Types of Pipe Supports

Pipe supports carry the weight of piping systems, control thermal movement, absorb dynamic loads, and restrain the pipe at specific locations. The selection and spacing of supports is a critical output of piping stress analysis and directly affects system integrity, equipment nozzle loads, and maintenance access.

The primary standards governing pipe supports are MSS SP-58 (pipe hangers and supports—materials, design, manufacture), MSS SP-69 (selection and application), and MSS SP-89 (fabrication).

Pipe Support Categories

Category	Function	Movement Allowed	Examples
Rest supports	Carry dead weight (pipe + contents + insulation)	Free horizontal sliding	Pipe shoes, saddles, trunnions on steel
Guides	Allow axial movement, prevent lateral displacement	Axial only	Line guides, spider guides
Anchors	Prevent all movement and rotation	None	Welded anchors, anchor blocks
Hangers	Suspend pipe from above; carry vertical dead weight	Depends on type	Rod hangers, clevis hangers, trapeze hangers
Spring supports	Carry weight while accommodating vertical thermal movement	Vertical (controlled)	Variable springs, constant springs
Restraints	Resist loads in one or more directions	Restricted in load direction	Limit stops, snubbers, struts

Common Pipe Support Types

Support Type	Standard	Application	Typical Size Range
Pipe shoe	MSS SP-58 Type 35/36	Elevates pipe off steel for insulation clearance; rests on structural steel	2 in. to 48 in.+
Saddle support	MSS SP-58 Type 37/38	Cradle for large-diameter pipes (>12 in.); distributes load over a wider arc	12 in. to 72 in.
Trunnion	Project-specific	Welded pipe stub supporting the pipe; often used with shoes or springs	4 in. to 48 in.
U-bolt	MSS SP-58 Type 24	Clamps around pipe; simple restraint for small bore and utility lines	1/2 in. to 8 in.
Rod hanger	MSS SP-58 Type 1	Suspends pipe from overhead steel using threaded rods	1/2 in. to 36 in.
Clevis hanger	MSS SP-58 Type 1	Rod hanger with clevis at pipe connection; allows angular movement	1/2 in. to 30 in.
Trapeze hanger	MSS SP-58 Type 39	Channel or angle supporting multiple small-bore pipes	Multiple lines
Spring hanger (variable)	MSS SP-58 Type 52	Carries weight while allowing vertical thermal displacement; load varies with travel	1 in. to 48 in.
Constant spring hanger	MSS SP-58 Type 53	Maintains constant support load regardless of vertical movement	4 in. to 48 in.
Snubber (hydraulic/mechanical)	MSS SP-58	Resists dynamic loads (seismic, water hammer, safety valve reaction) but allows slow thermal movement	All sizes

Support Selection Criteria

Criterion	Consideration
Dead weight	Pipe weight + fluid + insulation + snow/ice loads
Thermal movement	Axial growth, lateral displacement, vertical rise/drop from thermal expansion
Dynamic loads	Seismic, wind, water hammer, slug flow, safety valve discharge
Insulation clearance	Pipe shoes must elevate pipe above steel to protect insulation (typically 75-150 mm)
Friction	Sliding supports generate friction loads on equipment nozzles; use low-friction pads (PTFE) to reduce
Corrosion	Dissimilar metals require isolation pads; carbon steel shoes on stainless pipe need SS or alloy wear pads
Access	Supports must not block valve operation, instrument access, or maintenance routes

Common Mistake

Welding carbon steel support attachments directly to austenitic stainless steel or duplex pipe. This creates a dissimilar metal weld that can cause carbon migration, sensitization, and corrosion at the contact point. Always use stainless steel or alloy wear pads between carbon steel supports and stainless/duplex piping.

Variable vs Constant Spring Supports

Parameter	Variable Spring	Constant Spring
Load variation	Load changes with displacement (typically 25% max variation allowed)	Load remains constant through full travel range
Cost	Lower	3-5x more expensive
Size	Compact	Larger and heavier
Application	Most thermal displacement situations	Critical equipment nozzles; large vertical movements where load variation must be minimized
Variability limit	Max 25% per MSS SP-58 (some specs limit to 15%)	0% (by design)

Support locations, types, and loads are documented on the stress isometric and piping support drawing, which reference the pipe class and piping isometric for the system.

Read the full guide to pipe class specifications