Achieving the certification was not without its challenges, and it required an extraordinary effort from our R&D team. Calculating the geometry of a valve is a complex process, made even more difficult by the ambiguity in the standard's formulas for calculating inertia momentums/torques for this type of product.
The process was further challenged when we discovered a typo error in the calculation formula used, resulting in the initial calculations indicating that the valves were not strong enough. However, it was already established experimentally that they were indeed robust.
The R&D team then turned to FEA simulations and used them as a basis, but they did not meet the documentation requirements as per EN13445-3. According to the simulations, the valve design was at the edge of the allowable limits, and though the result was closer to what we had documented in real life, we needed more confidence in the accuracy.
A pressure equipment consultant advised us to turn to another standard, the German AD Merkblätter. This standard was simpler and clearer on how to calculate the pressure volumes for a geometry such as the valves.
Using the AD Merkblätter standard, we could document what we had proven experimentally. The results showed that the valves were well within all limits, and with these calculations, we achieved the marine type approval certification from DNV.
Even though the process was not as straightforward as we might have hoped, we learned many valuable lessons:
The certification is a significant achievement, and despite the challenges faced during the process, the team's efforts have paid off. The certification not only proves the valves’ reliability and safety. It also provides maritime operators peace of mind that they help keep their water-based systems at maximum operational efficiency and reliability.
If you’d like to know more, please reach out to David Nadji, Senior R&D Engineer & Project Manager, at dna@frese.dk.
