Dry Gas
Dry Gas
(OP)
Dear All,
The company I work for operates a dry gas pipeline, I was just wondering can we inject the pipeline with corrosion inhibitor to control corrosion (If any) and how can we monitor the corrosion, please note that pigging is not an option.
Your help is much appreciated
The company I work for operates a dry gas pipeline, I was just wondering can we inject the pipeline with corrosion inhibitor to control corrosion (If any) and how can we monitor the corrosion, please note that pigging is not an option.
Your help is much appreciated





RE: Dry Gas
Unless someone messed up and let it get wet.
Filming inhibitors will coat the inside of the pipe and protect against the occasional moisture exposure.
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Plymouth Tube
RE: Dry Gas
RE: Dry Gas
With aerosol injection, the collisions of the droplets with other droplets and/or with the pipe walls will end up with zero buoyant droplets within a few dozen feet. When I've cut open pipe with aerosol injection, I never find any chemical after the first or second sag in the pipe. Aerosol injection is worse than worthless.
Liquid injection is just as bad, but less expensive.
Batching chemical behind a pig can work, but getting the batch size right (i.e., put in enough that there is still some left when the pigs arrive) can be a challenge and I usually see the pigs arrive stone dry and no one knows how far the line is protected.
I have never seen a "protected" line with a lower failure incidence rate than a line in similar service without chemical injection. Never. Not once.
I have also never seen a corrosion failure in lines that are regularly pigged. Getting rid of the water is the only effective corrosion treatment that I've ever seen in "dry gas" lines (the term "dry gas" in my industry means "gas without hydrocarbon liquids", I've never seen a line with zero water in it--even dehydrated mainline pipes will accumulate some amount of water in cold places).
David Simpson, PE
MuleShoe Engineering
www.muleshoe-eng.com
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RE: Dry Gas
http
for "dry gas" service corrosion allowance is not specified or a minimum, say 1 mm, is used.
The only reason to inject inhibitor is if you want to continue operation even if the dehydration is not working nad you'll have water in the pipeline.
http://web
S
Corrosion & Rust Prevention Control
RE: Dry Gas
RE: Dry Gas
Your definition of "dry gas" is not the one that I find used in the industry over most of the world. I looked at the link you provided and that definition is not there either. In fact the only time the phrase "dry gas" is used in the Norsk document is in conjunction with the corrosion allowance discussion.
In general usage, "dry gas" is gas without liquid hydrocarbons. I find that usage in every country that I work in. The term has nothing to do with water at all in my experience. When a stream is anticipated to be free of water, the term "free of water" is explicitly defined, usually in terms of a mass of water per volume of gas since the industry has long known that it is very expensive an generally pointless to get the stream to approach zero water vapor.
David
David
RE: Dry Gas
PS. You need to look at the second paragraph of 4.3.2 in NORSOK M-001 (under the bullet points)
Steve Jones
Materials & Corrosion Engineer
http://www.oilandgaspeople.com/cv/11499664
http://www.linkedin.com/pub/8/83b/b04
RE: Dry Gas
The OP was talking about injecting chemicals into a "dry gas" pipeline. People do this a lot. It never provides better corrosion performance than not injecting the chemicals. That seems more important than a pedantic definition.
David
RE: Dry Gas
Steve Jones
Materials & Corrosion Engineer
http://www.oilandgaspeople.com/cv/11499664
http://www.linkedin.com/pub/8/83b/b04
RE: Dry Gas
Since I retired I've looked at several dozen dry gas lines around the world for many operators that have chemical injection (either aerosol or liquid, it doesn't matter) and had them sample the liquid that always comes out when you cut the line. If the cut is close to the injection point, the liquid is nearly pure chemical. If it is more than a couple of dozen joints downstream there is no chemical in the liquid.
Neither the CAPEX or the OPEX (or the manpower) is justified in slathering corrosion chemicals into a gas line.
David