Material Receipt Inspection and Witness Sampling
Material acceptance is the first gatekeeper of engineering quality control. Key acceptance points: (1) Pipes and fittings: Check factory certificates of conformity, quality inspection reports, and type test reports; verify that specifications and models match the design drawings. For stainless steel pipes, confirm the material grade (304/316L); for PPR pipes, confirm the S series (S5/S4/S3.2) and the service condition class (Class 1/2/5); (2) Valves: Perform shell strength tests (1.5 times nominal pressure) and tightness tests (1.1 times nominal pressure) on each unit, with a sampling ratio of no less than 10%; (3) Sanitary fixtures: Verify water efficiency labels; products must have CCC certification (if applicable) and water efficiency test reports; (4) Pumps, heat exchangers, and other equipment: Verify that nameplate parameters match design requirements, check equipment appearance for damage, and confirm that accessories are complete. After materials arrive on site, they should be stored by category with clear labeling, and witness sampling and testing should be conducted as required by specifications (e.g., chemical composition analysis of stainless steel pipes, hydrostatic testing of PPR pipes, etc.).
Key Points of Concealed Works Acceptance
Concealed works acceptance is a focal point of plumbing and drainage quality control; the next process shall not proceed if acceptance fails. Key acceptance items: (1) Pipe installation: Check whether pipe slopes meet design requirements (measured with spirit level + level instrument), whether pipe support and hanger spacing complies with specifications (e.g., DN100 steel pipe support spacing not exceeding 7m), and the construction quality of pipe anti-corrosion and insulation layers; (2) Pipe connections: Check whether the crimping depth of stainless steel pipe press fittings meets standards, whether PPR hot-melt weld beads are uniform and defect-free, and whether drainage pipe solvent-cemented joints are dense and tight; (3) Waterproofing: Install waterproof sleeves where pipes penetrate floor slabs (two sizes larger than the pipe) and apply sealant; apply arc-shaped water stops and waterproof additional layers at the base of pipe shafts; (4) Reserved openings and embedded parts: Verify that reserved hole positions and dimensions match the drawings, and that the inner surfaces of embedded sleeves are corrosion-protected. Concealed works acceptance must be jointly attended by the owner, contractor, and supervision engineer, with photos archived and concealed works acceptance records signed.
System Commissioning and Performance Verification
System commissioning and performance verification are the final stages of acceptance. Core verification items and standards: (1) Water supply system: The water pressure at the most unfavorable point in each zone shall not be less than 0.15MPa, the pressure at the service pipe inlet shall not exceed 0.35MPa, and terminal flow shall be normal; (2) Hot water system: Hot water delivery time in guest rooms shall not exceed 5 seconds (5-star) or 10 seconds (4-star), supply water temperature 55-60°C, return water temperature not less than 50°C; (3) Drainage system: Drainage stack flow capacity test passed (drainage fixtures on 2-3 floors operating simultaneously drain normally), ball test passed (ball diameter not less than 2/3 of pipe inner diameter, 100% pass rate); (4) Fire protection system: Fire hydrant effective water column not less than 10m (not less than 13m for Class I high-rise hotels), sprinkler terminal test pressure not less than 0.05MPa; (5) Pump performance: Measured flow and head not less than 95% of design values, motor current not exceeding rated value. Commissioning data shall be recorded in detail and archived.
Completion Acceptance Documentation and Filing Requirements
Plumbing and drainage documentation to be submitted for completion acceptance includes: (1) Design documents: Construction drawing design documents and drawing review qualification certificates, design change documents, detailed design drawings; (2) Material certificates: Factory certificates of conformity for materials/equipment, quality inspection reports, on-site re-test reports; (3) Construction records: Concealed works acceptance records, pipe pressure test records, water filling/flow/ball test records, system commissioning records; (4) As-built drawings: As-built drawings reflecting actual completed conditions (BIM as-built models preferred); (5) Operation and maintenance instructions: Equipment operation manuals, maintenance manuals, spare parts lists; (6) Water quality test reports: Potable water quality test qualification reports. After documentation review passes, the owner shall organize the design, construction, and supervision units to conduct completion acceptance; after acceptance passes, completion acceptance filing shall be processed with the local housing and construction authority. All documentation shall be retained at least until the end of the warranty period (2 years for plumbing and drainage works, 5 years for waterproofing works).