1. Purpose: The purpose of this method statement is to make sure that Hydro-static pressure testing of chilled water piping system is done safely as per client requirements and applicable standards.
2. Scope Of Work: This method statement covers the Hydro-static testing of CHW pipework at the project and to be followed for all piping works at site.
- Prior to the start of the hydro-static pressure testing all other works on the system shall have been snagged by construction team and de-snagged and signed off by the quality department.
- This method statement is for chilled water system black mild steel piping and fittings.
- Construction Manager
- Mechanical Engineer/Foreman/Superintendent
- QA/QC Engineer
4. Pressure Testing Method Of Statement
- Permit to work for pressure test to be obtained from safety department
- All open flanged, valved or screwed ends will be blanked off.
- The fill point will be installed at the lowest point of the system, and a valved vent at the highest point of the system to be tested. The vent will be piped to a drain point.
- Pressure gauges with valid calibration certificates/stickers will be fitted adjacent to the pressure pump.
- Pipework will be filled with water sufficiently in advance of the test to allow it to come to room temperature so that any sweating can evaporate. When the systems sufficiently filled the vent valve will be opened and allowed to run freely for a period of 5 minutes to ensure all the air is out of the system, at that point the valve will be closed.
- When the system is full and vented the test rig will be linked to the system and the pressure increased to the required system test pressure, as required by the specification 1.5 the operating pressure. When the test pressure is reached the valve at the fill point will be closed for a period of 15 minutes to stabilize the system, the gauges will be checked to see if any pressure loss has occurred due to the stabilization, if so the test rig will be applied to bring the system test pressure back up to the specification requirements. Upon re-pressurization the test rig shall than be dismantled from the system.
- Care will be taken at this point to record the ambient room temperature of the start and finish time of the test. The duration of the test will be 24 hours and temperatures should be recorded frequently.
- A visual inspection of joints will take place during the test period to check for leaks, if any leakage found the test will be aborted. After the leakage is rectified, the above procedure will be repeated for a re-test to take place.
- On satisfactory completion of the test, witnessed by the client, the pressure will be released through the vent pipe. The system then shall be drained. Pressure testing report shall be prepared and signed by the client or any other concerned party.
5. Health & Safety Requirements
In ordered to ensure that all hydrostatic testing of chilled water works to takes place in a safe manner the following shall be considered:
- Spot safety meeting will be done by competent engineer to the working group
- Fitting, thread and connections will be checking up for broken or unthreaded parts
- To make sure every one in testing area knows that the pressure test will be done and proper tags to be displayed.
- Ensure that all pipes are fastened properly.
- Warning signs will display in both English and the local language
- Valves operations to be understood by operator before pressure test starts
- Restrict the access for common people to testing area, use communication system for announcements etc.
- Only authorized persons are allow to check the pipes during the pressure in progress
- After test is complete the pressure should be released slowly and open all valves once the pressure is zero, to ensure that there is no pressure trapped any where in the system.
6. Reference Records
- Permit to work for pressure testing
- Hydrostatic Testing Certificate
- Calibration Certificate of pressure gauges
- System latest Construction Drawing