| According to ASME Section VIII Division I, | | | | * All the temporary tools (such as valve, fitting, |
| hydrostatic pressure is conducted at the pressure | | | | hoses, flanges, blind plate, etc) have to be rated |
| of 1.5 times design pressure. If a vessel is design | | | | more than the maximum hydrostatic pressure. |
| for holding 1.0 kg/cm2.g pressure, the hydrostatic | | | | * Isolate other equipments and pipe lines that do |
| pressure test has to be done at 1.5 kg/cm2.g. | | | | not include in the hydrostatic test. |
| Hydrostatic test is also applied to existing | | | | * Vents are available and installed the high points |
| equipments and pipe lines to check for leakage | | | | to vent air. Check the vent line before testing and |
| after being repaired or maintained. Hydrostatic job | | | | make sure it is not blocked. |
| number increases during plant Turn Around period. | | | | * Choose drain valve at the lowest point in order |
| Because at that time, most of equipments are | | | | to completely empty the vessel and pipe. |
| opened for checking, inspection, clean-up, repairing, | | | | * Safety relief valve is already installed. Safety |
| replacing certain parts or performing internal | | | | relief valve setting is 1.5 times maximum allowable |
| modification. | | | | working pressure. |
| The use of high pressure is the main source of | | | | * Safety relief valve is calibrated. |
| hazards associated with hydrostatic pressure test. | | | | * Isolate the test area and surround it with |
| Hydrostatic test stores energy. High pressure | | | | safety line. Put appropriate safety sign at that |
| could damage the facilities and endanger worker's | | | | area. |
| safety. You should have included this into your | | | | * Do not allow person who does not have any |
| own hazard identification. | | | | relation with the hydrostatic test, to enter the |
| Safety Checklist: | | | | test area. |
| In order to prevent accident from hydrostatic | | | | * If possible perform the test from a remote |
| test operation, we have to make good | | | | area. |
| preparation prior to do the test, during the | | | | * Make sure that all pipe and vessel supports are |
| pressurization process and depressurizing | | | | in good condition and have been inspected. |
| operation. These jobs should be made in the form | | | | * All hoses must be tied down. |
| standard operating procedure. And here are the | | | | * Water temperature must be more than 16oC |
| safety checklists for each stage. | | | | (60 F). |
| Hydrostatic test preparation: | | | | * The hydrostatic-pressurizing pump is completed |
| Specification sheet of the equipments and or pipe | | | | with safety relief valve. |
| line, which mentions pressure and temperature | | | | * Wear proper personal protective equipments. |
| designs are available and complete. | | | | * Do not start the test if a problem is identified. |
| * Hydrostatic test pressure and temperature | | | | * Issue a work safety permit by authorized |
| standard are already clearly defined in the related | | | | personnel. |
| document. | | | | Pressurization process: |
| * Supported documents such as P&ID and | | | | * Remove all air from the vessel and pipe line by |
| isometric drawing are available and conform to as | | | | water through vent line. |
| built facilities at the field. | | | | * Pressurization is conducted gradually/slowly. |
| * Pressure test planning has to be distributed to all | | | | * Mark all leak points and repair them before |
| relevant sections in the plant site at least two | | | | preceding the test. |
| days before the execution date. | | | | * Do not monitor during pressurization step |
| * Make good coordination among related sections | | | | directly from the front of sight glass or level glass. |
| that involve in the test. | | | | De-pressurization process: |
| * All test equipments and tools shall be inspected | | | | * Start de-pressurization by opening gradually the |
| for wear and damage. | | | | vent valve. Do it slowly. |
| * Pressure measurement tools are calibrated and | | | | * Do not open the drain valve if the vent valve if |
| their statuses of calibration are still valid. | | | | still closed. This is to avoid vacuum condition inside |
| * Pressure gauges used in the test have enough | | | | the vessel. |
| capacity. The gauges are recommended to have | | | | * Open the lowest drain point to completely |
| 150% of the maximum allowable working | | | | remove water from the vessel and pipeline. |
| pressure. | | | | * Ensure that no remaining pressure trapped |
| * The pressure gauge is safety type, with | | | | inside the pipe line or vessel. |
| blowout back. | | | | The above hydrostatic pressure test safety |
| * Pressure gauges must be installed at a proper | | | | checklist will ensure worker's safety and the |
| location so that it can be easily read and do not | | | | facility of the plant. Thus, do not try to ignore |
| create additional hazards to the hydrostatic test | | | | them. |
| or expose personnels to the vessel being tested. | | | | |