Hi

I need your help for finding out the basis for axial pressure force on the pipe when subjected to internal pressure.
Example:
For analysis purpose I took 2 pipe segments of 4” Sch 40S A312 TP 304L (length along Y direction).

Pipe A is a straight pipe of 60” in length and both ends anchored

Pipe B is also a straight pipe having a flexible joint of 20” in the middle i.e. 20” from any end, and is anchor at both ends.

Properties of Flexible joint is

Axial stiffness = 1000 lbs/in

Rest all stiffness are of value 25.

Pressure thrust area = 14.27in^2
Both the pipe is subjected to pressure of 20 psig and temperature of 70 degF.

After running analysis with pressure extension cases, following were the forces reported, (only P1 case)

For pipe B
Anchor forces: Fy = 285 lbs
This I am getting from hand calculation also as
Fy = Pressure thrust area x Design pressure
Fy = 14.27 in ^2 x 20 psig
Fy = 285 lbs (on both anchors with reverse direction)

For pipe A
Anchor forces: Fy = 102 lbs (on both anchors with reverse direction)
I am unable to get the basis for this force.
This is not equal to P x A

I need your help in this regard and appreciated better if you can provide some hand calculation to understand the basics. Also what is the reason for the difference in the values?

Your immediate response will be highly appreciated.

Thanks and Regards
Mahesh

So your surprised that a solid piece of pipe with a solid pipe wall can restrain to some extent the longitudinal pressure thrust, really?????

Pipe A will only develop the anchorage load based on pressure elongation of the element which in this case will be a function of modulus E.

Imagine the Pipe A with both ends capped on the ground before you being pressurized.... with a very precise distance measurement device watching its over all length. How many thousandths of an inch would it grow by???

Thanks for your reply John. Is there any formula to calculate those loads which are coming to anchor for pipe A?
It will help a lot to understand.
Thanks and Regards

mech mahesh

You can search that on your favorite search engines if you already forgot your basics in engineering.