Abstract
To use bolted flange connection is a common way to connect the piping system components in oil and power industry. In most of the cases the functionality, strength and tightness are assured by a proper flange type and material selection, followed by the existing design rules and hand calculation or FEA (Design by Analysis). In most cases the time dependent material properties are not considered, as the high temperature effects are minor. In this paper the author will focus on the high temperature applications, where time dependent material and flange properties need to be addressed. Shown on the Compact Flange example the design process and challenges related with high temperature conditions will be discussed. The definition of the critical temperature will be defined based on material creep properties. Design techniques used to predict long term connection behavior including bolt relaxation, flange material creep, loss of tightness and functionality within component lifetime will be presented. The design prediction based on hand calculation will be followed by a detailed time dependent FEA analysis of the connection, including thermal analysis. The influence of the thermal load conditions (steady state or transient) as well as thermal and structural loads fluctuation will be shown. The interaction between fatigue and creep will be shortly discussed. The industrial experience related with high temperature Compact Flange usage will be briefly presented.
