As you move through your facility, you might notice familiar sights, sounds and even smells that appear normal at first — small droplets forming under steam tubing, hissing from compressed air lines or the faint scent of processed gas. While these occurrences may seem like routine background noise in a chemical processing, oil and gas processing, or other industrial plant, they could actually be signals of something more serious: potential leaks.
Most leaks occur at connection points within a fluid system, potentially impacting the facility’s bottom line via wasted material and lost productivity. While not every leak is catastrophic, a leak usually signals that a system is not operating at peak efficiency. Additionally, depending on the type of process fluid involved, a leak could pose risks to both employees and the environment. Each of these deficiencies represents a good reason for plants to address leaks throughout their facilities.
Three different types of leaks can occur:
- Real leak: When sealing surfaces in a fluid system are cracked or damaged, gases and fluids can escape, leading to potential issues. A real leak occurs when pressure barriers fail to contain or isolate system fluids from their surroundings.
- Virtual leak: Internally trapped fluids may be released due to material outgassing, fluids absorbed or adsorbed into the containment system’s walls, or fluids trapped in crevices or dead legs.
- Permeation: This occurs when fluids penetrate, pass through and exit a pressure barrier. With this type of leak, small fluid molecules can seep through tiny openings in the barrier, potentially creating hazardous conditions for the environment and employees.
As governments impose stricter environmental regulations and investors urge cost reductions, it is crucial for facilities to minimize emissions from even small leaks in the fluid system. Understanding how to categorize different types of leaks and how to reduce the risk of catastrophic failures in your fluid system is essential.
Enhancing workplace safety by eliminating emissions
Uncontrolled gas leaks can endanger employees by compromising air quality. Process gases such as benzene, methane and ethanol can create hazardous conditions and contribute to ozone formation.
A good example of how governments and corporations are beginning to target these emissions is seen in the Greenhouse Gas Protocol’s (GHGP) definition of Scope 1, Scope 2 and Scope 3 emissions (Figure 2).
- Scope 1 emissions are direct emissions resulting from a company’s operational activities, including those from burning fuel and direct leaks of greenhouse gases into the environment – often occurring unnoticed in many industrial process facilities.
- Scope 2 emissions are generated from a company’s purchase of electricity, steam, heat and cooling.
- Scope 3 emissions include all indirect emissions not covered by Scope 2, linked to a company’s upstream and downstream activities.
Leaks can affect the bottom line
While carbon leaks are the most common in industrial settings, they are not the only leaks that occur. Some leaks are obvious issues due to the hazardous nature of the fluid or the high cost of lost expensive fluids. Others may not pose an immediate threat but can still be costly by reducing operational efficiency.
For example, steam – a common gas used in many production facilities – may not pose an immediate threat, but it is costly and energy-intensive to produce. The process of purifying water, generating steam and transporting it makes leaks particularly expensive and can reduce profitability over time.
Similarly, leaks in compressed air lines, though seemingly harmless to the environment or employees, can be costly as well. If the system struggles to maintain consistent pressure, additional compressors may need to compensate. Over time, such leaks can impact profits if left unchecked. However, repairing these leaks could eliminate the need for auxiliary compressors, along with the costs of installing and running them.
Identifying and addressing common leak sources
Leaks often occur at fitting and valve connections, and they can go unnoticed for extended periods of time. Fittings might be improperly installed, and some types are more prone to leaking than others. For example, NPT threaded fittings – a common type of small-bore fitting – are known to leak more frequently than certain mechanical grip tube fittings, which create longer sealing contact lines between their ferrules and the tubing. By selecting higher-performance tube fittings throughout your fluid systems, you can ensure more reliable leak-tight performance. Choose fittings with higher tolerances as they provide the best connections, no matter the installer’s expertise, application, or tubing material (Figure 3).
Valves are another common leak point. The quality of the components selected can mean the difference between maintaining a leak-free system or not. Valves consist of several individual parts, such as the stem and body seals, each of which could become a potential leak path. Improperly installed handles can also lead to leaks if they do not allow the gas or fluid to be shut off downstream. In such cases, the fluid or gas may move downstream to an open system and be released into the environment. Since valves are dynamic and subject to frequent opening and closing, some components may wear out over time, increasing the likelihood of leaks. Adjusting the packing gland nut often solves these issues.
Proper training on tube fitting installation is essential. Work with your supplier to create training modules specific to your system or application. This step provides technicians with the ongoing knowledge necessary to keep the systems leak-free over the system’s life span (Figure 4).
Proactively detecting leaks
Work closely with your suppliers to determine which leak-tight components are right for your specific application. They can also advise on system designs that minimize potential leak points. Reputable suppliers may also offer leak-detection services, helping you significantly reduce emissions and costs by identifying leaks early and enabling prompt remediation (Figure 5). Such services may involve using some or all of the following methods to identify leaks throughout a facility:
- Visual testing to look for actual drips or surface wetting below leaks.
- Bubble testing using either a thin film surfactant or submergence in a water bath; the presence of bubbles indicates a leak.
- Pressure change testing to determine any measurable pressure drops over time by pressurizing and isolating a system for a prescribed duration.
- Airborne ultrasonic testing on gas systems that uses a measurement device to locate the presence of a leak.
- Mass spectrometry testing on gas systems to detect the presence of trace amounts of leaked gas and quantify the leakage.
The longer a leak goes unrepaired, the greater the risk it poses to both the operating environment and the facility’s bottom line. As with most industrial systems, monitoring potential leaks in your fluid systems and addressing them proactively are keys to achieving a leak-free operation.
Note: An original version of this article appeared on the Swagelok Reference Point blog here: https://www.swagelok.com/en/blog/reduce-fluid-system-leaks-fugitive-emissions#.
