Piping for challenging applications

Paul Boughton

A high-performance industrial piping system is proving its worth in a chemical manufacturing plant, reveals Peter Kilburn

When a chemical manufacturing plant in Delfzijl, the Netherlands was first constructed in 1997, the design engineers knew there was only one piping solution that could reliably and cost effectively transport highly corrosive, high-temperature chemicals and treated water throughout the plant. That solution came in the form of a chlorinated polyvinyl chloride- (CPVC) based range of industrial pipe and fittings.

Over the years, CPVC has proved that it possesses the durability and corrosion-resistance attributes necessary to endure harsh environments. For the Lubrizol plant in the Netherlands, Corzan CPVC became the piping material of choice for numerous plant modifications and additions over the years. Such additions were necessary to more than double the plant’s yearly capacity.

Lubrizol is a global producer of advanced speciality chemicals, polymer-based formulations and chemical additives for a range of consumer and industrial applications. The Delfzijl facility was built as one of two plants in Europe manufacturing CPVC to help meet growing international demand. A variety of highly corrosive acids and bases, as well as demineralised water, are used to manufacture the CPVC resin. As part of the manufacturing process, chlorine vapours are also collected and transported through pipes to prevent their escape into the atmosphere. It is industrial piping that transports most of these high-temperature, corrosive fluids and vapours.

The reason why Corzan CPVC piping was chosen for the plant is because its resistance to high pressure and high temperatures exceeds most plastic alternatives at a fraction of the cost. Compared with metal systems, CPVC represents an alternative notably due to its corrosion resistance. Stainless steel or titanium could be a technical option, but are a good deal more expensive.

Corzan piping is used in many of the plant’s manufacturing operations, as well as in its wastewater treatment process. The pipes installed vary in size from 25 to 800mm. Corzan CPVC sheet was also used to build an acid storage tank. This tank has been in service since 2008, with a minimum of maintenance.

A lot of hydrochloric acid is formed during the manufacturing process, which requires acid removal from the water prior to discharging it. This leaves water with a very high salt content. Calcium chloride is very aggressive and can wreak havoc on many piping materials, but the plant has not had any leaks or maintenance issues as a result of chemical corrosion since 1997.

Corzan is considerably lighter in weight than metals, which is a major benefit because it’s faster and easier to install and requires less support throughout the plant. Because of the piping’s solvent welding jointing process, a strong permanent chemical bond is created. This enables the plant to set up complex systems quickly and efficiently in-house and have them up and running in less than a day. Installation time can be further reduced by prefabricating the pipe and cutting it offsite, which is a reasonably simple procedure. Building these operations with metal piping or glass fibre-reinforced plastic would take at least twice as long because of the welding or laminating processes. The resulting cost would be far higher than for the Corzan system.

The fluids in the CPVC resin producing plant frequently reach temperatures higher than 60°C and at times close to the boiling point of water. For protection, the plant needs to wrap and insulate metal pipes to prevent any burn hazard. This is typically not necessary with CPVC pipe, saving the plant additional time and money during the installation process.

CPVC also features outstanding flame properties compared with other plastics, which is especially important when used for air ducts. CPVC will not sustain a flame on its own and does not support combustion, due to its limiting oxygen index (LOI) of 60.

Outside the plant building, Corzan CPVC continues to be used as transport pipe for highly corrosive acids, bases and salts – including hydrogen chloride, caustic soda, calcium hydroxide, sodium carbonate and sodium chloride. Many of these pipes have been installed outside, unpainted and uncoated, subject to UV exposure and all sorts of harsh weather conditions, for more than 17 years and are still going strong.

Lubrizol has noted a growing trend for companies to replace all of their existing – and problematic – piping with CPVC. There have been several instances where CPVC has been used to solve a piping performance problem, yet the company seldom sees it specified in the original design. This is an unfortunate situation, as compared with other alternatives, CPVC consistently wins on performance, price and lifespan.

For more information visit www.engineerlive.com/epe

Peter Kilburn is Lubrizol plant manager at Delfzijl, the Netherlands.

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