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Force required to rupture a pipe.

Force required to rupture a pipe.

(OP)
Does anyone have reference to calculate the force of a (vehicle)collision required to put a hole in a steel pipe?

RE: Force required to rupture a pipe.

Kevin,

For too many variables
Pipe size, wall thickness, grade, impact size, impact area, pipe restraints / supports, internal pressure at time of impact, angle of impact, size of vehicle etc etc

Also no one really wants to know. If your pipe is vulnerable to impact then you protect it.

British Gas back in the 70's did some tests where they buried different sized pipes of different wt in a field and then got excavator drivers to dig a trench without telling them any pipes were there. They found that for any size, a wall thickness > 19.1mm with the largest excavator a bucket tooth only dented the pipe, but less than that there was an increased chance of leak.

You could FEA your particular pipe with your particular vehicle parameters, but this looks to me like an answer to a question for which there is no purpose other than curiosity.

Remember - More details = better answers
Also: If you get a response it's polite to respond to it.

RE: Force required to rupture a pipe.

There are some formulas in DNV RP F107 which might be of some interest

RE: Force required to rupture a pipe.

You might look at designs for bollards to use to stop traffic. Not the same but it will give you an idea, hint fairly large and real thick.

= = = = = = = = = = = = = = = = = = = =
P.E. Metallurgy, Plymouth Tube

RE: Force required to rupture a pipe.


What application do you have to make this consideration necessary? Seems to me that protecting or mounting the pipes to avoid crashing possibility is far cheaper, simpler and more safe. Example: By pipes crossing a tunnel you would both use 'best tubing available' and protect with buffers at entrance both sides to stop cars too high.

RE: Force required to rupture a pipe.


......and if it is really, really important you could always do a falltest with a swinging or falling load (crane hoisted) down on a clamped pipelength, both with empty and filled pipeline.

RE: Force required to rupture a pipe.

(OP)
We have to ask this question because our above ground pipelines are caught up in the same regulations as buried pipelines. The regulations (AS/NZS 2885.6) require detailed risk assessment from external damage. With buried pipelines there is a lot information on external risk from digger strike and we need to look a impacts from vehicles. If our case it going to be drunk farmers on run away tractors!

RE: Force required to rupture a pipe.

The risk assessment should look at where there is a risk of impact and provide suitable protection against it. I think trying to go down the path of saying the pipe is strong enough to not break isn't the way to go.

It's one of the downsides to above ground lines....

Remember - More details = better answers
Also: If you get a response it's polite to respond to it.

RE: Force required to rupture a pipe.

I'm not familiar with that standard, does it provide instruction for providing a "detailed risk assessment from external damage"?
This is, in my opinion, a very broad statement. What level of detail of risk assessment is required? Who is going to review the assessment?

To calculate when a vehicle will put a hole in a steel pipe seems an awful lot of effort when a broader assessment/solution is more economical. If it can get hit by one vehicle, it can get hit multiple times. Protect the pipe from getting hit, then calculating the force to put a hole in the pipe becomes a mute point.

RE: Force required to rupture a pipe.

I found following:


Draft for comment
12 July 2017
DR AS/NZS 2885.6:2017 Pipelines—Gas and liquid petroleum Part 6: Pipeline safety management
The comment period closed on 13/09/2017

????

A pity that the draft is not available for further comments, seems that eng-tips.com has some input that should have been there. Anyway, since the text has to be bought, and is illegal to copy, could you please tell us (direct citations must be allowed?) what the text says on the relevant issues?

I fully understands the necessity of regulations here, but have following comment on a general basis:

In our days a rupture by sabotage is possible, but statistically very unlikely, but consequences large. Same with being hit by falling airplanes, lightening, trains or any vehicle. My assessment: This risk is probably far less than failure cased by bad construction, materials, component failure, false operation and failing inspection and maintenance.

A calculation or assessment of risk has no meaning if it is not followed up by restrictions and prevention devices minimizing both risk for rupture and consequences by rupture. Devices and restrictions are probably already incorporated in the 'safety management regulations', along with full engineering strength calculations of pipeline and support

If a believable risk calculation could be done, the reasoning should not be that we drop the normal preventions below x% risk, or what else should be done, not already taken care of in construction and management instructions?

RE: Force required to rupture a pipe.

(OP)
gerhardl

Here are some of the words from AS 2885

Pipeline system safety management applies controls to identify threats and reduce residual
risk to a level that is as low as reasonably practicable

Where a threat is not a controlled threat, the threat shall be further analysed to determine
the extent of the damage that it may cause to the pipeline system, for input into the
consequence analysis.

To be most useful in the safety management process a full threat identification will contain
all of the following elements:
(a) Description of the activity or condition that comprises the threat.
(b) Location of the threat.
(c) Failure mode(s) if the threat eventuates.
(d) The magnitude of the threat if applicable (e.g. size of machine involved in an external
interference activity). Magnitude is always important for external interference threats
but may not apply to others

Definition of the external interference threats involves systematic assessment along the
pipeline of the activities of parties who could damage the pipeline, together with an
assessment of the type(s) of plant or equipment that those activities would involve in the
location. This assessment requires considerable knowledge of the land uses at all points
along the pipeline, and knowledge of the plant, equipment, and practices of entities that
may conduct activities in the vicinity of the pipeline route.

RE: Force required to rupture a pipe.

But getting back to your original point.

IMHO, any impact from a vehicle bigger than a ride on lawnmower has the potential to damage an above ground pipeline. It could be damage that causes a hole instantly or a dent which might take some time to develop a crack and a hole.

I can see no benefit in trying to determine if a vehicle at one size and speed won't cause a leak or rupture, but another larger, higher velocity vehicle will. You can't legislate for which one is going to crash into your pipeline. If you're in an agricultural area, many farm implements carried by tractors ( e.g. ploughs) will damage a pipeline very easily.

Therefore the item d in you list of things to do is basically any vehicle capable of travelling along the road or track. Unless you pipe is quite small, but very thick and is at a DF of 0.3 to 0.4 then it will be at risk from a vehicle collision. Protect it (burying it is quite a good idea usually....) and don't waste time trying to calculate this.

Remember - More details = better answers
Also: If you get a response it's polite to respond to it.

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