HVAC Fabrication & Structures

Common materials include structural steel (angles, channels, beams, tubes), stainless steel for corrosive environments, aluminum for lightweight applications, galvanized steel for corrosion resistance, and composite materials for specialized applications.

Load calculations include dead weight (equipment, piping, insulation), live loads (maintenance personnel, tools), dynamic loads (vibration, seismic, wind), thermal expansion forces, and safety factors (typically 1.5-2.0). Manufacturer data and structural codes guide calculations.

Types include rigid supports (clamps, saddles), adjustable supports (cradles, rollers), spring hangers (for thermal movement), constant supports, guides (limit lateral movement), anchors (prevent movement), and trapeze hangers for horizontal pipe runs.

Vibration isolation prevents transmission of equipment vibration to building structures. Required for rotating equipment (chillers, pumps, fans, compressors), typically using spring isolators, rubber pads, inertia bases, or isolation rails. Selection depends on equipment frequency, weight, and isolation efficiency required.

Design follows OSHA/ANSI standards including minimum width (600mm), guardrail height (1070mm), toe boards (100mm), load capacity (2.5-5 kN/m²), non-slip surfaces, proper lighting, and safe access points. Materials include grating, checker plate, or expanded metal with appropriate coatings.

Methods include hot-dip galvanizing, zinc-rich primers, epoxy/polyurethane paint systems, stainless steel construction, powder coating, and cathodic protection for severe environments. Selection depends on exposure conditions (marine, chemical, humidity) and maintenance requirements.

Equipment skids are pre-fabricated structural frames that support multiple equipment pieces as a single module. Advantages include faster installation, precise alignment, reduced field welding, easier relocation, vibration control, and simplified piping/electrical connections.

Seismic design includes lateral bracing, adequate anchor bolts, flexible connections, seismic snubbers, and compliance with local building codes (IBC, ASCE 7). Calculations consider seismic zone, soil conditions, equipment importance factor, and dynamic characteristics.

Spacing depends on pipe material, diameter, contents, temperature, and codes. Typical spacing: steel pipes 3-6m, copper pipes 1.5-3m, plastic pipes 0.6-1.5m. Additional supports are needed near valves, fittings, equipment connections, and changes in direction.

Standards include AWS D1.1 for structural steel, ASME Section IX for pressure components, and specific codes for material types. Requirements include qualified welders, proper welding procedures (WPS), inspection (visual, NDT), and documentation (PQR, WQR).

Thermal expansion causes dimensional changes in pipes and equipment. Design accommodates this through expansion joints, flexible connectors, sliding supports, guide arrangements, proper anchor placement, and calculation of expansion forces to prevent stress on supports and connected equipment.

Documentation includes fabrication drawings, material certificates, welding procedures, inspection reports, load calculations, installation instructions, as-built drawings, maintenance manuals, and compliance certificates (if applicable).