Answer
Survey Scope & Preparation
- Isolation & Safety: Isolate air bottle from main/auxiliary starting lines, depressurize completely, lock open drain valves, unbolt access manhole door, and gas-free/ventilate space.
- Internal Cleaning: Thoroughly degrease and clean internal shell surfaces to remove oil sludge, moisture residue, and loose rust scale.
Inspection & Testing Requirements
Check Category | Inspection Details & Action |
|---|---|
Visual Internal Inspection | Examine dished ends, longitudinal/circumferential weld seams, and areas around internal drain pipes for pitting corrosion, erosion, or oil contamination cracking. |
Thickness Gauging (UT) | Perform Ultrasonic Thickness measurements on the dished ends and lower shell plating (where moisture accumulates) to verify shell plate thickness meets minimum Class limits. |
NDT Testing | Conduct Magnetic Particle Inspection (MPI) or Dye Penetrant Testing (DPT) on high-stress weld seams, nozzle attachments, and manhole compensation rings if visual defects exist. |
Safety Fittings Overhaul | Overhaul and pop-test safety relief valves ashore/onboard to confirm set pressure. Calibrate pressure gauges and verify internal drain pipe integrity. |
Pressure Test (If Repaired) | Conduct a hydraulic pressure test at 1.5 x Maximum Allowable Working Pressure (MAWP) if major structural welding/repairs were carried out or required by Class. |