Electrical Heat Tracing: Lessons Learned From Extreme Weather Events Such as the Recent Freeze in TexasPosted on May 7, 2021 2:13:45 PM by Dusty Robinson
The recent cold weather event in Texas has left many facilities with a mess of busted pipelines, forcing management to take a deeper look at heat tracing —or lack thereof—within their facilities.
With changing weather patterns around the world, and regions facing cold weather surprises like this, we now ask ‘what should be done, if anything, to mitigate future damage like this’?
In the past, companies have analyzed historical weather data to evaluate the risk and cost of downtime due to frozen pipes, against the cost of installing electrical heat tracing for freeze protection. Based on this evaluation, many facilities in warmer climates —like Texas—were able to justify not installing electrical tracing.
Other companies may have installed electrical tracing only to still experience problems in the recent cold snap. They are likely looking back to see what went wrong, as they thought they were protected from events such as this. The key to answering their questions likely revolves around one thing: maintenance.
To ensure electrical tracing systems are functioning properly, periodic maintenance must be performed, typically before each winter. Depending on the number of lines, or the size of your facility, properly maintaining your tracing can be a time consuming and costly effort. However, the use of heat tracing controllers can help reduce the burden of maintaining the tracing system. Controllers are often overlooked for freeze protection applications, where a simple thermostat is viewed as a more cost effective solution. Up front the reduced cost of a thermostat compared to a heat tracing controller seems like an easy choice, but considering the long term benefits, the additional monitoring and feedback provided by a controller shows a different picture.
Controllers have the ability to monitor many parameters such as ground-fault and current that assist with maintenance of the tracing system. They can periodically check the tracing circuits and provide alarms when a problem is sensed, allowing maintenance to address the problem in a timely manner. A few benefits of utilizing a controller for heat tracing control are discussed in additional detail:
- Ground fault Current Monitoring – The NEC (NFPA 70) requires ground fault protection on heat tracing circuits. When using thermostats for heart tracing control, this protection is typically provided by a breaker and no indication of a ground fault issue is provided until the breaker trips. Furthermore, these breakers are typically not monitored which leads to a potential situation where the problem is not identified until it has become severe enough to freeze the line and cause issues in the process. Controllers have the ability to monitor ground fault current and provide alarms at various setpoints, indicating the potential for problems before they happen and before the required ground fault trip. This is useful in indicating when heating cable insulation may be compromised or when water has penetrated a tracing power connection or end seal kit.
- Temperature Monitoring – Controllers have the ability to monitor line temperature via line mounted rtd’s. This provides feedback to confirm the tracing is maintaining the desired line temperature and allows the ability to set an alarm if the line temperature drops below a minimum setpoint, before the line begins to freeze.
- Current Monitoring – Controllers have the ability to monitor circuit current. This circuit current can indicate problems with the heating cable when the current is outside of the normal operating range.
- Voltage Monitoring – Most controllers monitor system voltage and can provide alarms when the system voltage is out of range.
- Internal diagnostics – Controllers have the ability to identify a problem in the control system. When the controller calls for the heating cable to be on, it immediately knows if the current or voltage is out of normal range and flags the problem with an alarm. If a relay fails to close to energize the circuit, the controller can immediately provide feedback of the problem. Utilizing a thermostat for control does not inherently provide diagnostics and feedback which allows problems to go unnoticed, often for extended periods of time.
- Remote communication/alarms – Controllers have the ability to communicate alarms via most standard communication protocols or via a dry contact. Identifying the alarms and more importantly, addressing/correcting the problem is key to a properly functioning tracing system.
When preparing for the next cold weather event, remember the best electrical tracing design and installation means little without proper maintenance. Let technology work for you by utilizing a heat tracing controller for freeze protection to ease the troubles of tracing system maintenance.
Dusty Robinson is the Electrical Engineering Group Leader for the Process & Industrial (P&I) division of Day & Zimmermann. He has been with Day & Zimmermann for more than ten years leading the electrical design for various chemicals and fibers projects ranging from smaller upgrade projects to larger greenfield new facility construction. Dusty holds a BSEE degree from Clemson University and is a registered Professional Engineer in multiple states.