Capillary Tubes, Capillary Coil Tube: Types and Applications

--Process-Based Classifications & Key Industry Applications

Explore capillary tubes: Learn their process-based types (seamless/welded) and uses in oil & gas, medical, electronics—backed by precision standards for industrial needs.

Capillary tubes are key components for precision metering and pressure control in industrial fluid systems, featuring extremely small inner diameters and precise dimensions. This article provides engineers and technicians with an overview of the core technologies of capillary tubes, helping them understand their classification and application value in key areas.

Main Types of Capillary Tubes

Classification by Process

Seamless Capillary Tubes: Manufactured through cold drawing or cold rolling, these tubes lack welds. They are suitable for high-pressure fluid transmission, ensuring minimal resistance and free of impurities.

Welded Capillary Tubes: Using laser welding, they can be produced in longer lengths (e.g., 50,000 feet per coil), offering significant cost advantages and suitable for low-pressure signal transmission.

Capillary Tubes can also be categorized by material: stainless steel, nickel alloy, copper, and copper alloy.

Typical Applications of Capillary Tubes

Oil and Gas: Capillary Tubes are commonly used as control lines in oil and gas wells, transmitting downhole pressure signals. Common materials include 316L, 625, and 825, and must withstand extreme operating conditions.

Medical: Used in endoscopic instruments, minimally invasive surgical instruments, and diagnostic equipment, requiring extremely high cleanliness and biocompatibility.

Electronics and Refrigeration: Cooling pipes in electronic equipment and throttling capillaries in air conditioning systems are typically made of copper or stainless steel.

Instrumentation: The core of precision instruments such as pressure sensors and chromatographs requires low permeability and high dimensional accuracy to prevent leakage or signal distortion.

Aerospace: Used in aircraft hydraulic systems, fuel lines, and sensor circuits for precise fluid control.

As an integral part of MTSCO's "Oilfield Services" product line, MTSCO's Siri Tubing facility specializes in capillary tube production, offering seamless and welded capillary tubes in a variety of materials, including stainless steel and nickel alloys. Our capillary tubes undergo 100% eddy current testing and other rigorous non-destructive testing methods to ensure every meter of tubing meets "zero defect" delivery standards, meeting the stringent demands of various industries.