IP68 vs IP69K for Subsea Connectors -- Which Rating Do You Need?

When specifying waterproof connectors for marine and subsea applications, two IP (Ingress Protection) ratings cause the most confusion: IP68 and IP69K. Engineers sometimes assume IP69K is "better" because the number is higher -- but for subsea connectors, this misunderstanding can lead to a costly specification error. Here is everything you need to know.

What Does the IP Rating Mean?

The IP rating system is defined by IEC 60529 (EN 60529). The two digits represent:

• First digit (0-6): Solid particle protection. 6 = dust-tight (no ingress of dust).
• Second digit (0-9K): Liquid ingress protection. Ratings 7, 8, and 9K test for progressively different water exposure scenarios.

IP67 vs IP68 vs IP69K Explained

The Critical Difference: Static Immersion vs. High-Pressure Jet

IP68 tests resistance to continuous static immersion at a user-defined depth and duration. For subsea connectors, the manufacturer states the depth (e.g. "IP68 -- 7,000 m continuous immersion"). This is the relevant test for any connector that will be submerged in water -- from a shallow-water instrument housing to a deep-sea ROV connector.

IP69K tests resistance to high-pressure, high-temperature water jets at close range. The test involves a rotating spray nozzle at 80 bar and 80 degrees Celsius. This is specifically relevant for equipment that must withstand industrial cleaning, food processing washdowns, or agricultural machinery hosing -- not for continuous submersion.

Key insight: A connector can pass IP69K and fail at just 1 meter of depth. The high-pressure jet test does not validate watertightness under hydrostatic pressure. The seal design for jet resistance (radial O-rings, elastomeric boots) is different from the design for hydrostatic pressure resistance (face seals, oil-filled pressure compensation).

Why Subsea Connectors Are Rated IP68 (Not IP69K)

All RV Power Group subsea connectors are rated IP68 per IEC 60529 with a specific depth statement (e.g. "IP68 -- 7,000 m, 168 hours"). The test protocol includes:

1. Pressure chamber immersion at 1.5x rated depth (e.g. 10,500 m equivalent for a 7,000 m-rated connector)
2. Minimum 168 hours (7 days) continuous exposure
3. Post-test insulation resistance measurement (>1,000 M-ohm at 500 VDC)
4. Post-test dielectric withstand test

This is far more demanding than the IP69K jet test for subsea applications, and it is the correct test method per IEC 60529 for continuously submerged equipment.

Do You Need Both IP68 and IP69K?

Some applications genuinely need both ratings -- for example, deck-mounted connection panels on an ROV support vessel that may be hosed down with high-pressure salt water spray while also needing to withstand accidental submersion. In this case, look for connectors with dual rating statements such as "IP68 (3 m, 30 min) + IP69K."

For pure subsea applications -- ROV, AUV, seabed instruments, SCMs -- IP68 with a manufacturer-stated depth rating is the correct and complete specification. Specifying IP69K is neither necessary nor meaningful for these applications.

How to Read an IP68 Data Sheet

When evaluating an IP68 connector, always confirm the stated depth and duration. IEC 60529 allows the manufacturer to define these parameters. A product claiming "IP68" without a stated depth is essentially claiming compliance at 1 m depth (the standard IP67 condition) unless stated otherwise.

All RV Power Group connector data sheets explicitly state: IP68 -- depth rating per series, 168-hour minimum test duration. Third-party test reports are available on request for project qualification documentation.

Questions about IP ratings for your specific application? Contact our engineers at [email protected].