BS 5422 Pipe Insulation Thickness Tables
The following tables provide indicative minimum insulation thicknesses under BS 5422 for the most common UK pipe insulation applications. Always verify against the current BS 5422 standard and manufacturer lambda data for your specific application and operating temperature.
Table 1 — Heating Pipework (LTHW, up to 75°C) — Kingspan Kooltherm (λ = 0.025 W/mK)
| Pipe OD (mm) | Minimum Wall Thickness | Collection |
|---|---|---|
| ≤17.2mm (15mm copper) | 15mm | 15mm wall |
| ≤21.3mm (22mm copper) | 20mm | 20mm wall |
| ≤26.9mm (28mm copper) | 20mm | 20mm wall |
| ≤33.7mm (35mm copper) | 25mm | 25mm wall |
| ≤42.4mm (42mm copper) | 25mm | 25mm wall |
| ≤60.3mm (54mm copper) | 30mm | 30mm wall |
| ≤76.1mm | 30mm | 30mm wall |
| ≤114.3mm | 35mm | 40mm wall |
| ≤168.3mm | 40mm | 40mm wall |
| ≤219.1mm | 50mm | 50mm wall |
Indicative values for LTHW heating at up to 75°C in a heated internal space. Always verify against current BS 5422 tables.
Table 2 — Heating Pipework (LTHW, up to 75°C) — Armaflex EVO (λ = 0.033 W/mK)
| Pipe OD (mm) | Minimum Wall Thickness | Collection |
|---|---|---|
| ≤17.2mm (15mm copper) | 19mm | 19mm wall |
| ≤21.3mm (22mm copper) | 25mm | 25mm wall |
| ≤26.9mm (28mm copper) | 25mm | 25mm wall |
| ≤33.7mm (35mm copper) | 32mm | 32mm wall |
| ≤42.4mm (42mm copper) | 32mm | 32mm wall |
| ≤60.3mm (54mm copper) | 32mm | 32mm wall |
Indicative values for LTHW heating at up to 75°C. Armaflex EVO is not typically specified for BS 5422 commercial heating compliance — phenolic or mineral wool is preferred. Always verify against current BS 5422 tables.
Table 3 — Chilled Water & Condensation Control — Armaflex EVO (λ = 0.033 W/mK)
| Pipe OD (mm) | Pipe Temperature | Minimum Wall Thickness | Collection |
|---|---|---|---|
| ≤17.2mm | 6–12°C | 19mm | 19mm wall |
| ≤21.3mm | 6–12°C | 19mm | 19mm wall |
| ≤33.7mm | 6–12°C | 25mm | 25mm wall |
| ≤60.3mm | 6–12°C | 25mm | 25mm wall |
| ≤17.2mm | 0–6°C (refrigeration) | 25mm | 25mm wall |
| ≤33.7mm | 0–6°C (refrigeration) | 32mm | 32mm wall |
| ≤60.3mm | 0–6°C (refrigeration) | 32mm | 32mm wall |
Indicative values for standard UK ambient conditions (25°C, 60% RH). Higher humidity environments require thicker walls. Always verify against current BS 5422 tables.
Table 4 — High Temperature & Steam — Rockwool Rocklap / Kingspan K-Roc (λ = 0.033–0.040 W/mK)
| Pipe OD (mm) | Operating Temperature | Minimum Wall Thickness | Collection |
|---|---|---|---|
| ≤21.3mm | Up to 200°C | 30mm | 30mm wall |
| ≤33.7mm | Up to 200°C | 40mm | 40mm wall |
| ≤60.3mm | Up to 200°C | 40mm | 40mm wall |
| ≤114.3mm | Up to 200°C | 50mm | 50mm wall |
| ≤168.3mm | Up to 200°C | 50mm | 50mm wall |
Indicative values for high-temperature applications. Steam and superheated water pipework requires detailed calculation. Always verify against current BS 5422 tables and manufacturer data.
Key BS 5422 Principles
- Performance-based — BS 5422 specifies minimum thermal performance, not a single material. Different materials achieve compliance at different wall thicknesses depending on their lambda value
- Lambda value is critical — Kingspan Kooltherm (λ = 0.025) achieves compliance at a thinner wall than Armaflex EVO (λ = 0.033) or Rockwool (λ = 0.034+)
- Pipe size matters — required thickness increases with pipe diameter for the same operating temperature
- Temperature band matters — higher operating temperatures require thicker insulation walls
- Location matters — pipes in unheated spaces (plant rooms, roof voids, external) require thicker insulation than pipes in heated spaces
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