Natural Gas Effects on Metals

There's a lot of different elemental metals known to mankind. A quick glance at the periodic table shows this.

Then there are all of the possible alloys one can get from combining these elements into a new metal. Some of these metals will act as a catalyst that can "crack" a hydrocarbon chain under the right temperature and pressure. So without some clarification on which metals, the specific hydrocarbons present, the other gasses if any that are present and the temperature and pressures of these gasses it is impossible to say what chemical reactions might occur. However, CO2 is an extremely stable molecule, so no corrosion will happen from this gas.

You can find the effects of hydrocarbons on metals and visa versa from a full study of chemistry.

Redfred: I am in agreement with everything in your comment with one exception:

'However, CO2 is an extremely stable molecule, so no corrosion will happen from this gas.'

CO2 corrosion is a common, thoroughly researched phenomena that occurs in various types of steel. I can think of a couple metals for which the 'corrosion' would be violently fast (nobody I know uses those metals for anything structural).

BBB

Flee to me remote elF

Well if you are going to spilt hairs then I hope you don't mind if I split one myself.

Yes, carbon dioxide in the presence of water or water vapor will create carbonic acid. Acids that dissolve in water will eventually corrode most metals. The OP did not mention the presence of water. So I still say that the gas, CO₂, will not cause corrosion. But you are quite correct that the reversible process of CO₂ + H₂0 ↔ H₂CO₃ makes a water soluble acid that will corrode many metals, particularly many steel alloys. On the other hand, many organic acids that could exist in the realm of the other hydrocarbons the OP listed (without another reagent molecule required) could instead chelate a protective coating on the metal. So will corrosion or protection happen to the unspecified metal by the other unspecified gasses, who knows?

Hey Guys

Im sorry I started this conversation with so little info. However I do appr. all of the comments. I hope this will help the metal is x52 carbon steel erw pipe at 900 psi std wall. The gas analysis is as follow below. Please keep in mine this analysis does not show the free standing liquids. My consern is the ERW PIPE but so far I have not found any standards on where to draw the line and upgrade from ERW to seamless or if there are differences. Im not an eng. and could use some help with this. Thanks guys

co2 4.88 nc4 .73

n2.19 Ic5 .32

c1 80.85 nc5 .21

c2 8.9 c6+ .37

c3 2.8

ic4 .64

Well, I guess I should point out first that Chemistry is not my engineering field. Like most engineers it is always a part of my discipline but it is not my main focus. Because of this I do not recognize your acronyms with any level of certainty. This combined with your spelling makes everything I write here a guess.

It appears that your analysis lists ten items of hydrocarbon chains and a few other molecules (CO₂, N₂) present with a percentage associated that adds up to a total of 99.89%. Probably this is a molecular percentage distribution, but it might be a mass percentage distribution. Regardless, the predominant hydrocarbon appears to be methane. So if this is a complete gas analysis and water vapor actually is not present at all, then the carbonic acid corrosion problem discussed earlier will not occur. At least it won't until water does appear in the gas stream.

That as far as I feel safe venturing out of my field. I hope that I helped you appreciate the need for precise information and more importantly a real petrochemical chemist.

were you so worried about my spelling that you missed the sentence about the free standing liquids. that the gas analysis was taken so as not to pick up the FREE STANDING LIQUIDS, and I did not see the need to carry the decimals out to tens of thousand. REDFRED Thankyou anyways

I was worried about the spelling of your acronyms since your spelling of common English words were so obviously wrong.

Now if you really want me to guess the composition of your FREE STANDING LIQUIDS I'll do it. (I never understood why people shout here but I can do it if you wish. ) I guess that your liquid is a combination of Cyclopentane and the a few of the isomers of Pentene. The vapor pressure from these hydrocarbons account for your Ic5 0.32% value. Benzene and Cyclohexane will also be in the mix but will only show as part of you c6+ 0.37% for you will clearly have many more complex hydrocarbons in this mix. Likely all of the carbon fractions will include alcohols that might suspend water in solution of this hydrocarbon soup. This will permit the carbonic acid corrosion mentioned earlier but I would've expected that some fraction of water vapor to also exist in your gas analysis.

This was fun. But I still think that you should consult with a petrochemical chemist for a better answer.

Thanks Red

Carbonic Acid, I think is what I,m looking for. ERW pipe has small hydrogen blisters a few mm from the weld. these are coused from alum. particulates when welding the pipe and that is where Im getting my pin holes in the pipe The line is not mine But Im afraid it will fall under my responsibility soon. Just trying to get a jump on it.

Google, natural gas 101; really good info there.