Blow-in Epoxy Pipe Liner

Summary: Epoxy is an amazing substance when applied correctly. But what if it is not?

Epoxy is a magnificent substance used in many important applications where strength, hardness, moisture protection and strong adhesion are a requirement. Epoxy coatings are used to protect industrial applications from factory floors to reinforcement bar embedded in Al Kaline Jerseys concrete. When applied correctly to a strong surface, few coatings are as tough as epoxy.

Sample_set_epoxy_FailRecently, epoxy manufacturers have developed a lining process to coat the inside of an old potable water system with epoxy. The blow-in epoxy pipe liner method is touted as a fast, 60 year, non-invasive, and inexpensive alternative to re-piping a whole building. However, when applied incorrectly, epoxy coatings can create a dangerous sense of false security especially where hidden from view such as the internal surface of a pipe.

Many blow-in epoxy pipe liner failures are appearing in the field where litigation is often protected by gag orders thereby never reaching the public domain. This document identifies a wrinkle in the market that supports the rapid liner industry as well as the consequences of an unseen failure, should they occur.

This article arrives at the following conclusions:

  • The potential for epoxy liner failures may be high in galvanized steel potable water systems.
  • There is no reliable way to inspect the adhesion of epoxy inside a pipe.
  • If an adhesion failure is found, there is no practical way to repair it except re-pipe — so, why not just re-pipe?
  • Blow-in Epoxy pipe liner failures may typically occur at the precise location where the galvanized steel pipe is already at its weakest.

These observations are very important for the insurance underwriter who would otherwise classify a water system that has been repaired with epoxy liner as a “new” system. These observations are important for the forensic analyst that may determine the cause of a major water system failure on a condition other than being weakened by the epoxy coating. These observations are very important to the insurance broker who may inadvertently force a condominium community into an epoxy liner “solution” as a condition for maintaining coverage on their property.

Insurers should allow their condominium clients to perform a condition assessment without threat of cancellation. A small leak does not necessarily mean that the big rupture is imminent. In any case, epoxy does very little to eliminate the risk of a large rupture and possibly increases the likelihood. Then the insurance industry should work with the community to save enough money to perform a superior re-pipe with new materials such as polypropylene or copper. Together, a strong case can be made for the reserves or lending process. In the long run, a superior re-pipe may cost several times less than an epoxy “solution.”

The Vicious Circle
Something as simple as a pinhole leak can generate thousands of dollars of water damage claims. Imagine what a fracture in a main riser cascading down 10 floors of luxury condos can cost? Unfortunately, many insurance underwriters believe that after a few small water claims, the big one is imminent. This may not necessarily be the case. Yet, many a condo is put on notice that they will lose their coverage unless the whole system is immediately replaced.

Long before the first pinhole leak, insurance companies stipulate in their policies that they are not responsible for a pipe failure if the condominium board is aware of the problem and fails to take corrective action. This condition essentially removes the incentive for the condo board to perform a quantitative piping condition assessment — if they don’t know that there is a problem, they are insured. If they do know that there is a problem, they are not insured. This creates a compound moral hazard because they have no basis for saving reserve funds for a replacement.

After awhile, a few small leaks may appear leading to some minor insurance claims — this can trigger the threat of insurance cancellation for the condo. But this is the least of their worries; the condominium construction market is renowned for litigation, and many insurance companies make it very difficult or impossible for a contractor to be insured for condominium work. Condominium homeowners associations quickly learn that many contractors are simply unable or unwilling to work on condominiums.

If the homeowners association fails to save for a re-piping project, they are forced into an expensive bank loan from lenders who are equally wary of litigation … this can become a Orlando huge mess far beyond the knowledge and capability of a condo board to manage effectively. The inability to manage a project in a litigious environment leads invariably to more litigation!

Herein lies the wrinkle  in the market caused largely by the insurance industry betting against itself thereby creating a vicious circle that has very little to do with actual plumbing. In the midst of this condo / contractor / insurance / banking madness arises the epoxy liner salesman who is quick to provide everyone with exactly what they need — a cheap, fast fix.

The Epoxy Liner Process
The blow-in epoxy pipe liner process involves isolation of sections of the existing pipe, drying the pipes with hot air and then sandblasting the inside walls with pressurized air and an abrasive mineral that is supposed to remove all corrosion, leaving bare metal in order to prepare the pipe walls to accept adhesion of the epoxy liner. Once prepared, the paint-like epoxy is blown through the pipes in a liquid state using pressurized air. The epoxy is then “cured in place” either by the application of heat and/or the passage of time (pot life).

A Case Study
A reputable plumbing contractor in the Seattle Area provided samples of epoxy liner sections that were removed from at least three properties and which failed within 4-7 years of entering service.

Failure Modes
The following video demonstrates common epoxy liner failure modes correlated to available literature on epoxy liner vulnerability. The most common vulnerabilities of the blow-in epoxy pipe liner systems are associated with the planning and quality of the preparation as well as training of the applicator personnel.


Literature Review
Epoxy coating of steel is a widespread practice in construction and mainline water service2 3 4. While epoxy is tested safe to drinking quality standards by independent studies1 and national water quality standards6, any such “certification” is dependent upon actual adhesion to the surface of the pipe. The failure modes and vulnerabilities of epoxy are widely known and highly consistent in the progression7 of adhesion failure. It is also widely recognized that the project planning, surface preparation, and precise measurement and application of the ingredients to the substrate are the most significant variables in determining the probability of a successful epoxy coating assignment.

These factors are addressed in significant detail by the U.S. Army Corp of Engineers3, The American Water Works Association9, the American Society of Testing and Materials10, the Society of Protective Coatings, etc., who have all developed standards for the planning, preparation, measurement, and application of epoxy coatings. It can be assumed that if, and only if, these standards are followed and documented, then failures in epoxy coatings will not occur.

A comprehensive collection of tests and inspection criteria has been developed for epoxy coatings in any number of applications including internal water pipe coatings.3Such tests as the knife blade test or those tests specified in ASTM F2831 are simple, fast and conclusive.10

The Epoxy Paradox
Epoxy coating is extremely strong and adherent if, and only if, applied correctly.7 The question arises that if an application should fail a test, inspection, or in service, what is the contingency plan to remediate the flaw? How will the epoxy be removed and how will the re-coating be applied? If re-pipe is the answer, why wasn’t re-pipe considered in lieu of epoxy in the first place? If a single failure is found, what test sampling strategy must be applied to give a high likelihood that no other flaws exist in the system? Under what warranty claim would a failure be covered and to what extent will total coverage be warranted? These questions would be imminent in any litigation related to epoxy failures.5

Double Jeopardy: When an epoxy failure does happen, it is likely to occur at the location where the pipe is already at its weakest; i.e., pitted areas and threads. As such, a poorly applied epoxy liner could weaken a pipe considerably.6 The result could be a catastrophic high-volume pipe failure requiring a high insurance payout, which would not otherwise be attributed to epoxy coating.

Therefore, engineering and construction management representation and oversight can help assure that the epoxy liner material and contractors are aware of the expectation that industry standards will be applied. Independent testing should be applied as a condition of the contract bidding and warranty claims so that they may adjust their pricing to meet customer expectations. Again, epoxy is an amazing substance when applied correctly. But what if it is not?


1 Impact of an Epoxy Pipe Lining Material on Distribution System Water Quality by Ryan Price and supervised by Andrea M. Dietrich, PhD., Chair, Environmental Engineering, Virginia Polytechnic Institute.

2 Epoxy Adhesison Testing Sponsored by the Texas Department of Transportation.

3 PUBLIC WORKS TECHNICAL BULLETIN 420-49-35 15 June 2001 IN-SITU EPOXY COATING FOR METALLIC PIPE; Department of The Army; U.S. Army Corp or Engineers.


5 Canadian law suit brought against the epoxy applicators.

6 Potable Water Pipe Condition Assessment For A High Rise Structure In The Pacific Northwest.

7 Layman’s Guide to Epoxy Paint / Coating Failures.

8 NSF/ANSI Standard 61 Drinking Water System Components.

9 AWWS C210-3; Liquid-Epoxy Coating Systems for the Interior and Exterior of Steel Water Pipelines.

10 ASTM F2831 – 12: Standard Practice for Internal Non Structural Epoxy Barrier Coating Material Used In Rehabilitation of Metallic Pressurized Piping Systems.

Engineering opinions rendered by any author are solely for the purpose of education and are not engineering advice. If you use any opinion presented in this document or on the website in any way whatsoever, you agree to hold The Engineer and the website harmless of your use of those opinions.

Addressing Water System Failures Before They Happen

water failure

In the heyday of the real estate bubble, developers flipped tens of thousands of apartment structures into condominiums – with little regard for the condition of the potable water system. Many of these galvanized steel or early copper systems are rapidly approaching the end of their service life.  Unseen, a small leak can cause thousands of dollars of damage and a ruptured main riser can amount to millions of dollars in claims and severe hardship for the community of homeowners.

Many Factors are involved

While it may be tempting to react to failure statistics, not all water systems are equal. Water chemistry varies substantially across the country, as do workmanship and materials quality – these variables may have a greater influence on mode and consequences of the failure than the age of the system itself.  The least appropriate action may be for the insurer to put the community in an emergency situation.  Poor or rushed Homeowners Associations (HOA) decisions can end up costing everyone far more than a properly replaced system that is well planned.

Insurers must first help the community to resolve to replace their potable water system.  Then, they must encourage the community to have a comprehensive piping condition assessment overseen by a qualified engineering representative. It is essential to determine the stability of the existing system without the threat of policy cancellation. Small leaks may be tolerable as long as the possibility of a large rupture is fairly remote – they are not necessarily related conditions.  Once these probabilities are known, then good decisions regarding a replacement system can be made.

Unfortunately, The HOA board is often left with a daunting task of selecting the right technology that both heals the pain and fits the budget. All pipe renewal solutions have different risks and vulnerabilities and many HOAs can fall for a slick contractor’s peddling inferior products. Potable water is a matter than requires rational analysis.

Piping Materials:

The three main classifications of piping renewal materials on the market include epoxy liner, copper re-pipe, or a variety of plastic products.  All have vulnerabilities and limitations so it is important for the insurer to take a deep hard look at the risks while the HOA can focus on the costs.

Epoxy Pipe Liner

Epoxy pipe liner is a continuous paint-like coating that is blown through an existing pipe system that has been cleaned by an abrasive sandblasting. Epoxy has the advantage of being relatively fast and minimally invasive. The problem with epoxy is there is no certain way to know the pipe is clean on the inside and no certain way to know if the cleaning process compromises the strength of the pipe.  Finally, if we were to test the epoxy, and adhesion is shown to be poor – then what?  There is no way to remove the epoxy and breaking the continuity of the coating breaks the protection. Our research has found that an epoxy failure can very likely happen at the exact place where the pipe is already at its weakest. This does little to mitigate the peril of the multi-million dollar rupture claim.  While we are confident that epoxy may be applied correctly, we are not confident the epoxy would be risk/cost competitive over a far superior re-pipe.

New Copper Re-pipe:

Copper is a very familiar to most people from its use in the penny.  The tarnish that forms on copper actually protects it from corrosion. Under the right conditions, a 50-year service life is a reasonable expectation if that tarnish coat is not disrupted. Copper plumbing has been extensively studied and many professional codes and standards apply to its use. Consequently, many copper failures can be traced directly back as failures to apply these standards; improper design, poor workmanship, aggressive water chemistry, or inferior materials, etc. All are known perils, which may be avoided or mitigated with the assistance of a good technical advisor representing the best interest of the owners.

Cross Linked Polyethylene (PEX)

PEX is a white or colored plastic that is fairly stiff but also quite flexible.  A slightly weaker form is commonly used in plastic milk jugs. PEX has been used in the US for 20-25 years, and has demonstrated an excellent track record in millions of installations.  PEX is easy to install, relatively low cost, and enjoys broad market acceptance.   PEX has two main problems – both of which are avoidable.  Lawsuits have been filed over failures due to ‘dezincification’ of low cost brass fittings.  It is extremely important to avoid some sources of fittings with high zinc composition in alloy.  Lawsuits have also been filed over the leaching of chemical compounds from types A and C PEX – the use of Type B PEX largely eliminates this problem.   Again, a good owner’s representative can help navigate this landscape. Many other plastic piping materials exist, but not without similar controversies.

New Polypropylene Pipe

A newcomer to the pipe materials selection is polypropylene – polypropylene is a common recyclable material with important uses in medical and food grade applications. Polypropylene is a very simple molecule of carbon and hydrogen – nothing bad goes in so nothing bad can leach out.  While new to the US, we have traced its use in Europe to at least 30 years back with a very low failure incident rate. Polypropylene has excellent thermal and acoustic properties and is widely considered the most environmentally friendly piping material available.  Some disadvantages include special fusing irons and specially trained installers are required.

Addressing Water System Failures Before They Happen

Water system renewal can be a confusing process – and certainly not a hands-off affair for the insurer.  A qualified owner’s representative to help navigate the landscape of technologies and contractors who sell them.  When the project is complete, the representative can help petition the underwriter, the financial industry, and the real estate market for adjustments that reflect the value of your renewed new system.   The technical representative can help eliminate engineering and construction risks without interfering with the normal dynamics of a wise and proactive homeowners association.