Heat Treatment Applications
Heat Treatment
Superheat is the only company in the world dedicated exclusively to the remote control and operation of on-site heat treatment equipment, and we want to aid in the understanding of various heat treatment applications. Due to strict codes and recommendations, including ASME and AWS, Heat Treating has become an essential provision for capital and maintenance projects within the refining and energy sector.
PWHT
Post Weld Heat Treatment (PWHT), is an application of uniform heat applied after welding to a structure, or portion thereof, at a sufficient temperature – below the transformation temperature range and with the intention of retaining the material’s strength/quality and ductility. The primary benefits of PWHT are recognized as relaxation of residual stress, tempering, and hydrogen removal.
Preheating
Preheating is the application of heat to a base metal (weld metal, HAZ, and adjacent base metal) prior to and throughout welding, as well as at the start of each pass in a multi-pass weld. The primary purpose of preheating is to drive off moisture prior to the start of welding, reduce the cooling rate, and increasing hydrogen diffusion within the weld to prevent cracking.
Post Bake aka Bake Out
Post Bake aka bake out is a heat treatment process that is performed immediately following welding; after Preheat and before Post Weld Heat Treatment (PWHT). Post Bake eliminates hydrogen that may have been introduced during welding by thermal expansion on a molecular level.
Solution Annealing
Solution Annealing is a heat treatment process which alters the metallurgical structure of a material to change its mechanical or electrical properties. Typically, this process is used to decrease metal crack sensitivity of aged material that needs to be returned to a weldable state.
Thermal Stabilization
A heat treatment process performed on chemically stabilized alloys (primarily Stainless Steel) to introduce certain carbides while avoiding other carbides. During welding or other heating processes, sensitization occurs which precipitates chromium carbide at the Heat Affected Zone (HAZ) resulting in a reduced amount of chromium solution in the alloy.
Line Thaw
A Line Thaw is the application of uniform heat to a section of piping or component that has been affected by unfavorable environmental temperatures. Said temperatures can result in the freezing or solidification of the product inside, or affect the functionality of the component and/or piping. The application of heat via electrical resistance heat treatment will reverse the undesirable effects of hostile temperatures.
Case Studies
Not all heat treatment processes are created equal. Get the facts on our Superheat SmartWay™ and see why we’re the industry leader in safety and reliability.