Exam Question

### (a) Monitoring the Perforation of a High-Pressure Fuel Pipe
**Concept:** High-pressure fuel lines carry fuel at pressures up to 2000 bar or more. A perforation can result in a fine, high-velocity spray of hot, atomized fuel, which, if it impinges on a hot surface (e.g., exhaust manifold, turbocharger casing), will immediately ignite, leading to a catastrophic engine room fire. To prevent this, SOLAS regulations mandate the use of double-walled (sheathed) fuel pipes with an effective leak detection system.
**Construction & Operation:**
* **Double-Walled Design:** The fuel delivery pipe (inner pipe) is enclosed within a second, larger pipe (outer pipe or sheath), creating an annulus (gap) between the two. Both ends of the annulus are sealed. The outer pipe must be robust enough to contain any leak from the inner pipe.