Pre-weld Heating and Post-weld Heat Treatment: Essential Steps for Infrastructure Integrity

Pre-weld heating and post-weld heat treatment play crucial roles in welding critical infrastructure such as pipelines, ships, boilers and bridge support systems. These processes ensure the structural integrity, longevity, and safety of welded components that bear significant loads and operate under various environmental conditions.

Pre-weld heating is essential when welding materials like high-strength steel in critical applications. Heating the base metal before welding minimizes thermal gradients between the weld area and the surrounding metal. By reducing these gradients, welders prevent the rapid cooling that can lead to the formation of brittle microstructures. Pre-weld heating also helps eliminate moisture, which can introduce hydrogen into the weld metal and cause hydrogen-induced cracking. By controlling the temperature of the base material, welders achieve a more uniform and ductile weld, reducing the risk of cracks and other defects that could compromise the structure's integrity.

Post-weld heat treatment, on the other hand, addresses the residual stresses and microstructural changes that occur during welding. Welding introduces significant thermal cycles, leading to the expansion and contraction of materials and the development of residual stresses. These stresses can cause distortion, reduce fatigue life, and even lead to catastrophic failure under service conditions. By applying controlled heat after welding, engineers relieve these stresses and restore the material's toughness. Post-weld heat treatment also refines the microstructure of the weld and the heat-affected zone, enhancing mechanical properties such as strength and ductility.

Moreover, regulatory standards and codes often mandate pre-weld heating and post-weld heat treatment for specific materials and thicknesses. Compliance with these standards not only ensures safety but also enhances the durability and reliability of the infrastructure. By adhering to best practices in welding, engineers and construction professionals contribute to the sustainable development of critical infrastructure.

In conclusion, pre-weld heating and post-weld heat treatment are indispensable processes in welding critical infrastructure components. They mitigate risks associated with thermal stresses, prevent the formation of detrimental microstructures, and enhance the overall performance of welded joints. Investing time and resources in these processes safeguards the infrastructure, protects the environment, and ensures public safety.

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

The Crucial Role of Part Temperature Control in Pre-Weld and Post-Weld Heating

In the welding world, ensuring the final product's quality and strength requires more than just skilled welders and advanced equipment. One critical aspect that welders and fabricators must pay close attention to is part temperature control, particularly during the pre-weld and post-weld heating processes. This article will explore the importance of maintaining proper part temperature and its impact on the welding process.

Pre-Weld Heating: Setting the Stage for Success

Before welders even strike an arc, they must consider the temperature of the base metal. Pre-weld heating involves raising the temperature of the workpiece to a specific range, depending on factors such as the material type, thickness, and the welding process employed. This step is crucial for several reasons:

1. Reduces Hydrogen Cracking: Pre-weld heating helps reduce the risk of hydrogen cracking, a common issue when hydrogen atoms become trapped in the weld metal during the cooling process. By preheating the base metal, welders can minimize the temperature gradient between the weld and the surrounding area, allowing hydrogen to diffuse out more quickly.

2. Improves Weld Penetration: Preheating the workpiece lowers its thermal conductivity, which allows the welding heat to penetrate deeper into the joint. This improved penetration results in a stronger, more uniform weld with fewer defects.

3. Reduces Residual Stresses: As welders heat and cool the metal during welding, residual stresses can develop within the material. Preheating helps minimize these stresses by reducing the temperature difference between the weld and the base metal, promoting a more gradual cooling process.

Post-Weld Heating: Ensuring Long-Term Stability

Once welders complete the welding process, their job must still be finished. Post-weld heating, also known as stress relief heat treatment, is essential in maintaining the welded component's long-term integrity. Here's why:

1. Relieves Residual Stresses: Welding can introduce residual stresses into the material. Post-weld heating helps relieve these stresses by allowing the molecules within the metal to rearrange themselves, reducing the internal tension and preventing potential distortion or cracking.

2. Improves Mechanical Properties: Subjecting the welded component to a controlled post-weld heat treatment can enhance its mechanical properties, such as toughness and ductility. This improvement is significant for components that will face demanding operating conditions or heavy loads.

3. Increases Corrosion Resistance: In some cases, post-weld heating can also boost the corrosion resistance of the welded joint. Allowing the formation of a more uniform and stable microstructure helps prevent localized corrosion and extends the component's service life.

Implementing Effective Temperature Control Measures

To reap the benefits of pre-weld and post-weld heating, welders must implement accurate and reliable temperature control measures. This implementation involves using high-quality heating equipment, such as ceramic heaters or induction coils, and precise temperature monitoring devices, such as thermocouples or infrared thermometers.

Additionally, welders must follow established guidelines and procedures for the specific materials and welding processes they are working with. Industry standards, such as those set by the American Welding Society (AWS) or the American Society of Mechanical Engineers (ASME), provide detailed recommendations for pre-weld and post-weld heating temperatures and durations.

Conclusion

Part temperature control, through pre-weld and post-weld heating, plays a vital role in ensuring the quality, strength, and longevity of welded components. By understanding the importance of these processes and implementing effective temperature control measures, welders and fabricators can produce welds that meet the highest performance and reliability standards. As the welding industry continues to evolve, mastering the art of temperature control will remain a critical skill for professionals in this field.

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

Pre and Post Weld Heat Treatment

Heat treatment in any large-scale welding process (such as pipeline welding, shipbuilding, boiler manufacturing) is critical to a weld's efficiency and, therefore, essential in a structure's performance, and therefore its importance can never be overlooked. 

An examination of industrial code or a consultation with a welding specialist is imperative if in doubt. A review of the welding code is the first determinant of whether preheating is required. The welding code carefully defines the minimum preheat, the temperature, the soak time, and the welding method. Many requirements, all obtained from years of rigorously checked data, are recognized by welding codes. This data is well supported by several sources, including metallurgical research, chemical material properties, and radiographic analysis. 

Welding heat treatment in its simplest form is the process of heating the base metal (parts to being welded) before welding to the desired temperature and then allowing it to cool at a given rate under regulated conditions. The exact temperature the component needs to achieve (before welding) is called the "preheat temperature." 

There are several main reasons why preheating before welding is necessary. A preheated part cools more slowly, which slows down the welded part's overall cooling rate. This slow cooling strengthens the metallurgy (crystalline structure), which makes it less susceptible to cracking. Hydrogen that could be present immediately after a weld is therefore released more effectively, reducing cracking risk. Preheating at the weld joint and surrounding metal often mitigates stress from the shrinkage. It is preheating that decreases the risk of fractures due to brittleness during processing. 

Electric preheaters for welding, known as "ceramic mat heaters," are durable and versatile heating components built to fit evenly around the weld and surrounding area. Ceramic mat heaters are temperature controlled by a power console that uses thermocouples and electronic controllers to regulate the preheat temperature profile, track it, and record the temperature data. 

Another less favored method for heating the target piece is with a torch or open flame, but this method has apparent safety issues and controllability problems. Also used are heat treat furnaces, but these usually involve off-site transport of the target item. 

For safety, portability, and controllability, induction heaters give an appealing alternative. Induction heating is endorsed because, instead of open flames or external electrical components, it uses molecular excitation as its source of heat. Induction heating operates very rapidly, and there are far fewer worries about component contamination since there is no interaction with the target item. When very high temperatures and uniform control is required, many industrial processes use induction heating.

It is critically important to review and discuss your heat treating requirements with an expert before welding. Don't risk safety or waste time and money by "winging it" when it comes to heat treatment.

Hotfoil-EHS
609-588-0900
www.hotfoilehs.com

Hotfoil-EHS Heat Treating Power Consoles

Precise control over your pre-weld and post-weld heat treatment parameters are critical. Accurate temperature control, specific soak times, uniformity, and controlled heat up and cool down times are required to ensure strong welds. Hotfoil-EHS power consoles are designed to provide the best control, easiest user interface, and longest lasting operation, even in the toughest environments. Using only the highest quality components, Hotfoil-EHS power consoles are field-tested and application proven. Control systems can be specified with or without recorders or ramping controllers, and are standardly available in 6, 9, 12, 18, and 24 zone configurations.

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

New Hotfoil-EHS UK Ltd. Product Brochure

Hotfoil-EHS UK has just released a new general product capability brochure. You can download the PDF here.

Hotfoil-EHS UK Brochure from Hotfoil EHS, Inc.

Pre Weld and Post Weld Heat Treatment

Welding between insulated heating areas
Heating done by ceramic heaters (pink). 

There are several key reasons why it's important to preheat before welding. First, a preheated part cools more slowly, which slows the overall cooling rate of the welded part. This improves the metallurgical (crystalline) structure and makes it less prone to cracking. Additionally, hydrogen that may be present immediately after a weld is also released more efficiently, which further reduces the possibility cracking. Preheating also mitigates stress from the shrinkage at the weld joint and nearby metal. Finally, pre-heating reduces the possibility of fracture during fabrication due to brittleness.

An industry standard means of accurately managing the pre-heat and post-weld heat treatment is through the use of specialized electric heaters. Electric welding preheaters, known as "ceramic mat heaters", are rugged and flexible heating elements designed so that they conform uniformly around the weld and surrounding area.  Ceramic mat heaters are normally controlled by a power console that uses thermocouples and electronic controllers to regulate, monitor, and many times record, the preheat temperature profile.

Ceramic heaters on spool piece.

Welding codes, gathered from years of rigorously tested data, including metallurgical science, chemical properties of materials, and radiographic analysis, provide specific detail on the minimum preheat temperature, the soak time, and the welding process to be used.

Before deciding to preheat or post heat any welding job, consult with a heat treating expert to make sure proper welding code requirements are being followed.

Induction Heating Basics

Induction heating coils
around large pipe for
pre-weld heat treatment.

Induction heating occurs when passing alternating magnetic fields through conductive materials. This is accomplished by placing an alternating current carrying coil around or in close proximity to the materials. The alternating fields generate eddy currents in the materials. These currents interact with the resistance of the material to produce heat. There is a secondary heating process called hysteresis. This disappears at the temperature at which the material loses its magnetic properties.

Direct Induction

Direct induction heating occurs when the material to be heated is in the direct alternating magnetic field. The frequency of the electromagnetic field and the electric properties of the material determine the penetration depth of the field, thus enabling the localized, near-surface heating of the material. 

Comparably high power densities and high heating rates can be achieved. Direct induction heating is primarily used in the metals industry for melting, heating, and heat treatment (hardening, tempering, and annealing).

Indirect Induction

With indirect induction heating, a strong electromagnetic field generated by a water- cooled coil induces an eddy current into an electrically conducting material (susceptor), which is in contact with the material to be treated. Indirect induction heating is often used to melt optical glasses in platinum crucibles, to sinter ceramic powders in graphite crucibles, and to melt materials in crucibles prior to drawing crystals. Indirect induction is also used to heat susceptors used for joining operations.

Weld Heat Treatment is Critical to Structure Integrity

Welding pre-heat is critical to the quality of the weld and
and the integrity of the structure.

In any large scale welding operation (such as pipeline welding, shipbuilding, boiler fabrication) heat treatment is critical to the quality of a weld, and therefore critical to the performance of a structure, and never should not be taken lightly.

When in doubt, review of industry code or a consultation with a welding expert is imperative. Welding code is the first determinant to whether pre-heating is needed. Welding code carefully specifies the minimum preheat temperature, the soak time, and the welding process. Many criteria are considered by welding codes, all gathered from years of rigorously tested data. This data is accumulated from many sources, including metallurgical science, chemical properties of materials, and radiographic analysis.

In its simplest form, weld heat treatment is the process of heating the base metal (parts to be welded) to a desired temperature prior to welding, and then allowing it to cool at a given rate under controlled conditions. The specific temperature to which the part needs to be heated (before welding) is referred to as the “preheat temperature”.

There are several key reasons why it's important to preheat before welding. 

• A preheated part cools more slowly, which slows the overall cooling rate of the welded part. This improves the metallurgical (crystalline) structure and makes it less prone to cracking. 
• Hydrogen that may be present immediately after a weld is also released more efficiently, which further reduces the possibility cracking. Preheating also mitigates stress from the shrinkage at the weld joint and nearby metal. 
• Pre-heating reduces the possibility of fracture during fabrication due to brittleness.

Electric welding preheaters, known as "ceramic mat heaters", are rugged and flexible heating elements designed so that they conform uniformly around the weld and surrounding area.  Ceramic mat heaters are normally controlled by a power console that uses thermocouples and electronic controllers to regulate, monitor, and many times record, the preheat temperature profile.

Another less preferred method to heat the target piece is with a torch, or open flame, but this method carries safety concerns as well as controllability issues. Furnaces are also used, but these typically require the transport of the target piece off-site.

Induction heaters offer an attractive alternative for safety, portability and controllability. Induction heating is unique because it uses molecular excitation as its source of heat, as opposed to open flames or external electric elements. Induction heating works very quickly, and since there is no contact with the target piece, there are far less concerns about part contamination.  Many industrial processes use induction heating when very high temperatures and uniform control is desired.

Each welding application has it's own unique set of circumstances which dictate the optimal heat treating method.  It is always best to contact an expert and solicit their opinion on your best available option.

Welding Heat Treatment Power Consoles

Welding Heat Treatment Power Consoles by Hotfoil-EHS

When it comes to Hotfoil-EHS power consoles, there's no cutting corners. By using thicker gauge sheet metal and tubing, top quality electrical components, and quality craftsmanship, Hotfoil-EHS power consoles provide years of reliable and trouble-free service.

Power consoles are standardly offered in 6, 9, 12, 18, and 24 zone configurations with a variety of control and recording systems. All Hotfoil-EHS power consoles are available in Stainless Steel and can be customize to your requirements.

Have a special requirement? Just ask. Need a special color, coating or controls? Hotfoil-EHS is eager to provide a custom power console to meet your exact needs.

Temperature recorders are available for applications requiring documentation and certification. Fully automatic controllers are provided when specific heat-up and cool-down profiles are needed.

EHS manufactures and sells accessories including:

• ceramic heaters, 
• thermocouple attachment units (TAU) 
• pin welders 
• hardness testers 
• thermocouple wire 
• insulation

Hotfoil-EHS Heat Treatment Power Consoles from Hotfoil EHS, Inc.

Applying Ceramic Mat Heaters for Pre and Post Weld Heat Treatment

Designed for pre and post weld heat treating, ceramic mat heaters function efficiently for both curved and flat applications. The flexibility of these heaters provides a convenient means to heat treat large metal surfaces in the field.

The application of ceramic mat heaters is straightforward - the heater is placed directly on the part to be welded, insulation is normally laid over the heater, and voltage is applied. A thermocouple is tack-welded near to monitor the part. The part is brought up to temperature and then the welding is done. After the weld, the part is cooled at a controlled rate.

Welding a large pipe with localized heating using
ceramic mat heaters.

Preparing the pipe for the weld and allowing
the heaters to raise the temperature of the pipe.

Wrapping ceramic mat heaters around
spool piece.

Close-up of ceramic mat heaters around
spool piece.

Fusion45: New Rugged Induction Heater Improves Weld Quality

New Welding Induction Heater

Heat treating isn’t done in a laboratory, or a clean room. Applications are out in the real world, where dirt, grease and grime are normal. Hotfoil’s new induction heater is designed to work in the toughest conditions, and continue to run shift after shift.

Induction heating works very quickly, and since there is no contact with the target piece, there are far less concerns about part contamination. Many industrial processes use induction heating when very high temperatures and uniform control is desired.

Pre and post-weld heat treating (stress relieving) is a growing market for induction heating systems because it offers significant benefits such as excellent heat placement and distribution, lower cycle times, safety, ease of use, and efficiency.

Induction heating can improve your bottom line by decreasing weld failures, and decreasing setup and tear down times. The technology allows for accurate temp control, without heavy electrical service or complicated controls. The portability and ease of use will allow you to heat more welds faster.

Check out the new Hotfoil-EHS Fusion45 Induction Heater:

The Hotfoil-EHS Fusion45 Induction Heater from Hotfoil EHS, Inc.

Custom Heat Treating Power Consoles Solve Many Potential Field Problems

Weather-proof, Stainless Steel
Power Console

Standard heat treating power consoles available from a variety of manufacturers pretty much cover the same set of basic welding requirements. In many field situations however, there can be unusual circumstances such as difficult locations, available power sources, and environmental concerns. In these situations custom manufactured power consoles will provide welding outcomes with fewer operational problems, higher quality output, and greater safety.

Standard power consoles are available 3, 6, 9, 12, 18, 24 and 36 zone configuration (zones are many times referred to as "way" such as 3 way console, 6 way console, 9 way console, etc.) Each zone provides a point of control. The type of control can vary depending on the requirement of the weld. Some zones only need simple on-off or proportional control. Some welding jobs require more sophisticated temperature control profiles, thus requiring tight control with temperature vs. time ramping. Additionally, these more sophisticated control requirements may also need data logging or recording for quality compliance. In many situations custom cable sets are required to deliver the heater power and thermocouples to the workpiece. A power console manufacturer should have the experience and knowledge to consult, recommend, and install whatever zone control and cabling requirements your job needs.

Power console and
custom cable sets

The operating environment is another important consideration for power console customization. Standard power console cabinets are usually made from a medium gage sheet metal and painted with an industrial grade rust-resistant paint. While fine for relatively dry and non-corrosive atmospheres, these are subject to quick deterioration when moved into areas where higher than normal concentrations of salt, chlorine, or other corrosive gasses exist. In these situations, careful consideration of exposed materials needs to be applied. Perhaps an all stainless steel design is needed? Or maybe special corrosion resistant paints or epoxy resins should be specified? Or maybe you only need a special color paint? Working with a power console manufacturer who has the flexibility in their manufacturing process and experience on the floor to provide these options is preferred.

Custom painted
power console

Finally, look for a power console manufacturer who can handle unusual power system requirements. A manufacturer who can adapt their systems to unique voltages and current requirements is a big plus. Look for an equipment company that has experience and production capabilities for a wide variety of transformers - single or dual- and can even supply custom built transformers.

And of course, always try and find equipment built right here in the USA.

For more information on ANY welding power console, contact:

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

www.hotfoilehs.com
Email: dap@hotfoilehs.com

New Video on Ceramic Mat Heaters for Welding Heat Treating

Just a short video on Hotfoil EHS pre and post weld heat treating mat heaters (also known as pad heaters).

Ceramic Pre Weld and Post Weld Heaters Get The Heat to the Weldment Efficiently

Ceramic mat heaters

The most important feature of a resistance heater is the ability to transfer the heat away from the resistance wire to the outer covering where it can be absorbed by the work piece. Even when accurately controlled, a poorly designed or poorly applied heater can cause the wire temperature to exceed the wires operational limits. Ceramic mat heaters, also known as ceramic pad heaters, are designed to produce more even and efficient heat transfer while maintaining maximum flexibility.

Design:

1) Sintered alumina oxide is formed into shapes and fired at precise temperatures to produce a ceramic insulator with a combination of high dielectric strength and efficient, fast heat transfer. This ceramic is also solid enough to withstand physical shock and resistance to oxidation and corrosion from a broad range of chemicals and atmospheres.

2) An accurately measured length of stranded nickel-chromium wire is precisely wound through the ceramic beads ensuring electrical isolation to produce a compact and flexible resistance heater. Suitable for operation at 2000 deg. F.

3) The resistance wire is then metallurgically bonded to a stranded nickel-copper wire to provide trouble free electrical continuity. The flexible stranded cold junction wire is connected to brass Twistlock connectors fitted with insulated sleeves. The cold junction extension leads are rated for 250 deg. C continuous temperature.

Ceramic mat heaters are efficient, time-tested, and proven heater technology in pre-weld and post weld heating, and are designed for the harsh realities of the welding environment.

For more information, contact:

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

Rely on Experienced Welding and Heating Applications Experts for Improved Outcome and Efficiency

Work with the manufacturer's experts for better outcomes

When it comes to selecting the right equipment for welding and industrial heating jobs, projects and tasks are best completed and accomplished through the proper application of the right resources. There exists an access point to high level technical knowledge and assistance that can be easily tapped and brought to bear on your successful task or project completion. The manufacturer's own internal experts.

 
Manufacturers provide services that may help you save time and cost, while also achieving a better outcome for the entire project. Consider a few elements the technical sale rep brings to your project:

• Product Knowledge: Product managers and sales support personnel will be current on product offerings, proper application, and capabilities. They also have information regarding what products may be obsolete in the near future. This is an information source at a level not generally accessible to the public via the Internet.
• Experience: As a project engineer, you may be treading on fresh ground regarding some aspects of your current assignment. There can be real benefit in connecting to a source with past exposure to your current issue. 
• Access: Through the manufacturer's internal applications people, you may be able to establish a connection to “behind the scenes” information not publicly available. The people at the manufacturer can provide answers to your application questions.

Certainly, any solutions proposed are likely to be based upon the products sold by the manufacturer. That is where considering and evaluating the benefits of any proposed solutions become part of achieving the best project outcome.

Develop a professional, mutually beneficial relationship with the manufacturer's technical sales team, and don't be shy to develop a professional and trusting relationship. Their success is tied to your success and they are eager to help you.

HofoilEHS - Your Preferred Source for Pre and Post Weld Heat Treating

HotfoilEHS is a premier manufacturer of pre weld and post weld heat treating equipment. EHS manufactures and sells pre and post-weld heat treating equipment including power consoles, ceramic mat heaters, thermocouple attachment units, pin welders, Brinell testers, Poldi hardness testers, thermocuple wire, insulation, and accessories.

The below video is a little shameless, self promotion.

Power consoles are standardly offered in 6, 9, 12, 18, and 24 zone configurations with a variety of control and recording systems.

Twin heating modules, with and without recorders, and optional ramping controllers are available from EHS.

For special projects, EHS can provide mineral insulated (MI) heating circuits designed into a blanket-type layout, using clips to attach the circuits to a wire mesh in a configured pattern. The circuits are CSA and FM Approved for hazardous and non-hazardous areas.

EHS also offers short or long term rentals on power consoles, temperature recorders, and ceramic mat heaters along with complete support and training services.

EHS engineers, designs, and manufactures proven systems to effectively complete any project more efficiently than competitive systems, while staying within budget. Years of application experience and successful installations have produced thousands of happy customers.

Welding Preheat Basics

Why preheat welds?

Weld preheating is the process of heating the base metal (parts to be welded) to a specific temperature prior to welding. The specific temperature to which the part needs to be heated (before welding) is referred to as the “preheat temperature”.

The area requiring preheat may be the whole (entire) part, or just the area immediately surrounding the weld.

Preheating may continue during the actual welding process, but many times the energy generated from welding will be sufficient to maintain the desired temperature.  The temperature of the weld between the first pass and the last pass is referred to as “interpass temperature”. As long as it can be assured that interpass temperature will not fall below the preheat temperature, continued preheating is usually not required.

There are several key reasons why it's important to preheat before welding. First, a preheated part cools more slowly, which slows the overall cooling rate of the welded part. This improves the metallurgical (crystalline) structure and makes it less prone to cracking. Additionally, hydrogen that may be present immediately after a weld is also released more efficiently, which further reduces the possibility cracking. Preheating also mitigates stress from the shrinkage at the weld joint and nearby metal. Finally, pre-heating reduces the possibility of fracture during fabrication due to brittleness.

Electric welding preheaters, known as "ceramic mat heaters", are rugged and flexible heating elements designed so that they conform uniformly around the weld and surrounding area.  Ceramic mat heaters are normally controlled by a power console that uses thermocouples and electronic controllers to regulate, monitor, and many times record, the preheat temperature profile.

Welding code is the first determinant to whether pre-heating is needed. Welding code carefully specifies the minimum preheat temperature, the soak time, and the welding process. Many criteria are considered by welding codes, all gathered from years of rigorously tested data. This data is accumulated from many sources, including metallurgical science, chemical properties of materials, and radiographic analysis.

Determining whether or not preheating is required should not be taken lightly, as it is critical to the quality of a weld and therefore critical to the performance of a structure. When in doubt, review of industry code or contacting an industry expert, is imperative.

Ceramic Mat Heaters for Pre & Post Weld Heat Treating

Ceramic mat heater
for pre and post weld
heat treatment.

Flexible ceramic mat heaters (also known as flexible ceramic pads or FCPs) are designed to provide stress relief for pre and post weld heat treatments for large scale welding requirements, such as those needed for piping fabrication, boilers, pressure vessels, storage tanks, pipeline construction, and mining equipment.

It's very important to pre-heat metal to a specific temperature prior to welding. Pre-heating metals reduces stress in the finished weld,  as well as eliminates moisture and improves the metallic microstructure of the weld material.  For post weld heat treatment (PWHT), use of resistance heaters to apply carefully controlled  cool-down can significantly increase the cross-weld toughness of the heat-affected zone.

Ceramic mat heaters are manufactured using high grade nickel chrome (NiCr) 80/20 wire insulated with interlocking sintered alumina ceramic beads, providing flexibility and convenience for use on curved or flat surfaces. Their design also allows for good contact and high heat transfer. Ceramic mat heaters are intended for repeated use and have considerable mechanical strength and durability. They are capable of achieving temperatures of up to 2050°F.  and are most often are supplied with ceramic insulated leads with either Camlock or Dinse type welder terminations.

The most common voltages used are 40, 60, and 80 volts (as supplied by arc welders) but many custom voltages are available. Special sizes, heating patterns and terminations are also easily accommodated with ceramic mat heaters.

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