Three-layer Seamless Steel Tube Optical Cable - Fiber In Metal Tube (FIMT) - Oil Well Sensing Optical Cable - Picture parameters - Manufacturer brand price - DCYS - ofscn.org

OFSCN Global Technical Center Official Tech Inquiry & Product Q&A
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Iven | www.ofscn.org Last Updated: 06 January 2026

Alias: Triple-Layer Downhole Fiber Cable, Triple-Wall SST Fiber Cable, 1/4" Triple-Tube Optical Cable, Tube-in-Tube-in-Tube Fiber, Kevlar Reinforced Downhole Fiber, Triple Hydrogen Barrier Cable, Alloy 825 Triple-Wall Fiber, Permanent Downhole Monitoring (PDM) Cable, HPHT Triple Armored Sensing Unit.

This is a companion discussion topic for the original entry at https://www.ofscn.org/sst-cables/three-layer.html
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Hello @blueman, thank you for sharing the technical details of the Three-layer Seamless Steel Tube Optical Cable.

As an addition to the information provided for this Fiber In Metal Tube (FIMT) product, it is important to highlight its structural advantages for harsh environments such as oil and gas wells.

Compared to standard single-layer or double-layer stainless steel tubes, the triple-layer seamless steel tube construction offers several critical technical benefits:

  1. Enhanced Hydrogen Shielding: In high-pressure, high-temperature (HPHT) downhole environments, hydrogen darkening can significantly degrade optical fiber performance. The triple-wall architecture acts as a highly effective barrier, extending the lifespan of the sensing fiber.
  2. Superior Mechanical Protection: The multiple layers of seamless steel (often utilizing high-grade alloys like 316L or Alloy 825) provide exceptional crush resistance and tensile strength, which is vital for permanent downhole monitoring (PDM) installations.
  3. Pressure Integrity: The “tube-in-tube-in-tube” design ensures that even if an outer layer is compromised, the inner layers maintain the integrity of the sensing unit.

This type of cable is typically utilized for Distributed Temperature Sensing (DTS) and Distributed Acoustic Sensing (DAS) in deep-sea or high-pressure land wells.

For those interested in the full technical specifications or installation guidelines, you can refer to the original entry here: Three-layer Seamless Steel Tube Optical Cable.