As post-pandemic business gets back to normal, it may be time to update your furnace equipment, possibly through a retrofit. There are likely two areas of failure in an industrial furnace: the insulating refractory system or the combustion and controls system. This article includes two brief case studies: a controls and combustion system overhaul and a complete furnace retrofit. These practices give you the opportunity to update on best industry practices and maximize the return on your equipment investment.

The forging and heat-treating industry is undergoing a transformation. Technology is advancing, equipment is aging and the rules and regulations centered around operational safety are at the forefront of customers’ minds. More so now than ever, safe and efficient operation of your industrial furnace is crucial to meet your clients’ unique and demanding needs. At the end of the day, your furnace is a key component to getting the finished products out the door.

Manufacturers have options when seeking to improve plant operating efficiencies and maximizing equipment uptime. One option is a furnace retrofit that allows you to do a “remodel” using the existing furnace structure while upgrading critical safety components. These upgrades extend the useful life of the equipment by installing new controls for regulatory compliance specifications. Another option is to install new equipment when additional capacity is required or when your current equipment is not suited for a new product line.


Time to Explore a Retrofit

Begin the furnace retrofit process by understanding the current system operation and knowing the long-term goals of the business. Then prepare and follow a plan to make sure your investment is maximized by ensuring the asset is operating as predicted for your future production needs.

Knowing when to upgrade an industrial furnace is often a combination of a few factors, such as forecasted market demand, safety and regulatory requirements, unexpected downtime occurrences and, as always, availability of capital. Let us take a closer look into each decision to better understand why you may need to upgrade equipment.


Market Demand

Right now, the entire industry is caught in the middle of a supply-chain catastrophe as we recover from the worldwide coronavirus pandemic. While business is getting back to normal, you may be experiencing a lack of inventory due to the just-in-time inventory principles in place before the pandemic. If inventory is not a problem, maybe it is logistics issues between a freighter stuck in the Suez Canal or not enough trucks on the road to deliver the required goods.

Domestic manufacturing demand is expected to continue to increase, which is good news for manufacturing companies looking to make capital investments. To ensure maximum production uptime, you may have to decide to temporarily take equipment out of service to make necessary upgrades. As a business leader ask, “Is your equipment operating at optimal conditions to meet the rising demand of your customer base?”


Safety, Regulatory or Traceability Requirements

Safety is the most important component in maintaining a healthy and compliant operation. The biggest areas of concern and opportunities for safety improvements in an industrial furnace are its combustion system and its controls. Flame safety, pilot valves, functioning shutoff valves, limit switches and a well-tuned control system are just a few components required to meet the compliance of the National Fire Protection Act (NFPA) 86.

The other instance that comes up often is a change to a product or a new customer who may require traceability and record logging of the furnace during each furnace cycle. This traceability often causes end users to invest in new systems (such as a data logger integrated into the controls) to handle the incoming opportunity.


Furnace System Downtime

Production downtime is frustrating for all parties involved. A best practice is to keep a log of the failures and understand why they occurred so that you have an idea of when the upgrade will need to happen. When a failure first occurs, it is important to perform a root-cause failure analysis using both photos and personnel interviews to detail what happened. This information will be used to communicate with the internal team and its external partners.

There are likely two areas of failure in an industrial furnace: the insulating refractory system or the combustion and controls system. A refractory failure can usually be seen and may look like a collapsed roof, chemical attack, abrasive wear or a break due to impact. A combustion system or controls failure may not be so obvious. The culprit may be a clogged burner, a valve failure, a dirty blower or a glitch in the control programming. Gather a team of experts to identify the root cause of the failure and work to get the equipment back online as quickly as possible. Your clients are expecting a quality product – on time, every time – so your equipment needs to operate at peak performance.


Retrofits Driven by New Requirements

Domestic manufacturing is heating up, and the demands of future incoming business – coupled with aging and outdated equipment – may require you to review your equipment capabilities and make appropriate changes. Let us review two case studies that we recently completed. The first is a controls and combustion-system overhaul to ensure regulatory compliance while meeting the client’s traceability needs. The second is a complete furnace retrofit including refractory, combustion and controls to process products requiring tighter temperature uniformity.


Case Study 1: Controls and Combustion System Overhaul

Our first case study is about a client who had an aging control system based on a version of Windows that was no longer supported. Coupled with the aging controls, combustion parts on the furnace had become obsolete and the customer’s critical spare inventory was near depletion.

The client requirements for the new controls and combustion system were that the existing furnace burners were to be used, thereby not altering the furnace operating zone. Each furnace was to utilize the same logic and sequence for start-up, temperature ramp, soak time and cool-down.

To tackle these requirements, Onex upgraded key combustion components such as strainers, switches and valves to bring each furnace into compliance with NFPA 86. The control system was also updated and integrated to meet the client’s needs.

With over 30 burners in the system, the design and engineering required many iterations between plant personnel and Onex to complete. Since these furnaces run daily, tight collaboration was required between the installation team and plant maintenance and production. The project spanned over six months. In the end, the client requirements were met, and they are running new products in retrofitted furnaces.

Control panel build in progress


Control panel and HMI (human-machine interface) installed


Case Study 2: Combustion System and Refractory Overhaul

The second case study was triggered by a client’s requirement for increased temperature uniformity across a wider low-end and high-end operating temperature. The goal was to accurately survey the furnace down to a low setpoint temperature of 325°F with a uniformity rating of ±10°F between 325°F and 1250°F. This requirement resulted in a furnace retrofit with a completely new burner system, controls and an engineered refractory design to support tighter temperature tolerances – all working in parallel to achieve the goal.

Onex installed 32 burners with four zones of control to complete the project while meeting the client’s requirements. In addition, the furnace car had to be redesigned to ensure a tight seal. All the furnace components had to be configured to work together to achieve the new operating requirements, allowing for new product production.


New combustion system



Unique systems demand experience. No two furnace systems are alike. Operations may be the same, but subtle differences between product materials, work zones, soak times, uniformity requirements, operating systems and customer preferences all lead to a unique engineered solution. If designed properly, a furnace can last years and provide you with the maximum available uptime to meet the demands of your growing customer base. Working with a trusted partner who “has seen a thing or two” gives you the opportunity to stay up to date on best industry practices in addition to maximizing the return on your investment.