Question

An oil and gas treater has undergone repairs and requires a hydrostatic test prior to being returned to service. Describe the procedure that should be followed in preparing the vessel and conducting the test.

Answer 1

To prepare an oil and gas treater for a hydrostatic test after repairs, a thorough inspection is required, followed by cleaning, filling the vessel with water, pressurizing above operational levels, monitoring for leaks, eventually depressurizing, draining, and a post-test inspection.

Step-by-step explanation:

When an oil and gas treater has undergone repairs, a hydrostatic test is essential to ensure the integrity of the vessel before it is returned to service. The procedure for preparing the vessel and conducting a hydrostatic test involves several steps:

1. Inspection and Cleaning: Firstly, the vessel should be thoroughly inspected for any defects that could affect the test results. It must be cleaned to remove any debris or residue that might compromise the integrity of the test.
2. Filling the Vessel: The vessel is then completely filled with water, which often includes a dye to make any leaks visible. The water is typically treated to prevent corrosion during the test.
3. Pressurization: Once filled, the vessel is pressurized to a specific test pressure, usually a percentage above the normal operating pressure, and maintained for a predetermined time to check for leaks.
4. Monitoring: During pressurization, all joints, welds, and repaired areas are checked for leaks. If any dye was used, it aids in identifying leaks.
5. Depressurization and Draining: Following the test, the pressure is gradually released, and the water is drained from the vessel.
6. Inspection Post-Test: After draining, a final inspection is conducted to ensure that no damage was done during the test and the vessel has maintained its structural integrity.

It is crucial to perform these steps meticulously to guarantee the vessel can safely return to service after the completion of the hydrostatic test.