*The piping, welding and its fittings contribute to around 25-35% of the total material of any process plant. The quantity of piping and fittings required in critical pipes (lines) is largely influenced by the flexibility requirements to comply with applicable codes. Since the pressure and weight driven stresses are primary in nature and taken care of by thickness & supports respectively; the Secondary stresses mainly caused due to temperature determine the route of the pipe. Unfortunately, there is no sufficient awareness amongst the Process engineers, who dictate the temperature, about the effect of temperature (listed inline list) on plant cost. To make the situation worse, very often the pipe stress engineers follow thumb rules, conservative design basis while applying temperature to pipes without questioning process engineers the basis and without having experimental evidence which in turn ends up adding to the cost, labor and time of the plant. Another factor influencing the ‘flexibility need’ is ‘Stress Intensification Factor’ which, as well, incorrectly multiplied by conservative numbers, especially in the case of 45^°^ branch fittings. Even ‘Flange leakage analysis’ needs to be performed to ensure the safety of the plant which can also add to the cost.*

*This paper challenges the mis-concepts in the temperature distribution of a piping system by analyzing a real-life problem. Also, it provides the actual temperature measurements and compares them with theoretical values. In the end it provides a ‘Temperature de-rating factor’ which can be used to derive actually expected temperature distribution. Further, this paper provides a graph or table to get the actual SIF of Tee and Fittings obtained by FEA.  In the end it provides a comparison between the results obtained by present industry practices against practical analysis and its effect on cost.*

 

Keywords: SIF, Temperature de-rating factor, Stress, Temperature Distribution, cost, Piping, Flexibility

 


Challenging the Industry Practices of Temperature Distribution, Sif and Its Effects on Piping Design

Division / Sponsors: 
Pressure Vessels & Piping (PVP)


Paper Proceedings: https://asmedigitalcollection.asme.org/PVP/PVP2020/volume/83815

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