Why Bürkert’s new hydroformed tube diaphragm valve is the new benchmark in efficient hygienic design
Bürkert has once more revolutionised an enduring valve design. This time it’s with their latest incarnation of the hygienic ball valve, as they unveil their lighter, cleaner, greener, more economical hydroformed tube diaphragm valve. In this article, Ian Webster, Hygienic Processing Segment Manager at Bürkert UK, explains why this is now the benchmark in efficient hygienic design.
Hygienic ball valves haven’t changed much since they were introduced 20 years ago. They are usually made from either a forged or a cast stainless steel body and then machined and polished, which may still be a manual process. Bürkert’s new hydroformed tube diaphragm body is the new benchmark for efficient, hygienic valves.
How the Bürkert hygienic diaphragm valve is manufactured
Bürkert begin with a length of 316L Stainless Steel tube and a matching supporting flange laser-cut from the same material. The two components are then placed in the hydroforming machine, where they are subjected to a liquid pressure of over 3,000 bar. Mandrels are forced inwards to produce a V-shaped weir on one side and a bulb on the other. In this patented process, the stainless steel material of the tube is not stretched but forced to flow into the required shape.
The bulb is then cut and rolled, so that the material is now flush with the supporting diaphragm. The tube is then laser-welded to the flange; both on the bottom and the top. It is important to note that no material is added at this point. The weld on the bottom part eliminates any areas that can’t be cleaned. The only part of the valve that is in contact with the fluid is the tube material itself. The top surface is then CNC machined to give the optimum sealing surface. In between the different manufacturing steps, the whole component is annealed to release stresses and to bring the tube back to its original structure.
The internal part of the body then goes through an automated polishing process. This is followed by the whole valve being electroplated to give an internal finish of .38 microns. This also improves the chemical resistance of the tube body. Destructive pressure testing of the body, resulting in pressures of between 90 and 250 bar are achieved. This is much higher than normal process pressures in the pharmaceutical industry, but it does illustrate the mechanical strength and robustness of the body.
Hygienic diaphragm valve reduces costs
The result is a hygienic diaphragm valve body made from the same tube as the tube you’re using in your process plant, with dimensions conforming to ASME BPE requirements and a significant reduction in weight. The reduction in weight can also lead to a reduction in energy. In any hygienic process, the system must be heated up to be sterilised and cleaned. The lower mass of steel in the tube valve body requires less time and energy to heat up and, just as importantly, cool down. This will result in a lower steam requirement for the whole process plant and therefore a reduction in costs.
The tube valve body can have a full seat size lower than a conventional valve, thereby reducing the cost of the diaphragm. Over its whole life in a pharmaceutical process, this can lead to significant savings in the cost of replacement diaphragms. The tube valve body will help reduce your overall costs, improve your production efficiency and also help reduce your carbon footprint.
To talk to the Bürkert team about your application, please call +44 (0)1285 648720 or email firstname.lastname@example.org.
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