What Is a Pipe Shoe? Insulated Support
A pipe shoe is a welded or clamped support attachment that raises a pipe above the structural steel beam or sleeper it rests on. The primary purpose is to protect pipe insulation from being crushed by the support and to maintain a defined clearance between the pipe outer surface and the bearing surface. Pipe shoes also prevent direct metal-to-metal contact between the pipe and the support steel, reducing crevice corrosion.
When Pipe Shoes Are Used
Pipe shoes are required whenever:
- The pipe carries hot or cold fluid and is insulated (the shoe height must exceed the insulation thickness)
- Direct pipe-to-steel contact would cause galvanic or crevice corrosion
- The pipe must slide on the support to accommodate thermal expansion
- A defined bearing width is needed to distribute the pipe load on the support beam
Pipe shoes are standard on pipe racks, pipe bridges, and pipe sleepers in process plants, refineries, and LNG terminals.
Types and Specifications
| Type | Construction | Typical Application |
|---|---|---|
| Welded pipe shoe (T-type) | Two vertical plates welded to the pipe bottom, with a base plate | Most common for carbon and alloy steel pipes NPS 3 and above |
| Welded channel shoe | Channel section welded to the pipe bottom | Heavy pipes or where wider bearing is needed |
| Clamped pipe shoe | Bolted clamp around the pipe with extended legs | Stainless steel, duplex, or non-ferrous pipes where welding to the pipe is restricted |
| Saddle-type shoe | Curved saddle plate welded to pipe, with legs | Large-diameter pipes (NPS 16+) |
| Adjustable pipe shoe | Threaded legs for field height adjustment | Where exact elevation is critical |
Height Sizing
The shoe height (H) must provide clearance above the insulation outer diameter:
| Pipe Insulation Thickness | Minimum Shoe Height | Notes |
|---|---|---|
| Uninsulated | 50 mm (2 in) | Minimum to prevent crevice corrosion |
| 25-50 mm (1-2 in) | 75-100 mm (3-4 in) | Typical for warm services (60-150 C) |
| 50-75 mm (2-3 in) | 100-150 mm (4-6 in) | Hot services (150-350 C) |
| 75-100 mm (3-4 in) | 150-200 mm (6-8 in) | High-temperature pipes (350-550 C) |
| 100-150 mm (4-6 in) | 200-300 mm (8-12 in) | Cryogenic or very high-temperature services |
Material Selection
Pipe shoe material must be compatible with the pipe material to avoid galvanic corrosion and must meet the same design temperature requirements:
| Pipe Material | Shoe Material | Standard |
|---|---|---|
| Carbon steel (ASTM A106) | Carbon steel (A36/A283) | ASTM A36 / EN 10025 S235 |
| Low-alloy steel (ASTM A335) | Matching alloy or carbon steel with alloy pad | ASTM A387 |
| Stainless steel (304/316) | Stainless steel or clamped carbon steel with isolation pad | ASTM A240 |
| Duplex stainless steel | Duplex stainless or clamped with isolation | ASTM A240 UNS S31803 |
For stainless and duplex pipe materials, clamped shoes with PTFE or composite isolation pads are preferred over welded shoes to avoid sensitization and maintain corrosion resistance.
Design Standards
Pipe shoe design is covered by MSS SP-58 (Pipe Hangers and Supports - Materials, Design, and Manufacture) and MSS SP-69 (Pipe Hangers and Supports - Selection and Application). The pipe stress engineer specifies shoe locations and heights; the structural engineer verifies the support beam capacity for the concentrated load from the shoe base plate.
Friction between the shoe base plate and the support beam affects pipe stress analysis. Typical friction coefficients are 0.3 for steel-on-steel and 0.1 for PTFE slide plates. Where thermal movement is large, slide plates (PTFE bonded to stainless steel) reduce friction forces transmitted to the support structure and pipe anchors.
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