Pipeline casing 2

[texliner]

I am in the process of conducting an annual pipe to soil survey and have come across many road crossings that have shorted casing. I know that if there is an aduit by any regualtory agency that they will require that we address these problems. Im looking for the most cost efficent practical technique to clear shorted casing.

 

[Goahead]

You may wish to see if the equipment offered by

http://www.farwestcorrosion.com/fwst/instrum/universal03.htm

may help in solving your problem.

Regards,

http://www.welding-advisers.com/

 

[flatlander1]

In my past experience, the line would have to be cut and pulled from the casing. The pipe would then have to be reinserted with new insulators(spacers)and then tied back in.

 

[texliner]

Thanx flatlander1, that would more than likeley clear the short but this line is a NGL at approx. 1200 psi that runs to a refinery in Beaumont. I'm looking for suggestions on clearing the shorted casing while leaving the line in operation.

 

[brimmer]

Textliner,

Do you have information on what might be causing the shorts? The first step would be to determine if it is a direct electrical short or if it is some electrolytic coupling. More testing to confirm is recommended as suggested above, hopefully you use a competent CP consultant who knows how to complete various tests. If it is not a direct short, you can probably fill the casing with dielectric inhibitor; you may also want to install new seals. If it is direct metal contact, you wouldn't have much option but to physically clear the short. You may also want to check and see if the casings are shorted through the test post wires and not the pipe. As far as taking the line out of service, I don't know your procedures but many operators allow excavations with a reduced pressure.

 

[dcasto]

after many shorted casings and tries, the best I found was a hot wax pumped into the annualus.

http://pipelinepigs.net/9wax_tapes.htm

We used a diesel fuel/barrite mud in the 70's. In the 80's, they seperated and in the summer, the diesel came out of the vents, hazardous waste clean up time. We switched to the melted wax in the 90's. It worked. These wer casings from CC to Houston to LC, right in your area.

Other than this, never put in a casing. The railroads even have allowed the switch to deep slick bore installations.