Actually, the contact stress formulas detail the use of an infinite diameter for a flat support so I am pretty confident the formulas provide a good approximation of the maximum stresses for contact on a flat surface.
You have to keep in mind that the formulas are actually already conservative...
3 & 4) If using butterfly valves\check valves, particularly wafer installations it is important to check the butterfly disk and check valve flap distance. If you put a wafer check valve directly upstream of another valve the flap will actually be obstructed, same goes for a wafer butterfly...
So I have gone away for a while and analysed this problem to death and have an answer, so for those interested I will share my results.
Using hertzian stress calculations from Shigley's Mechanical Engineering Design which can be found here...
Sorry mate I don't have anything technical regarding it specifically. What exactly are you concerned about mainly? Is it the expansion of the pipe during hot\cold? If so this is pretty easy to calculate. Or are you concerned about high stresses on joints or just failure of the pipe material...
HDPE is pretty forgiving and ~PN25 PE100 pipe is commonly used in this way around Western Australia, even though it's not ideal. Provided it's supported well at the top and the area is well suited to allow the movement of the pipe and a risk assessment is carried out, intermediate supports are...
Thanks for the thoughtful reply rconner.
I've been reading some of the Australian standards and there's no requirement for seats detailed there but it does say:
It also says this
So that means I have a maximum shear capacity of 150MPa.
If my supports were at the specified 12m spacing I...
Okay, i'm hearing what you all are saying but every calculation I do I don't see any of these high local stresses.
With my 600NB pipe I have 1.410KN/m of steel and 2.690KN/m for water.
Depending on the length of the line and therefore the number of supports I can assume that if the spacing is...
Thanks for all the replies so far. I agree that the loading on the edge of the support should definitely be the critical factor, rather than the 'crushing' seen centrally on the support... At the edge you would have a stress resultant due to the bending moment and the axial force (ie mohrs...
Can't find anything on section 13 dealing with this loading case.
If the loading is 1856Kpa what does that even mean? Surely the buckling load would be a lot less than gross yielding?
Do you think that a solid cylinder can approximate a pipe in this case though?
The Roarks formula indicates a 20mm contact zone due to deformation which seems rather high to me considering the wall thickness is 9.53mm thick (does it to you?), does this mean that the area would have yielded and...
Hi, I have a 600NB Std Wt pipe that is full with water and supported every 5m. My question is whether or not the pipe requires a seat or whether it can just lay flat on a concrete pedestal? Obviously if it is sitting in a rounded pipe seat it would be better due to greater contact support on the...
