PVT-17-1119 - Calculating pressure stress intensity of welding teesThe required thickness of welding tees is neither specified in ASME B16.9 nor is a clear calculation method provided in Codes such as ASME B31.3. This can lead to uncertainty regarding the pressure capacity of a tee fitting, particularly one that has suffered from erosion or corrosion. This technical paper presents a method based on a hybrid empirical/ theoretical stress calc.
B31.3 branch stress own-goalSustained bending stresses are underpredicted at some branches in ASME B31.3-2016. How to avoid falling prey to this issue. Comparison to B31J approach.
Pipe Support Selection for Bare PipeA thorough run-down of the pipe support selection options for bare pipe and the author's preferred solutions.
Quick and Dirty FFS of FittingsAssessing fitness for service of pipe fittings is tricky. Whilst we’d encourage you to assess them carefully, what about when you just want to know if you should expend the effort to do more detailed analysis or FEA? Here is a simple approach that can sometimes be employed when you need a first pass answer.
Hot sustained stress – method comparisonIn the past few years there has been an increased focus on the so-called 'hot sustained' stress in piping system analyses. The ASME B31.3 2006 edition clarified that Sustained stress requirements must be met for all operating conditions of a piping system. There had always been practitioners whose view was that any stress due to change in temperature should be considered secondary.
Calculating pressure containment of welding teesArticle compares four methods for pressure calculation of ASME B16.9 welding tees. An approach for applying the ASME B31.3 Area Replacement method is developed for welding tees. The method appears to give very similar results to the Pressure-Area method for the tees considered.
Piping fatigue and corrosionHow should loss of wall thickness be accounted for in fatigue analysis? ASME B31.3 contains the footnote ‘Corrosion can sharply decrease cyclic life; therefore, corrosion resistant materials should be considered where a large number of major stress cycles is anticipated’. But what happens if carbon steel with high corrosion allowance has been selected and changes are out of the question? Or you may be assessing an existing system with heavy wall loss and many past cycles.