Swagelok SS-810-6 Tube Fitting Union, 1/2 in. Tube OD

The Swagelok SS-810-6 is the plain straight union for 1/2 in. tubing: two tube-fitting ends joined through a hex body, used to couple two lengths of tube, to repair a damaged section or to make a run demountable. It is the best-known fitting in the Swagelok range and the part most buyers mean when they ask for a 1/2 in. Swagelok union.

Technical specifications

How the union seals

Each end carries a front and a back ferrule and a nut. The front ferrule seals against the body and on the tube outside diameter; the back ferrule hinges inward to grip the tube. In sizes from 1/4 to 1 in. the back ferrule uses the advanced hinging-colleting geometry that the catalog says is standard on stainless fittings, with a case-hardening process intended to give vibration fatigue resistance. The body is cut from 316 stainless bar, and the 1/2 in. union measures 2.02 in. long with a 0.90 in. nut dimension.

The same catalog also lists a bored-through version, SS-810-6-0030, with a longer 4.30 in. body for applications such as thermocouple or dip-tube insertion. That is a separate part number and should be requested by its own code.

Ordering information

Read the number as SS (316 stainless), 810 (1/2 in. tube) and 6 (union). A reducing union adds a second size block, for example SS-810-6-4 for a 1/2 in. to 1/4 in. connection, and a bulkhead union is code 61, as in SS-810-61. Metric 12 mm unions use 12M0, for instance SS-12M0-6. Additional designators describe cleaning and packaging: CP gives individual bagging and BQ applies the oxygen-service level cleaning with a silver-plated front ferrule that the catalog describes.

The catalog states that fittings over 1 in. need a hydraulic swaging unit, but the 1/2 in. union is installed with ordinary hand tools.

Pressure, standards and use

The union does not carry its own pressure rating: the connection is rated to the working pressure of the tubing, which depends on tube material, outside diameter and wall. Look up the figure in Swagelok Tubing Data MS-01-107 for your tube and derate for temperature. Swagelok lists test and registration information including ECE R110 for certain stainless tubing ranges and a set of third-party approvals; ask for the specific report if your project needs it.

Good make-up starts with soft, round tubing that is free of scratches. Insert it to the stop, snug the nut by hand, turn it one and one-quarter turns and gauge the result; never rotate the body while pulling up, and always release pressure beforehand.

Key features of the 1/2 in. union

• Two-ferrule design on each end: the front ferrule seals, the back ferrule grips, so the connection holds against pressure, vibration and temperature cycling.
• 316 stainless steel body, nuts and ferrules suited to process, instrument and utility service where corrosion resistance matters.
• Connection rating follows the tubing, so the same fitting serves low-pressure air lines and high-pressure hydraulic or gas lines when matched with the right tube wall.
• Installed with hand tools at this size, without special preparation of the tube end beyond square cutting and deburring.
• Can be disconnected and retightened, which makes the union a convenient break point for maintenance.

Making up the connection correctly

Most fitting leaks trace back to the tube rather than the fitting. Use seamless or welded-and-drawn tube of a hardness and wall thickness suitable for the pressure, cut it square, deburr the inside and outside, and make sure the outside surface is free of scratches where the ferrules will seat. Insert the tube fully until it bottoms against the shoulder in the body, then tighten the nut finger tight. For 1/2 in. fittings, Swagelok’s installation instructions call for 1¼ turns from finger tight, holding the body with a backup wrench. Marking the nut at the six o’clock position before tightening makes it easy to count the turns.

For checking first-time installations, Swagelok offers a gap inspection gauge: if the gauge will not enter the gap between nut and body, the fitting has been sufficiently tightened. When reassembling, tighten the nut to its previously pulled-up position, where a rise in torque is felt, then snug it slightly.

Avoid mixing components

Do not mix or interchange nuts, ferrules or bodies with parts from other manufacturers. Ferrule geometry and material treatment are matched to the body, and the performance claims of the fitting depend on using the complete Swagelok assembly.

Where the union is used

• Instrument impulse lines to pressure transmitters and gauges.
• Analyser sample systems and calibration gas lines.
• Hydraulic and lubrication lines on skid packages and rotating equipment.
• Chemical injection lines at wellheads and process units.
• Utility air, nitrogen and cooling water tubing.

Considerations for Oman and GCC installations

Coastal plants, desalination facilities and offshore platforms expose tubing systems to chloride-laden air and high temperatures. 316 stainless steel is widely used in these environments, although severe marine exposure can still cause pitting or tea staining on stainless tube and fittings; plants with harsh conditions sometimes specify higher alloy materials for critical lines. Keep tube clamps correctly spaced to limit vibration, and protect fittings from sand and grit during construction by keeping caps and plugs in place until connection.

What to state in an RFQ

• Part number SS-810-6 and quantity, or the reducing, bulkhead or metric variant if needed.
• Any special cleaning, for example oxygen service, using the relevant designator.
• Tube material, outside diameter and wall thickness, if tubing is to be quoted at the same time.
• Whether gap inspection gauges, caps and plugs are required.
• Project name, delivery point and required documentation such as material certificates.

Documents and quotation

Download the official Swagelok catalog MS-01-140 from this page for the full ordering tables. Requests for SS-810-6 are quoted against the exact order code, so include quantity and any cleaning or packaging option.

Verify the order code and connection standard against your specification and the catalog before ordering. Related items: product category.