allowable distance between two adjacent pipelines
allowable distance between two adjacent pipelines
(OP)
Hi; How we can find allowable distance between two crossing or beside pipelines.
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allowable distance between two adjacent pipelines
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RE: allowable distance between two adjacent pipelines
At 0.5 m either over or under you pretty much avoid cathodic interference. People that require more distance than that are generally just making numbers up.
For lines that parallel each other, I like to be as far as the right of way will allow. I've seen cathodic interference on lines that were 5 m apart running in parallel for more than a few hundred meters.
David
RE: allowable distance between two adjacent pipelines
Let your acquaintances be many, but your advisors one in a thousand' ... Book of Ecclesiasticus
RE: allowable distance between two adjacent pipelines
Let your acquaintances be many, but your advisors one in a thousand' ... Book of Ecclesiasticus
RE: allowable distance between two adjacent pipelines
In gathering systems (a LOT smaller pipe than you usually work with), the norm in the states has become to excavate around lines with hydrovac equipment. I don't always agree with the trend, but the risks are lower.
With the requirements to hydrovac, I'm a lot more concerned about my line becoming a sacrificial anode than getting hit. At 12" the cathodic interference (for parallel lines running together any distance) is almost guaranteed. At 10 ft interference is pretty common if the pipes run together more than a few dozen yards.
For over/under, I use the 12" as well.
David
RE: allowable distance between two adjacent pipelines
I think we would tend to bond the CP of parallel lines together as well, whereas you may actually be talking about different company's pipelines running parallel, we could bond together two parallel company lines. CP interference between different systems can happen over several hundred meters or more as well, and with overhead electrical lines and railroad electric power etc., something you probably don't often see in a US gathering system line.
Vertical separation I use a 18" minimum of sand-cement bags with rock shield, since gravity tends to get closer in a vertical environment anyway.
Let your acquaintances be many, but your advisors one in a thousand' ... Book of Ecclesiasticus
RE: allowable distance between two adjacent pipelines
David
RE: allowable distance between two adjacent pipelines
RE: allowable distance between two adjacent pipelines
When buried pipes are installed in parallel, principles of analysis for single pipes still apply, however soil cover must be greater than minimum. In other word, the design of parallel buried pipes requires an additional analysis for heavy surface loads (given that a common trench is used). In fact for buried parallel pipes soil slip between the pipes becomes the bottleneck for the distance calculation. Talking about 1 m or more separation then the concern becomes faded but it all depends on your pipelines diameters and soil density.
If the pipelines are in separate trenches, then embedment stability becomes a concern when a trench is excavated parallel to an existing buried flexible pipe. You should address what would happen to a buried flexible pipe when some or all the side support is removed in a parallel excavation. Ans also the existing trench stability itself is an issue to concern. At less than minimum side cover, X, side support is lost and the soil on the pipe must be supported by the pipe. If ring stiffness is inadequate, the pipe collapses.
For a detailed discussion, please refer to "Buried Pipe Design" by A. P. Moser, Steven Folkman chapter 3.
RE: allowable distance between two adjacent pipelines
In piping support design specs & codes we see tables of pipe spans, as distance between two supports in a straight line cannot exceed this amount.Now the question is if the line is not straight and there is a change in the direction of line (for instance by elbows), what amount shall be used for pipe span.
RE: allowable distance between two adjacent pipelines
We are more connected to everyone in the world than we've ever been before, except to the person sitting next to us. Lisa Gansky
RE: allowable distance between two adjacent pipelines
ASCE MOP #89, "Pipeline Crossings" (1996) contains the somewhat generic statements, "The commodity being carried by a pipeline will be of importance to the Owner of the facility being crossed...." , "The type of facility being crossed is of paramount concern in designing the pipeline crossing...." , and of course, "Of greatest concern will be combustable fluids (hydrocarbons) under pressure, which may require special protective design features..." (its spelling). This MOP also talks about situations when different entities might be involved in ownership of the pipelines etc. involved, and even if they don't have "primacy" all might at least deserve a "say"!
The are some more specific guidelines with regard to some aspects and services in the "Ten States Standards" for water and wastewater, and I am also aware e.g. another fairly well-vetted standard ANSI/AWWA C600-05, Installation of Ductile- Iron Water Mains and Their Appurtenances contains the guidance,
"4.3.1.3 Clearance. When crossing existing pipelines or other structures, alignment and grade shall be adjusted as necessary, in accordance with the contract documents, to provide clearance as required by federal, state, or provincial, and local regulations or as deemed necessary to prevent future damage or contamination of either structure."
All that being said, there are for whatever reasons many situations that have reportedly occurred in the field that have brought about at least discomfort and sometimes worse with some close-together pipes. I suspect a search using the term "cross-bore" will yield multiple perhaps rather extreme examples. Another ongoing, highly visible current event that has recently caused at least some consternation is that it was reported months ago that a "pipe bursting" operation, with 10" hdpe upsizing from existing 6" clay, was routed in 2008 just a few inches away from the disaster involving the 30" San Bruno high-pressure gas pipeline installed decades earlier (I noticed while a newspaper report of this alleged association entitled, "Link between sewer job and San Bruno explosion grows stronger" has been removed from its original location at http://
While I understand that occasionally, due to right-of-way restrictions, common utilidors, other strong desires/necessity of the Owner etc., some pipelines inevitably will be placed rather closely together at some point (and huge numbers of quite close clearances or crossings likely remain problem-free.) It is however clear that there needs to be reasonably good Engineering and construction judgment, as well as investigation or knowledge of all applicable issues, codes and regulations, etc. employed. [And at least at some point, maybe the (red) lights need to start flashing and the call go out, http
One thing is for sure, with inreasing population and congestion underground and elsewhere, problem will not go away!