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Proven Performance, Zero Leaks

A combat, sonar or propulsion system is only as good as the infrastructure connecting it. While some platforms still suffer failures, SMI’s systems are designed for 30+ years of service life without leaks. Our technology is proven across every UK submarine class since the 1960s — from Oberon through to today’s Vanguard and Astute fleets.

Where right-first-time and fit-and-forget technology isn’t always feasible, naval platforms must be designed for agility. SMI helps customers achieve this through modular, scalable system architectures and open standards — enabling rapid upgrades without costly overhauls.

Multi-Gland Penetrators (MGP)

Submarine build programmes require connectorised penetrators, but these can be costly and introduce potential leak paths. SMI’s MGP solution combines the peace of mind of a pressure hull gland with the flexibility of connectorisation — based on our fit-and-forget moulding expertise.

Polyethylene (PE) Leadership

SMI is the market leader in moulding polyethylene (PE) cable assemblies for harsh environments. PE offers unique advantages — it does not degrade over time and provides unrivalled insulation resistance, even at high operating temperatures. Although notoriously difficult to process, our specialist knowledge ensures fault-free bonding and sealing.

PlastEthUrm Dual Jacket Technology

When SMI developed the cable system for the UK’s Fibre Telemetry System, we introduced PlastEthUrm dual-jacket sealing technology. Combining PE and PU through molten pressure moulding, this process delivers unmatched robustness and a 10-year moulding warranty.

A Trusted Partner in Defence & Energy

For over 30 years, SMI has been the preferred supplier to the UK MOD and international defence companies. Our proven PE cable assemblies and harnesses continue to support naval capability, while also enabling growth in offshore wind, tidal power and subsea innovation.