4mm Capillary Tube

Inconel 825

0.030" Wall

Our unique 4mm capillary tube offers the same great strength, handling, and weight benefits as our industry-leading 4mm TEC.

Capillary Tube (4mm Pair) [Web] GEO PSI

0.160″ Capillary Tube Inconel 825 0.030″

Our Inconel 825 Capillary Line is ideal for use in downhole wells due to its high 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 ESP applications this product can be utilized as a discharge pressure line. It connects from the ESP sensor to the discharge pressure sub. The 4mm design provides superior strength and durability over traditional 1/4” capillary tube.


High Crush Strength





General Properties

Inconel 825 is a nickel-iron-chromium alloy with additions of molybdenum, copper and titanium. This nickel steel alloy’s chemical composition is designed to provide exceptional resistance to many corrosive environments. It is similar to alloy 800 but has improved resistance to aqueous corrosion. It has excellent resistance to both reducing and oxidizing acids, to stress-corrosion cracking, and to localized attack such as pitting and crevice corrosion.
Alloy 825 is especially resistant to sulfuric and phosphoric acids. This nickel steel alloy is used for chemical processing, pollution-control equipment, oil and gas well piping, nuclear fuel reprocessing, acid production, and pickling equipment.

Forming 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.


Additional Information

We recommend the use of SwageLok™ or DK-Lok™ compression fittings to ensure reliable grip and seal with the Inconel 825 Capillary Tubing.


Inconel 825 Chemistry

(by weight)

Carbon (C)


Manganese (Mn)


Silicon (Si)


Chromium (Cr)


Nickel (Ni)


Aluminum (Al)


Molybdenum (Mo)


Phosphorus (P)


Sulfur (S)


Iron (Fe)


Titanium (N)


Copper (Cu)


Physical & Mechanical Properties

Outer Diameter

4mm / 0.16” (1)

Wall Thickness

0.030” (1)


0.0419 lbs/ft

Burst Pressure

31,800 psi (2)

Internal Pressure

13,100 psi (3)

Collapse Pressure

10,600 psi (4)

Working Pressure

9,400 psi (5)

Test Pressure

10,800 psi (6)


(Pitting Resistance Equivalent Number)

32.89 (7)

Metal Cross Section

0.0119 in2

Flow Cross Section

0.0076 in2

Minimum Tensile Strength

85,000 psi (8)

Minimum Yield Strength

35,000 psi (8)

Hardness (HRC Max)

30 (9)

(1) Dimension Tolerances per ASTM A632-19: O.D. +0.003”, -0.000”; I.D. +0.000”, -0.003”; WT ± 10%
(2) Calculated using Barlow’s formula at Tensile Strength (ASTM A312).
(3) Calculated using Barlow’s formula at Minimum Yiedl 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 A370-19e1, using yield strength method 0.2% offset.
(9) Vickers 500g (HV0.5) hardness test conforms to ASTM E384-17. Rockwell Hardness conversion per ISO 18265-2003
* 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.

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