Main Structural Components of Steel Wire Detection Cables

Main Structure of Steel-Wire Fluoroplastic Detection Cable (Load-Carrying Detection Cable)

Described layer by layer from the inside out, with the function of each layer noted. The industry standard structure consists of a copper conductor + fluoroplastic insulation + shielding + steel-wire armor + outer sheath:

1. Conductive Core (Conductor)

Material: Multi-strand tinned copper wire stranded together (some use pure copper); flexible and resistant to breakage, enhancing bend resistance and oxidation resistance.

Function: Transmits electrical signals and supplies power; serves as the core of the circuit.

Specifications: Commonly available in single-core, 3-core, 4-core, and 7-core configurations; conductors have a relatively small cross-sectional area, suitable for detecting low-voltage signals.

2. Insulation Layer

Material: Primarily F46 (polytetrafluoroethylene-propylene), though PFA fluoroplastic may also be used.

Properties: Temperature resistance from -30°C to 200°C; high dielectric strength; resistance to oil, acids, alkalis, and hydrogen sulfide corrosion.

Function: Isolates the conductors to prevent electrical leakage and signal crosstalk; suitable for high-temperature, corrosive environments underground or underwater.

3. Shielding Layer (Phase-by-Phase Shielding + Overall Shielding)

Structure: Each individual conductor is first shielded with a phase-by-phase copper tape or copper wire shield; the entire bundle of conductors is then enclosed in an overall shield.

Function: Protects against external electromagnetic interference, ensuring stable and undistorted detection signals; this is an essential component of logging cables.

4. Inner Liner / Wrapping Tape

Material: Polyester tape and fluoroplastic film winding.

Function: Isolates the shielding layer from the outer steel wire layer, cushions friction, protects the internal structure, and prevents the armored steel wire from scratching the shielding.

5. Load-Bearing Armor Layer (Core Load-Bearing Layer)

Structure: Double-layer high-strength galvanized steel wire / stainless steel wire twisted in opposite directions (mainstream structure).

Features: Extremely high tensile strength; capable of suspending downhole detection instruments and withstanding the combined weight of the entire string of equipment and the tension during deployment.

Function: Bears all mechanical loads; resists stretching, crushing, and abrasion; this is also the origin of the name “steel wire detection cable.”

6. Outer Sheath

Material: F46. ETFE (F40) fluoroplastic, sometimes combined with special oil-resistant rubber.

Function: Provides overall protection against water, seawater, and chemical corrosion; resists aging; protects the internal steel wires and conductors; and extends service life.