1/4" Capillary Tube

Duplex 2205

0.035" Wall

Due to our unique manufacturing processes and strict quality control, our 1/4” capillary tube outperforms the best on the market.

Capillary Tube (0.250 Pair) [Web] GEO PSI

0.250″ Capillary Tube Duplex 2205 0.035″

Our Duplex 2205 Capillary Line is ideal for use in oil and natural gas wells due to its higher strength, resistance to pitting, corrosion, and chloride stress corrosion cracking. For injection applications, the tubing is self-supporting inside the production casing and facilitates the injection of chemicals to enhance production flow rate, inhibit corrosion and de-water. In control line applications, the tubing is strapped to the production casing and facilitates the hydraulic actuation of surface-controlled subsurface equipment such as valves.

General Properties

2205 is a nitrogen-enhanced duplex stainless steel alloy. When heat-treated, the composition of 2205 (Listed below) produces a microstructure of a roughly equal mixture of austenitic and ferritic phases that results in a yield strength approximately double that of austenitic alloys such as 316L, as well as superior corrosion resistance in many hostile environments.

The higher chromium content in 2205, as well as the molybdenum and nitrogen components, results in better chloride pitting and crevice corrosion resistance than found in standard austenitic stainless steels such as 304L and 316L.

Forming & Annealing Process

The strip is passed through a series of rollers to form it into a tubular cross-section. The tubing is continuously welded along the seam with a gas tungsten arc welding (GTAW) process. To achieve the desired length of tubing, individual lengths are joined by orbital welding. Continuous eddy current testing is performed to detect holes. Exiting the tube mill, the tubing is passed through an induction coil and annealed at between 1,070°C – 1,100°C.


Additional Information

We recommend the use of gaugeable Alloy 2507 Super Duplex Tube Fittings to ensure reliable grip and seal with the 2205 Capillary Tubing.


Duplex 2205 Chemistry

(by weight)

Carbon (C)


Manganese (Mn)


Silicon (Si)


Chromium (Cr)


Nickel (Ni)


Molybdenum (Mo)


Phosphorus (P)


Sulfur (S)


Iron (Fe)


Nitrogen (N)


Physical & Mechanical Properties

Outer Diameter

0.250” (1)

Wall Thickness

0.035” (1)


0.0803 lbs/ft

Burst Pressure

26,600 psi (2)

Internal Pressure

19,600 psi (3)

Collapse Pressure

16,800 psi (4)

Working Pressure

14,100 psi (5)

Test Pressure

16,200 psi (6)


(Pitting Resistance Equivalent Number)

35.2 (7)

Metal Cross Section

0.0237 in2

Flow Cross Section

0.0255 in2

Minimum Tensile Strength

95,000 psi (8)

Minimum Yield Strength

70,000 psi (8)

Minimum Elongation

25% (8)

Hardness (HRC Max)

30 (9)

(1) Dimension Tolerances per ASTM A632-19: O.D. +0.004”, -0.000”; I.D. +0.000”, -0.004”; WT ± 10%
(2) Calculated using Barlow’s formula at Tensile Strength (ASTM A312).
(3) Calculated using Barlow’s formula at Minimum Yield Strength.
(4) Collapse pressure calculated per API 5C3.
(5) Working pressure is defined as Internal Pressure x 0.72 Fd (design factor).
(6) Testing recommended at 15% above Working Pressure.
(7) (%Cr + 3.3%Mo + 16%N), API Technical Report 938-C, 2nd Edition, 2011.
(8) Tensile tests conform to ASTM A370-21, using yield strength method 0.2% offset.
(9) Vickers 500g (HV0.5) hardness test conforms to ASTM E384-17. Rockwell Hardness conversion per ASTM E140-12b (2019).
* The data are typical and subject to normal manufacturing tolerances. The data are provided for information purposes and should not be construed as maximum or minimum values for specification or design purposes. The data are subject to change at any time without notice.

Want to know more?

One of our team members would be happy to help.