The test setup and the results
MFPA Leipzig GmbH conducted a test program for Hilti AG to assess the water vapor permeability of four pipe insulation system configurations. The study followed DIN EN 13469, adapted for composite specimens combining clamps, insulation, and adhesive. The primary objective was to confirm equivalence between the existing reference setup and a new alternative using Hilti MRP-KF clamps.

Tested Configurations (details see fig.1):
1. Reference: Hilti MIP-M/27-30 clamp with AF-EVO insulation and Armaflex 520 adhesive.
2. Alternative with MRP-KF: Hilti MRP-KF 27 clamp with identical insulation and adhesive.
3. Hilti MRP-KF, double insulation: Same as Setup 2 but with two insulation thicknesses.
4. Armacell assembly guideline: Current manufacturer-prescribed multilayer assembly.

Results (mean values):
1. Reference MIP-M: sd-value = 31.4 m
2. MRP-KF Alternative: sd-value = 38.8 m
3. MRP-KF, two thicknesses: sd-value = 23.7 m
4. Armacell guideline: sd-value = 69.0 m 2 of 3


Fig. 1 – schematic test setup

Key findings
The results show that Setup 2 (Hilti MRP-KF) achieves performance equivalent to the reference system, with slightly better vapor diffusion resistance. This demonstrates that the Hilti MRP-KF solution provides the same protective function as the Hilti MIP-M system. The setup 3, with two insulation thicknesses, did not deliver additional benefits and was only considered as an optional variant. Setup 4, while providing the strongest barrier, represents the most complex and cost-intensive method, which may be unnecessary if Setup 2 is accepted as equivalent by the customer and specifier.



Conclusion
The study confirms that the Hilti MRP-KF clamp system (Setup 2) can replace the current reference setup without loss of performance. This makes the Armacell guideline assembly redundant for our use case, streamlining installation and reducing complexity in future projects.

Hilti MRP-KF portfolio
If you are interested in learning more about the portfolio we offer, you can find more information via the Hilti website or contacting your local Hilti representative.