Diaphragm seals make it possible to adapt measuring instruments to even the most extreme conditions. One example is the deep-sea extraction of oil and natural gas. For offshore companies in this industry, a particular OEM company manufactures flow measuring systems using Venturi tubes and differential pressure transmitters. WIKA manufactures specific diaphragm seals for this purpose, which are adapted to the respective marine environment.
Harsh conditions prevail in deep seas. Flow measurement there is exposed to high pressures and a wide temperature range. It must fulfil two tasks: firstly, to monitor the flow of the extracted raw material and secondly, to measure the supply of chemical additives into the extraction process. An inaccurate or unstable flow measurement, let alone its failure, would lead to sizeable economic losses. The measuring system must therefore be able to withstand, continuously, the load of flow forces at a depth of up to 3,500 metres. All components must also withstand salt water corrosion.
To realise a suitable measuring system, the OEM company mentioned was looking for suitable diaphragm seals. Due to its expertise, WIKA was able to implement the requirements within a customised solution. The diaphragm seal is manufactured from chrome-nickel stainless steels and nickel-based materials. These ensure the necessary resistance. If required, the diaphragm is given an additional gold coating. This further increases its resistance. The fluid for pressure transmission matches the application. Field tests have confirmed its suitability. To make the measuring assembly, and especially the welded joints, suitable for deep-sea operation and fail-safe, a special welding process was qualified.
Separate production process
WIKA has set up a separate production process for these orders. In this process, the diaphragm seals are first manufactured, and then welded together with the differential pressure transmitters, via capillaries, to form a single unit. The diaphragm seal system is calibrated in WIKA’s own DAkkS-accredited calibration laboratory. In order to simulate the operating conditions, the testing is carried out with an increased static pressure. The customer thus receives certification that the measuring assembly complies with the accuracy within the scope of the specification.
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How do diaphragm seals work?
Watch the following video to learn more about the functionality, application areas and advantages of diaphragm seals: