Internal Coating of Pipe for Non-Piggable Pipe

[elaineabc]

Dear everyone,

I have issues with a few of our pipelines which are non-piggable and are under active corrosion. I wonder if you know any company or technique could assist to remediate the corrosion for internal pipe corrosion? Thanks in advance for your assistance.

 

[BigInch]

Have you tried a corrosion inhibitor treatment?

What type of corrosion do you have now?

What's the pipe made of, what's the product and phase gas, liquids or both, what are the impurities (of corrosion contributing substances & concentrations) and whats the temperature?


BP's case is an unregulated gathering system pipeline. They don't have to do anything except stop spilling the stuff... well, so far they don't have to do anything else. I expect that'll change.

Going the Big Inch!

http://virtualpipeline.spaces.msn.com

 

[IRstuff]

True, but their basic rationale was the the processed oil didn't corrode the pipes, hence no need for pigging and that ultrasonic survey was good enough.


TTFN

 

[BigInch]

They're rationale is without apparent flaw, as far as the CNN crowd goes. Pure oil does not corrode pipes. Its the salt water, sulfur, co2, microbes and the rest of the crap that comes from the wells that eats them up. Not to mention that the break was in the gathering system, which by definition (and coincidently(?) also the regulation starting point) is before the treatment plant and pump station. However, even at the treating plant, they probably just dewater some and degass a little and zip... straight into TAPS.

Question: If treated and processed oil does not corrode pipes, why do they do they spend 250 million on all the inspections, internal pigging, instrument pigging, anode installations etc. on the TAPS line? Especially if the oil has been treated and processed. "Supposedly", only processed oil gets into the TAPS line anyway, no? I think they spend it on TAPS because the regs require and they do just like everybody else does in the unregulated gathering system... little if anything. Have you seen those south Texas dust devils? They're not all dust devils. When I worked in a 862 well south Texas gas gathering system with 1800 miles of pipelines (not BP), we blew up at least one pipe/week, sometimes 2 or 3. No corrosion control program was in effect at all ... before I got there, but by that time, most of the damage had already been done. I started designing and building everything to B31.8, so I didn't stay there too very long.

Going the Big Inch!

http://virtualpipeline.spaces.msn.com

 

[IRstuff]

Well, supposedly, that's the big mystery. They've got oil that was supposed to non-corrosive, yet, they've got pipe so badly coroded that there was supposedly barely 0.06" of steel left.

Additionally, their ultrasonic external monitoring turned out to be a total debacle, hence, they went back to pigging.

TTFN

 

[SJones]

"Processed" oil can still contain sufficient water to cause corrosion. Just depends on the level of "processing" and the desire to shut down or institute mitigation when the "processing" goes off spec.

Steve Jones
Materials & Corrosion Engineer

http://www.pdo.co.om/pdo/

 

[zdas04]

Can we get back to the thread here? BP's corrosion issues are being discussed very well in the Corrosion Engineering Forum.

First, why are the lines "non piggable"? I've put Argus pigging valves in many previously non-piggable lines with good success for a couple of thousand dollars an inch (up to 6-inch).

If the line is really "non piggable" then your other options are limited. For some lines you can pull a HDPE liner through the pipe. The liners are pretty effective up to about 1,000 ft as long as there are no bends tighter than 40 D.

Chemical treatments really require continious-phase liquid (you didn't say if it was a gas or liquid line) to be effective, and none are very good at addressing corrosion under scale.

Other than that you are pretty much out of luck. For piggable lines there are some pig-distributed chemicals that can do an ok job.

David

 

[elaineabc]

We are in the Natural Gas business. You are right about lateral lines, there is so much H2S in the system that ate the pipe alive. I am performing this research with the objective to prevent our pipe from R-Strength deficiencies.
1. To inject corrosion inhibitors.
2. Find small piggable segments of the pipe to coat internally (if that is possible).
3. Replace the whole system to make it become piggable.

What you think? Thanks.

 

[BigInch]

I think that your list is in the proper order to arrive at the cost efficient solution, however to maximize resource allocation and minimizing day to day risk exposure in the process, you may want to consider a multi-remediation program, doing a bit of each in different areas of the system according to extent of present observed corrosion, existing or forecast deterioration rate vs remaining wall thickness, piping point topographic location, areas near highways and river crossings, nearness of public facilities or private housing, etc.

In addition to the usual correlation between stream components and corrosion, pay some attention to velocities in various pipes in relation to their topographics. I discovered one company where I worked had a high correspondence observed hi corrosion rates and outright failures of low velocity lines that were also at relatively low elevation points in a given pipeline segment. That might help you discover some hot zones to move up on the priority list.

Going the Big Inch!

http://virtualpipeline.spaces.msn.com

 

[zdas04]

You want to be careful about corrosion inhibiters. In order for them to work they must be transported to the problem sites and that is very difficult in gas lines. In liquid lines with a continious liquid phase it is possible to apply inhibiter and have it affect the entire line.

With a gas line the injected liquid inhibiters will always accumulate some short distance from the injection point and even that short distance will be inconsistently protected.

You can inhibit gas lines successfuly using pigs to distribute the chemicals to the pipe walls, but this requires that the line be piggable. If the line is piggable it is usually less expensive to just run the pigs to prevent liquid accumulation in the first place than to put a bunch of chemicals into the line.

I've seen a lot of gas gathering lines operated by a lot of different producers and the only corrosion mitigation techniques that I've ever seen work are: (1) use of inert materials (fiberglass and Poly); (2) preventing liquid accumulation (with dehydration or VortexTools to create a flow profile that shifts liquid); or (3) pigging. The rest of the options (in gas lines) are simply throwing good money after bad.

David