Sigma Thermal Manufactures Four 100MM BTU/hr Hot Oil Heaters for a Liquified Natural Gas (LNG) Plant

Amid the COVID-19 Pandemic and Project Scope Challenges, Sigma Thermal Completes a Groundbreaking Project

Project Challenge

After securing the contract for the design and manufacturing of these systems, Sigma Thermal was well-aware of the difficulty of completing a project of this scope within the given timeline. Changes in project scope throughout the project and a global pandemic three-quarters of the way into the project introduced extra challenges the team had to face and overcome.

Project Outcome

Sigma Thermal executed the project from beginning to end, ensuring everything was in order from the documentation and drawing stage to the delivery of the heaters and installation of the stacks. At the end of the project, the client received four custom 100MM BTU/hr hot oil heaters that would serve as the heart of the plant’s operations.

Project Summary

Executive Summary: The client needed assistance with designing and constructing a series of hot oil heaters that would support a liquefied natural gas (LNG) export facility in the Southeastern United States. Sigma Thermal worked with them to complete the project on a tight timeline, accommodating multiple design changes in the process. The end result was an innovative custom heating system capable of burning six fuel gas mixtures, while maintaining strict emissions compliance.

Application: A liquefied natural gas export facility

Location: Southeastern, USA

Timeline: 18 months

Project Scope

The project called for the design and construction of four highly engineered hot oil heating systems with the following design specifications:

  • Hot oil heaters. 4 X 100 MMBtu/hr Sigma Thermal HC-2 dual helical coil thermal fluid heaters with a process coil designed specifically to meet the facility process requirements. The heater, combustion air fan, flue gas duct, fuel gas train, and control panel were mounted on a common skid frame designed for a single lift, which eliminated the need for heater assembly field work.
  • Multiple fuel gas combinations. Low emissions fuel gas burners, fuel trains, and control systems to accommodate six different fuel gas combinations, at elevated supply temperatures, up to 250° F, while maintaining emissions compliance and combustion efficiency.
  • 160-foot-tall exhaust stacks. Supply and installation of freestanding 160’ tall exhaust stacks with ladders and platforms, designed to withstand up to 180 mph wind gusts.

At Sigma Thermal, there were several teams involved with bringing this project to fruition, including:

  • Sales
  • Process engineering
  • Electrical engineering
  • Mechanical engineering
  • Project management
  • Commissioning

By closely working with each other and the client, they were able to deliver an effective solution within the estimated timeline.

“This project has had more twists and turns and been more complex than any project in my career. Seeing it from day one, knowing that it was going to be very difficult to attain this scope of work in the timeline that we had, to then three-quarters of the way in, face something that the world has never experienced, set up the project for a whole different set of challenges.”

Dave Parker, Sigma Thermal’s Project Manager

The challenges Sigma Thermal faced and overcame include:

Short Timeline/Delivery Date

The client had already received supply contracts from customers in various parts of Asia prior to the completion of the facility design. This resulted in a hard deadline to finish facility construction and begin production. Given the hard delivery date and the tight production schedule, Sigma Thermal engaged with numerous fabrication partners across the country to ensure all of the pieces necessary for all four heating systems were manufactured and delivered on time.

Multiple Fabrication Partners

Working with multiple fabrication partners enabled Sigma Thermal to manufacture all four systems by the required date, which meant regular communication and coordination with other companies to keep the project on track. Fortunately, the company has long-standing relationships with many highly experienced and dependable fabrication partners. For this project, Sigma Thermal utilized its in-house fabrication facility to build the fuel train and control panel (the brains of the system).

Numerous Fuel Gas Types & Conditions

One of Sigma Thermal’s biggest challenges was developing a system capable of burning six types of fuel gases in various combinations, all while maintaining strict emissions compliance and combustion efficiency . Furthermore, one of the six fuel gases had a very high density and contained solids that needed to remain in solution. The heating system had to keep this gas at a sufficiently high temperature and high flow to prevent it from falling out of solution and becoming solid in the gas stream.

Excessive Component Size and Weight

The completed heater skid assembly was too large and heavy to ship by land. As a result, the client requested all large pieces be delivered by barge to the construction site. The logistical team at Sigma Thermal had to plan and coordinate with trucking and barge suppliers extensively throughout the project to ensure a successful delivery.

Project Scope Expansions

The scope of the project was modified and expanded many times, which led to Sigma Thermal having to double back on completed work and engineer new solutions to accommodate the changes while sticking to the original timeline. The project scope changes that occurred were:

  • Increase in exhaust stack height. Originally the four freestanding exhaust stacks were supposed to be 25 feet. The client requested that the height of the stacks be increased to 160 feet.
  • Adding installation scope. Sigma Thermal was initially responsible solely for manufacturing the stacks. Further into the project, Sigma Thermal also assumed responsibility for the installation of the stacks. This was a complex responsibility that involved supplying the installation equipment, ensuring the delivery of the installation equipment aligned with the delivery of the four stacks, and finding an installation crew that was qualified to complete this type of work.
  • Increase in wind load capacity. Halfway into the fabrication process, the client requested a design change that allowed the exhaust stacks to handle higher wind loads. Sigma Thermal procured more steel and fortified the structure of the stacks to meet the new design requirements without extending the project’s timeline.
  • Higher gas temperatures. The client’s requirement for process heaters that can accommodate six different fuel gases was an engineering feat in and of itself. Since one of the fuel gases required higher temperatures to prevent liquids from falling out of solution, all of the instruments and paint specifications needed to be redesigned to withstand the higher temperatures.


Manufacturing of the major pieces of equipment was close to completion when the SARS-CoV-2 (aka COVID-19) pandemic began. This catastrophic global event had a significant impact on Sigma Thermal’s supply chain. Fortunately, most of the raw materials and instruments had already been received by the time the effects of the pandemic became evident. The primary challenge would be with fabrication resources. With multiple collaborators in different areas of the country, it was difficult to predict how the pandemic would impact their ability to maintain a consistent workforce from day to day.

Despite this unknown variable, Sigma Thermal forged ahead with the project while keeping the client updated as frequently as possible. Ultimately, a new delivery date was agreed upon to account for the effects of COVID-19. Sigma Thermal was able to complete the fabrication and deliver the final assemblies to the facility within the new timeline.

Contact the Industrial Processing Heating Experts at Sigma Thermal Today

Despite the many challenges faced (e.g., scope expansion, shipping issues, and COVID-19), Sigma Thermal finished the project within the client’s timeline. The success of the project hinged on the process engineering, electrical engineering, mechanical engineering, project management, commissioning, and sales teams, whose combined knowledge, skills, and resources led to the creation of a new and innovative project solution that met the client’s demands.

If you’re looking for a partner for your next custom process heating project, turn to the experts at Sigma Thermal. We look forward to continually pushing the boundaries of process heater technology to meet the needs of our customers. To learn more about our capabilities or previous projects, contact us today.

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