Gas Venting Stations (GVS)
 

Never really put much thought about them being a serious hazard, there is one about 3 miles off the departure end of my grass strip, I would give it a slight swerve and move on. As I have mentioned before most of my flying throughout the 90’s early 2000’s was done in the US southwest and I can’t recall seeing GVS’s marked on the sectionals or terminal charts if there was there was not many compared to the UK. I recently bought UK charts and the symbol tends to jump out at you. Last Sunday night in the pub I got talking to the maintenance guy from the GVS near me and he gave me a whole new appreciation of their dangers. The conversation started out with me saying “what’s the big deal if I am flying over the top at 1500 feet and you release a bit gas”, he responded with “ was 3 half mile lengths of 36 inch pipes pressurised to 80 bar my idea of “a bit gas”? I was astounded at the amount of gas that may be released during routine pipe maintenance. He also said that for it to be a danger it had to have a content of between 5 to 15% oxygen. I asked what altitude did he estimate during a average no wind day would the rising gas get to that threshold of oxygen, he was not sure but did say that if he was a pilot he would not be knobbing around directly above a station venting under the 5000 ft. level This gave me a whole new appreciation for the symbol on the chart !

I have never been exactly sure what the risk is with GVSs. Is it explosion? Has there ever been a single recorded case of an aircraft exploding over one of these? or a motor car on the ground? or anyone who ever lit a fag? Is the risk that the aircraft engine will be deprived of oxygen and simply stop?Will the pilot be gassed? Has anyone on the ground ever been gassed when walking past? What is the friggin risk ???

From what they guy told me, once the gas rises and acquires a 5 to 15% oxygen content all bets are of for anybody in a buddy holly special that throws a spark or electrical charge. I am obviously no engineer or chemist and don't fully understand what it would take to ignite/explode the gas but I aint going anywhere near or downwind from them again.

Additionally, all those big gas towers you used to see in the big towns and cities are all gone, remember the huge cylinders that used to rise and fall, and are replaced by those gas pumping and venting stations, so they have some serious pressures at those network junctions

Wilmington refinery flare causes black plume in South Bay - The Daily Breeze

HTC

About a month ago I drove past a GVS (Not in the UK) whilst it was venting. I could see it from quite some distance and with the low cloud/early morning mist, I thought it was some sort of meteorological phenomena. Its appearance was like a twister with a very high pressure stream of gas going vertically upwards into the cloud at a tremendous rate. Having seen it, I think I will take more notice of them in future.

A bit academic really, but that is expressed the wrong way round.

Natural gas is flammable in a standard atmosphere (ie 21% Oxygen) when the gas is present in concentrations (approximately) between 5 and 15% vol. :8

How often does the average GVS let out gas? I assume not very and as the average GVS probably has a light aircraft over it less than 0.1% of the time the two happening in sync must be very unlikely?

Rod1

The GVS's marked on the chart are usually on the main transmissions lines from offshore. In the event of a mjaor plant upset they can depressurise the plant and for non-routine operations the pipelines.

In terms of frequency this should be less than once a year - the only problem is there would be no warning for the plant upset. The flare (venting is usually ignited) can be up to 100m plus high, the thermal effects considerably higher. If unignited there is some possibility of an engine 'self-fuelling' and destroying itself.

However as Rod1 says the chances of this are pretty small - rather like those rocket NOTAMS and similar stuff.

In the UK the CAA charts quote an altitude for each GVS below which flight is ill-advised (usually a few thousand feet - at least for ones I quickly checked).

H

Piperboy84. Looking at the description of your location, I think I may just be working currently at the site you refer to. Spooky.

Between Kirrie and Forfar?

The very one.

Well if you see a really handsome and intelligent looking chap flying past in a snazzy looking Maule don't be letting any gas off !!!!!!!!!!!!

Gas,gas,gas
 

Useful post, thank you. For anyone heading from/to Barton in the LLC there is one neatly in line from Thelwall to the airfield. Of course, it is never overflown...... .

Not seen a Maule around these parts although we had a low flying Chinook pass us by this morning. I should especially avoid overflight between now and 28th of the month.

Have to admit to being unable to avoid looking skyward at the merest hint of an a/c engine so, shall look out for you.

Have to wait until weekends and the weekly return south to get my aviation fixes these days.

Useful post, thank you. For anyone heading from/to Barton in the LLC there is one neatly in line from Thelwall to the airfield. Of course, it is never overflown...... .


That would be Partington?

Well if you PM me your contact info, I go up for a flight most afternoons/early evenings weather permitting, would be a pleasure to have you aboard. I usually do a local circuit, Lunan bay, Montrose, Brechin Kirrie Forfar then home.

PM sent :)

Barton GVS
 

Not sure what it is called. About 3nm NE of Thelwall and north of the Ship Canal. Partington village is south of the canal and well worth a visit if you enjoy Shameless.

A lovely Super Cub almost found out what happens to aircraft overflying gas venting stations today as he overflew us at no more than I would say 500-600ft. We were carrying out venting tests at high pressure at the time.

Caught my eye because it was A) Flying Very Low, B) Flew right through the centre of the GVS, C) It was a nice one and I am a Cub fan.

Would have hated a blast of high velocity gas to have ruined his day.