Key Construction Technologies for HVAC Systems
According to GB 50243 "Code for Acceptance of Construction Quality of Ventilation and Air Conditioning Works," the key control points include: First, duct fabrication and installation—duct sheet thickness is selected according to side length; when the side length does not exceed 320 mm, the thickness shall be no less than 0.5 mm. For duct sealing class, the hotel air-conditioning system shall meet the medium-pressure system standard (air leakage not exceeding 2.7 m3/h·m2@300Pa), and smoke exhaust ducts shall meet the high-pressure standard. After duct installation, light leakage and air leakage tests shall be performed. Second, water pipe installation and testing—in accordance with GB 50242, chilled water pipes with DN not exceeding 80 mm shall use galvanized steel pipes with threaded connections, and those with DN greater than 80 mm shall use seamless steel pipes with welded connections. Pipeline pressure test shall be at 1.5 times the design pressure and not less than 0.6 MPa, held for 10 minutes with pressure drop not exceeding 0.02 MPa. Third, insulation construction—the insulation layer shall be continuous and complete, joints shall be sealed, and cold bridges are strictly prohibited. Removable insulation boxes shall be provided at valves, filters, and flange connections. For DN50 chilled water pipes in the Shanghai area, the rubber-plastic insulation layer shall be no less than 40 mm. Fourth, equipment installation—large equipment shall be provided with vibration-damping foundations, flexible joints shall be used between equipment and pipes, and installation levelness deviation shall not exceed 1/1000. Fifth, air outlet installation—supply and return air outlets shall be installed flat and tight, and connections with ducts shall be sealed.
Electrical Engineering Construction Quality Control
According to GB 50303 "Code for Acceptance of Construction Quality of Building Electrical Engineering," the key control points include: First, cable laying—horizontal support spacing for cable trays shall not exceed 1.5 m, and vertical spacing shall not exceed 2.0 m. Cable bending radius shall be no less than 10 times the outer diameter for power cables and no less than 6 times the outer diameter for control cables. Second, distribution box installation—verticality deviation shall not exceed 1.5 mm/m; wiring inside the box shall be neat and clearly labeled; N and PE lines shall be provided with separate busbars. Third, lightning protection and grounding—GB 50601 requires the grounding resistance value for common grounding to not exceed 1 ohm, and for lightning protection grounding to not exceed 10 ohms. Local equipotential bonding terminal boxes (LEB) shall be provided in bathrooms to equipotentially bond metal components. Fourth, emergency lighting and evacuation indication—GB 51309 requires evacuation lighting fixtures to be installed at a height not exceeding 1.0 m above the ground, with spacing not exceeding 15 m, and battery continuous power supply of not less than 90 minutes. Fifth, intelligent system cabling—integrated cabling shall meet GB 50312 requirements; the spacing between weak-current cable trays and strong-current cable trays shall be not less than 300 mm for horizontal parallel runs and not less than 150 mm for vertical crossings.
Key Installation Points for Plumbing and Fire Protection Systems
According to GB 50242 and GB 50261 "Code for Construction and Acceptance of Automatic Sprinkler Systems," the key control points include: First, pipeline slope control—the slope of horizontal sewage pipes shall be not less than 0.012 for DN100, not less than 0.007 for DN150, and not less than 0.005 for DN200. Pipe support and hanger spacing shall not exceed 3.0 m for DN50 steel pipes and not exceed 4.5 m for DN100. Second, pipeline penetration and waterproofing—flexible waterproof sleeves shall be provided where pipes penetrate basement exterior walls; steel sleeves shall be provided where pipes penetrate floor slabs, extending 20-30 mm above the floor; firestop materials shall be filled where pipes penetrate fire-rated walls. Third, fire sprinkler installation—the sprinkler deflector shall be 100-300 mm from the ceiling, and the spacing from luminaires and air outlets shall be not less than 300 mm. Fourth, water pump installation—fire pumps shall use flooded suction; the horizontal section of the suction pipe shall have an upward slope of 1‰-2‰ toward the pump to prevent cavitation. Fifth, fire hydrant installation—the center of the hydrant outlet shall be 1.1 m above the ground, with the outlet facing outward. GB 50974 requires the residual pressure at the fire hydrant outlet not to exceed 0.5 MPa.
MEP Construction Coordination and Quality Control Methods
MEP construction involves multi-discipline cross-operation and requires systematic coordination and quality control measures. First, BIM pipeline coordination—Revit + Navisworks are used for full-discipline pipeline coordination and layout to resolve issues such as duct-cable tray crossings, elevation conflicts between water pipes and ducts, and reserved maintenance space for equipment. GB/T 51301 requires the MEP pipeline coordination model accuracy to reach LOD350 or above. Second, on-site mock-up first—before construction of each discipline, a mock-up section shall be made and confirmed by four parties before large-scale construction. Third, concealed works acceptance system—all concealed works shall pass supervision acceptance and retain photographic records before covering. Fourth, functional testing system—the HVAC system shall undergo air volume balance and hydraulic balance commissioning; the electrical system shall undergo insulation resistance (not less than 0.5 M ohm) and grounding resistance tests; the plumbing system shall undergo ball passage tests (100%) and closed-water tests. Fifth, combined trial operation—after each system is independently commissioned and qualified, combined trial operation shall be conducted for not less than 24 hours, recording all operating parameters and comparing them with design values.