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With HFMI, you can reduce costs by producing in a significantly more sustainable and economical manner as a manufacturer or by avoiding machine/system failures as an operator.
PIT (Pneumatic Impact Treatment) is a reproducible HFMI (High-Frequency Mechanical Impact) process for the post-weld treatment of welded joints. It introduces compressive residual stresses and improves the weld toe geometry, significantly increasing fatigue strength and fatigue life.
In addition to extensive scientific evidence confirming the HFMI (High-Frequency Mechanical Impact) effect, the University of Stuttgart has demonstrated the high reproducibility of PIT without the risk of overtreatment.
The application of HFMI is covered by relevant standards and guidelines:
IIW Recommendations on HFMI Treatment 2026-10↗
Eurocode 3 – DIN EN 1993-1-9:2026-10↗
→ Additional listings are in progress.
Since 2008, PITEC has rapidly emerged as the global leader in the field of HFMI (High-Frequency Mechanical Impact). Through many years of experience and continuous development, PITEC has established itself as the international leader. In 2018, PITEC was acquired by Hermann Fliess & Co. GmbH. Hermann Fliess & Co. GmbH .
Fliess is a manufacturer of welding consumables with particular expertise in high-strength steels. With PIT enabling the use of high-strength steels even under fatigue conditions, a unique synergy arises.
The SMS Group is constructing, on behalf of the OTTO FUCHS Group, at the Paramount USA site, within the subsidiary Weber Metals, the new hydraulic press with a force of 540 MN. To achieve the required strength values according to FKM, the SMS Group decided to treat the free surfaces of the bores extensively with our PIT process, thereby introducing high compressive residual stresses deep into the surface.
It’s noteworthy that, despite a total area of over 8m², SMS chose PIT over shot blasting.
In the steam drums of the heating plant at Stadtwerke München, despite professional repairs, cracks in the inner circumferential seams occurred repeatedly. In May 2011, in cooperation with TÜV Süd, the decision was made to treat the entire seam area including the heat-affected zone (HAZ) on two drums with PIT.
However, due to the high operating temperatures exceeding 500° C, we at PITEC were skeptical whether the introduced compressive residual stresses would be excessively reduced, potentially impacting a sustainable effect.
In February 2020, the PIT team learned that no new cracks have appeared in the PIT-treated area during regular inspections, even to date.
At the ArcelorMittal plant in Ghent, Belgium, in 2012, 8,000 cracks were detected in the crane system area.
Through their R&D project at their own institute, OCAS, they recognized in 2014, after conducting their own experiments, PIT as the most promising solution and implemented the process in the repair work.
Starting immediately, repair seams and yet undetected hot spots were proactively treated with PIT.
Five years later, in 2019, the number of detected cracks had dropped to only 700. This represented a reduction of over 90%!
After cracks in the upper beam of the 200 MN press were mechanically prepared, the repair welding specialist Casper Hahn reconstructed the material through welding techniques.
To prevent warping of the beam due to the large amount of welding material and the associated shrinkage stresses, it was decided to treat each layer extensively with PIT.
Subsequently, pressure residual stresses were introduced into the particularly stressed areas using PIT to enhance the fatigue strength of the press.
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