The paper presents the proposal of a leakage prediction method in flange joints, after pipeline deformation, based on FEM (Finite Element Methods). The stages of developing the design are discussed, and a complex, multi-stage method of applying the loads is presented in detail. Moreover, the gasket material data obtained in experiments were used. The paper also presents the results of calculations on a non-uniform stress distribution in the radial direction of the gasket. In addition, it has been shown that the deflection of the pipeline with a minor displacement causes an increase in the diversification of the circumferential pressure of the gasket, and also has a significant influence on the determination of the actual state of stress to which the gasket is subject. Moreover, it was found that the distribution of contact pressure on the deflection of the pipeline has a significant influence on the level of leakage. The results of tests are compared to the results of the numerical calculations of the stress in bolts. By comparing the bolt tension changes obtained by numerical and experiment analyses, it has been shown that the assumptions made in developing the numerical model are correct.

The paper presents the method of design and strength analysis of the flange-gasketed-bolted joint. In the first part, analytical calculations were carried out. Their purpose was to determine the assembly torque of nuts to achieve the desired tightness. The flanged joint designated as DN100 PN40 with two different gaskets was taken into consideration. The analytical calculations were performed in accordance with the algorithm included in PN EN 1591-1. In the further step, the numerical calculations were carried out to support the analytical results. The outcome of these calculations were maps of the contact stress distribution on the gasket surface, estimation of safety factors of individual joint elements as well as determination of the flange rotation. Data from the numerical calculations were compared with the analytical results, which confirmed their satisfactory compliance. In the last stage, the experimental tests of the joint were carried out. The main results of the test were the measured values of the leakage level, tightening force of the bolt and estimated safety factors. An indirect result of the experimental measurements were maps of the stress distribution on the contact surface of the gasket, which were determined by means of the measuring film. Ultimately, based on the experimental results, it was found that the proposed analytical method of calculation and simulation of the joint by means of the finite element method was a very good tool for the design of the joint at the required tightness level.

The paper presents the experimental research results and numerical computations of two constructions of a spiral wound gasket with a PTFE filling. The first construction was a standard one in which the shape of the spiral’s windings in a cross section view resembles the shape of the letter ‘V.’ The second solution has an original, asymmetric shape of windings’ profile. Based on the vast experimental research tests, it was proved that the gasket with an asymmetric shape of windings is characterized with larger stiffness than the standard design, as well as increased tightness. Numerical calculations and a topography analysis of the contact surface of the gaskets showed that the asymmetric gasket under load is characterized with a larger effective contact surface when compared to the standard gasket. The gasket of an asymmetric construction can have a special application at small contact stress, which allows to avoid an excessive stress of flanges and bolts.

The paper presents simulations of mechanical properties of compressed expanded graphite. To model the stress and strain states of compressed expanded graphite, a hyperelastic material model formulated by the Blatz–Ko was adapted. The idea of using this model resulted from the assumptions that compressed expanded graphite exhibits similar mechanical properties to polyurethane foam with high density. The material constant of the Blatz–Ko model was determined by numerical calculations where deformation energy equation was parameterized with the shear modulus. Such material model used in a compressed expanded graphite simulation was experimentally validated. Subsequently, the Blatz–Ko model was used in a numerical simulation of the graphite-metallic structure in the form of a spiral wound gasket which is composed of metallic and elastic tapes. This structure was subjected to an optimization process which included the reduction of stress in the elastic graphite tape obtaining the appropriate axial stiffness of the gasket. In the final stage, the optimal design of the gasket was experimentally tested. The experimental results were compared with the data obtained numerically, which allowed to verify the adapted material model and boundary conditions of the numerical gasket model.

This article presents the results of a study of oil lip seals with a modified outer lip layer texture. In the first step, the interaction of flat rubber samples with different surface layer textures with the steel surface was recognised. Measurements of the friction coefficient of flat samples with different surface layer textures were carried out. The next step was an experimental study of rotating shaft lip seals in standard and prototype versions. The contact width of the sealing lip before and after durability tests was examined, and the clamping force of the lip on the shaft before and after durability tests was measured. The final step was to create a FEM model of the interaction of the sealing ring lip with the shaft to determine the lip seal pressure and width. These calculations, in cooperation with the previously determined friction coefficient and porosity of the lip seal, allowed the calculation of the friction torque. The solution proposed in this article was intended to be simple and viable for industrial applications. Satisfactory results were achieved with prototype rings in terms of reduced resistance to movement, tightness, and durability.