4mm Capillary Tube

Stainless Steel 316L

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 Stainless Steel 316L 0.030″

Our Stainless Steel 316L Capillary Line is ideal for use in oil and natural gas wells due to its high strength, hardness, and corrosion resistance. For injection applications, the tubing is self-supporting inside the production casing and facilitates the injection of chemicals to enhance the production flow rate, inhibit corrosion and de-water. In ESP applications this product can be utilized as a discharge pressure line. This line 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

316L is an austenitic stainless steel possessing excellent mechanical properties (strength and hardness). Compared to other chromium-nickel austenitic stainless steels, 316L provides higher creep, stress to rupture and tensile strength at elevated temperatures.

The high amounts of nickel and chromium provide outstanding corrosion resistance to most chemicals, salts and acids. This is improved further by the molybdenum content, particularly with higher resistance to pitting and crevice corrosion in chloride environments.

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 Stainless Steel 316L Capillary Tubing.


Stainless Steel 316L 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

4mm / 0.16” (1)

Wall Thickness

0.030” (1)


0.0412 lbs/ft

Burst Pressure

28,100 psi (2)

Internal Pressure

11,200 psi (3)

Collapse Pressure

9,100 psi (4)

Working Pressure

8,100 psi (5)

Test Pressure

9,300 psi (6)


(Pitting Resistance Equivalent Number)

24.45 (7)

Metal Cross Section

0.0119 in2

Flow Cross Section

0.0076 in2

Minimum Tensile Strength

75,000 psi (8)

Minimum Yield Strength

30,000 psi (8)

Hardness (HRB Max)


(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 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 A370-19e1, using yield strength method 0.2% offset.
* 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.