MechChem Africa

MechChem Africa talks to Kansai Plascon protective coatings’ specialist, Alvin Varaden about the latest in protective coating solutions, passive fire protection (PFP) and the modern trend towards fewer and thicker coatings designed for faster application and a longer life.

Kansai Plascon has been involved in delivering coating-based protection for industrial plant and building structures in South Africa since the 1970s, and has worked on many prestigious projects such as the Engen refinery in Durban and several Eskom power stations.

“We cover solutions for various segments, including oil and gas; infrastructure for shopping malls and airports; road and rail bridges; and industrial equipment such as tanks, plants, piping and their support structures,” begins Varaden.

“We at Kansai Plascon have a strong presence in the mining industry, offering maintenance services for mines such as Anglo Platinum and other metal and materials processing plants, including ArcellorMittal in Saldanha Bay and to Sasol.

Passive fire protection (PFP) coatings

Passive fire protection is critical in safety-critical steel constructions such as hospitals and shopping malls, as well as high fire risk plants such as refineries. “The legislative requirements for PFP are also growing,” Varaden continues.

He cites the huge fire in the Rossburgh area of Durban – a Transnet warehouse storing containers of wax and polypropylene that caught fire in March 2017 – as an example of why these coatings are so critical.

Kansai AlesChar PFP petrochem“As well as for corrosion protection, steel structures need to be protected in case of fire to insulate the steel and provide enough time for people to escape the building before the fire takes hold and the structure collapses,” he tells MechChem Africa.

Passive fire protection (PFP) coatings, often referred to as intumescent coatings, are designed to protect the steel integrity during a fire and solutions are designed to provide 30 to 120 minutes of fire resistance to a building’s support structure.

Intumescents produce a low-density foam char, which is a poor conductor of heat so it retards heat transfer to the steel. The coating formulation also contains hydrates, which release water vapour in the presence of fire to produce a cooling effect. “So these PFP coatings first cool the surface to slow down the fire’s progress, then, once the hydrates are spent, the insulation characteristics of the char slow down the transfer of heat to the steel,” Varaden explains.

“For the replacement of the Transnet warehouse building, PFP coatings became a legislative requirement, as they are for many high-risk buildings such as these,” he adds.

In terms of PFP coating thicknesses, Varaden says that total layer thicknesses of between 500 and 2 000 µm are typical for cellulosic fires, with the coating generally being applied after fabrication in the shop and before erection.

The coating thickness required is governed by on two factors, the fire resistance rating required and the building’s design. “A longer evacuation time together with a design based on using thinner steel sections – such modern lightweight steel frame (LSF) construction – tend to require thicker coatings, because the steel itself has a lower fire resistance so the retardation time has to be higher,” he explains.

To apply PFP coatings, spray techniques are preferred. “The success of PFP is dependant on a correct and uniform layer thickness. Application using a roller or brush cannot deliver uniformity required and weak spots tend to compromise the fire protection properties. So the tendency is to spray apply the PFP coating during fabrication and then use a brush and roller for touching up areas exposed during erection,” he informs MechChem Africa.

Kansai Plascon offers two broad types of PFP coating. “Petrochemical, offshore and LNG facilities are at risk from hydrocarbon fires and explosion accidents and they need higher temperature protection: above 1 000 °C,” he says.

AlesChar Epoxy PFP is the recommended product in this environment. “In the event of a hydrocarbon fire, a relatively thick (±5 000 µm) Epoxy PFP coating is required to propect steel structures for long enough.

Also offered are PFP coatings to mitigate against cellulose fires, for coating wooden floors and doors, for example, for protection in the 250 °C to 600 °C temperatures range, with Kansai Plascon’s C-Therm IC 600WB being an example used for such applications.

Corrosion protection

“We have a market segment approach in providing corrosion protection solutions as each segment has specific requirements and approvals. The mining segment requires chemical resistance coatings where our Plascotuff 6000 performs exceptionally well, along with high abrasion resistance coatings for slurry tanks where Plascotuff 5000 is better suited. Similarly, in the oil and gas segment, approvals for petrol; diesel and jet fuel would be required,” Varaden continues. Read more…

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