Large-Scale Post-Welding Heat Treatment Furnaces

Post-welding heat treatment is a critical process in the manufacturing of large steel components. It alleviates residual stresses, refines microstructures, and enhances mechanical properties, ensuring that steel parts perform optimally under operational loads. Large-scale heat treatment furnaces, both electrically and flame-heated, provide the controlled environments necessary for these treatments.

Electrically Heated Furnaces

Electrically heated furnaces offer precise temperature control, essential for the uniform heat treatment of large steel parts. These furnaces generate heat using electrical resistance elements, such as nichrome or silicon carbide. Advanced control systems regulate the power input, allowing accurate temperature profiles during the heating and cooling phases.

The design flexibility of electrically heated furnaces allows for customization to accommodate various sizes and shapes of steel components. Modular construction techniques enable manufacturers to build furnaces that fit specific operational needs. The absence of combustion gases results in a cleaner process environment, reducing the risk of oxidation and contamination. This cleanliness is vital when treating high-grade steels or components with tight tolerances.

Electrically heated furnaces can achieve the high temperatures required for austenitizing and tempering. Improvements in insulation materials and the incorporation of heat recovery systems have enhanced their energy efficiency. Despite potentially higher electricity costs, these furnaces remain viable due to their precise control and clean operation.

Flame Heated Furnaces

Flame-heated furnaces, also known as gas-fired furnaces, generate heat by burning fuels like natural gas, propane, or oil. They are often favored for their rapid heating capabilities and lower operational costs in regions with competitive fuel prices. The combustion process creates a high-temperature environment suitable for various heat treatment processes.

Controlling temperature uniformity in flame-heated furnaces presents more challenges than in their electrically heated counterparts. Engineers address this by designing advanced burner systems and incorporating circulation fans to promote even heat distribution. Flame-heated furnaces are robust and capable of handling large steel parts with significant mass.

Direct flame impingement can enhance heating rates but requires careful control to prevent localized overheating or surface decarburization. Modern flame-heated furnaces mitigate these risks through sophisticated control systems and atmosphere regulation, ensuring that the heat treatment quality meets industry standards.

Comparative Analysis

Choosing between electrically heated and flame-heated furnaces depends on several factors, including specific heat treatment requirements, energy costs, environmental considerations, and the steel components' characteristics.

Electrically heated furnaces excel in applications requiring precise temperature control and a clean processing environment. They are ideal for treating complex alloys and critical components where tight temperature tolerances are necessary. The lack of combustion by-products minimizes the risk of unwanted chemical reactions, preserving the integrity of the steel's surface and microstructure.

Flame-heated furnaces offer faster heat-up times and potentially lower operational costs, particularly in areas with affordable natural gas. They are well-suited for large-scale operations where throughput and cost efficiency are significant concerns. Advances in burner technology have improved their temperature control capabilities, making them a competitive option for many industrial applications.

Large-scale heat treatment furnaces are essential for the post-welding processing of steel parts, ensuring that the final products meet the required mechanical and structural specifications. Electrically heated furnaces provide superior temperature control and a clean environment, making them suitable for high-precision applications. Flame-heated furnaces offer cost-effective and efficient heating solutions for large components where slight temperature variations are acceptable.

Choosing between electrically heated and flame-heated furnaces ultimately hinges on balancing technical requirements, economic factors, and environmental impact. As industries evolve, developing more efficient and environmentally friendly heat treatment technologies will continue to play a vital role in supporting the fabrication of large steel structures.

Hotfoil-EHS, Inc.
2960 East State Street Ext.
Hamilton, NJ 08619
Phone # 609.588.0900
Fax # 609.588.8333
www.hotfoilehs.com

Industrial Heat Treatment Furnaces, Big and Small

Here at Hotfoil-EHS, we are capable of building furnaces of many sizes, big and small. From small, low-throughput furnaces, to much larger high yield furnaces, to rail-driven furnaces designed to move back and forth over the materials being heated, Hotfoil-EHS Design Engineers and Fabrication Shop has done it all. Gas or electric, Hotfoil-EHS has the experience to build a custom furnace to your exact specification.  If you can think it, we can build it!

Hotfoil-EHS
https://hotfoilehs.com
609-588-0900

Custom Heat Treatment Furnaces Designed for the Most Challenging Applications

Hotfoil-EHS is a New Jersey based company who will design and fabricate custom heat treatment furnaces. From small, low-throughput furnaces, to high yield furnaces, to rail-driven furnaces designed to move back and forth over the materials being heated, Hotfoil-EHS has done it all.

From decades of experience in furnace production, many important furnace engineering discoveries were made that save time, money, and improve the end product.

Contact Hotfoil-EHS for your next heat treatment furnace requirement.

https://hotfoilehs.com
609-588-0900

Large, Custom Heat Treat Furnace Fabrication

The video below demonstrates the erection of a 16' x 16' x 62' heat treat furnace built out of a 6x6 I-Beam skeletal structure with 11 gauge steel skin. Full size doors, two per end, will allow the furnace to heat loads using it's full volume. The furnace is equipped with eight 3-Million BTU burners, one at either end and 3 down each side, to circulate the air. Four dampers are included, two at each end. It will move back and forth on a rail system by (16) 10" crane wheels. A hydraulic system will act to lift the furnace 3" in the air off the hearth. This will allow the furnace to move freely and without damaging the insulation on the bottom seals. It will be controlled via a remote HMI screen with full SCADA capabilities.

For more information, visit http://www.hotfoilehs.com or call 609.588.0900.

Large Scale Post Weld Heat Treating Project? Use a Custom Heat Treating Furnace

Custom PWHT furnace

As opposed to factory production, onsite production of large fabricated steel equipment could be the most cost-effective way to proceed on a large construction project. When you consider the costs of factory production, which includes complexities in permitting and approvals, logistics of materials and personnel, and most importantly transportation costs, the argument for onsite production starts to make sense.

The benefits of onsite fabrication of large vessels, heat exchangers, condensers, sections of pipe, spool pieces or any other large item are compelling.

They include:

Heated parts exiting furnace

• Elimination of costly transport of large parts, including permitting and bureaucratic issues
• Reduction of fabrication cost and time
• Reduction of inspection and approval complexity
• Close control over production 
• Fabrication under local, consistent and watchful quality control methods

Onsite manufacturing is complex, and requires localized production equipment and know-how. All aspects of the fabrication process which include engineering, material logistics, material preparation, field heating, welding, post heat weld heat treatment, and testing must be carefully considered.

With regards to post weld heat treatment (PWHT), it is advantageous to have a large enough capability to do the stress relieving in one shot with a field erected heat treating furnace. The most common approach for large part PWHT is to place the fabricated part inside the furnace and heat it to the required temperature in a single firing, as per procedure. This is the most desirable type of PWHT because all parameters in the heating, soaking and cooling can be carefully controlled.  

Large field erected PWHT furnace

PWHT furnaces can be diesel, gas, or electrically fired, and can be built to accommodate very large work-pieces. Computer controls accurately ramp the item up to temperature, assure the required soak, and then cool the parts down according to specification.

Custom furnace designs range from smaller low through-put sizes, to much larger rail-driven furnaces designed to move back and forth over the materials being heated.  These larger furnaces may include crane wheels and drive systems, or even hydraulic lifting systems that lift the entire furnace for optimal transport and placement.

Large field erected PWHT furnace with vessel entering

If you have any questions about custom PWHT furnaces, contact Hotfoil-EHS for a no obligation consultation. Hotfoil-EHS has years of experience in the engineering, design, fabrication, and commissioning of large scale post weld heat treating furnaces with many successful installations around the USA.

Hotfoil-EHS, Inc.
2960 East State Street Ext.
Hamilton, NJ 08619
Phone # 609.588.0900
Fax # 609.588.8333
www.hotfoilehs.com

10 Million BTU Burner for Custom Designed Heat Treating Furnace

Custom heat treating furnaces are designed for the tempering of metals. These furnaces can be electrically heated, or gas heated, depending on the energy source available. Tempering is defined as (from Wikipedia):

"Tempering is a heat treatment technique applied to ferrous alloys, such as steel or cast iron, to achieve greater toughness by decreasing the hardness of the alloy. The reduction in hardness is usually accompanied by an increase in ductility, thereby decreasing the brittleness of the metal. Tempering is usually performed after quenching, which is rapid cooling of the metal to put it in its hardest state. Tempering is accomplished by controlled heating of the quenched work-piece to a temperature below its "lower critical temperature". "

The video below shows the testing of a 10 million BTU ratio air burner designed for a custom heat treating furnace used to pre-stress large metal components prior to welding. Hotfoil-EHS manufactures complete furnace systems using OEM burners and in-house developed control systems.

For more information, contact:

Hotfoil-EHS
2960 East State Street Ext.
Hamilton, NJ 08619
Phone # 609.588.0900
Fax # 609.588.8333
Email: dap@hotfoilehs.com