🔍 Key Concepts

• Valve maintenance sequence – what must be done before reassembling a valve bonnet • Differences between disks/seats, bonnet gaskets, and stem packing – what each part does and how failure shows up • Good marine engineering practice: when one part is inspected, do you usually service only one area or all affected sealing surfaces?

💭 Think About

• Think about which components are actually disturbed or exposed when you remove a valve bonnet for inspection – which parts are now accessible and logical to service at that time? • Ask yourself: if you skip any one of these checks, what type of leak or failure could occur later (internal leakage, external leakage, or leakage around the stem)? • Consider typical shipboard maintenance philosophy: when the valve is already open and apart, what is the most preventative and efficient work to do before closing it up again?

✅ Before You Answer

• Verify which items directly affect leak-tightness once the valve is reassembled: internal sealing (disk/seat), body/bonnet joint (gasket), and stem area (packing). • Check whether any option excludes another, or whether one option could reasonably include the others as part of a complete maintenance step. • Be sure you understand that the question is asking what should be done prior to re-securing the bonnet, not what might be done later in a different maintenance evolution.