Pipe Ovality Question
Pipe Ovality Question
(OP)
Guys,
Consider a pipe of 100mm OD and lets say this is subject to a maximum ovality of, say, 10%.
Taking a section through the pipe, does this mean that:
1) The pipe can be 110mm in the x-plane with 90mm in the y-plane?
2) The pipe can be 105mm x-plane / 95mm y-plane?
3) The pipe can be 110mm x-plane / 100mm y-plane?
4) Something other than this?
Consider a pipe of 100mm OD and lets say this is subject to a maximum ovality of, say, 10%.
Taking a section through the pipe, does this mean that:
1) The pipe can be 110mm in the x-plane with 90mm in the y-plane?
2) The pipe can be 105mm x-plane / 95mm y-plane?
3) The pipe can be 110mm x-plane / 100mm y-plane?
4) Something other than this?





RE: Pipe Ovality Question
Narendranath R
Pipeline engineering is made easy with state of the art computer software, visit www.narendranath.itgo.com.
RE: Pipe Ovality Question
it states
fo = [Dmax - Dmin] / [Dmax + Dmin]
Where fo is the initial ovalization of the pipe cross section (not to be taken as less than 0.025.
The same as the above is for flexible pipes with a maximum permanent ovalisation of 0.2% considered acceptable.
But
For reeling calcs the formula is the same as narendranath's. eg DNV OS-F101. Section 6 Clause E1200 for measurments of tolerances.
RE: Pipe Ovality Question
They probably spell ovalization with an "s" too.
http://virtualpipeline.spaces.msn.com
RE: Pipe Ovality Question
The notes talk about "a runaway flattening of the pipe". Ulp!
Trevor Jee's ovality is the same as narendranath's but they state that BS8010 has a different inherent factor of safety and that the ovality in BS8010 is defined differently, having a less conservative lower limit.
RE: Pipe Ovality Question
Runaway flattening at a pressure lower than critical pressure can happen once colapse has been initiated at a local buckle. The pipeline needs to have stiffener joints to stop it.
http://virtualpipeline.spaces.msn.com
RE: Pipe Ovality Question
Those stiffener joints. Can you recommend a code for these stiffeners?
RE: Pipe Ovality Question
http://virtualpipeline.spaces.msn.com
RE: Pipe Ovality Question
RE: Pipe Ovality Question
Pipe ovality is an input data for local buckling and buckle initiation/propogation in offshore pipelines which are prone for collapse (due to external pressure)is mitigated with buckle arrestors. These are higher wall thickness pups designed for buckle resistance and spaced considering the water depth for laying.
I think the original question is more looking in geomtrical sense as pipelines with 10% ovality cannot be used at all.
Narendranath R
Pipeline engineering is made easy with state of the art computer software, visit www.narendranath.itgo.com.