I was truly surprised by the results from our initial testing and am now looking at all of our equipment problems to find other areas where this technology can help us

Jack Few

Maintenance Manager

Gulf Lumber



put uit to work

Post Weld Heat Treatment (PWHT) Stress Relief


About Post Weld Heat Treatment for Stress Relief


Post Weld Heat Treatment, often simply referred to as PWHT, uses the application of heat to reduce and redistribute residual stresses in weldments. PWHT is one of the most common methods of stress relief and is used in a wide-range of industries and high-pressure applications where brittle fracture is likely to occur.

Challenges Associated with Post Weld Heat Treatment


While PWHT definitely provides some benefits it also has some significant challenges. If not performed properly Post Weld Heat Treatment can actually harm the material properties of the treated component. In addition, it often cannot be applied to a tightly controlled area and can take a substantial amount of time to apply.

Ultrasonic Impact Technology (UIT) Post Weld Treatment


Ultrasonic Impact Technology, or UIT for short, uses ultrasonic energy to improve metal, reduce residual tensile stress in critical zones and introduce beneficial compressive stress where it is most needed. The technology was developed and first brought to market by Progress Rail's Ultrasonic Technology (UIT) Division and is specifically designed to be applied to welds. The Ultrasonic Impact Technology is portable and can be applied by a single technician using a handheld tool. Unlike heat treatment, UIT can be applied in hard-to-reach places and even robotically. This flexibility makes it the perfect solution for field, shop, manual or automated applications. As a result, UIT has proven to be an extremely safe, efficient and effective method of stress relief and is currently utilized in oil and gas, defense, shipbuilding, mining, infrastructure maintenance (weld treatment on bridges) and a host of other industries.

Benefits of UIT Compared to Post Weld Heat Treatment

  • UIT application is fast and flexible and does not require heating or soaking
  • UIT application is tightly controlled and can target critical locations with a much higher degree of precision than post weld heat treatment
  • UIT is an excellent solution for difficult work environments and UIT can even be applied remotely via robot
  • UIT is simple and ergonomically friendly so it is easy for an operator to use

Faster, easier to apply, more precise and controllable! Ultrasonic Impact Technology has many benefits compared to traditional post weld heat treatment. Learn more about UIT from Progress Rail and how you can use UIT in your industry to relieve stress from welds.