What must test fittings (not integral to the sprinkler valve) be stamped with?

Test fittings that are not integral to the sprinkler valve must be stamped with the valve damage control number. This number is critical as it identifies the specific control measure in place for managing potential damage or failures within the sprinkler system on the ship. The valve damage control number links the fitting to the overall safety and maintenance protocol, ensuring that it can be easily referenced in case of inspections, repairs, or compliance checks.

The other options pertain to different aspects of equipment identification or safety protocol that, while important, do not specifically apply to test fittings outside of the valve assembly. For instance, serial numbers and installation dates are typically associated with tracking the history or age of the equipment but do not address their specific role in damage control. Safety inspection numbers are related to the broader context of equipment monitoring but do not have the same direct relevance to the specific identification and management of test fittings in relation to damage control protocols.