Larry Gillanders: What contractors should look for in epoxy coating when restoring pipe
The past several decades have seen dramatic improvements and growing acceptance, nationally and internationally, in the arena of in-place pipe restoration that uses a “blown-through method.”
This particular type of process does not insert liners into the pipe, but rather a barrier coating is blown into the piping system to coat the pipe’s interior. The focus is not on large-diameter waste lines, but on small-diameter pressurized pipes, such as water pipes, fire sprinkler systems and natural gas lines.
In the case of water pipes, pipes as small as 1/2-inch diameter that run from a water main into and through a building’s piping system can be restored in-place without the need for extensive excavation and tearing into the fabric of the building.
You may have your customers ask, “Do you do that pipe restoration thing where they don’t have to tear up my house?” or “Can you repair my water-service line without digging up my yard?”
As a contractor, you may ask yourself: What should I be looking for to consider the use of this technology?
Typically, an epoxy resin is used as the coating material that is applied by forced air, providing a protective barrier coating to the inside of the pipe. The barrier coating protects the pipe from the effects of corrosion, erosion, is a preventative tool against leaks and — depending on application, the type and make of the coating — can be effective at reducing lead and other metals from leaching into the water supply.
If you are considering in-place pipe restoration where reduction of lead leaching is involved, ask the pipe restoration installer about the effectiveness of their process at reducing lead leaching.
General application steps
The blown-through method uses flowing, compressed air and at least two pipe ends have to be exposed. Using compressed air as the “driver,” the pipes, once isolated, are drained and dried, and the inside of the pipe is cleaned and prepared for the coating to be applied. Once these preparation steps are completed, the resin coating is applied, as per the manufacturer’s instructions. After the coating has cured, the piping system is reassembled, pressure-checked and it is ready to be returned to service.
In the infancy of the technology, it was not uncommon for coatings to have long cure periods; seven days and more were not uncommon. Advances in the science of coatings have produced coatings that are approved for contact with drinking water in small-diameter pipes in as little as 90 minutes. Service and single lines can be treated in about four hours per line and an entire house can have its water piping system restored in a day.
Advances also have been made to the equipment used in the process, which now includes a variety of equipment packages that can be tailored to the job and can even be designed to work along a business model.
Equipment packages can address specific project types, such as single-line restoration or the rehabilitation of underground service lines, to whole-house packages, right up to commercial packages that can be used on multifamily, hotels and school-type projects where larger-diameter pipe and complex piping systems can be treated.
Industry approvals and intellectual property
Coatings and process specifics are governed by various model code agencies such as IAPMO and ICC.
In the United States, when materials are used in contact with drinking water, they require approval to at least ANSI/NSF 61 standard. There are only a handful of testing agencies approved to conduct testing to ANSI/NSF61. Every product approval comes with application instructions that include the condition of application, cure temperatures, cure times, resin thickness, water contact temperature use (cold water and/or hot water) and to what temperature the cured resin was tested to. Application to a pipe should describe the smallest diameter of pipe that can be coated. Make sure you choose the right resin for the job.
Coating materials vary by manufacturers and you need to ensure the coating material is appropriate for its intended use and application. Ask for proof.
Plumbing codes may apply, so check to see if the resin and process are approved by the major code applicable to your jurisdiction (UPC, IPC, IAPMO, etc.). You may want to check with your local plumbing officials to see if permits are required and any special conditions they may have for the application of the technology.
Many of the companies offering pipe restoration application and licensing services have acquired patents that cover certain aspects of the process they use, as well as materials and methods.
Durability of the barrier coating material
The barrier coating industry is a well-developed industry with protective coatings found in widespread use in our daily lives. Estimates tell us the industry of corrosion control using barrier coatings exceeds $15 billion annually. Testing of coatings for their intended use, application and durability also are well-established.
While there are various testing methods that can be applied to estimate durability of the coating, the electrochemical impedance spectroscopy testing method (aka EIS) is recognized as the premium testing method. Above is a chart that can assist you to better understand the corrosion protection of a coating product when tested using the EIS method.
The photograph below shows a 3/4-inch diameter coated copper pipe after exposure to some 4 million gal. of pressured flowing water at elevated temperatures (140° F – 165° F) over a two-year period. The pipe was extracted and independently tested using the EIS method. The end result rated in good to excellent corrosion protection.
Whether or not the supplier has an EIS test report that can be provided, be sure to ask for any independent durability reports that support the life of the applied coating.
Contact a pipe restoration company, understand what they offer and ask to watch their process. RJ
This article was originally titled “Small diameter in-place pipe restoration” in the June 2018 print edition of RJ 2.0.