Reinventing pipe seals? AlphaGary and Wavin team up to try something new

Before becoming sister companies, compounding company AlphaGary and piping systems manufacturer Wavin, both of whom today are subsidiaries of Mexico's chemical giant Mexichem, had little to do with one another. Today, the companies are reaping the fruits of a synergistic business relationship, in which AlphaGary, headquartered in the U.S. supplies the material and Netherlands-based Wavin manufactures the product - in this case pipe and sanitary ware seal components - for use in the non-pressure thermoplastic piping systems it produces. 

During the past recession, the plastic pipe industry was heavily hit, as residential and commercial construction came to a halt and infrastructural investments plummeted. Today, as plastic pipes continue to supplant traditional materials, such as iron, and with global demand for plastic pipe forecast to rise 6.2 percent annually through 2017 to 23 million metric tons, the future looks bright for manufacturers of pipes and pipe fittings. Factors such as environmental concerns and the low cost, ease of installation and better performance of plastic all play a role in the surging popularity of plastic pipes: less water is lost due to leakage, the material is strong but light, does not corrode, causes no deposit buildup and is extremely durable.

An important part of this performance is due to the quality of the pipe joint seals used in thermoplastic piping systems. "Historically, seals made of vulcanized rubber - EPDM, SBR - were used, which were necessarily loose-fit seals, as vulcanized rubber cannot be joined to plastic," explained Adam Killoran, technical manager of industrial products AlphaGary-Mexichem. "The solution was to use a thermoplastic elastomer instead. This led to the development of TPE seal materials, usually TPV, which could be co-molded with the plastic fitting to produce a highly efficient, leakproof joint."

As the strategy of parent company Mexichem was aimed at the vertical integration of its subsidiaries into various highly efficient production chains, AlphGary was soon invited to supply Mexichem with TPE solutions for a variety of sealing applications. The compounder has more than thirty years of experience in developing and manufacturing its Evoprene TPE compounds, which belong to the family of hydrogenated styrene block copolymers and were found to offer a number of advantages that made these a successful replacement for the more traditional EPDM. EPDM materials are permanently cross-linked, which means that processing scrap cannot be recovered for reuse. As a thermoplastic, this is no problem for Evoprene TPE. Moreover, it offers shorter cycles times, because of the lack of a crosslinking stage, and can be processed on conventional processing machines. Its lower densities mean that more parts can be produced per kilogram of material and, importantly, it is co-moldable - thus suitable for two-component processing.

Sister company Wavin, however, manufactured, among other things, two-component polypropylene sealing rings, co-molded with TPV. Hence when Mexichem asked AlphaGary to team up with Wavin, which would enable the material to stay in house, thus maximizing the synergies within the group, the company faced the challenge to come up with a new solution using its Evoprene TPE. "We basically had to fit a styrenic compound against a TPV," said Killoran.

On the basis of trials and feedback from Wavin, AlphaGary developed a new Evoprene TPE grade for the two-component sealing rings produced by the company. "We not only met the challenge, we exceeded it," said Adam Killoran. "The new sealing material more than satisfied Wavin's expectations. Our TPE was found to deliver improved cycle times, which meant that more parts were produced per hour, plus much shorter mold cleaning times. TPV compounds contain a crosslinking agent, which can deposit chemical residue on the tool. TPE has no such problem and is therefore much cleaner to process."

Wavin has since approved the material for seal applications in four- and six-inch non pressure wastewater pipes and large diameter riser chamber seals. It also meets the property requirements of the European standard EN681-2 and is in the process of complying with the more stringent Dutch building guideline BRL 2020. This guideline includes all relevant requirements on the basis of which the KOMO product certificate for TPE pipe joint seals for non-pressure waste water applications is granted. KOMO certification is expected to be obtained in May 2014. 

"We're extremely pleased about that. KOMO certification is what counts in the Netherlands, as it's much stricter than the industry standard - it includes a stress-fall test, which really separates the men from the boys, so to speak.  Also KOMO-certified products automatically come with a 50-year lifetime guarantee."

He added: "It's worked out well. We were able to replace a TPV material at no cost disadvantage with a styrenic compound that technically is a better solution and that offers efficiency benefits. That's synergy."