Double Coupon Housing (DCHP)

The DCHP Double Housing Coupon is a sealed coupon-and-reference assembly designed for cathodic-protection (CP) monitoring of buried or submerged structures. It combines a permanent reference electrode with two steel coupons in a durable housing, enabling accurate, long-term corrosion testing and CP system verification under real field conditions.

By encapsulating the reference cell and coupons in a protective housing immersed in the same soil or backfill environment as the protected structure, the DCHP unit provides reliable, representative measurement data without the need for excavation or frequent maintenance.

Key Features & Benefits

Connection & Monitoring Accuracy:

Reference Electrode Cell: Incorporates either a Cu/CuSO₄ or Zn/ZnSO₄ reference electrode with a hard ceramic plug and solid electrolyte, providing a stable, low-resistance half-cell ideal for accurate potential measurements.
Sealed, Contaminant-Resistant Housing: The outer housing uses a hydrophilic porous membrane that shields the internal reference cell and coupons from soil intrusion or contamination, preserving measurement integrity over time.
Multiple Coupon Capability: Includes two “on-system” coupons plus one “instant-off / free-corrosion” coupon, allowing both live-current monitoring and IR-free “instant-off” potential readings from a single installation point.

Flexibility & Versatility:

Coupon Size Options: Supports exposed coupon areas of 1 in², 1 cm², 2 cm², 5 cm², or 10 cm² (and larger upon request), enabling design flexibility to match coating-holiday assumptions or system requirements.
Standard and Custom Leads: Supplied with 14–10 AWG RHH/RHW cable leads in standard stock lengths (30′, 50′) with custom length options (100′, 150′, 200′) to suit a variety of installation needs.
Long Shelf Stability and Service Life: The dry reference-cell technology provides virtually unlimited shelf life; once activated, the assembly is rated for decades of service with proper maintenance.

CP System Integrity & Compliance:

IR-Drop-Minimized Monitoring: The separate coupon and reference leads allow for accurate “instant-off” potential measurements, reducing IR-drop error common in high-resistivity soils or high-current CP circuits.
Standard-Compliant Design: Designed to meet or exceed industry practices and standards for CP coupon installation, testing, and monitoring on pipelines, tanks, and buried structures.

Applications

Buried pipeline CP monitoring and verification
Soil-side monitoring of storage tanks and buried vessels
Coating-holiday detection or evaluation at welds, joints, or repair areas
Long-term CP systems requiring periodic corrosion-rate or potential testing without excavation
Remote or distributed CP networks with difficult access for regular inspections

Installation & Flexibility:

Location & Placement: Install the housing adjacent to the protected structure, in the same back-fill or electrolyte to ensure realistic environmental conditions.
Lead Routing: Route coupon leads and reference-electrode leads to an above-ground test station or junction box; use RHH/RHW cable as supplied.
Backfill & Sealing: Fill housing with the conductive casing backfill mixture supplied (or as specified) to ensure solid electrolyte contact; ensure the hydrophilic membrane seal remains intact.
Measurement Setup: For “instant-off” potential measurements, include a switch or disconnect in the test station wiring to isolate coupons from CP current during measurement.
Maintenance: Periodically inspect the housing, seals, cable integrity, and lead insulation—replace or reseal as needed for reliability
Documentation: Label coupon assemblies (coupon area, reference type, date installed) and log in the CP monitoring record book.