Pipe Casing need some information 1

[AMINATAISSA]

Hello every body,

I really need help about pipe casing:

1- Wath kind of material can we use to fill the annular space between the carrier and casing pipe - I know that it is a dielectric element but i need examples??
2 - If someone have information about how to dimension the casing and choice of materials and numbers of elements i will be very thankful.

Thank you

 

[1503-44]

Casings are usually a minimum of 4" larger, or can be 6" greater than the carrier pipe, if the carrier pipe is 24" or greater.

Spider & spacers with center to center depending on the allowable span of the carrier pipe.

https://duckduckgo.com/?q=pipeline+casing+spacers&t=brave&iax=images&ia=images

You do not need to gill the casing with anything, but if you want to, paraffin works. So does grout.

 

[cvg]

 

[AMINATAISSA]

Hello,
Thank you that really help, I have others questions:
1-How we choose the casing pipe length ?
2-And how we calculate the depth to set casing?
3-if we don't fill the system for me there is any need of vent pipe or what ?

 

[1503-44]

Length of the casing is determined on why you are using it. If you are crossing a road, it must be as wide as the road's right-of-way (RoW) plus 10 ft or so on each side. A railroad crossing should be as wide as the railroad's RoW plus 10ft each side, etc.

Depths are determined by the load placed on the casing. Trucks, heavy equipment, trains, etc. Depth might be specified by the railroad company, or road authority as a condition of their allowing you to cross. Your design code may also have specified minimum depths, such as 4ft for a highway, 6ft for a railroad. You should also see API 1102

https://duckduckgo.com/?q=API+road+crossing&t=brave&ia=web

A vent pipe may be attached to one end with a draining vent to the other end. Make the vent and vent-drain connections outside the road RoW. Slope the casing downward with a uniform slope of 0.25"/ft to the drain vent. The casing can still be filled with paraffin if need is determined at a later date. Corrosion protection electrical short and potential connection box and posts, MP or KP marker, "NO DIG" road crossing warning signs, etc should also be placed just outside road RoW.

Note that cased crossings are only used these days when required to reduce loads on the carrier pipeline, ie. when the pipeline cannot be buried deep enough, or when required by the RoW authority.

More info PDF doc,

https://onlinepubs.trb.org/Onlinepubs/nchrp/nchrp_rpt_309.pdf

https://duckduckgo.com/?q=pipeline+road+crossings+&t=brave&ia=web

https://www.ingaa.org/File.aspx?id=20405&v=1aed587b

 

[AMINATAISSA]

Thank you so much 1503-44,you really help me.

 

[1503-44]

Great.


Another

https://www.researchgate.net/public...2_Code_to_Evaluate_Gas_Pipeline_Road_Crossing

 

[AMINATAISSA]

Thank you 1503-44, If you have any information about the difference between spacer configurations (standard , centred restrained or not etc....).When we use each one??

 

[1503-44]

It's centered when the spider touches all walls at the same time. If it fits inside the casing and secures the pipe from touching the walls, I'm happy. That's about all I know.

 

[AMINATAISSA]

Thank you so much 1503-44.But i don't understand what the science behind spacer configurations why this configuration and not the other or there is no difference all configuration do the same job.
Thank you 1503-44 you are very helpful and Kind.

 

[LittleInch]

Well first you need to know why you are using a casing?

is it because the authorities tell you you have to or because your pipe is too delicate to withstand the forces?

What is the casing pipe made of?
what is the main pipe made of?
Are there any other ducts or cables strapped to it?

historically pipes in casings have been subject to corrosion due to water ingress and lack of CP in a casing pipe. Seals rarely last for more than 15 to 20 years and the casing itself can sometimes corrode and leak water. Non shrink grout is a common fill material, often pumped in from the centre back out via a grout fill tube or hose to make sure you don't have any voids or a small slope and then pump in from the lower end.

Spacers are normally less than ID so that there is no chance of the pipe getting stuck when you insert it. There is rarely a need to centralise the pipe.

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

 

[1503-44]

Yes. Casings have been out of favour since the 1980's.
Try to avoid a casing if you can.
They are only used today if you cannot Bury deeper, or you cannot get enough wall thickness to ensure the pipeline will not collapse from high surface loads. Or if the crossing authority specifies their use. Otherwise try to avoid casings.

 

[AMINATAISSA]

Thank you ,It really help

 

[AMINATAISSA]

Hello how are you,
Please i have a question about casing:
we are an executing unit (in piping ) it is possible that we make the casing system without experience in this filed (without a deep study and experience in it )or we need experience and test to validate the casing system ... ???

 

[1503-44]

For a short simple one, probably not, but unusual conditions, long length, large diameter, deep placement, bad soil, thin wall casing, high loads, high water table, other nonstandard installations, of course yes.

And yes, absolutely, somebody should have knowledge and experience, otherwise its going to be a learning experience, probably about how not to do this, at best.

 

[AMINATAISSA]

Hello 1503-44 I really appreciate your help.
So i think that we don't have an extreme condition 2 casing (12 m and 17 each one) :
1-for the casing I choose APL 5L GR B ,DN 16" (carrier pipe 10"),(the same MOC For vent DN4")
2-For spacer and End seal (see picture bellow):

 

[1503-44]

There are many similarities. There are many differences. There are many ways to do it.
Maybe there are some details you can use here...

https://duckduckgo.com/?q=pipeline+cased+crossing+drawings+images&t=brave&iax=images&ia=images