HYDRAULIC TEST OF A CYLINDRICAL BOILER AFTER MAJOR REPAIRS

1. Complete all repairs and ensure the boiler is clean (water side and fire side) and all manholes/ handholes are closed with new gaskets.
2. Isolate the boiler from the steam, feed, fuel and air systems; blank off or secure all connections.
3. Fit a test pressure gauge (calibrated) and a vent at the highest point.
4. Fill the boiler completely with water (treated/ clean water) through the feed/ filling connection, venting the air until the boiler is full.
5. Connect a hydraulic test pump (hand or power) to the boiler.
6. Ensure all safety valves are gagged/ locked closed (or removed and blanked) so they do not lift during the test.
7. Ensure the boiler is at a safe, stable condition (cool, no pressure) before starting.

• The hydraulic test pressure is typically 1.5 times the working pressure (or as per the Class/ maker's requirement). For a boiler that has undergone major repairs, the test pressure is set by the classification society (usually 1.5 x the design/ working pressure). The pressure is applied slowly and held for the required time (e.g. 15-30 minutes) while the boiler is examined.

Before the test:

• Inspect the boiler internally and externally for any obvious defects, and confirm all repairs are complete and sound.
• Check that all openings are closed and the boiler is properly filled and vented.
• Confirm the test pump, gauge and connections are in order.

During the test:

• Apply the pressure slowly and steadily.
• Examine the boiler (all welded seams, tube ends, manhole/ handhole joints, and the repaired areas) for leakage, weeping, distortion or bulging.
• Hold the test pressure for the required time and observe for any pressure drop or leakage.
• Check for any deformation/ movement of the boiler structure.

After the test:

• Relieve the pressure slowly and drain the boiler.
• Re-inspect the boiler, particularly the repaired areas and the joints, for any permanent deformation, cracks or leaks.
• Record the test results (pressure, duration, findings) on the test certificate.
• If the test is satisfactory, the boiler is re-commissioned (refill, reconnect, and bring back on line). If defects are found, they are repaired and the test repeated.
• The test is witnessed/ approved by the Class surveyor as required.