Acceptance standards for pressure testing and flushing of hotel water supply and drainage pipes
I am Daniel Wang, a water supply and drainage specialist. The pressure testing and flushing acceptance of hotel water supply and drainage pipelines is a key step in ensuring the long-term safe operation of the system, especially in hotels, which are high-load and high-demand buildings where any leakage or water quality issue can affect operations and guest experience. Below, I will elaborate on the standards in detail based on GB50242-2002 "Code for Acceptance of Construction Quality of Building Water Supply, Drainage and Heating Engineering" and my engineering experience.
Pressure Testing Standards
1. Water Supply Pipelines (Domestic Water Supply, Hot Water Systems):
- Test Pressure: According to Article 4.2.1 of GB50242-2002, the test pressure for indoor water supply pipelines shall be 1.5 times the working pressure, but not less than 0.6 MPa. For example, the working pressure of a hotel hot water system is usually 0.4–0.6 MPa, so the test pressure must reach 0.6–0.9 MPa.
- Pressure Holding Time: For metal and composite pipes, hold the test pressure for 10 minutes, with a pressure drop not greater than 0.02 MPa, then reduce to the working pressure for inspection; no seepage or leakage is acceptable. Plastic pipes (such as PPR) must be held for 1 hour, with a pressure drop not exceeding 0.05 MPa.
- Experience Case: In a five-star hotel project, during pressure testing of PPR hot water pipes on the guest room floors, we once had excessive pressure drop due to inadequate heat fusion of pipe fittings. After readjustment, the pressure drop after 1 hour of holding was only 0.03 MPa, meeting the code.
- Test Type: Drainage pipelines require water-filling tests and ball-passing tests. According to Article 5.2.1 of GB50242-2002, concealed or buried drainage pipes must undergo a water-filling test before backfilling. The filling height shall not be lower than the upper edge of the lowest sanitary fixture or the lowest floor level. After 15 minutes of full water, the water level drops; then refill and maintain for 5 minutes; if the liquid level does not drop, it is acceptable.
- Ball-Passing Test: A rubber ball with a diameter not less than 2/3 of the pipe inner diameter shall be dropped from the top of the riser; smooth passage through the outlet pipe is acceptable. In a hotel project, the ball-passing test once failed due to construction blockage, which was ultimately resolved by clearing with a high-pressure water jet.
- Test Pressure: According to Article 6.2.3 of GB50261-2017 "Code for Construction and Acceptance of Automatic Sprinkler Fire Extinguishing Systems", the system strength test pressure shall be 1.5 times the working pressure and not less than 1.4 MPa. Hold for 30 minutes, with a pressure drop not greater than 0.05 MPa, then reduce to the working pressure for inspection.
- Tightness Test: The test pressure shall be the working pressure, held for 24 hours with no leakage. In a hotel project, leakage occurred during pressure testing because the threaded joints of fire pipes were not tightened; re-tightening and repair welding were required.
Flushing Acceptance Standards
1. Water Supply and Hot Water Systems:
- Flushing Requirements: Article 4.2.3 of GB50242-2002 requires that the flushing flow velocity of pipelines shall not be less than 1.5 m/s, and the outlet water quality shall be visually consistent with the inlet water quality. For hotel hot water systems, attention must be paid to high-temperature disinfection flushing (hot water circulation above 70°C for 30 minutes) to kill Legionella.
- Experience Case: After flushing the hot water system of a resort hotel, water quality testing found excessive iron, because a Y-strainer had not been installed. After installation and re-flushing, the water quality met the domestic drinking water standard.
- Flushing Requirements: Drainage pipelines require water-flow tests. According to Article 5.2.2 of GB50242-2002, after passing water through the drainage riser, check that all joints have no leakage and drainage is smooth. Rainwater pipes require a closed-water test, filled to the height of the rainwater hopper, with no leakage for 24 hours.
- Case: During flushing of the basement drainage pipes in a hotel, construction debris was found inside the pipes, causing poor drainage. After repeated flushing with a high-pressure cleaning truck, the drainage smoothness rate increased to 100%.
- Flushing Requirements: Article 6.2.5 of GB50261-2017 requires that the flushing water flow direction of fire pipelines shall be consistent with that during fire extinguishing, with a flow velocity not less than 1.5 m/s, until the outlet water is clear. The fire hydrant system requires flushing riser by riser, and the sprinkler system requires zoned flushing.
- Case: After flushing the sprinkler branch pipes on a hotel guest room floor, the water from the end test device was turbid, because the pipe openings had not been plugged during construction. After re-flushing and installing filters, the water quality met the standard.
Summary
The pressure testing and flushing acceptance of hotel water supply and drainage pipelines must strictly follow the GB50242-2002 and GB50261-2017 codes, with key control of test pressure, pressure holding time, and flushing water quality. During pressure testing, focus on pipe joints and concealed works; during flushing, ensure flow velocity and disinfection effectiveness. In actual projects, I have dealt with a hotel guest room leakage accident caused by negligence in pressure testing, so I recommend that the project team prepare a special plan in advance and entrust a third party to test water quality.
The above are reference opinions. The actual project situation still needs to be comprehensively evaluated and implemented in combination with specific working conditions, site conditions, and other factors.