Interpretation of stresses at points

Question

Greetings, I have a quesion regarding stresses shown at points (code and general) of a model. I've been looking for an answer in AutoPipes Help but couldn't find one. 
 As far as I know, codes provide us with equations to evaluate stresses for straights and fittings. AutoPipe shows calculated values of stresses at points which are located at joints between pipes and fittings. Unless one inserts intermediate ones. 
 How does one interpret those values: Which component do they refer to, if a point is located for example between a pipe and an elbow? 
 Kind regards, Piotr Łukowicz Proen

Mike Dattilio · Accepted Answer

Greetings Piotrek, 
 What could be different between these 2 points that would affect the sustain calculations? 
 With out being able to review the actual model, one should be able to assume that the following would be the same between the 2 end points of a bend component: 
 
 Pc = defined pressure 
 do = Outside pipe dia 
 en = nominal thickness on drawings 
 i = Sif calculation 
 Z = section modulus for a pipe 
 
 However the following could be different: 
 
 Ma = resultant moment from the sustained mechanical loads 
 
 This would explain the difference in the reported results. 
 Regards, Mike Dattilio Design Analysis Engineering Group Senior Analyst Bentley Systems Inc =============================================================================

Mike Dattilio · Answer

Greetings Piotr, 
 Ahh.. now I understand your question, 
 Please noted that every node point has a +ve (downstream) and -ve side (up stream). If the results are the same on both sides of the node point then only one set of results are reported. However if there is a difference, then both sides of the node point results are reported. 
 With regards to elbows, they are comprised of 4 node points (TIP, Near, Far, and Mid) A bend component really starts on the +ve side of the Near point and ends at the -ve side of the far point. For locations outside of the bend (i.e. both -ve side of the Near and +ve side of the Far) will be considered straight pipe.

Therefore to answer your question 
 "Which component do they refer to, if a point is located for example between a pipe and an elbow?" 
 Answer: 
 Straight pipe stresses are calculated on the outside of a bend component and Bend pipe stresses are calculated on the a bend component. 
 As you know AutoPIPE will report stress at defined node points. There is a feature in the program where users can define intermediate points, see the following AutoPIPE help section: Help > Contents> Search Tab> enter " Intermediate stress points " (include the quotes), press List Topics button, double click on the selected topic from the list provided to see more information. 
 Keep in mind that you can add additional node points (ex. S20 to S22), however suggest that you do not place a node point at the exact location as the bend's Near or Far point. Doing so may result in error message " E732-3: Not enough clearance to fit bend ..". This message will prevent you from analyzing the model. 
 Regards, Mike Dattilio Design Analysis Engineering Group Senior Analyst Bentley Systems Inc =============================================================================

Interpretation of stresses at points

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