IACS: Watertight testing in passenger ships

The International Association of Classification Societies (IACS) has released a Unified Interpretations document relating to watertight testing after fire testing of penetrations in watertight divisions in passenger ships.

This document (UI SC299 New) has been released on 1 July 2023 and will enter into force on 1 July 2024.

SOLAS Regulation II-1/13.2.3 prohibits the use of heat-sensitive materials in systems that pass through watertight bulkheads in passenger ships.

The materials used in these systems should be able to withstand exposure to heat or be considered part of an open piping system.

Closing devices using intumescent material (swelling when exposed to heat) for open piping systems should not be considered equivalent to valves, as they may not create a watertight seal if the fire is too far away.

To ensure compliance, pipe penetrations fitted with heat-sensitive materials must undergo prototype testing for watertight integrity after the standard fire test.

The prototype test involves subjecting the fire-tested pipe penetration to a pressure test.

The test pressure should be 1.5 times the design pressure, and there should be no leakage during the test.

After 30 minutes of testing with the pressure, the total water leakage should not exceed 1 liter.

The pressure test need not be conducted on the hot penetration arrangement, and ample time can be given to prepare for the test.

The pressure test should be carried out with the pipe section used in the fire test still in place, but pipe insulation fitted for the fire test may be removed.

Prototype testing is not necessary for steel or equivalent pipe penetrations with a thickness of 3 mm or greater and a length of at least 900 mm, provided there are no openings.

However, such penetrations must still meet the watertight integrity requirement in regulation 2.17.

The interpretation clarifies that any penetration used for heat-sensitive piping systems in watertight bulkheads or decks of passenger ships must be tested and type-approved for watertight integrity following the guidelines in the explanatory notes to regulation II-1/13.2.3.

Additionally, SOLAS regulation II-1/13.2.3 is specific to heat-sensitive piping systems and does not apply to cable penetrations in watertight bulkheads and decks.

For more information, please see the document below (available only to subscribers):