Hotfoil EHS Provides "The Heat" for Strong, New Tappan Zee Bridge

welding heat treating
The Tappan Zee Bridge stretches over the Hudson River and connects South Nyack, NY with Tarrytown, NY. The original bridge, completed in 1955, was only intended to last 50 years. Construction on a new, $3.9 billion replacement bridge started in 2013 and is scheduled for completion in 2018.

Hotfoil EHS is working closely with the bridge contractors supplying welding heat treating equipment. Large metal structures, such as bridge supports, pilings, and girders need careful pre-heating and post heating to ensure strong, lasting welds. Contractors on the Tappan Zee Bridge specified Hotfoil EHS power consoles, electric heaters, and thermocouples for their welding heat treating requirements.

welding heat treating
Clam shell heater.
Here are photos from the pre-heating of piling welds. The applications uses "clam shell" heaters with magnetic thermocouples. The clam shell heaters are named that because of their hinged design, making it easy to place them around large, round workpieces. The magnetic thermocouples are very convenient because the magnets keep them firmly in place and are quick to remove.

welding heat treating
Close-up of heater fastener.
A Hotfoil 6-way (six zones) power console is used to control the temperature of the workpiece by controlling the power provided to the clam shell heaters.

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








welding heat treating
Piling with clam shell heater and
thermocouples installed.
   

welding heat treating
6 Way Power Console




Custom Heat Treating Power Consoles Solve Many Potential Field Problems

Weather-proof, Stainless Steel Power Console
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
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
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).

New Hotfoil EHS Welcome Video

We just introduced a new Hotfoil EHS Welcome video for our YouTube Channel. Check it out!

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

Ceramic mat heaters
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

Use External Electric Heating Panels for Ease and Simplicity

ELP tank heater
ELP tank heater construction
When it comes to heating process tanks electrically, you have two options - immersion or externally mounted panels. Immersion heaters must penetrate the tank wall, or be placed of over-the-side in an open top tank. Both approaches add cost and/or safety considerations. Sometimes entry to the tank may not be possible at all.  A good alternative are electric heating panels.

One type of exterior heater design, the epoxy laminated panel (or ELP), is a very versatile tank heater. Possessing unique flexibility, ELP heating panels can be used in a variety of heating applications ranging from freeze protection to process heating up to 212 deg. F . These panels can be used on either vertical or horizontal tanks of metallic or non-metallic construction. They can be used in dry, wet, or corrosive environments in ordinary or approved hazardous locations.

ELP heating panels are quick and easy to install, require no special tools or skills. Heaters are usually installed by banding them to the tank with metal bands or polyester straps. Installation of several ELP heating panels takes only a few minutes.

Check out the following document for more information on the epoxy laminated panel heaters.

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

custom PWHT 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:
custom PWHT furnace
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.  

custom PWHT furnace
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
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