Determination of the lifetime of sealings working under high pressure

Most of the sealing elements used extensively in the industry operate under low pressure like up to 250 bars. When the sealing elements operating under low pressure are mounted on the constructions manufactured within the tolerances given by the manufacturers, the desired lifetimes are obtained. However, there is not enough data on the long-term working life of sealing elements operating under ultra-high pressure in industrial conditions. Pumps used to achieve high pressures are called pressure intensifiers. The most important component for the pressure intensifiers to fulfill their duties in a healthy way is the sealing elements. In order for the pressure intensifiers to operate in the targeted time and cycles, the parameters affecting the sealing element life must be determined and the sealing system must be designed accordingly. In this master thesis, the parameters affecting the sealing life under a liquid pressure of 4500 bar were investigated. In this context, the effects of the material, geometry, number of the sealing element and the shaft material, surface roughness and interference on the service life of sealing were determined. A life test system was established with two levels for each parameter, and life tests were carried out by operating two pressure boosters with a capacity of 4500 bar mutually. Taguchi L8 experimental design matrix was used in the experiments and the number of cycles until the sealings were damaged was measured. ANOVA (analysis of variance) was applied to the experimental results in Minitab 19 software. According to the results obtained, the most effective parameter on the sealing life was the interference, followed by the surface roughness of the shaft. It has been determined that the effects of other parameters on the sealing life are more limited.