Designing fire resistant MEP and HVAC supports:

In this article we examine the guidelines available at the European level and explain why you should use them instead of other commonly used formulations.

Improper use of Eurocode 3 (EN 1993-1-2)

Eurocode 3 (EN 1993-1-2) is used to determine the strength and deformation of system supports. It proposes reduction factors as the temperature increases.
 

This method is certainly correct for structures, but generally is not valid for thin-walled and cold-formed profiles, such as those used in modular systems.

This was demonstrated by a study conducted by the German MFPA  Leipzig GmbH, a notified and accredited testing, inspection and certification body, as well as in several tests conducted by the Hilti Engineering test center.

This research shows ­– at low temperatures – the Eurocode formulations do work for these profiles. However, as the temperature increases, the deformation predicted by the analytical formulations of the Eurocode is different to the results of real-world tests. This is shown in the graph below, which compares the deformation of the supports of implants calculated according to EC3 with laboratory tests.
 
This means the Eurocode can underestimate the deformation of steel elements with thin walls. As a result, a regulatory gap was recognised for the fire calculation of non-structural elements. This led to a new EAD.

The EAD for the calculation of implant supports.

An EAD (European Assessment Document) contains guidelines that define the methods of verification, simulation and analytical calculation used to deduce the performance of a single product or group of products. It also defines how designers should undertake the design for the uses defined in the EAD.

EAD 280016 (“Products related to installation systems supporting technical Equipment for building services such as pipes, conduits, ducts and cables”) has, as its field of application, the elements that support pipes, ducts and cables. These systems must continue to maintain their function even at high temperatures ranging from 750 ° to 1214 °, such as in a potential fire situation.

The document has several sections which include:

• How the tests for collars, rails, threaded rods and connections should be performed

• Determination of the characteristic and design strength
• Configuration of types for high temperature tests

• Method for determining the characteristic resistance at elevated temperatures with respect to the exposure time

• Method for calculating the deformation of the system support at high temperatures as a function of time

 
In the new ETA (European Technical Approval) all our tested components are presented, based on our installation system MT

Are you interested in learning more about the support we can offer with modular support systems, you can find more information here or contact 0800800100 to be put in contact with your local engineer.


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This article is part of ongoing series dedicated to MEP topics, learn more.