New and unique standard to address welding and performance specs for plastic pipe

The baby boom generation witnessed the entry and early growth of plastic in manufactured products. Perhaps nowhere was its impact more recognized than in automobiles, where the shiny chrome trim, grill, and hubcaps that adorned American cars through most of the 1960s gave way to plastic substitutes that were lighter, less expensive, and rust-free. The process continues today as better, stronger plastics appear in countless consumer and industrial products.

Can plastics play a larger role in pipe in the future? There is one international group of people that believe the future is already here. The applications for thermoplastic pipe are no longer limited to gas distribution, high purity water, pharmaceutical processing or other small-diameter systems. They have spread into larger diameter hot and chilled water piping, for example.

As thermoplastic pipe finds more and more uses, the specifications and installation requirements will also grow. The above international group came together to write a standard for welding procedures and performance tests for those who join plastic pipe. It is the first of its kind in the U.S. The “Consensus Group” consists of chemical engineers, mechanical engineers, Ph.D.s, an insurance person, and a member of the British Welding Institute. Their current chairman is Brian MacDonald, a special representative for the United Association.

While thermoplastic pipe has been around a long time, there has never been a standard for it. “What you’ve always seen is something like, ‘See manufacturer’s recommended practice.’ This was the statement you would see in bidding documents,” MacDonald said.

The American Welding Society (AWS) has reviewed the first standard developed by the Consensus Group. MacDonald said a second standard will tackle chemical fusion and other issues. “Now we’ll do a socket fusion, solvents in the chemical joint. And that will start incorporating the plumbing more. Then we are looking at the structural,” he said.

What is the UA’s stake in the new standards?

“Basically, we are looking at a tremendous amount of work that is going to be in this stuff. I am reasonably sure that pretty soon you’ll see all the condenser water, chilled water, cooling towers — everything being done in plastic,” MacDonald said. “I think you are going to see what happened to the plumber with plastics happen to the pipe fitter soon,” he added.

When the rules change and require pipe fitters to be qualified to join plastic pipe — and change is on the horizon — MacDonald wants to make sure the union is ready to train and test UA welders.

“We can qualify our people,” he said. “We’re way into it; we have been for quite awhile.” MacDonald said some states already have laws requiring that all pipe carrying materials hazardous to the environment or the human body to be joined by qualified welders. He expects more states to follow.

“We are trying to prepare ourselves,” MacDonald said. The UA’s Annual Instructor Training Program last August in Ann Arbor, Mich., included courses preparing instructors to teach in three areas of thermoplastic pipe welding. The information and training techniques they learned here they’ll take back to their local unions.

MacDonald said an important challenge for pipe fitters working with thermoplastic pipe is that it has higher expansion characteristics than metal. Installers will have to allow for greater expansion, which will affect hanger spacing, for one.

In addition to technical knowledge, some individuals will need a degree of attitude adjustment. MacDonald realizes there is still a lot of resistance to plastic pipe out there. “A lot of contractors don’t understand it and don’t have faith in it,” he said. “So the philosophy has to change a little first.”