tube fitting x 1/4 in. Swagelok tube fitting
Flow coefficient Cv	0.36
Internal volume	0.10 in.3 (1.6 cm3)
Stem tip	Cobalt-based alloy, spherical, non-rotating
Body seal	Silver-plated 316 SS gasket, metal seat
Handle	Phenolic round handle
Pressure at 100 F	1000 psig (68.9 bar)
Pressure at 200 / 300 / 400 / 600 F	830 / 660 / 500 / 400 psig
Temperature range	-20 to 600 F (-28 to 315 C)
Testing	Helium leak testing per Swagelok SCS-00020
Cleaning	Standard cleaning and packaging SC-10

Why a bellows instead of packing

Every packed valve eventually weeps at the stem. In toxic, high-purity, hot or costly service that weep is not acceptable, so the B series replaces the packing with a welded metal bellows. The bellows flexes as the stem moves and holds the system fluid on one side and the atmosphere on the other, and the catalog lists the 4BG with a very small internal volume of 0.10 in.3 (1.6 cm3), which keeps trapped fluid and purge time to a minimum. The stem tip does not rotate against the seat, which reduces wear and gives repeatable shutoff.

A silver-plated 316 stainless steel gasket seals the body to the bellows assembly. This gasketed construction is the “G” in the code; the welded construction is a separate “W” model.

Pressure and temperature

For 316 stainless steel valves with a gasket, the catalog rates 1000 psig (68.9 bar) from -20 to 100 F, falling to 830 psig at 200 F, 660 psig at 300 F, 500 psig at 400 F, 450 psig at 500 F and 400 psig at 600 F (27.5 bar at 315 C). Those ratings apply to manual valves. Compare with the PCTFE soft-tipped SS-4BK-V51, which is limited to 200 F for its soft seat; the metal-tipped 4BG is the choice for hotter service.

Valves are helium leak tested to the Swagelok standard, and flow is given by the 0.36 Cv.

Choosing and ordering

SS is 316 stainless steel, 4 is the 1/4 in. size, B is the B series and G is the gasketed spherical-tip model. Other models in the same catalog change one feature at a time: K for a PCTFE conical tip, R for a regulating tip, W for a welded seal, T for a toggle handle, plus VCR, weld and NPT end options. Brass and alloy 400 versions use B- and M- prefixes. Pneumatic actuators are available as accessories.

Because several look-alike models differ only by a letter, quote the full code. Fit tube ends on annealed tubing and make up with one and one-quarter turns of the nut.

Documents and quotation

For the full data, download the Swagelok bellows-sealed valves B series catalog MS-01-22 (EN) attached here. Quotation requests for SS-4BG are matched to the exact model or order code, so include the quantity and any option or certification. We are an independent supplier based 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 bellows-sealed valves B series catalog MS-01-22 (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.