Wednesday, December 12, 2018

Happy Holidays from Hotfoil-EHS

From all of us at Hotfoil-EHS, we wish our customers, partners and vendors a safe and happy holiday season and a wonderful 2019!


Wednesday, December 5, 2018

Weld Preheating Low Alloy Steels

Weld Preheating
Low alloy steels are defined as consisting of less than 10.5% Ni, Cr, Mo, and other alloy elements. In general, low alloy steels are required to be preheated to some temperature (TPH), prior to welding. It has been suggested that TPH for any given steel should be about 50 F above the martensite start temperature (MS) for the particular steel being welded. Most low alloy steels, however, have fairly high MS temperatures, making welding at or above them somewhat uncomfortable to the welder, thereby potentially compromising weld quality. For such steels, therefore, manufacturers often opt for TPH temperatures below MS. A case in point is AISI 4130 with an MS of 700 F;  For this steel, federal, military, industry and company specifications typically list TPH temperatures in the 200-600 F range, all below MS.

Why Preheat?

Preheating drives moisture and other contaminants off the joint; moisture, lubricants and other contaminants are sources of hydrogen. More importantly, preheating serves to reduce the rate at which the metal cools down from the welding temperature to TPH. This is so whether preheating is above or below MS. Cooling rate reductions will lead to a general reduction in residual stress magnitudes, and also allow more time for hydrogen removal.

Most low alloy steels that may be susceptible to hydrogen-induced cracking transform from austenite during cooling through the 800-500 C (1470-930 F) temperature range. The length of time a steel spends in this range during cooling, will establish its microstructure and, hence, its susceptibility to cold cracking. To maximize cracking resistance, a microstructure that is free of untempered martensite is desired; that is, the austenite would have transformed to ferrite + carbide and no austenite will be available to transform to martensite upon reaching MS.

For more information about preheating low alloy steels, contact Hotfoil-EHS at 609-588-0900 or by visiting their web site at https://hotfoil-ehs.com.

Wednesday, November 28, 2018

Ice Star Heat Treatment Controllers


The most innovative and versatile heat treatment control system available today. Ice Star designs, engineers and manufactures heat treatment controllers for electric and gas furnaces, as well as for induction and resistive heating consoles.

Hotfoil-EHS is the exclusive distributor for Ice Star in the United States, Canada, and Mexico.

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

Saturday, November 10, 2018

Mobile Generator and Power Console Trailers by Hotfoil-EHS


Hofoil-EHS manufactures mobile generator trailers for welding heat treating power and temperature control. Custom designed from large to small, Hotfoil-EHS will build to your specification.

609-588-0900

Wednesday, October 31, 2018

Dissimilar Metal Junctions (How Thermocouples Work)

When two dissimilar metal wires are joined together at one end, a voltage is produced at the other end that is approximately proportional to temperature. That is to say, the junction of two different metals behaves like a temperature-sensitive battery. This form of electrical temperature sensor is called a thermocouple:

This phenomenon provides us with a simple way to electrically infer temperature: simply measure the voltage produced by the junction, and you can tell the temperature of that junction. And it would be that simple, if it were not for an unavoidable consequence of electric circuits: when we connect any kind of electrical instrument to the thermocouple wires, we inevitably produce another junction of dissimilar metals. The following schematic shows this fact, where the iron-copper junction J1 is necessarily complemented by a second iron-copper junction J2 of opposing polarity:


Junction J1 is a junction of iron and copper – two dissimilar metals – which will generate a voltage related to temperature. Note that junction J2, which is necessary for the simple fact that we must somehow connect our copper-wired voltmeter to the iron wire, is also a dissimilar-metal junction which will also generate a voltage related to temperature. Further note how the polarity of junction J2 stands opposed to the polarity of junction J1 (iron = positive ; copper = negative). A third junction (J3) also exists between wires, but it is of no consequence because it is a junction of two identical metals which does not generate a temperature-dependent voltage at all.

The presence of this second voltage-generating junction (J2) helps explain why the voltmeter registers 0 volts when the entire system is at room temperature: any voltage generated by the iron-copper junctions will be equal in magnitude and opposite in polarity, resulting in a net (series-total) voltage of zero. Only when the two junctions J1 and J2 are at different temperatures will the voltmeter register any voltage at all.


Reprinted from "Lessons In Industrial Instrumentation" by Tony R. Kuphaldt – under the terms and conditions of the Creative Commons Attribution 4.0 International Public License.

Thursday, October 25, 2018

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

Thursday, October 11, 2018

The ICE Advanced Heat Treatment Control System

The ICE IS System, is developed for precise, reliable and efficient heat treatment control. It consists of IS controllers and ISPort software. With ISPort software you can define process parameters as temperatures, rates, tolerances etc; operate and control one or many processes from one or several controllers; edit PID values; fill in needed information, ex. customer info, work info etc.; print all work documents and heat treatment certificates. For more information contact Hotfoil-EHS,

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

Friday, September 28, 2018

Common Temperature Sensors Used in Industry

Temperature SensorsTHERMOCOUPLE
Due to their simplicity, reliability, and relatively low cost, thermocouples are widely used. They are self-powered, eliminating the need for a separate power supply to the sensor. Thermocouples are fairly durable when they are appropriately chosen for a given application. Thermocouples also can be used in high-temperature applications.

Thermocouple Advantages:
  • Self-powered
  • Simple
  • Rugged
  • Inexpensive
  • Many applications
  • Wide temperature range
  • Fast response
Thermocouple Disadvantages:
  • Nonlinear output signal
  • Low voltage
  • Reference required
  • Accuracy is function of two separate measurements
  • Least sensitive
  • Sensor cannot be recalibrated
  • Least stable
RTD
Resistance temperature detectors are attractive alternatives to thermocouples when high accuracy, stability, and linearity (i.e., how closely the calibration curve resembles a straight line) of output are desired. The superior linearity of relative resistance response to temperature allows simpler signal processing devices to be used with RTD’s than with thermocouples. Resistance Temperature Detector’s can withstand temperatures up to approximately 800 C (~1500 F).

RTD Advantages:
  • More stable at moderate temperatures
  • High levels of accuracy
  • Relatively linear output signal
RTD Disadvantages:
  • Expensive
  • Self-heating
  • Lower temperature range
THERMISTOR
Thermistors work similarly to RTD’s in that they are a resistance measuring device, but instead of using pure metal, thermistors use a very inexpensive polymer or ceramic material as the element.

Thermistor Advantages:
  • High output
  • Fast
  • Two-wire ohms measurement
Thermistor Disadvantages:
  • Nonlinear
  • Limited temperature range
  • Fragile
  • Current source required
  • Self-heating

Monday, September 24, 2018

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

Tuesday, September 11, 2018

Indirect Resistance Heating

weld preheat heater
Indirect resistance heating example:
Weld preheat ceramic mat heater.
With indirect resistance heating, a heating element transfers heat to the material by radiation, convection, or conduction. The element is made of a high- resistance material such as graphite, silicon carbide, or nickel chrome. Heating is usually done in a furnace, with a lining and interior that varies depending on the target material. Typical furnace linings are ceramic, brick, and fiber batting, while furnace interiors can be air, inert gas, or a vacuum.

Indirect resistance heating can also be done with an encased heater, in which the resistive element is encased in an insulator. Called metal sheath heaters this type of heater can be placed directly in liquid to be heated or close to a solid that requires heating. Numerous other types of resistance heating equipment are used throughout industry, including strip heaters, cartridge heaters, and tubular heaters.

Clamp-on pre-weld electric heater
Indirect resistance heating example: 
Clamp-on pre-weld electric heater.
Resistance heaters that rely on convection as the primary heat transfer method are primarily used for temperatures below 1,250 ̊F. Those that employ radiation are used for higher temperatures, sometimes in vacuum furnaces.

Indirect resistance furnaces are made in a variety of materials and configurations. Some are small enough to fit on a counter top, and others are as large as a freight car. This method of heating can be used in a wide range of applications. Resistance heating applications are precisely controlled, easily automated, and have low maintenance. Because resistance heating is used for so many different types of applications, there are a wide variety of fuel-based process heating systems, as well as steam-based systems, that perform the same operations. In many cases, resistance heating is chosen because of its simplicity and efficiency.

Electric hopper heater
Indirect resistance heating example: 
Electric hopper heaters.
Indirect resistance heaters are used for a variety of applications, including heating water, sintering ceramics, heat pressing fabrics, brazing and preheating metal for forging, stress relieving, and sintering. This method is also used to heat liquids, including water, paraffin, acids, and caustic solutions. Applications in the food industry are also common, including keeping oils, fats, and other food products at the proper temperature. Heating is
typically done with immersion heaters, circulation heaters, or band heaters. In the glassmaking industry, indirect resistance provides a means of temperature control. Many hybrid applications also exist, including “boosting” in fuel-fired furnaces to increase production capacity.

Resistance heating applications are precisely controlled, easily automated, and have low maintenance. Because resistance heating is used for so many different types of applications, there are a wide variety of fuel-based process heating systems, as well as steam-based systems, that perform the same operations. In many cases, resistance heating is chosen because of its simplicity and efficiency.

Contact Hotfoil-EHS for any industrial resistance heating project. With decades of application experience, Hotfoil-EHS engineers can help you design a system tailored to your exact needs.

Thursday, August 9, 2018

Gas Trains and Combustion Systems by Hotfoil-EHS


Hotfoil-EHS manufactures complete gas trains and combustion systems complete with:
  • Dual ASCO valves for start-up (6 to 10 million BTU systems only)
  • Air light and air switch
  • Low-gas and high-gas switch
  • Gas light
  • Ignition transformer and ignition light
  • Burner on light
  • Dual main gas valves
  • Strobe light and horns as well as the mute buttons
  • Proof of Closure Switch
  • UV Sensor
  • UV Meter
  • Re-set button
  • Veriflame control module
  • Relays mounted inside a Nema 4 control box
  • Ramping controller for timing the ramp
https://hotfoilehs.com
609-588-0900


Thursday, July 19, 2018

Hotfoil-EHS Heat Treatment Equipment

EHS engineers, designs, and manufactures proven heat treatment systems to effectively complete any project more efficiently than competitive systems, while staying within any budget. Years of application experience and successful installations have produced thousands of happy customers. A focus on customer service second to none.

Friday, July 6, 2018

Job Posting: Sales Associate - Hotfoil-EHS UK

Hotfoil-EHS is a USA based manufacturer of industrial heating systems, heat treatment equipment, and accessories. The company recently opened a facility in Birmingham, England and is looking for a qualified candidate to fill the role of Sales Associate.

For more information about the job, visit this link.

Monday, July 2, 2018

Happy Fourth of July from Hotfoil-EHS

"One flag, one land, one heart, one hand, One Nation evermore!"

Oliver Wendell Holmes


Tuesday, June 26, 2018

Hotfoil-EHS Expanding to United Kingdom with New Engineering and Manufacturing Center

Hotfoil-EHS UKHamilton, N.J., June 8, 2018 - Hotfoil-EHS, Inc., America's premier manufacturer of industrial heating equipment, announced today the opening of their United Kingdom facility in Birmingham, England.

"The opening of our UK facility signals a homecoming of sorts, since our original company, Hotfoil, was founded in the mid-1960's in England,” said Hotfoil-EHS President, Matt Richards. “The Birmingham location makes perfect sense for Hotfoil-EHS. After several ownership changes, my father, Neville Richards, took ownership in 1993." Richards continued, "Since then, we have grown though key acquisition and new product development. This move also is the first step in our aggressive strategy to expand into the international market.”

The new Hotfoil-EHS facility in Birmingham will provide the UK with a large local inventory of power consoles, recorders, ceramic heaters, and a full line of accessories used for heat treatment. Hotfoil-EHS UK will also supply hopper heaters, tank heaters, vessel heaters as well as control systems.

According to UK General Manager David Robbins, “The opportunity to introduce such a high quality product line to the UK is wonderfully exciting. I am delighted to be working with such a well established US company and progressive management team."

About Hotfoil-EHS
Manufacturer of America's premier heat treatment and industrial heating equipment, Hotfoil- EHS is driven by providing the highest quality products, delivering the best customer service, and keeping costs low. Their headquarters and main manufacturing facility is located in Hamilton, NJ and have two additional manufacturing operations in Laporte, TX and Chattanooga, TN.

For more information contact Dean Prassas by emailing dap@hotfolehs.com or by visiting:

https://hotfoilehs.com
https://hotfoilehs.co.uk
https://www.facebook.com/hotfoilehs

Friday, May 25, 2018

Hotfoil-EHS Manufacturing and Distribution Facilities

Hotfoil-EHS, Inc. is an organization with over 70 employees and an impressive engineering capability. Through continued re-investment of profits, Hotfoil-EHS acquired additional large fabrication facilities and today is a full-service engineering, design, and manufacturing company of industrial heating equipment. Their Hamilton, NJ headquarters provides 68,000-square-feet of manufacturing space, with other manufacturing and distribution facilities located in Chattanooga, TN, LaPorte, TX, and Birmingham, England.

609-588-0900

Wednesday, May 16, 2018

The Importance of Post-weld Heat Treatment for Welding Repairs

welding
Welding is the process of melting two metals together. During the welding process, the metal is exposed to very high temperatures and undergoes a phase change, first from solid to liquid, then back to solid as it cools.

During welding, residual stresses are formed in an area referred to as "the heat affected zone" or HAZ. In the HAZ, differential contractions occur as the metal heats, liquifies and then cools to ambient.

Residual stresses have a significant impact on the performance of a weld and their reduction is highly desirable. The undesirable impact of residual stresses in welded metal structures involve fatigue performance and corrosion resistance.

heat treating furnace
Heat treatment furnace.
pwht with resistance heaters
PWHT with resistance heaters
Welding repairs are increasingly a structural integrity concern for aging  equipment such as pressure vessels, piping systems and other large steel systems. The make up of residual stresses near repair welds can be drastically different from those residual stresses of the original weld.  Post-weld heat treatment (PWHT) is used to reduce residual stress in steel and and should be used for welding repairs ( as well as on new welds).

PWHT is proven very effective in reduction of high residual stress around the weld repair. Conventional PWHT can be done by combustion furnace, induction heaters or electric resistance heaters (ceramic pad heaters). Accurate ramp and soak times, as well as data recording can be done with modern power console systems. It is strongly recommended to apply PWHT for all original and repair welds.

Thursday, May 3, 2018

What Are External Electric Tank Heaters?

External Electric Tank HeaterExternal Electric Tank Heaters: Eliminate Concerns about Material Compatibility and High Watt Densities when Dealing with Viscous, Aggressive, or Erosive Contents


Many industries use large fiberglass or steel tanks that need to be heated. A common way to heat the tank contents is with electric heating elements designed to penetrate the tank through an existing flanged or threaded opening. This type of heating element, known as an immersion heater, is put directly in to the process media and heats the tank contents. While this heating method is efficient, it's not alway practical. Some tanks contain very viscous, chemically aggressive, or physically erosive media. Using an immersion heater for these applications gets tricky. Very careful consideration needs to be taken when determining proper watt density, maximum sheath temperatures, and material compatibility.
External Electric Tank Heater
Another way to electrically heat steel or fiberglass tanks is with externally mounted "pad" heaters, also known as heater panels. This type of heating element is mounted directly to the exterior tank surface and provides evenly distributed heating over a large area of the tank. These heaters are designed to deliver the required amount of energy (watts) distributed over a larger surface area, and provide "gentle" heating that will not burn or react with the process media. Furthermore, since heating panels are mounted externally, there's no concern with corrosion or erosion from aggressive or abrasive contents.
External Electric Tank Heater
External electric panel heaters are constructed of flat foil based heating elements or nichrome resistance wire patterns sandwiched between flexible and tough silicone or fiberglass layers. Because of the heating element pattern, even distribution of heat is assured with no hot spots. Panel heaters come in many standard sizes, volts and wattages. Custom shape and sizes are available too for tanks with complex geometries. Installation is easy and requires no special tools or skills.  Heaters are usually installed by banding them to the tank with metal bands or polyester straps, which takes only a matter of minutes.

For optimal performance and greatest energy savings, external panel heaters should be insulated to minimize backside loses.  The job of the insulation is to direct the majority of the heating panels energy into the tank. Failure to insulate allows for heat energy to escape to the surrounding area.

For tank heating applications where immersion heater sheath temperatures, or sheath material compatibility is a concern, or where penetrating the tank is impractical, externally mounted electric heating panels are an excellent solutions.

Saturday, April 14, 2018

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

Wednesday, April 4, 2018

American Made Heat Treatment Equipment: Everything You Need from One Reliable and Knowledgeable Source

Hotfoil-EHS manufactures pre and post-weld heat treating equipment including: power consoles; ceramic mat heaters; thermocouple attachment units (TAUs); pin welders; Brinell testers; Poldi hardness testers; thermocouple wire; insulation; and accessories.

EHS engineers, designs, and manufactures proven systems to effectively complete any project more efficiently than competitive systems, while staying competitive within any budget. Years of application experience and successful installation history have produced thousands of happy customers.  Quality and durability at an affordable price, and a focus on customer service second to none.


Friday, February 16, 2018

Electric Heating 101: Ohms Law



The most basic circuit involves a single resistor and a source of electric potential or voltage. Electrons flow through the circuit producing a current of electricity. The resistance, voltage, and current are related to one another by Ohm's law, as shown in the figure. If we denote the resistance by R, the current by i, and the voltage by V, then Ohm's law states that:

V = i R

Resistance is a circuit property that offers opposition to the flow of electrons through a wire. It is analogous to friction in a mechanical system. The resistance is measured in ohms and depends on the geometry of the resistor and the material used in the resistor.

Other manipulations of Ohms Law:



Wednesday, January 31, 2018

Pre Weld and Post Weld Heat Treatment

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 mat heaters on spool piece
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.