The hollow bolt H 43631 is a precision-engineered fastening component used in the Sulzer ASL25 engine where secure mechanical fixing must be combined with controlled fluid passage. Designed to withstand high internal pressure, vibration, and thermal cycling, this bolt ensures reliable sealing and uninterrupted flow of oil or fuel through integrated channels. Its robust construction and accurately machined bore provide long-term dimensional stability, minimize leakage risk, and support the safe and efficient operation of critical lubrication or injection circuits within the engine.