Pipe insulation · Elastomeric foam
AEROFLEX Tube Insulation
- Tube bore
- 6–165 mm
- Wall thickness
- 6–50 mm
- Service temp.
- -57 – 125 °C
How should elastomeric pipe insulation be protected from UV outdoors?
In short
Elastomeric (rubber) insulation outdoors is exposed to UV, ozone, rain and built-up heat, so it should have a protective finish such as the manufacturer's coating or metal cladding, as that product's manufacturer specifies. The requirement differs from brand to brand. Whatever finish is used, every seam must be glued shut first: the finish deals with sun and rain, but it does not replace seam sealing.
How is outdoors different from indoors?
Refrigerant lines on a roof, chilled-water pipes on an outside wall or solar hot-water pipes work in much harsher conditions than pipes in a ceiling void.
- UV and ozone can degrade the rubber surface over time. Manufacturers test resistance to these and state their outdoor recommendations in their documents.
- Rain and standing water. If a seam opens or the surface cracks, water can sit between the insulation and the pipe.
- Heat and movement. Strong sun followed by rain makes the material expand and contract repeatedly, and seams that were not fully glued usually open first.
- Mechanical damage, such as being stepped on, knocked, or leaned on by other equipment.
On a cold pipe, the result is water vapour and water reaching the pipe surface, causing condensation and wet insulation, which lowers performance and may rust the pipe. See the principle in Why do AC pipes drip?
What does each manufacturer recommend?
The statements below summarise the documents of the manufacturers whose products we sell. Follow the guidance for the brand actually installed; do not apply one brand's guidance to another.
| Product | What the manufacturer's document says about outdoor use |
|---|---|
| --- | --- |
| ArmaFlex Class 1 | UV protection with ArmaFinish paint or the Arma-Chek covering system is required, and for outside use it should be protected within three days of installation |
| MAXFLEX FR Tube | Outdoor applications should be clad with metal sheet (aluminium or stainless steel) or painted with 2–3 layers of Maxcoat |
| AEROFLEX Tube | EPDM rubber for indoor and outdoor use; painting with Aerocoat (an exterior acrylic paint) is recommended for an extra layer of UV protection or for appearance |
The MAXFLEX and AEROFLEX documents also report ozone and UV resistance tests, but a material test result does not mean the surface needs no care for the whole service life. Jobs that need a long life, or that are hard to reach for repair, are therefore usually given a protective finish from the start.
Coating or metal cladding?
| Insulation manufacturer's coating | Metal cladding | |
|---|---|---|
| --- | --- | --- |
| Protects against | UV and weather | UV, weather and impact |
| Suits | Small pipes, fittings and complex shapes, areas without foot traffic | Long straight runs, places where people walk or impact is likely |
| What to look after | Number of coats and recoating interval in that coating's data sheet | Sheet joints must not let water run in and collect inside |
The paint must be one the insulation manufacturer states is compatible with that insulation, because it has to flex with the rubber and must not react with it. Do not substitute a general-purpose paint without checking.
Seal the seams before finishing
- Apply the manufacturer's elastomeric adhesive across the full face of the lengthwise slit and every butt joint, then press the seam together along its length.
- Do not stretch the insulation when sliding it on or closing a joint. Stretched insulation shrinks back and pulls the seam open.
- Choose a bore that fits the pipe. See Pipe sizes and insulation bore.
- Fittings, valves and pipe hangers are where water most often gets in; insulate them continuously with no gaps.
More on sealing in Sealing insulation joints.
Aluminium foil tape is made for sealing joints in foil-faced insulation, such as glass wool or stone wool on ducts. None of the three elastomeric manufacturers' documents above lists foil tape as the UV protection for rubber insulation, so use the coating or covering system the manufacturer specifies. See what each accessory is for in Insulation fixing and sealing accessories.
Thickness for cold pipes outdoors must be recalculated
Outdoor air is hotter and more humid than an air-conditioned room. A thickness that prevents dripping indoors may not be enough outdoors. Have the designer calculate from the real climate, or send us the site details to check. See How thick should insulation be?
Common mistakes
- Installing rubber insulation outdoors and leaving it without the protective finish the manufacturer requires
- Painting over seams that were never glued, hoping the paint will close them
- Cladding with the sheet seam facing upward, so rain runs in and collects under the sheet
- Not inspecting the surface from time to time; cracked surfaces or flaking paint should be repaired before water reaches the pipe
Sources
- Armacell — ArmaFlex Class 1 TDS (11/2019, APAC), UV resistance entry
- Vandapac Co., Ltd. — MAXFLEX FR STANDARD catalogue (FLEX 08/24), note under the specification table
- Aeroflex Co., Ltd. — AEROFLEX brochure (AF/OCT 2024), hot-water piping section and specification table
- ArmaFinish HN coating product information (via distributor Pipelagging.com) — background on coating and recoating
Related products
Categories and example products for this topic
- AEROFLEX Tube Insulation — Closed-cell EPDM; the maker's document covers indoor and outdoor use.
- ArmaFlex Class 1 Tube — The maker requires paint or covering for UV within 3 days outdoors.
- MAXFLEX FR STANDARD Tube — Closed-cell EPDM for chilled and hot-water pipes, indoors and outdoors.
Pipe insulation · Elastomeric foam
Armacell ArmaFlex Class 1 Tube
- Tube bore
- 6–168 mm
- Wall thickness
- 6–50 mm
- Service temp.
- -50 – 105 °C
Pipe insulation · Elastomeric foam
MAXFLEX FR STANDARD Tube
- Tube bore
- 6–165 mm
- Wall thickness
- 6–50 mm
- Service temp.
- -57 – 125 °C