What must be performed on boilers under specific lay-ups before shifting to a hydrazine lay-up?

Before transitioning to a hydrazine lay-up, it is essential that the boiler must be dumped. This process involves removing all water from the boiler to prevent contamination and ensure that the interior surfaces are dry and ready for the hydrazine treatment. Dumping the boiler eliminates any residual water that could interact negatively with the hydrazine or lead to corrosion if left in place.

By maintaining the boiler in a hydrazine lay-up situation, the hydrazine helps to control corrosion and provides a suitable environment for the boiler's protection during periods of inactivity. Proper preparation through dumping is a critical step in this process to ensure the effectiveness of hydrazine in protecting boiler internals.

Other steps, such as cleaning, inspecting, or sealing, while important in boiler maintenance, are not the primary requirements before shifting to a hydrazine lay-up. Therefore, dumping is crucial to ensure that the system is adequately prepared for the introduction of hydrazine.