Vent and drain hole location on casing pipe

[rizpet23467]

Hello,

What is the basis of keeping vent and drain hole location on casing pipe in between second and third spacer?

please refer attached pdf file in below link for more clarity.

 

[bimr]

It seems like the drawing is requiring two insulator spacers on the end of the casing, so the vent will be located just inboard of the two insulator spacers on the end of the casing.

http://www.pipelinepsc.com/images/documents/PDF/Brochure - Casing Spacers.pdf

 

[BigInch]

I haven't seen a drain on these things, API 1102 does not require vents, or drains. Two vents yes to make filling with dielectric material easier, pumping from vent to vent. Drains will probably get plugged by rust anyway as moisture will collect in the drain.

Note that casing can be filled with corrosion inhibitor or inert gas, if no vents are used.

50 m of casing to either side is pretty far. Normally it could be cut off much nearer to and on the outside edge of the road's right-of-way boundary.

You should have a look at API 1102.

Learn from the mistakes of others. You don't have time to make them all yourself.

 

[LittleInch]

What is the basis? Heaven only knows - certainly no technical one, just something the designer saw somewhere and has repeated not knowing why it was there in the first place.

I've never liked casings, but the design of the "drain" is laughable. No driving force so how exactly is any water going to get out? And I've never seen a slope on a casing before. If you think a railway company is going to let you put a big casing pipe 2m below their precious rails you've got a big shock coming....

My motto: Learn something new every day

Also: There's usually a good reason why everyone does it that way

 

[BigInch]

I agree that's usually true, especially for us pressure pipeliners, but sloped casings are necessary for gravity driven flowing sewer lines where the pipeline must maintain a precise slope for long distances (still without drains).

2m = 6.56', so that's usually true too, but I used to cross the BN often, so I remember that they only need 5-1/2 feet below track.

http://www.bnsf.com/communities/faqs/pdf/pipeline.doc

Learn from the mistakes of others. You don't have time to make them all yourself.

 

[LittleInch]

Note 2 on the drawing says "Gas pipeline"..... 50 m is ridiculous as an extension distance - even for expansion purposes that is a long way for little benefit.

My motto: Learn something new every day

Also: There's usually a good reason why everyone does it that way

 

[BigInch]

Certainly no doubt about that!

Learn from the mistakes of others. You don't have time to make them all yourself.