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Stainless Steel Duolok Tube Fitting, 0.25 Inch Tube OD To 1/4-18 Male NPT, Straight

Description & Features

Duolok tube fittings are engineered to provide reliable leak-proof connections in instrumentation and process tubing systems. They feature a double ferrule design that compensates for variations in tubing materials hardness and wall thickness.

Manufactured from 316 stainless steel these fittings are subject to stringent quality controls ensuring they are gaugeable for sufficient pull-up during installation. They are fully interchangeable with the Swagelok brand of tube fittings.

Duolok fittings generally match the maximum allowable working pressures of the recommended stainless steel tubing. They operate effectively across an extensive range of temperatures. The fittings' straight and shaped bodies are machined from 316 stainless steel conforming to ASTM A-276 ASTM A-479 and ASTM A-182 standards. Certified material test reports (CMTRs) are available emphasizing the product's high standards.

For applications requiring elevated temperatures or specialized information please contact us.

MPN: C1FN98

Supplier Part Number: ISSD4MC4

Specifications

A 1.49	B 1.20	D 0.60	E 0.19	Brand Ssp Fittings Corp	Brand SSP Fittings Corp	Pack Size 1.00	UOM EA	Supplier Part Number ISSD4MC4	T 0.25	Thread 1 1/4-18	Alternate Part Numbers Alternate Part Number C1FN98, Alternate Part Number MI-04172103, Alternate Part Number MINO-00766X58906, Alternate Part Number SS-400-1-4	Product Weight 0.14 lbs

Similar Products

Model Number	T	Thread 1	A	B	D	E
ISSD10MC8 Stainless Duolok To NPT Fitting	0.63	1/2-14	1.93	1.53	0.96	0.47
ISSD4MC4 Stainless Duolok To NPT Fitting	0.25	1/4-18	1.49	1.2	0.6	0.19
ISSD6MC6 Stainless Duolok To NPT Fitting	0.38	3/8-18	1.57	1.28	0.66	0.28

Product Questions & Answers (4)

Question by: Gary C on Dec 3, 2025, 8:50 PM

got 1/4 inch stainless tubing here, does this fitting go from that tube to 1/4-18 male npt?

Answer by: Customer Support on Dec 5, 2025, 8:57 AM

For a straight tube-to-thread hookup, this one matches 0.25 inch tube OD on the Duolok side and a 1/4-18 male NPT thread on the other end.

Question by: Melvin S on Aug 24, 2025, 7:26 AM

What kind of pressures can this fitting handle?

Answer by: Customer Support on Aug 25, 2025, 2:44 PM

Duolok tube fittings generally work up to the maximum allowable pressure of the stainless steel tubing recommended for use with them. Just keep in mind some specialized fittings might have a lower pressure rating.

Question by: Brenda H on Mar 17, 2026, 1:33 PM

these swap out direct with swagelok fittings or do i need to change anything out when i switch over?

Answer by: Customer Support on Mar 19, 2026, 6:04 AM

Duolok fittings are manufactured to be fully interchangeable with Swagelok brand tube fittings, so you can swap them in without any additional changes. The dimensions and double ferrule design are built to match, which means existing tubing and hardware stay put. No modifications needed on your end.

Question by: Brenda T on Nov 16, 2025, 6:00 AM

Is this fitting completely interchangeable with Swagelok fittings?

Answer by: Customer Support on Nov 17, 2025, 12:16 PM

Yes, Duolok tube fittings are designed to be totally interchangeable with the Swagelok brand.