Pressure thrust is present in all pressurized piping systems. It is simply the gage pressure times the inside area of the pipe. It acts at changes in direction, such as elbows, and at changes in pipe cross section, such as reducers. Pressure thrust is normally carried as an axial load by the pipe. However, inclusion […]
Bellows vendors will often quote two different cycle lives for their bellows. One is in accordance with ASME B31.3, Appendix X. The other is in accordance with the Standards of The Expansion Joint Manufacturers Association. The latter provides a significantly higher cycle life. The EJMA bellows fatigue curve is a best fit curve based on […]
The simple answer to this question is they should be used when the owner selects the use of these rules for a particular piping system. Note that the definition of High-Pressure Fluid Service simply requires that the owner specify use of Chapter IX. However, it is probably useful to understand why such a selection may […]
I was asked to participate in an engineering career development panel session at the 2013 ASME Pressure Vessel and Piping Conference which was held in Paris, France. I elected to talk about what engineers can do to improve their leadership skills. I am including some of the introductory material in this blog; the full presentation […]
There are three characteristics of motion which are all related by the natural frequency of vibration for steady state harmonic vibration: displacement, velocity and acceleration. Of these, which is the best indicator for cyclic stress (or strain) which in turn is related to fatigue damage? As it turns out, it is velocity. One may think […]
ASME B31.3 provides rules for Category M Fluid Service in Chapter VIII of the Code. These rules are designed to provide additional measures of leak tightness. For example, special precautions to prevent leakage past valve stems are included and a sensitive leak test designed to find even very small leaks in the system is required. […]
Serious floods rarely occur in the life of a refinery or petro-chemical plant. But when such an event does occur there are significant implications for the reliability of rotating equipment and associated business risks when it’s time to restart the plant. And because this scenario is so uncommon, there are few, if any, industry standards […]
In addition to the many clarifications, updated references to codes and standards, updates to basic allowable stresses, and added listed materials, there are several substantive changes to the 2012 Edition of ASME B31.3, Process Piping. These changes are: Category D Fluid Service The definition was revised to include piping with design minimum temperatures below -29⁰C […]
It is useful to have a screening rule for evaluation of piping vibration in order to determine if the vibration is potentially harmful (can lead to damage or fatigue failure) or if it is simply a nuisance and can be accepted without doing a more detailed assessment or anything to mitigate it. A very useful […]
Pump Trips and Check Valve Closure Systems running multiple pumps in parallel can undergo serious equipment and piping damage during a pump trip caused by a power outage or pump mechanical failure. Uncontrolled reverse flow in the system can occur and if improperly selected check valves are used it can result in pumps running backwards […]
