“Safety and Safety Factors: The impact on heat tracing system designs”

For many years engineers have relied heavily on the use of electrical heat tracing (EHT) "Safety Factors" to offset design and installation contingencies. The impact of arbitrarily selecting or changing safety factors is often overlooked, but can have a significant impact on the final system. The primary consideration in assigning safety factors is to offset deficiencies in the installation of thermal insulation, and can range from 10% to over 50%. As the objective of the EHT is to protect the integrity of the overall process operations through all possible ambient conditions, changes in the performance of the heat tracing system can and often will impact the performance of the processes themselves. Increasing safety factors will suggest increased heat losses that will require higher heat loads, often in the form of a higher wattage heat tracing. However, higher wattage heat tracing will introduce higher operating temperatures and increased concerns for installation in hazardous (classified) locations common in refinery and petrochemical operations. Additionally, higher estimated heat losses and increased electrical loads may in turn require shorter lengths of electrical heat tracing meaning more heater sets, more control points, more electrical circuits, more transformers and significantly increased field wiring requirements and of course more costs. The development of detailed engineering for electrical heat tracing (EHT) is an activity requiring a great deal of care and some level of expertise to balance process safety and any inappropriate safety factors. This paper will demonstrate the impact of insufficient consideration to EHT design safety factors as well as the value of properly addressing all aspects of an electrical heat tracing system.