Tackling corrosion in active fire protection systems

Corrosion is a topic of growing concern in the active fire protection industry. There is mounting evidence that the performance of galvanised pipes traditionally used to combat increased corrosion activity is not as expected. Here Chris Gill, Product Manager – Water, Viking SA, Luxembourg introduces the new Fendium piping technology with significantly improved corrosion protection and improved hydraulics compared to standard black steel and galvanised steel pipe networks.

Corrosion is a significant issue in sprinkler and water mist systems, particularly in dry, pre-action or deluge systems where oxygen and water are freely in contact with the pipe, with leaks causing damage and the potential to cause significant business interruption. In addition, the products of corrosion could prevent the proper and effective function of a system by restricting or even completely blocking the flow of water.

The biggest challenge is that corrosion progress cannot easily be predicted or monitored, in most cases the situation inside the pipes is not visible from the outside. In fact, there is a considerable risk that the function of the system will be significantly impaired or disrupted without being discovered and thereby impacting the ability of the system to control a fire.

More recently independent research and testing as well as field experience has cast some doubt on the ability of galvanised pipes to withstand corrosion as much as we had previously thought. In addition, there have been some worrying instances of explosions in galvanised systems due to hydrogen formation and so this has led to a reduction in scope of use for galvanised pipes. For example, the next edition of EN 12845 will not recommend galvanised pipes for either wet or dry systems and both FM and VdS do not allow the use of galvanised pipes for wet pipe systems. This leaves a significant gap for water mist in particular which requires something more corrosion resistant than black steel.

Stainless steel pipes do of course provide excellent corrosion resistance but this comes at a

significant price premium. In addition, the contractor often has to use specialist fittings and tools. CPVC is certainly the product of choice for residential and light hazard and has excellent corrosion resistance but cannot be used in many commercial applications, and any storage or industrial risks.

Viking has now launched their new Fendium piping technology, which is a patented process adapting technology from the automotive industry with a long and proven track record in providing excellent corrosion protection under harsh environmental conditions. This technology provides a polymer protection which is permanently bonded with the steel surface, both on the exterior and on the interior of the pipes.

These Fendium polymerenhanced pipes prevent the contact of water with the steel, significantly reducing the effects of corrosion. This has several positive impacts:

Reduced possibility of rustthrough and leaks

Reduced production of corrosion products and potential blockages

Reduced surface corrosion which contributes to friction losses

By maintaining grooved and threaded end connections, standard industry grooved and threaded products can be used

Fendium pipes have been thoroughly tested by both FM Approvals and VdS Schadenverhütung to evaluate their corrosion-resistance. Evaluations carried out by the approval agencies included the following: Salt-spray ageing tests which compare the corrosion of samples of standard black steel, galvanised and stainless-steel pipes compared to those treated with Fendium, to evaluate the impact of rust through and corrosion products; and Comparing the hydraulic performance of different pipe materials vs Fendium to recalculate a C-factor for Fendium pipes.

Fendium pipes have been shown to out-perform both black steel and galvanised pipes in terms of corrosion performance allowing them to be used in wet, dry, deluge, water mist and other similar systems. Both FM and VdS have not only approved Fendium for these applications but have also approved the completely new, purpose-built factory in Wittenberge, Germany. This is now the world’s largest facility dedicated to producing prefabricated pipes for the fire protection market.

One important additional benefit of the Fendium treatment and the reduction in corrosion is that the hydraulic performance of Fendium systems is improved. The smooth pipes, which are much less roughened with age, allow the water to flow through with reduced frictional losses. This may allow for a reduction in pump sizing which can result in cost saving for the contractor and the end-user. Alternatively there is the possibility to reduce certain pipes sizes within the system and still retain the same pump size – reduced pipe size reduce installation time and can also lower associated costs as smaller pipes mean smaller grooved fittings and fixing materials.

This performance improvement is recognised by FM and VdS with the allowance for the system designer to use a C-factor of 140 in hydraulic calculations.

Corrosion can have several detrimental effects on the performance of water-based fire protection systems. The products of the corrosion process can restrict or even completely block the flow of water through the system, rust-through can cause costly damage and business interruption, and the roughness can reduce the hydraulic performance of the system over time.

As our industry grapples with corrosion, Fendium now offers better protection against corrosion and improves the system hydraulics when compared to traditional black steel or galvanised pipes.

VIKING SA viking-emea.com fendium.com