The technical requirements for high-pressure equipment are clearly defined by law. These laws state that the necessary requirements of a design are satisfied if it is directly taken (for a certain pressure-temperature rating additionally using the appropriate material specifications) from a harmonized standard, or meets the requirements of the relevant code. To meet these requirements the acting stresses or the dimensioning have to be verified by calculation. For the analytical strength assessment of a variety of commonly used high-pressure components, prefabricated analytical solutions are available in different codes. These analytical solutions mainly aim to ensure the safety of the components by calculating minimum allowable wall thicknesses or acting stresses. However, with increasing complexity of the components, the number of prefabricated analytical solutions decreases or they are not available at all.

Usage of Abaqus

For the strength verification of complex components or assemblies, as well as for the functionality of assemblies numerical simulations are indispensable. Examples of simulations at BHDT GmbH that are performed with finite element software Abaqus are:

  • Calculation of primary and secondary membrane stresses for strength verification using elastic stress analysis method
  • Influence of external self-limiting and non-self-limiting loads on the strength and functionality of components
  • Calculation of local stress concentrations for the determination of the fatigue endurance
  • Static elastic-perfectly-plastic analysis for the elastic-plastic-stress-analysis
  • Cyclic elastic-plastic calculations for ratcheting detection
  • Steady state coupled-temperature-displacement analysis for the determination of the influence of different coefficients of thermal expansion in the assembly
  • Transient coupled-temperature-displacement analysis for determining the functionality of the assembly during heating-up and cooling-down processes
  • Validation of the gasket contact pressure for the hydrostatic pressure test and the operating condition under combined pressure, temperature and external mechanical loads
  • Natural frequency analysis to designate critical excitation frequencies
  • Optimization of components in terms of weight, force flow, stresses and leakage

The video shows the development of the seal contact pressure of a flange assembly made of austenitic stainless steel during heating-up to 650 °C followed by cooling-down to 20 °C. In the left-hand picture below, the temperature contour-plot over time can be seen. The middle and right-hand picture show the development of the contact pressure over the time (and temperature) is illustrated. Here it can be clearly seen that the contact pressure varies greatly with the temperature, but it is never lost.