Pre Weld and Postweld (PWHT) Heat Treatment Furnaces

Industrial furnaces are used for pre and post-weld heat treating by welders and fabricators to heat-treat weldments or metallic parts. Industries that require these types of furnaces include pressure vessels and piping, storage tanks, building construction, bridge building, offshore platforms, petrochemical plants, power plants, and oil and gas refineries.

By using furnaces for PWHT,  stress introduced by the welding process is reduced and redistributed through the heating, soaking and cooling the weldment/machined surface. This greatly improves the weld properties. PWHT is most times mandatory in order to comply with welding codes and specifications for the welding of carbon steels, stainless/high alloy steels and work hardened steels.

Fairly sophisticated control systems carefully follow mandatory heating and cooling profiles, as outlined by welding code. Control systems with thermocouples that monitor internal furnace temperature, along with weldment part temperature are usually included. These control systems also include the ability to ramp up to temperature and cool off over specified time intervals. Finally, the use of recorders or data loggers is common for quality control documentation.

Additional benefits of pre and post weld heat treating are:

• Improved ductility and/or harness
• Lower risk of brittle fracture
• Improved metallurgical structure
• Reduction in diffusible hydrogen induced cracking 

Most pre or post weld heat treating furnaces are customized in one way or another, whether it size, total BTU output, energy source (electric, gas, oil), control scheme, door configuration, or having the furnace built on wheels or on rails.

Furnaces can be designed permanently, portable, or field erected. By having the furnace local, or right on-site, companies eliminate the need to send parts out and thus save time and costs associated with shipping. Depending on the scope of work, its not uncommon for the investment made in a fabricated furnace to pay off within the first year.

For more information on any custom built pre heat or post weld heat treat furnaces, contact:

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

Multi-Operator Welding Systems

Multi-operator welding system (Aftek Quad Arc 1200)

There are many different welding processes utilized in the welding industry today. Welding processes include stick arc welding, gas tungsten arc welding (GTAW), flux core arc welding (FCAW), shielded metal arc welding (SMAW), gas metal arc welding (GMAW), and air carbon arc gouging.

Most arc welding operations are performed using direct current from a DC power source an AC power source which has been rectified from AC to DC. Many industries use these welding processes in a wide variety of environments including factories, construction sites, power plant construction, boiler construction and repair, and shipyards.

Multiple operator welding equipment was developed to allow several welding modules to operate from a single common power supply. The power supply typically includes a transformer and rectifier to step down the supply voltage, and then convert the power from AC to DC.

Multi-station welding systems afford a number of advantages the principals of which are a lower initial capital cost, a much lower cost of installation, much lower maintenance cost and less power requirements as compared with single operator equipment. Multi-operator welding systems are practical and efficient as they provide a welding station where each welder has the ability to work. They provide for multiple simultaneous welding projects where workers can work efficiently and meet production deadlines.

The clear advantages of multi-operator welders:

• Improved productivity
• Lower total cost of ownership
• Less equipment to transport
• Reduced maintenance costs
• Noise reduction

Portable Auxiliary Power Boxes (PAPB) for Convenient Source to Run Tools, Save Time, Improve Safety

Portable Auxiliary Power Boxes (PAPB)
30kVA (left) and 15kVA (right)

In many field welding situations simply having convenient access to 120 volt or 240 volt supply power to run auxiliary power tools such as grinders, stud guns, and drills is important. In some situations, bringing power to these locations can difficult or nearly impossible. Worse yet, short-cuts and quick fixes can compromise safety. While its not uncommon to have an available 480 or 575 volt power source, conversion to 120 or 240 volts is a challenge. Simply running extension cords can be impractical or present a safety hazard. What's really needed is a portable power box, with all necessary transformers, circuit protection and safety devices built-in to conveniently convert high voltage to 120/240 volt power.

Internal view of cabling and outlets

A new product by Hotfoil-EHS has been developed for just this situation. Named the PAPB (short for portable auxiliary power box), the new product taps into the available high voltage feed and puts convenient, usable 120/240 volt power right at the worker's location.

The PAPB is designed with small supplementary circuit breakers at each of the outgoing power connections for protection and ease of resetting. The main power supply is also protected by a main circuit breaker.

Transformers made in-house

Portable auxiliary power box's can be custom made and manufactured in virtually any size.  The ones pictured above are relatively small; 15kVA and 30kVA. 

Internal view

All PAPB's are made in the USA with major components being fabricated in-house.  All framework, tubing, sheet metal, transformers, wiring, and assembly is done at Hotfoil-EHS's production facility in Hamilton, NJ.  The units are 100% QC'd and tested  prior to shipping. When the equipment leaves the factory, it is 100% ready to go to work.

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

The TAU: A Perfect Solution for Fast, Strong, and Inexpensive Thermocouple, Stud, and Pin Welidng

Thermocouple attachment unit (TAU) used for creating
thermocouples quickly and inexpensively, plus welding
studs and pins to metal structures.

Are you buying pre-made thermocouples? Do you know how easy it is to make your own? Are you always looking for a fast and easy way to attach studs or pins to a target structure? A thermocouple attachment unit (TAU) is the answer. TAU’s will help you save time and money in the fabrication of welding thermocouples and stud/pin welding.

Thermocouple attachment units (TAUs) are small, self contained spot welders that achieve superior results for welding thermocouple junctions and attachment. They are portable and are easy to use. Also known as thermocouple welders, these units are provide a capacitive discharge (as the energy source) in a compact, self-contained, hand welding unit. They are designed to form very strong, free standing junctions in just seconds using standard thermocouple wire. There's no need for clamping, bracketing or strapping. TAUs provide a direct bonding method for thermocouples, pins and studs that is quick, easy, and low-cost while still providing accurate temperature measurement.

Thermocouple attachment units continue to enhance their power outputs which creates more potential uses for TAUs. Higher power output opens doors to a broader application base. Higher power TAUs can be used to weld thermocouple pairs but also can be used to weld studs, rods and pins to a wide variety of metal structures. For example, a common use for TAU’s is attaching insulation pins to welding insulation blanket support.

An internal power supply constantly recharges an internal battery giving the operator portability in field thermocouple welding. Readily available controls allow for easy adjustment based on wire size and material.

Thermocouple attachment units offer a very convenient and economical method of forming and attaching thermocouple sensing wires, studs, and pins where and when you need them. Models vary based on requirements. Some models accommodate a greater range of wire sizes and materials, handling wire up to 14 gauge and capable of creating weld junctions in under a second. Because the power supply provides a short recharge interval, multiple welds can be done very quickly (4-6 welds per minute).

For more information on thermocouple attachment units, contact:

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