This test procedure shall be carried out to detect the leak in shell weld joints and to observe the load stabilization of liquid in interval level height. During the hydro test, all instrumentation shall be excluded to avoid the damage to instruments.
Since the hydro test is to be carried out by produced water, ensure all Hook ups of pipes with tank nozzles so that, produced water from operating plant can be fed to settling tanks.
After completion of the settling tank erection, welding and NDT the following points shall be checked before testing.
- All the mechanical activities completion in respect of the drawing.
- Radiography completion including repairs.
- The entire NDT test like chalk-diesel test, LPT (DP) , RF Pad pneumatic test, vacuum box test completion.
- During the hydro test of the tank all Instruments shall be isolated to avoid the damage during the hydro test.
Settling Tank Filling & Testing Procedure
- Required pipe shall be identified to allow the produced water to feed into the settling tank. Ensure the hook up to be completed to settling tank nozzles as per approved drawing.
- Markers shall be provided on the shell, 500 mm from the bottom to check tank settlement. Size shall be 50 X 50 X 6mm angle and 100 mm long. The nos. of setting marker shall be minimum 4.
- Setting marker shall be welded and initial level reading shall be taken with respect to the permanent benchmark using dumpy level / Total station.
- Shell settlement measurements shall be made after tank erection, prior to Hydro testing and during water filling at 1000 mm intervals up to maximum filling height of tank.
- The levels taken before water filling called as initial level of the tank and shall be recorded in an approved format.
- The water filling height shall be restricted to the max. Liquid Level or up to the curb record.
- The water filling shall be carried out in four stages (25%, 50%, 75% & 100% of the max liquid level of the tank).
- Any leaks observed in the shell joint during the hydro test shall be noted and repaired with the water level min. of 300mm below the leak spot.
- The repairing shall be carried out as per the procedure and tank test shall be recommended.
- After each stage of filling, a load stabilization period shall be observed as minimum 24 hours maximum between each stage of filling.
- During the stabilization period the settlement reading shall be observed and recorded through dumpy level.
- Filling rate shall not exceed 5 meters per day.
- After completion of the water filling the water load shall be maintained for 24 hours. After 24 hours the final settlement reading shall be recorded jointly with client.
- Tank shall be emptied at a maximum water level variation rate of 5 meters per day. Care shall be taken that top manholes are open during empty operation of conical roof tanks.
- If salt water is used then corrosion inhibitor should be sprayed (mixed) prior to filling / after hydro test the tank should be thoroughly cleaned with sweat water.
- After hydro test all instrument and Electrical items shall be restored to connection as per project / documents requirements.