A pipe rack is the elevated steel frame that carries process piping, cable trays and small equipment between the units of a plant. It is built to your layout, not picked from a catalogue. This guide covers the main types, the loads that drive the design, and how a certified fabricator builds a rack to your drawings.
What a pipe rack is, and how much of a plant it carries
A pipe rack is a load-bearing steel frame that routes process piping, electrical cable trays and instrument lines across a plant. It lifts the pipes off the ground, frees the floor for equipment and access, and keeps the runs in ordered corridors that crews can reach for maintenance. On a refinery or a power plant, the rack is one of the largest single steel items on site. Because the rack ties every unit together, a delay on it holds up the whole plant, which is why buyers check the fabricator early. Industry estimates put pipe racks at 15% to 25% of a plant's structural steel tonnage, so the choice of fabricator sets a large part of the steel budget. The scope we fabricate is on our pipe rack page.
The types of pipe rack: single-tier, multi-tier and equipment support
Pipe racks divide into a few clear types, and the type follows the plant rather than a product line. A single-tier rack carries one level of pipes and suits short utility runs. A multi-tier rack stacks two or three levels to separate hot lines, cold lines and cable trays, and it fits more service into the same footprint. Transverse frames repeat down the length of the rack at a regular bay spacing, and the number of tiers follows the service count, so a plant that plans to grow often builds in a spare level. An equipment-support rack adds platforms, stairs and walkways so operators can reach valves and instruments. Beyond the racks, a process plant needs heavy non-standard steel: plate hoppers, chutes and rolled cylindrical shells. According to Yu Hang, our welding coordinator, we fabricate all of these on the same lines, so the racks, the platforms and the shells arrive under one certificate. The shop that does it is on our capabilities page.
The loads that decide the design, and why the water test often wins
A pipe rack has to carry far more than the pipes. The design adds the weight of the fluid inside them, the pull of thermal expansion as lines heat and cool, plus wind and, on many sites, seismic load. One case often governs the beams: the hydrotest, when crews fill every line with water to prove it before start-up. Water weighs more than most process fluids, so the rack has to hold a load it may never see again in service. Because these loads change from bay to bay, the member sizes change too, which is the first sign that a rack is not a repeating catalogue product. The engineer of record sets these cases and sizes the steel. We do not design the rack. Our certificate records the boundary in plain words: "Design: Not include." We fabricate to the drawings your consultant or EPC contractor issues, which keeps the engineering responsibility where it belongs. You can read how we handle the class in our guide to EN 1090-2 execution classes.
Make-to-print, not modular: what that means for your rack
Much of the market sells pipe racks as modular or pre-engineered systems, built from repeating standard bays. That model works when the layout is regular. A real process plant rarely is. Every bay follows the piping and equipment drawing, so a pre-engineered building supplier usually stops at the standard portal frames, and the racks get split to a second vendor or welded on site. We work the other way round. We fabricate the non-standard racks, the equipment platforms and the access stairs as one package, to your engineer's drawings. A rack welded up on site, out in the weather, rarely matches the fit of one built and checked in a shop, and the difference shows when the pipe crews arrive. According to Yu Hang, keeping the racks and the buildings in one shop means they share the same tolerances and the same welding coordinator, which is where site fit-up problems usually start. The procurement side of this sits in our guide on how to specify and verify a pipe rack fabricator.
How a bay-by-bay pipe rack is fabricated in the shop
The rack starts as plate and section steel and becomes built-up H-section columns and beams, cut and welded to the member sizes on your drawings. Our works runs six H-section production lines and two heavy-structure lines, so a rack and its supporting frames move through the shop together. We weld with three qualified processes: 135 (MAG), 136 (FCAW) and 121 (submerged arc), and we run robot and submerged-arc welding on the repeatable joints for a steady weld. Our welding procedure records cover these processes at plate thicknesses up to 30 mm. On the members that have to fit first time, we end-mill and straighten the sections before assembly, because a rack that sits a few millimetres out will not bolt up on site. We shot blast and coat the steel in-house before packing. The plant behind this is on our capabilities page.
Coating the rack for the plant environment
The plant environment sets the coating on a pipe rack, not the lowest bid. An indoor utility rack may need only a primer and a topcoat, while a rack in a coastal or chemical plant needs a heavier system to hold back corrosion over the plant's life. We blast and coat every job in-house before it ships, so the surface preparation and the paint go on under controlled conditions rather than in an open yard. According to Yu Hang, coating scope is one of the three things that settle most rack enquiries, alongside the execution class and the welding records, so we ask for the specification early. The finishing capacity is part of the plant on our capabilities page.
The certificate that lets an export rack clear a European tender
On a tender written to EN standards, the execution class rules out most fabricators before anyone discusses price. A pipe rack for a high-consequence plant needs EN 1090-2 execution class EXC3, and only a shop certified to EXC3 by a notified body may build it. EUROCERT S.A. in Greece issued our EN 1090-2:2018 certificate 1128-CPR-10.09.0686 for execution class EXC3, valid until 13 March 2028 under annual surveillance. The welds behind that class run on a welding quality system: we hold ISO 3834-2:2021, certificate 10.09.0687, and our welding coordinator holds the International Welding Engineer qualification under ISO 14731:2019. According to Yu Hang, a buyer's inspector can confirm the EXC3 certificate with EUROCERT directly before any steel is cut. The scans and numbers are on our certifications page.
Shipping a pipe rack across borders
A pipe rack for an overseas plant has to survive packing, sea freight and site assembly, so the export record matters as much as the shop. We have shipped steelwork to 14 countries, including Thailand, Indonesia, Cambodia, the Philippines, Egypt and Türkiye, across 32 export projects. Individual jobs have run from 5 tonnes to 2,000 tonnes, so we plan around a real range rather than a single average. We pack for container or breakbulk by member length and tonnage, and we split long runs at bolted splices your engineer designs, so the pieces travel and then bolt up in the right order on site. According to Yu Hang, the site lifting plan drives how we break a rack down for shipment, so we ask for it early. The project list, with countries and scope, is on our projects page.
Who a make-to-print rack is for
A make-to-print rack fits three buyers in particular. The first is an EPC contractor bidding a project written to EN standards, where the execution class rules out most shops at prequalification and a verifiable EXC3 certificate clears the gate. The second is a manufacturer building its own plant overseas: fifteen of our thirty-two export projects sit in Thailand alone, from workshops to plant buildings for industrial clients. The third is a power or process plant retrofit, where new steel has to fit existing plant to tight tolerances, and the traceability that EXC3 carries is the reason the work holds. According to Yu Hang, the same client often comes back across more than one country, because a rack that fits first time and ships clean is worth repeating. The power and process work behind this is on our industrial plant structures page.
A short checklist before you award the rack
Before you award a pipe rack, settle five things in writing. Confirm the EN 1090 execution class with a certificate number you can check with the issuing body. Confirm the ISO 3834 welding tier and the coordinator's qualification. Ask for a project list with countries and tonnages, not a headline count. Check that the shop does blasting and coating in-house rather than sub-letting them. Confirm that the racks, platforms and stairs come from one shop. According to Yu Hang, most of a rack enquiry comes down to three answers before any steel is cut: the class, the welding records and the coating scope. Send us the shop or design drawings with a scope note and a target date, and we will confirm the execution class, the lead time and the price in writing through our contact page.