Could the gas from Nord Stream have caught fire?

The luck that the gas from these Nord Stream pipes did not catch fire was the first thought that came to mind when the sabotage was discovered. Because it had one hell like last year in the Gulf of Mexico when a natural gas pipeline burst near the Ku-Charly oil platform. Images went around the world: burning water.

But later you thought: wouldn’t it have been better if the gas had caught fire and it hadn’t been a small effort to ignite it? A plane could have dropped an incendiary bomb on it and then all the methane from the Russian gas would have been converted to carbon dioxide, saving a factor of 25 per grams in the greenhouse effect. In March 1967, the stranded supertanker Torrey Canyon was calmly bombed to set fire to her polluting oil. Oil companies have been burning their waste gas for years.

It didn’t happen. Perhaps because no one remembered who owned the gas that was still in the pipes. Or out of fear of liability if the fire were to derail. Apart from that: it probably wouldn’t have helped much either, it turned out that such an open methane fire is much less complete than always assumed. The magazine science covered it last month in a nasty piece about burnout.

Ships and planes had to stay far away from the bubble spots precisely because they could catch fire. Another argument was added for the ships: they risked sinking if they got too close to the bubble, because the sea water with all those gas bubbles gave less buoyancy. It is Archimedes’ law: the buoyant force of a liquid on a body that is half or completely immersed in it is equal to the product of the volume of displaced liquid and its specific gravity (density). Water with bubbles has a low density, water with sand – quicksand – has a high density. But the speed at which gas bubbles reach the sea surface from a depth of 70 meters can partially compensate for their effect on density. This can be demonstrated with a simple aquarium experiment, reported American Journal of Physics in 2010.

Huge amounts of methane

Now, an enormous amount of methane has unexpectedly been added to the global emission of greenhouse gases. Under water it probably wouldn’t have been better, it has been claimed from an environmental point of view. Russian natural gas may consist mainly of methane and some ethane and propane, but it may contain volatile substances that are less harmful. Benzene maybe, benzene is carcinogenic, nothing less. Yes, natural degradation of benzene has been described, but who knows what it represents in the Baltic Sea?

Outsiders fear that the natural gas leaks have mainly had a negative effect on the oxygen content of the Baltic Sea, which is not high anyway. In the bubbles of natural gas that rose from the depths, there was probably a lot of dissolved oxygen. bubble removalis it called.

There was so much that was not easy to understand. The gas that caught fire last year on the Mexican oil platform Ku-Charly flowed from a 12-inch pipe 80 meters deep. The fire was fought from various fire vessels, no doubt because it threatened the platform, but it was extinguished within a day probably due to divers closing a valve.

But why did the gas from Nord Streams keep flowing for so long? It is fairly generally assumed that the four Nord Stream pipes (each pipe is doubled) do not contain valves, even New Scientist (October 4) assumes that. 1,225 km pipeline without valve! This is probably not true: for the double Nord Stream 1, the Italian petrol valves supplied ten valves: four for the ends and three per touch the road. According to Bartjens, a valve is installed every 300 km. That is not much.

A smooth coating

Perhaps those valves would not close, but otherwise the endless backlog of gas could have come from the unprecedented high pressure generated by the compressor stations near St. Petersburg: as much as 220 bar. After that 1,225 km trip, only about 180 bar remains due to friction losses on the German coast, but it is still significant. Remember that the Nord Stream pipes have an inside diameter of 45 inches, which is 114 cm. It is not easy to calculate because you do not know the influence of friction on the flow rate.

Precisely to limit the friction with the inner wall of the gas pipe, it is provided with a smooth epoxy coating. That coating will not be seawater resistant, because it is also claimed: that the Nord Stream pipes lost because seawater has penetrated. Broken beyond repair. Whether it is true?

Nice to think about: the Nord Stream pipelines were worked on simultaneously in several places in the Baltic Sea. How do you connect the pieces together without water getting in? A complicated construction was devised for the oldest Nord Stream. With Nord Stream 2, loose ends were simply brought back to the surface and welded together. No problem.

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