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