Triple Coupon Housing (TCHP)

The TCHP Triple Housing Coupon is a robust, three-component coupon testing assembly that integrates a reference electrode and multiple test-coupons in a sealed housing. It allows for long-term monitoring of cathodic protection (CP) system performance by simulating exposed metal (coupon) and providing accurate, stable reference potentials. This makes it a valuable tool for periodic inspection, coating-break detection, and verification of CP effectiveness.

The housing, reference electrode and coupon combination ensures measurements are taken under representative soil/electrolyte conditions—helping operators confirm structure protection without excavation or system disruption.

Key Features & Benefits

Connection & Monitoring Accuracy:

Low-Resistance Reference Cell: The integrated reference electrode (Cu/CuSO₄ or Zn/ZnSO₄) uses a hard ceramic plug and solid electrolyte, providing stable, low-resistance measurements.
Multiple Coupon Types: Includes two “on-system” coupons and one “instant-off / free-corrosion” (AC) coupon, enabling both live monitoring under CP current and “instant-off” potential measurement or corrosion-rate estimation.
Sealed, Contaminant-Resistant Housing: Housing is sealed and uses a hydrophilic porous membrane to keep external contaminants and soil particles out, preserving reference and coupon integrity.

Flexibility & Versatility:

Various Coupon Sizes Available: Coupon exposed areas can be 1 in², 1 cm², 2 cm², 5 cm², or 10 cm², allowing adaptation to different coating-holiday assumptions or system requirements.
Standard & Custom Cable Leads: Supplied with 14 AWG–10 AWG RHH/RHW cable leads; standard stock lengths (30′, 50′) and extended lengths (100′, 150′, 200′) available. Custom lengths can be specified.
Long Life & Shelf Stability: The dry reference electrode technology offers essentially unlimited shelf life until hydrated, while service life is rated at 30 years (if not contaminated).

System Integrity & Compliance:

Simulates Coating Holidays: Coupons represent bare steel exposure, enabling detection of potential coating failures, holiday effects, or localized corrosion risk.
Enables IR-Drop-Free Measurements: By using separate coupon and reference leads and enabling “instant-off” readings, the system minimizes IR drop errors—a common issue in high resistivity soils or high CP current applications.
Meets CP Monitoring Standards: Designed to support industry-standard coupon test station requirements for pipelines and buried structures (surface area options, dual coupons, proper lead insulation, accessible reference).

Applications

Continuous corrosion monitoring on buried pipelines and steel conduits with CP systems.
Monitoring internal/external steel surfaces of storage tanks and vessels protected by CP.
Areas with coating holiday risk—joints, welds, bends, or repair zones.
Remote or long-distance CP groundbeds where periodic, long-term data is needed without excavating.
Projects requiring IR-free potential measurement, stray-current detection, or corrosion-rate estimation

Installation & Maintenance:

Location & Placement: Place housing at or near the pipeline/structure in the same electrolyte/backfill as the pipe to ensure accurate environmental representation.
Lead Routing: Route coupon leads, reference-electrode lead, and structure/anode leads to a test station or junction box above ground for easy access to terminals.
Backfill & Sealing: Fill housing around electrode with conductive backfill as specified to maintain electrolyte contact.
Measurement Setup: For “instant-off” potential measurements, include a switch or disconnect mechanism at the test station to isolate coupon from CP current during measurement.
Maintenance: Periodically inspect housing seals, membrane integrity, and lead insulation—replace or reseal if compromised to maintain measurement accuracy.
Documentation: Document coupon ID, exposed area, and installation location; routinely log potential and corrosion-rate data for trend analysis and CP compliance.