All mechanical systems, including insulation systems, require periodic inspections and maintenance to ensure that the cladding or insulation materials are not damaged, compromised, or even missing altogether. Failure to conduct these inspections in a timely manner or document repairs/replacement of insulating materials can result in compromised personnel protection, reduced process efficiency and control, increased rates of corrosion, and ongoing economic losses in energy efficiency – to name just a few.
At JM, we have had the opportunity to visit electric and biomass power generation plants, refineries, petrochemical facilities, etc. around the world. Our in-the-field experience suggests that most industrial facility owners embrace routinely inspecting and maintaining their processes to ensure that they have efficient and safely-run operations. Even though the guidelines for such inspection and maintenance procedures vary in scope, frequency, and priority based on the unique needs of the facility, they tend to target three primary categories:
- External:visual, checks of equipment and processes;
- Internal:inspectionswhere the insulation system is penetrated in order to conduct substrate inspections for moisture intrusion and/or CUI; and
- Risk assessment:a methodology that prioritizes the potential consequences of system failures and establishes appropriate inspection guidelines.
In many cases, external inspections can quickly identify damaged cladding in areas where either the caulk sealant has failed (allowing the seams to separate) or the cladding has been crushed by foot traffic and/or maintenance work. There are even some situations where the insulation is missing altogether - which typically happens when maintenance crews don’t replace insulation that was purposely removed for maintenance reasons or design modifications, or, the insulation was never installed in the first place.
External inspections should also include checking for hot spots on high-temperature applications or condensation/ice buildup on low-temperature applications. In these cases, the use of infrared imaging can quickly identify areas of concern that the naked eye may miss. External inspections are best for identifying the low-hanging fruit in terms of external damage; however, the appearance of the surface of the insulation is not always indicative of what is happening on the pipe beneath the insulation. This is why the second means of inspection, internal (which penetrates or removes the insulation), is fairly common.
When it is necessary to take a closer look at the substrate, the overall objective is to be as minimally invasive as possible. In some cases, systems are designed with convenient inspection locations identified during the planning stages of a project. However, in our experience, we’ve found that it is more common to see inspection ports installed by the insulation contractor at locations where corrosion is most likely to take place.
Inspection ports provide a quick and easy way for inspectors to see the substrate and to determine if there is a need to conduct further evaluations. One downside to the use of inspection ports is that the insulation plugs - which are inserted into the inspection ports and are removable so the inspector can see the substrate - can become damaged and/or be discarded after multiple inspections. This can create a thermal bridge in the process and an easy pathway for heat loss as it causes an open gap in the insulation. Another potential drawback of inspection ports is that determining their location can sometimes be a hit or miss process – while the pipe may look fine beneath the port, there is no guarantee that it is not deteriorating in another location. As a result, sections of the cladding and insulation will ultimately have to be removed in order to clearly assess the presence or risk of corrosion taking place.
Due to the substantial amount of piping systems at most industrial facilities, it can often be prudent to establish a risk assessment process that helps prioritize when and where maintenance work should be performed. These risk assessments can be used to identify the likelihood of a catastrophic event taking place within a spectrum of high to low risk areas throughout the facility. They will establish where the insulation will be inspected, repaired, removed, and replaced – ideally before it becomes a problem.
A typical risk assessment will identify certain processes that are critical to the safe and efficient operation of the facility. The management and/or operations personnel will use the assessment to assign a severity rating, to the production units or processes. In the higher risk areas, routine inspections take place and if problems or failures are noted, additional in-depth inspections are required to accurately assess the situation and corrective actions are taken. On lower risk areas, inspections still take place, however, they may not be as frequent or require as much scrutiny as the high-risk areas.
Damaged or missing insulation or undetected or ignored corrosion under insulation (CUI) can easily become an ongoing financial drain on the facility, as well as a potential safety hazard to plant personnel and the surrounding community. That’s why it is important to be aware of what you cannot see and avoid assuming that insulated processes will last forever. When serious and ongoing consideration is given to external, internal and risk assessment tools, the result can be a well-maintained mechanical insulation assembly that improves process control, reduces the likelihood of unplanned downtime, saves energy, and reduces overall operating costs.