11 Oct B31J: The answer to Markl’s 1950’s flexibilty factors
The new 2017 ASME B31J
Up to recent years most pipe flexibility analyses and more specifically Caesar II analyses have been using technology of the 1950’s. This technology concerns the flexibility factors, stress intensification factors as well as the sustained stress indices for standard piping intersections. These flexibilities have a significant impact on displacements, forces, and stresses, often skewing results from reality.
The B31J – 2017 brings presentday and valuable technology available to the pipe stress engineer with easily accessible tools. The B31J methods make designs more accurate and simultaneously safer, while providing many opportunities to reduce design time, construction costs, analysis time, and lifecycle maintenance costs.
The latest version of the software program FEAToolsTM allows for easy implementation of the updated SIF, k-factors and SSI’s that are found in B31J in the engineer’s Caesar II stress- and flexibility analysis. When purchased, it is integrated with, and can be started from within, the Caesar II program so that the end user can really use it and consider it a natural extension of the Caesar II program. Using FEATools™ the k-factors, SIFs, and SSIs of your piping design can be improved with just a few clicks of the mouse.
In addition, FEATools™ will go far beyond B31J in terms of applying the exact kinds of imrpovements that B31J offers, but for many more types of commonly used piping components and designs. So whereas B31J is only used to improve specific types of piping intersecions, in a recently extended yet limited range of geometries, FEATools™ allows you to use the concepts in B31J, but apply them to virtually any piping design you come across.
Because the accuracy of the flexibility factors for the entire piping design are improved, the calculated displacements, loads, and stresses in the piping system are much closer to what will actually take place in the as-built system. Current methods often result in designs that are either over-designed and overbuilt or underdesigned and underbuilt (on an intersection by intersection basis), resulting in either added costs, or added risk to the plant due to underestimated cyclic fatigue.
DRG has been using FEATools for a number of years to provide a better and more accurate design of piping systems that is just not possible by using instinct or experience alone.