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Stainless Steel Duolok Tube Fitting, 0.25 Inch Tube OD Union Bulkhead

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Description & Features

Duolok tube fittings ensure leak-proof connections in instrumentation and process tubing systems. The double ferrule design adjusts to variations in tubing materials and wall thickness delivering reliable connections across diverse applications.

Manufactured from 316 stainless steel straight fittings are machined in accordance with ASTM A-276 and A-479 standards while shaped bodies follow ASTM A-182 guidelines. Duolok components are traceable with certified material test reports available.

The fittings are interchangeable with Swagelok tube fittings maintaining compatibility and ease of integration. Designed for gageability they guarantee sufficient pull-up during installation. Contact us for detailed assembly instructions.

Typically Duolok fittings are rated for pressures equal to the maximum allowable working pressures of the recommended stainless steel tubing. Certain specialized fittings may have a lower pressure rating. For application assistance reach out to us.

Functionality extends across a broad range of operating temperatures although higher temperatures may affect the tubing system's maximum working pressure. Consult us for applications involving elevated temperatures.

**MPN:** C1FN91 **Supplier Part Number:** ISSD4BU

Specifications

A
2.27
B
1.69
E
0.19
Brand
Ssp Fittings Corp
Brand
SSP Fittings Corp
Pack Size
1.00
UOM
EA
Hole Dia.
0.45
Max Panel Thickness
0.40
Supplier Part Number
ISSD4BU
T
0.25
Alternate Part Numbers
Alternate Part Number C1FN91, Alternate Part Number MI-08750213, Alternate Part Number MINO-00766X89704, Alternate Part Number SS-400-61
Product Weight
0.11 lbs

Similar Products

Model Number T A B E Max Panel Thickness Hole Dia. Price Action
Stainless Steel Duolok Tube Fitting, 0.25 Inch Tube OD Union Bulkhead

ISSD4BU Stainless Duolok Bulkhead

0.25

2.27

1.69

0.19

0.4

0.4531

Product Questions & Answers (3)

Question by: Brett W on Mar 26, 2026, 9:52 AM
got a 1/4 inch stainless instrument tube, is this the right bulkhead union size for it?
Answer by: Customer Support on Mar 28, 2026, 6:52 AM
It’s a union bulkhead made for 0.25 inch tube OD, and it has a 0.4531 inch panel hole requirement with a max panel thickness of 0.4 inch.
Question by: Ronnie M on Feb 12, 2026, 5:07 PM
these fit in a 0.4531 inch hole, yeah? trying to figure out if I need to drill out my panel or if it'll drop right in
Answer by: Customer Support on Feb 14, 2026, 8:40 AM
That hole diameter is exactly right for this fitting. The panel hole spec is 0.4531 inches, and the max panel thickness it'll work through is 0.4 inches. As long as your panel isn't thicker than that, you shouldn't need to do any additional machining.
Question by: Glen M on Nov 6, 2025, 7:44 AM
Wondering if this bulkhead union fitting will work with standard Swagelok fittings?
Answer by: Customer Support on Nov 7, 2025, 8:21 AM
Compatibility is one of its key features; Duolok fittings are designed to be completely interchangeable with Swagelok tube fittings.