When expertise leads to insight
At PMF Piping & Mechanical, we believe that continuous improvement begins with expertise, curiosity, and a commitment to understanding.
As the first company in the Netherlands to qualify and certify the TIP TIG welding process for production applications, our welding specialists have accumulated extensive experience applying the process to demanding materials such as Duplex and Super Duplex Stainless Steels.
Through this experience, our welding specialists observed that TIP TIG welded Super Duplex Stainless Steel demonstrated exceptional corrosion performance during qualification testing. During ASTM G48 Method A and ASTM A923 Method C corrosion testing at 30°C, Labortech Testing Solutions and Spelt Engineering recorded no measurable weight loss and no evidence of pitting corrosion.
These results raised an important question: what was driving this performance?
This ultimately led to a collaboration with Professor Dirk Engelberg, Fidelity Gea (MSc) and the University of Manchester, where Super Duplex Stainless Steel samples prepared by PMF were independently analysed and compared against conventionally welded GTAW (TIG) specimens.
The findings were recently presented at the Duplex World Conference & Expo 2026 in the Netherlands.
The study investigated the microstructure, phase balance, hardness and corrosion behaviour of Super Duplex Stainless Steel welds, comparing conventional GTAW (TIG) welds produced using an Ar/2% N₂ shielding gas with GTAW-TIP TIG welds produced using 100% argon shielding gas. Among the observations presented were:
- A finer ferrite grain structure in the TIP TIG welds.
- Improved ferrite-to-austenite balance in critical weld regions.
- Consistent hardness values indicating sound metallurgical performance in both welding processes.
- Indications of improved corrosion resistance in the TIP TIG welds compared with conventional TIG welds, despite the conventional TIG welds benefiting from an Ar/2% N₂ shielding gas while the TIP TIG welds were produced using 100% argon. The researchers recommended additional testing to further validate these findings.
- Distinct microstructural characteristics associated with the lower heat input of the TIP TIG process.
While additional work is required to fully validate and quantify the corrosion performance benefits observed, the results provide valuable insight into how welding process selection can influence the final properties of Super Duplex Stainless Steel weldments.
We are proud that PMF's practical welding expertise could contribute to an independent academic study that advances understanding of welding performance in Super Duplex Stainless Steels.
Our sincere thanks go to Professor Dirk Engelberg, Fidelity Gea (MSc) and the University of Manchester for their work, insight and collaboration, and to our welding experts and craftsmen in preparing the test specimens to support the research programme.
It is through collaborations such as these that new insights are developed and shared across our industry.
