Pipe racks and pipe supports

What it is

A pipe rack is the steel spine of a process plant, utility site or factory: a line of portal frames (bents) joined by longitudinal beams that carry process and utility piping, cable trays and sometimes air-cooled exchangers above grade. Pipe racks keep piping off the ground, create clear corridors for vehicles and personnel, and give a predictable route between equipment areas. Smaller pipe supports – T-posts, goalposts, cantilever brackets and trapeze hangers – carry branch lines to individual equipment.

World Steel fabricates pipe racks within our structural steel scope and as part of complete equipment structure packages. Racks are often supplied together with equipment supports, walkways and crossover platforms so the whole access system is detailed in one model.

Types and options

Common options include multiple pipe levels, a top-level cable tray deck, maintenance walkways with guardrails, ladder access, guide and anchor brackets for thermal movement, and fireproofing-ready surfaces at lower levels.

Design and compliance

Pipe rack design is led by the engineer of record using piping stress output. Loads include empty, operating and hydrotest pipe weights, friction and anchor forces from thermal expansion, wind on pipes and steel, seismic actions and maintenance live loads on walkways. In the US, racks are typically designed to AISC 360 and ASCE 7, with many owners also specifying industry practice documents such as PIP STC01015; in Australia AS 4100 with AS/NZS 1170 and AS 1170.4; in Europe EN 1993-1-1 with EN 1991 and EN 1998. Because pipe racks are nonbuilding structures in seismic regions, the seismic system and its detailing must be stated on the design drawings.

Walkways and ladders on the rack follow OSHA 1910 Subpart D, AS 1657 or EN ISO 14122, the same as our other platforms and catwalks. Bolted connections use ASTM F3125, AS/NZS 1252 or EN 14399 bolts; see structural bolts and fasteners.

Fabrication and finishing at World Steel

Racks are detailed in Tekla, with each bent, beam and brace given a unique piece mark tied to the IFC model and the shipping list. Columns, beams and bracing are cut and drilled on CNC lines; welded connections are made by GMAW, FCAW or SAW to AWS D1.1, AS/NZS 1554.1 or EN ISO 3834-2 procedures, under AS/NZS 5131 CC3 or EN 1090-2 up to EXC3 where specified. Pre-assembled bents can be trial-fitted to verify bolt alignment before shipment.

Exposed racks are commonly hot-dip galvanized by qualified galvanizers to ASTM A123 / AS/NZS 4680 / EN ISO 1461, which suits bolted construction and coastal sites. Painted systems to EN ISO 12944, AS/NZS 2312.1 or SSPC specifications are used where fireproofing will be applied or the owner standard requires paint. Members are bundled and loaded to export packing standards in containers or on flat racks.

Installation and site notes

• Anchor bolts are cast into the foundations to a template; base plates are grouted after bents are plumbed.
• Bents are erected and braced bay by bay, starting from the braced (anchor) bay.
• Longitudinal beams, struts and bracing are bolted and tightened as specified (snug-tight or pretensioned).
• Pipe guides, anchors and shoes are installed to the piping isometrics; damaged galvanizing is repaired to ASTM A780 or the regional equivalent.

Selecting and specifying

For an accurate quotation, send the rack layout and design drawings or IFC model, the member list or tonnage estimate, the connection design responsibility, the finish and corrosivity category, and the delivery schedule by area. Where only a concept exists, World Steel's design team can develop the rack from the piping layout and load data.