Design a steel pipe rack

Pipe racks are the arteries of refineries, chemical plants and power stations: long, repetitive steel structures that carry pipes, cable trays and walkways between process units. A rack is a row of bents — portal frames across the rack — linked along its length by struts and braced in one bay. The Pipe rack template builds one with any number of bays and pipe levels.

#How a pipe rack carries load

Pipes rest on the beams of each bent, so the pipe weight arrives as a line load on every level beam. The beams carry it to the columns and down to the foundations.

Across the rack, each bent is a moment frame stiffened by knee braces at the beam-to-column corners — short diagonals that shorten the beam span and make the corners much stiffer. Along the rack, the bents on their own would fold over like dominoes; the longitudinal struts at every level tie them together and the X-bracing in the middle bay takes all the longitudinal force (pipe friction, anchors, wind along the rack, earthquake) down to the ground.

#Step 1 — Pick the template

1. In the gallery choose Industrial › Pipe rack.
2. The default is six bays at 6 m, 6 m wide, with two pipe levels at 5 m and 7.5 m, in steel with fixed bases.

#Step 2 — Set the size

Parameter	Section	Default	Range
Bays	Plan	6	2–20
Bent spacing	Plan	6 m	4–10 m
Rack width	Plan	6 m	3–12 m
Pipe levels	Height	2	1–4
First level height	Height	5 m	3–8 m
Level spacing	Height	2.5 m	1.5–4 m
Pipe load on each beam (kN/m)	Pipes	15	0–60

The pipe load is applied to every bent beam at every level, as part of the Dead load case. Estimate it from the pipes on one beam: the weight of each pipe full of its contents (or of water for the hydrotest) times the bent spacing, spread over the rack width. The knee braces are up to 1 m long, shorter for narrow racks or tight level spacing.

#Step 3 — Materials and sections

1. Pick the Design code and steel Grade.
2. Sections for Columns, Beams (the bent beams and the longitudinal struts share this group) and Bracing (the knee braces and the X-braces, designed as truss members).
3. Keep Size members for me on.

#Step 4 — Supports and loads

1. Bases are fixed by default — usual for racks, which rely on base fixity across the rack. Switch on Pad footings for the foundations.
2. There are no floors, so no floor use or finishes. The rack carries self-weight and the pipe load.
3. Wind: the rack has no cladding, so wind acts as drag on the members themselves (force coefficient 2.0 on the section width).
4. Switch on Earthquake for seismic sites; choose Ordinary moment frame for the bents (or Braced frame, which suits the longitudinal direction).

#Step 5 — Analyse

Press Run analysis (F5). Check:

1. Moment under the envelope: the bent beams sag between the knee braces; the columns bend most at the base and at the knee braces.
2. Displacement under Wind +Y (across) and Wind +X (along): the rack should sway little along its length — if it does, check the braced bay.
3. Axial: the X-braces in the middle bay carry the longitudinal loads; the struts deliver them.
4. With earthquake on, the first periods across and along the rack.

#Step 6 — Design

1. Press Run design (F6). Members are checked and sized; base plates, end and fin plates and brace gussets are designed.
2. Show Utilization and Steel connections in 3D. Click a base to see the base plate, anchors and welds.
3. Produce the Calculation report and Shop drawings — racks are repetitive, so the drawings group identical parts.

#Typical problems and fixes

• Struts are oversized. They share the Beams group with the heavily loaded bent beams. A member's Group can be changed in its properties, but the template only has three groups, and Bracing members are pin-ended truss members — moving the struts there changes how the rack works, so run the analysis again and check the sway. Often it is simpler to accept the heavier struts.
• Long racks need more braced bays. The template braces only the middle bay. For thermal movement, real racks are broken into blocks of 60–100 m with one braced bay each.
• Columns governed by base moment. Increase the knee brace size (stiffer corners) or the column section.

#Rules of thumb

• Bent spacing 6 m is typical; small pipes need intermediate supports at that spacing.
• Bent beam depth ≈ span / 20; with knee braces the effective span is shorter.
• Leave 20–25 % spare capacity on each level for future pipes.