Pipe insulation fails for three reasons: the wrong thickness, the wrong density, or joints that let heat — and water — through. This guide covers how pre-formed rock wool pipe sections are selected and installed, from a 25 mm condensate line to a high-temperature process header.
Why rock wool for pipes
- Temperature range — rock wool serves steam, hot water and process piping well beyond the limits of most foam insulations, and it does not melt or drip under fire exposure.
- Shape retention — pre-formed sections hold their circular form around the pipe, keeping the insulation gap uniform so there are no thermal bridges through compressed material.
- Non-combustible — A1 classification matters in plant rooms, tunnels, risers and anywhere the specification has to satisfy a fire authority.
- Acoustic benefit — useful on condensate and pumped lines where noise travels along the pipe.
Selecting density
80 kg/m³ is the standard section for most steam, hot water and HVAC pipework. Step up to 100 or 120 kg/m³ where the pipe is subject to mechanical load, where sections must stay rigid in long runs, or where the specification is driven by high-temperature process duty.
Selecting thickness
Thickness is set by the pipe diameter, the operating temperature and the acceptable surface temperature (usually for personnel protection and for heat loss). The pattern that holds in practice:
| Service | Typical thickness |
|---|---|
| Chilled / cold water, condensation control | 30–50 mm with a vapour barrier |
| Hot water and low-pressure steam | 50–80 mm |
| Medium and high-pressure steam, process lines | 80–100 mm, often double-layer with staggered joints |
Two layers with staggered joints is standard practice above roughly 100 mm of insulation: it stops the joint lines from lining up into a straight heat path.
The details that decide performance
- Joint staggering — longitudinal joints of the second layer must be offset from the first. This one detail has more effect on measured heat loss than the density you buy.
- Facing — aluminium foil for general work, glass cloth or a reinforced laminate where the surface is subject to abrasion, and a proper vapour barrier on cold lines. On cold service the vapour barrier goes on the outside of the insulation and must be sealed at every joint.
- Expansion and support — leave expansion allowance, and support the pipe rather than the insulation, or the insulation will be crushed at every hanger.
- End caps and closures — cut sections to fit valves, flanges and tees properly. Gaps around fittings are the usual source of both heat loss and condensation.
- Weather protection — outdoor lines need cladding or a weather-resistant jacket regardless of how good the insulation is.
Standards and documentation
Our pre-formed sections are produced to GB/T 11835-2016, A1 non-combustible, with thermal conductivity around ≤ 0.045 W/(m·K). Ask for the batch test report for your production run, plus EN or ASTM test reports if your project requires them for the submission file.
What to send us for a quotation
Pipe outside diameter, insulation thickness, density, service temperature, quantity in metres, facing type and destination port. With those seven numbers we can quote immediately — the range covers custom diameters and thicknesses from 30–100 mm. See the industrial and marine rock wool range — pipe sections 80, 100 and 120 kg/m³, felt blankets and industrial boards — or request a quotation. WhatsApp +86 175 6050 1246.
Related reading
- Rock Wool Thermal Conductivity and R-Value Explained
- How to Import Rock Wool from China: A Complete 7-Step Guide
- Rock Wool vs Glass Wool Insulation Cost: What Actually Drives the Price
Buyer questions we get most
What density are pipe sections supplied in?
Our standard pipe sections run at 100 and 120 kg/m³ — the denser grade is used where mechanical abuse or higher compressive strength is expected.
How do I size a pipe section?
Match the bore to the pipe outside diameter and choose the wall thickness for the R-value you need; custom diameters and thicknesses are available.
Are the sections foiled?
Foil and other facings can be applied where vapour control or surface protection is needed — say so when you request the quotation.
About this guide
Who maintains it
This guide is maintained by the Taishi Rock Wool export team in Shandong, China — factory-direct rock wool and glass wool from seven production bases with a combined capacity of 800,000 tonnes a year. Technical questions go straight to the factory rather than to a trading desk: WhatsApp +86 175 6050 1246 or email cliu32626@gmail.com.
Standards and sources referenced
- GB/T 25975-2018 — Chinese national standard for rock wool and its products; our production and test reports follow it.
- EN 13162 — European product standard for mineral wool, including how thermal conductivity (λ) is declared.
- EN 13501-1 — fire classification of construction products; class A1 means non-combustible.
- ISO 8301 / ASTM C518 — steady-state thermal conductivity test methods behind any quoted λ figure.
- ASHRAE Handbook—Fundamentals — definitions of thermal conductivity and R-value used here.
- EURIMA — European Mineral Wool Manufacturers Association, technical guidance on mineral wool performance.
- Insulation Institute (NAIMA) — industry technical resources on insulation performance and specification.
Last updated: September 23, 2026