1. Key Technical Points for Piping Construction
Piping works include water supply and drainage, HVAC water, and fire protection water construction technical points: Threaded pipe connections are suitable for DN ≤ 80 mm, with hemp thread or PTFE tape wrapped 3–5 turns in the thread direction, tightening torque determined by pipe diameter (DN25: 100 N·m, DN50: 200 N·m, DN80: 300 N·m), with 2–3 exposed thread turns; Pipe welding for DN ≥ 100 mm adopts TIG welding for root pass of 2 mm plus manual arc welding for cap pass, electrode E4303, groove angle 60–70°, root gap 1.5–2.5 mm, weld reinforcement ≥ base metal surface; Pipe flange connections: flange-to-pipe perpendicularity deviation ≤ 1 mm, gaskets selected as rubber gaskets for cold water and spiral wound metal gaskets for hot water.
2. Key Technical Points for Electrical Construction
Electrical construction technical points: Cable laying bending radius ≥ 12–15 times cable outer diameter; before laying, check cable insulation resistance ≥ 1 MΩ per km; armored cable grounding reliable; Distribution box/cabinet installation verticality ≤ 1.5 mm/m, enclosure grounding resistance ≤ 4 Ω, reserved conductor length inside box ≥ 1/2 box perimeter; Cable tray installation horizontal and vertical, grounding jumpers complete, firestop sealing at fire compartment penetrations; Lightning protection grounding using structural main reinforcement as down conductors ≥ 2 bars, welded lap length ≥ 6D for round steel or ≥ 2b for flat steel, grounding resistance ≤ 1 Ω for combined grounding.
3. Key Technical Points for HVAC Construction
HVAC construction technical points: Duct fabrication — galvanized steel sheet thickness determined by duct side length, smoke exhaust ducts use fire-resistant steel plate, duct seams are Pittsburgh lock seams, reinforcement frame spacing ≤ 1.2 m for side length ≥ 630 mm; Duct installation — flange gasket thickness 3–5 mm, fire-rated ducts use asbestos board, bolt spacing ≤ 150 mm, fire dampers installed where ducts penetrate walls and floor slabs; HVAC water pipe installation — pipe pressure test at 1.5 times working pressure and ≥ 0.6 MPa, condensate pipe slope ≥ 0.5% with trap and vent cap; Chiller installation — foundation levelness ≤ 1 mm/m, unit vibration isolation installed.
4. Key Technical Points for Equipment Installation and Commissioning
Equipment installation and commissioning technical points: Equipment positioning using forklift or crane, foundation acceptance passed before positioning, anchor bolt tightening torque meets requirements; Equipment alignment and leveling — longitudinal and transverse levelness ≤ 0.5 mm/m (precision) or ≤ 1 mm/m (general) using frame level or laser level; Equipment-to-pipe connection — flexible joints shall not bear pipe stress during installation, pipes shall be naturally aligned with equipment; Motor wiring — verify motor nameplate parameters, grounding protective conductor cross-section ≥ 1/2 phase conductor, motor insulation resistance ≥ 0.5 MΩ (380 V) or ≥ 1 MΩ (high voltage).