Armaflex Adhesive Guide — How to Use Armaflex 520 Correctly

June 7, 2026

Armaflex 520 is the contact adhesive manufactured by Armacell specifically for bonding and sealing Armaflex elastomeric pipe and sheet insulation. Using the correct adhesive and applying it properly is not optional — it is essential for maintaining the vapour barrier that makes Armaflex effective on cold pipework. An unsealed joint is a gap in the vapour barrier, and a gap in the vapour barrier means condensation.

This guide explains everything you need to know about Armaflex 520 adhesive: what it does, how to apply it, coverage rates, drying times and the most common mistakes to avoid.

What is Armaflex 520 Adhesive?

Armaflex 520 (also referred to as ADH520) is a solvent-based contact adhesive formulated by Armacell for use with all grades of Armaflex flexible elastomeric insulation. It creates a strong, flexible bond that maintains the integrity of the closed-cell vapour barrier at every seam and joint in the insulation system.

It is available in several sizes:

250ml tin — suitable for small domestic jobs
1 litre tin — suitable for medium residential and light commercial work
2.5 litre tin — suitable for larger commercial projects
ECO550 — Armacell's lower-VOC alternative adhesive for projects with environmental or indoor air quality requirements

Browse Armaflex adhesive at Pipelagging.

When Do You Need Armaflex Adhesive?

Armaflex 520 adhesive is required in the following situations:

Note: If you are using Armaflex Self Seal, the longitudinal seam has a factory-applied adhesive strip and does not require 520 adhesive. However, butt joints between lengths still require adhesive or Armaflex tape.

How to Apply Armaflex 520 Adhesive — Step by Step

What You Need

Armaflex 520 adhesive
A small brush or the brush supplied with the tin
Clean, dry cloths
Armaflex cleaner (for surface preparation on contaminated surfaces)

Step 1: Prepare the Surfaces

Both surfaces to be bonded must be clean, dry and free from dust, grease, oil or moisture. On new Armaflex insulation straight from the packaging, no special preparation is usually required. If surfaces are contaminated, clean with Armacell's Armaflex cleaner before applying adhesive.

Do not apply adhesive to wet or damp surfaces. Moisture prevents proper adhesion and will cause the bond to fail.

Step 2: Apply Adhesive to Both Surfaces

Using a brush, apply a thin, even coat of Armaflex 520 to both surfaces to be joined. This is a contact adhesive — it must be applied to both faces, not just one.

Apply evenly — avoid thick blobs or bare patches
Ensure full coverage to the edges of both surfaces
On longitudinal seams, apply adhesive along the full length of both faces of the slit

Step 3: Allow to Become Touch-Dry

Allow the adhesive on both surfaces to become touch-dry before joining. This is the most important step and the one most commonly rushed on site.

At 20°C, touch-dry time is typically 2–5 minutes
In cold conditions (below 10°C), allow longer — up to 10 minutes
In humid conditions, allow longer drying time
The adhesive is ready when it no longer feels wet to the touch but is still slightly tacky

Do not join the surfaces while the adhesive is still wet. Wet adhesive will not create a proper bond and the joint will peel open.

Step 4: Press the Surfaces Together Firmly

Once both surfaces are touch-dry, bring them together and press firmly with hand pressure along the full length of the joint. The bond is immediate on contact — you will not be able to reposition the surfaces once they touch, so align carefully before joining.

For longitudinal seams on pipe insulation, close the seam progressively along its length rather than all at once, pressing firmly as you go.

Step 5: Allow to Cure

The bond achieves handling strength immediately but reaches full strength after approximately 24 hours at room temperature. Avoid stressing the joint during this period where possible.

Coverage Rates

Coverage varies depending on surface texture and application method. Rough or porous surfaces will absorb more adhesive and reduce coverage.

Temperature and Conditions

Minimum application temperature: 5°C — do not apply in temperatures below this
Maximum application temperature: 40°C
Do not apply in rain or on wet surfaces
Ensure adequate ventilation — Armaflex 520 is solvent-based and produces fumes. Work in a well-ventilated area and avoid prolonged inhalation
Flammable — keep away from naked flames and sources of ignition during application and until fully dry

Common Mistakes to Avoid

Armaflex 520 vs ECO550 — Which Should You Use?

Armacell produces two main adhesives for Armaflex insulation:

Armaflex 520 (ADH520) — the standard solvent-based contact adhesive. Strong, fast-tacking and suitable for all Armaflex grades in all conditions. The default choice for most applications.
Armaflex ECO550 — a lower-VOC alternative with reduced solvent content. Suitable for projects with indoor air quality requirements or where solvent exposure needs to be minimised. Slightly longer drying time than 520.

For most standard installations, Armaflex 520 is the correct choice. ECO550 is specified where VOC emissions are a concern, such as in occupied buildings or projects with BREEAM or LEED requirements.

Armaflex Adhesive vs Armaflex Tape

For most bonding applications, Armaflex 520 adhesive gives a stronger and more reliable bond than Armaflex self-adhesive tape. Tape is best used for repairs, finishing exposed edges and sealing joints in locations where applying adhesive is impractical. For longitudinal seams and butt joints, adhesive is the professional standard.

Frequently Asked Questions

Can I use any contact adhesive with Armaflex?
No. Generic contact adhesives may not be chemically compatible with Armaflex elastomeric rubber and can cause the insulation to swell, crack or degrade over time. Always use Armacell's own Armaflex 520 or ECO550 adhesive.

How long does Armaflex 520 last once opened?
Once opened, Armaflex 520 should be used within 12 months if stored correctly with the lid tightly sealed. Store in a cool, dry place away from direct sunlight and frost. Do not allow the adhesive to freeze.

The adhesive has gone stringy or thick — can I still use it?
If the adhesive has thickened significantly, it may have partially cured or the solvent may have evaporated. Do not attempt to thin it with other solvents. Discard and use fresh adhesive.

Do I need adhesive on Armaflex Self Seal pipe insulation?
The longitudinal seam on Armaflex Self Seal has a factory-applied adhesive strip and does not require 520 adhesive. However, butt joints between lengths must still be sealed with Armaflex 520 adhesive or Armaflex tape.

Is Armaflex 520 adhesive waterproof?
Once cured, the bond created by Armaflex 520 is resistant to moisture. However, the adhesive should not be applied to wet surfaces or in wet conditions.