Engineering a Hermetic, Pressure-Rated Cable Assembly for Subsea Weld Inspection Probes
XACT engineered a fully hermetic, pressure-rated cable assembly for a subsea weld inspection probe used in harsh industrial and offshore environments. The redesigned interconnect system was developed to eliminate water ingress risk, withstand significant hydrostatic pressure, and preserve signal stability for a precision electromagnetic inspection platform.
The project required non-standard encapsulation methods and iterative engineering refinement before achieving a validated production-ready design.
Program Overview
A manufacturer of advanced non-destructive testing (NDT) instrumentation required a ruggedized cable assembly for a diver-operated weld inspection probe deployed underwater.
The probe is designed to inspect surface-breaking cracks within ground welds on submerged structures. Because inspection accuracy depends on stable electromagnetic measurements, the cable assembly must maintain consistent electrical performance while operating under pressure and exposure to moisture.
The engagement was executed through our Engineering Design Services team, combining interconnect design, encapsulation process development, and material optimization.
The assembly required:
- Full hermetic sealing
- Resistance to hydrostatic pressure equivalent to approximately 900 meters
- Mechanical durability under handling and bending
- Stable signal transmission for EMI-sensitive measurements
The Challenge
Traditional thermoplastic overmolded designs were evaluated but did not meet environmental performance targets for subsea deployment.
Primary risks included:
- Hydrostatic compression creating micro-leak pathways
- Voids within molded transitions
- Adhesion failure between cable jacket and encapsulation material
- Moisture ingress impacting signal amplitude and measurement accuracy
- Mechanical stress concentration at the cable-to-probe interface
In this application, even minor moisture intrusion can cause signal drift or inconsistent readings. The interconnect needed to function as a structural and environmental barrier — not simply a termination.
The Engineering Solution
XACT developed a custom epoxy-potted cable assembly using a specialized potting and application process in place of conventional molded materials.
The redesigned termination incorporated:
- Custom mold tooling for controlled encapsulation geometry
- Full epoxy potting to eliminate void formation
- Material selection optimized for compressive strength and adhesion
- Controlled cure methodology to reduce internal stress
- Iterative prototyping and refinement prior to final validation
This solution builds upon XACT’s expertise in Overmolded Cable Assemblies and advanced encapsulation strategies used in Rugged and Harsh Environment Assembly Solutions.
Where signal-sensitive systems require additional shielding reinforcement, integrated EMI and Metal Braiding Solutions can be incorporated to preserve electrical stability in high-interference environments.
The final design created a structurally reinforced, fully encapsulated termination capable of resisting hydrostatic compression while preventing moisture-driven degradation.
Validation
The completed cable assembly was pressure tested to simulate hydrostatic conditions equivalent to approximately 900 meters of depth.
The assembly successfully passed validation without leakage or structural compromise.
Following evaluation, the customer approved the initial production configuration and indicated that additional probe variants may be developed using the validated architecture.
System-Level Reliability Considerations
Subsea inspection systems require coordinated control of sealing, shielding, mechanical strain relief, and thermal stability.
Where enclosure-level environmental sealing is required, precision shielded gasket solutions or dispensed form-in-place gaskets can be integrated at housing interfaces to maintain environmental protection and EMI continuity.
If internal electronics generate heat within sealed housings, engineered thermal management solutions can be applied to stabilize operating temperatures and reduce long-term drift.
Where broader electromagnetic control is required, coordinated EMI shielding solutions may be incorporated at the system level.
Through an integrated materials and interconnect strategy, environmental protection, electrical performance, and mechanical durability are engineered together rather than addressed independently.
Results
- Successful hydrostatic pressure validation
- Hermetic sealing achieved
- Improved mechanical reinforcement at termination
- Reduced risk of moisture-driven signal instability
- Platform architecture supporting future probe variants
