N40475 Chapter 4 Dry systems Dry exhaust systems for marine installations need careful design to minimize the disadvantages of enclosing components that are at a high temperature in confined spaces. The first part of a dry system should include a flexible connection so that excessive weight is not carried by the connection to the engine. Connections of the stainless steel bellows type are suitable, but care must be taken to ensure that they are only required to accommodate movements that do not involve twisting the ends of the bellows relative to each other. The remainder of the exhaust system should be well insulated to avoid fire risk.
If there is a long exhaust run which gains height as it leaves the engine, it may be necessary to incorporate a trap to collect condensate and allow it to be drained. Figures 4 shows a typical system. The minimum bore of the exhaust pipe should be 85mm (3.34 inches). (1) Bracket with link to allow for movement due to expansion in the exhaust system (horizontal exhaust systems should be suspended from the deck head using similar brackets - rigid brackets should not be used). (2) Insulating lagging. (3) Rigid bracket to support the weight of the vertical exhaust system. (4) Heat blanket. Figure 4 (5) Twin stainless steel bellows fitted to avoid torsional load on bellows unit. (6) Heat blanket.
(7) Turbocharger adaptor. (8) Heat blanket. (9) 90 O Elbow. Note: When fitted, the bellows units should be in an unstrained condition so that the full bellows movement is available to absorb expansion and engine movement. Page 11