Swagelok SS-4BK 316 Stainless Steel Bellows Sealed Valve

Swagelok SS-4BK is a premium general-service bellows sealed valve designed to provide ultimate system integrity by eliminating the potential leak path around the valve stem. As part of the renowned Swagelok B Series, this valve utilizes a seamless metal bellows to create a dynamic, hermetically sealed barrier between the process fluid and the atmosphere.

This straight-pattern, manually actuated valve is constructed from forged 316 stainless steel and features 1/4 in. Swagelok® tube fitting connections on both ends, ensuring a leak-tight seal upon installation . It is engineered for applications where fluid containment is critical, including high-purity systems, toxic or hazardous fluids, and vacuum services.

Note on Variants: The SS-4BK is available with different end connections, such as VCR® metal gasket face seals (e.g., SS-4BK-VCR), socket weld ends, and with various actuator options (e.g., SS-4BK-1C) for pneumatic operation.

Key Features & Benefits

Hermetic Bellows Seal: The primary feature is the 321 stainless steel bellows . It provides a leak-tight seal that prevents fugitive emissions and atmospheric contamination, offering a service life far exceeding that of packed stem valves.

Reliable Shutoff: Equipped with a PCTFE (Kel-F®) soft stem tip, the valve provides bi-directional, leak-tight shutoff, even when handling entrained particles . The cone-shaped tip design ensures consistent sealing over time.

Gasketed Body Seal: This version of the valve utilizes a gasketed body-to-bonnet seal (typically a PTFE-coated 316 stainless steel gasket), allowing for maintenance without removing the valve body from the tubing system.

Forged 316 Stainless Steel Body: Constructed from corrosion-resistant, forged 316 stainless steel for durability and long life in demanding industrial environments .

Standard Cleaning (SC-11): The SS-4BK is available with SC-11 special cleaning and packaging, making it suitable for high-purity and oxygen service applications.

Technical Specifications (SS-4BK)

Specification Detail

Manufacturer Swagelok 

Part Number SS-4BK 

Series B Series (BK configuration) 

Valve Type Straight Pattern, 2-Way, Manual Shutoff 

Body Material 316 Stainless Steel 

Connection Size & Type 1/4 in. Swagelok® Tube Fitting (both ends) 

Flow Coefficient (Cv) 0.36 

Maximum Working Pressure 1000 psig (68.9 bar) @ 100°F (37°C) 

Temperature Range -20°F (-28°C) to 200°F (93°C) (with PCTFE tip) 

Stem Tip Material PCTFE (Polychlorotrifluoroethylene) 

Bellows Material 321 Stainless Steel 

Body Seal Type Gasketed (PTFE-coated 316 SS gasket) 

Handle Type Phenolic Round Handle (Green) 

Cleaning Process Special Cleaning and Packaging (SC-11) 

Compatibility and Applications

The SS-4BK is a versatile valve used across multiple industries where fluid containment is paramount . Common applications include:

Process Analyzer Systems: Providing leak-free sample isolation in gas and liquid chromatography.

Toxic and Hazardous Fluids: Containing dangerous media to ensure operator and environmental safety.

High-Purity Gas Systems: Maintaining gas purity by preventing ingress of atmospheric contaminants.

Vacuum Systems: The bellows seal is ideal for maintaining high or ultra-high vacuum integrity.

Heat Transfer Fluids: Preventing costly and dangerous leaks of thermal oils.

Pharmaceutical and Biotechnology: Ensuring sterile and contained fluid handling.

Related Products & Maintenance Kits

To maintain the SS-4BK valve, genuine Swagelok replacement parts are recommended. Key maintenance kits include:

Bellows Kit: Part number SS-4BK-K1 (includes bellows, stem, and stem tip assembly).

Stem Tip Kit: Part number SS-4BK-K5 (PCTFE stem tip).

Gasket Kit: For servicing the body-to-bonnet seal.

Ordering Information

The manufacturer part number for the valve described is SS-4BK . For purchasing, availability, and pricing, please contact your local authorized Swagelok sales and service center. Be sure to specify end connection type (e.g., tube fitting, VCR, NPT) and any special cleaning requirements when ordering.

Keywords: Swagelok SS-4BK, bellows sealed valve, 316 stainless steel valve, 1/4 inch tube fitting, PCTFE stem tip, 0.36 Cv, 1000 psig, Swagelok B series, hermetically sealed valve, fugitive emissions, SS-4BK-VCR, high purity valve, SC-11 cleaning.