K-Flex Pipe Insulation

K-Flex Pipe Insulation — Class O Elastomeric Foam & Mineral Wool

K-Flex is one of the world's leading manufacturers of flexible pipe insulation, producing a comprehensive range of Class O elastomeric foam and mineral wool pipe insulation for HVAC, plumbing, refrigeration and industrial applications. Manufactured in Italy by K-Flex S.r.l., K-Flex products are specified across the UK as a high-quality, competitively priced alternative to Armaflex, offering equivalent Class O performance across the full range of standard pipe sizes and wall thicknesses.

The K-Flex Range

K-Flex ST — Standard Elastomeric Foam

K-Flex ST is the core elastomeric foam pipe insulation in the K-Flex range — a closed-cell nitrile rubber (NBR) foam with Class O fire rating, built-in vapour barrier and low thermal conductivity. Available in 2 metre lengths with a standard slit closure, K-Flex ST is the direct equivalent of Armaflex EVO and is suitable for all standard HVAC, heating, chilled water and plumbing applications.

Fire classification: Class O (BS 476 Part 6 & 7), B-s2,d0 (EN 13501)
Thermal conductivity: λ ≤ 0.034 W/mK at 0°C
Water vapour resistance: μ ≥ 7,000
Operating temperature: -50°C to +105°C
Closure: Standard slit (requires adhesive to seal)
Available wall thicknesses: 9mm, 13mm, 19mm, 25mm, 32mm

K-Flex ST Self-Seal — Factory-Applied Adhesive Closure

K-Flex ST Self-Seal is the self-adhesive closure version of K-Flex ST, with a factory-applied pressure-sensitive adhesive strip on the slit closure for faster installation on straight pipe runs. Identical thermal and fire performance to standard K-Flex ST — the adhesive closure simply speeds up installation by eliminating the need to apply adhesive to the slit on straight runs. Butt joints and fittings still require K-Flex adhesive.

Same Class O, thermal and vapour performance as K-Flex ST
Factory-applied adhesive closure strip — peel and press to seal the slit
Faster installation on long straight runs in plant rooms and service corridors
Available in all standard pipe sizes and 9mm, 13mm, 19mm and 25mm wall thicknesses

K-Flex K-Rock — Mineral Wool Pipe Insulation

K-Flex K-Rock is a mineral wool pipe insulation with aluminium foil facing, designed for high-temperature applications where elastomeric foam cannot be used. K-Rock is the K-Flex equivalent of Rockwool Rocklap, providing A1 non-combustible fire performance and a continuous operating temperature up to +300°C. Specified for steam mains, high-temperature heating, industrial process pipework and any application requiring non-combustible insulation.

Fire classification: A1 non-combustible (EN 13501) — the highest fire rating available
Thermal conductivity: λ ≤ 0.034 W/mK at 50°C
Operating temperature: up to +300°C continuous
Facing: Aluminium foil with self-adhesive lap joint (K-Rock ALU Self-Seal)
Available wall thicknesses: 25mm, 40mm, 50mm, 60mm

K-Flex ST vs Armaflex EVO — Which Should I Choose?

Performance: K-Flex ST and Armaflex EVO are closely matched on thermal conductivity and vapour resistance. Both are Class O and suitable for the same range of HVAC, heating and chilled water applications
Price: K-Flex ST is typically priced competitively against Armaflex EVO, making it an attractive option where budget is a consideration without compromising on specification
Availability: K-Flex ST is available in 32mm wall thickness which is not standard in the Armaflex EVO range
Adhesive: K-Flex ST requires K-Flex adhesive — do not mix K-Flex and Armaflex adhesives on the same installation

Common Applications

Commercial and domestic central heating flow and return pipework (K-Flex ST)
Chilled water flow and return in HVAC systems (K-Flex ST)
Air conditioning refrigerant and chilled water pipework (K-Flex ST Self-Seal)
Domestic and commercial hot and cold water supply (K-Flex ST)
Acoustic insulation applications (K-Flex Acoustics range)
Rail vehicle pipework (K-Flex Rail range)
Industrial process pipework (K-Flex Industrial range)
Steam mains and high-temperature heating up to +300°C (K-Rock)
Fire-rated installations requiring A1 non-combustible insulation (K-Rock)

Shop by Pipe Size

15mm | 22mm | 28mm | 35mm | 42mm | 54mm | 76mm | 89mm | 114mm

Technical Downloads — K-Flex ST

Technical Downloads — K-Flex K-Rock

Technical Downloads — K-Flex Brand & Applications

Technical Support

For technical advice on K-Flex products, help selecting the right product for your application, or project specification support, call our team on 0161 775 1190 (Mon–Fri 8am–4pm).