On the bonnet of the valve, there is an EPDM rubber O-ring used to provide a watertight fit. The O-ring was constantly exposed to the treated water and, over time, it deteriorated, causing treated water to leak out of the bonnet. The leaking water constantly came into contact with the outside of the valve body and actuator housing, resulting in the corrosion, pitting, and deterioration visible in the picture. This damage pattern is characteristic of slow-forming chemical corrosion at the bonnet, rather than the result of mechanical failure.

What Specific Mistake, Error, or Oversight Does this Image Illustrate?

A simple mistake is shown in this picture. The chemicals used to treat the boiler water were not compatible with the materials of the two-way valve. As such, constant exposure of the valve components to the treated water resulted in deterioration of the O-ring, as well as corrosion of metal components of the valve body, resulting in loss of function of the valve in a short period of time.

Because this type of chemical incompatibility may not be immediately noticed while the valve remains functional, it is easy to believe that everything is in working order. Even though the O-ring is deteriorated and the metal parts corroded, the rate of deterioration has been gradual. Since no compatibility test was performed on the materials of the valve, the damage continued to build until the valve could no longer carry out its designed purpose.

How Did This Issue Go Unnoticed – Installation, Maintenance, or Commissioning Gap?

This issue went unnoticed because there was no proper verification of chemical compatibility at any stage: design, chemical treatment setup, or routine facility management. The design engineer, chemical treatment vendor, and/or facility maintenance team should typically confirm chemical compatibility with all system materials before introducing any chemical into a system. That step does not appear to have occurred.

Every party assumes that someone else has already verified the materials when they omit compatibility checks. Damage is not always directly visible in the early stages of corrosion; therefore, it may continue to progress until failure occurs. Typically, walk-throughs and/or inspections do not catch or discover this type of failure in the early stages of O-ring or part deterioration, as the damage is often internal to system components.

What Potential Consequences Did or Could This Have for Building Operations or Safety?

The consequences in this case were significant. The deterioration and leaking prevented sufficient treated water from being routed to the boilers. As a result, the boilers shut down. Once the boilers stopped producing steam, the facility’s steam coils began to cool. The steam inside the coils condensed into water and was left stagnant.

The steam coils were intended to preheat air coming into the hospital. As such, they were exposed to ambient air conditions. During freezing temperatures, the stagnant water in the steam coils froze and expanded, rupturing the tubes in multiple coils. The resulting water leaks created problems with maintaining heat in the hospital and resulted in costly damage.

What Simple Inspection, Documentation, or Commissioning Step Would Have Prevented It?

A simple review of the water treatment chemicals’ safety data sheets (SDS) would have prevented this issue. The SDS documents clearly provide the compositional components of the water treatment chemicals. If anyone had compared the components of these treatment chemicals to the valve’s materials, they would have immediately identified the incompatibility. This review would have led to a different chemical choice or a different valve selection.

Do You See This Issue Often? Why Is It So Common?

I do not see this particular issue often. When it does occur, it usually stems from assumptions. Teams often assume that a commonly used treatment chemical will be compatible with all system components. It is also common for multiple vendors or maintenance groups to believe someone else already checked compatibility. In older facilities or facilities with multiple contractors, these gaps can occur more easily.

One Practical Takeaway for Building Managers

Building managers have the ultimate responsibility for maintaining the health and safety of their systems (HVAC, roofs, plumbing, electrical, etc.). Verifying all system conditions – including chemical additives – to ensure they are compatible with every material that comes into contact with them is an effective and simple way to accomplish this. A few minutes spent reviewing the chemicals and materials can prevent shutdowns, equipment failures, and widespread secondary damage, like what occurred in this hospital.