AIS shows this warning pretty quick

[Porthandbuoy]

You did not read an earlier post or misunderstood it. The pig is normally propelled by water or other fluids which are non compressible. By counting the pump strokes pumping along and knowing the pipe dimensions the location of the pig is known . This is important when doing maintenance inspections. Pipe inspections are not| done with oil or gas in the pipe.

Oh yes they are! I've been involved in the commissioning of a few.

The Nordsea 2 is 1,234-kilometre-long and comprises two parallel lines, both with capacity of 27.5 billion m3 (970 billion cu ft) of natural gas per year. Pipes have a diameter of 1,220 mm (48 in), a wall thickness of 26.8 to 41 mm (other specification 38 mm (1.50 in)) and a working pressure of 220 bar (22 MPa; 3,200 psi). I would like to see the reciprocating pump that could shove a pig down that line!

When laid the pipelines would have been full of air at more or less atmospheric pressure. That air has to be displaced before gas is introduced or there would be an explosive mix in the pipeline. This is done by introducing a train of 'pigs', typically plastic spheres full of glycol and pressurised to be a snug fit in the pipe. A couple of these with methanol between them, to mop up any residual moisture, followed by a sizeable volume of inert gas, such as nitrogen, then another couple of 'pigs', all pushed along by the gradual introduction of natural gas. Liquids are captured in 'slug catchers' for treatment and disposal. The air and nitrogen are vented off and the gas goes to the customer.

Pigging is a normal and, in some cases, a frequent operation to remove liquids from gas pipelines and to coat the inside of the pipeline with corrosion inhibitors.

There are also 'gauging pigs' to measure the how round the pipeline is. I've known pipelines gone oval under road crossings. There are 'intelligent pigs' which measure wall thickness and determine the integrity of all the welded joints. All pushed along by the gas flow.

It is going to take a LOT of pigging to purge Nordstreams 1 & 2 of all the nice corrosive seawater which will rush in once all the gas has vented off.

 

[Bilgediver]

Oh yes they are! I've been involved in the commissioning of a few.

The Nordsea 2 is 1,234-kilometre-long and comprises two parallel lines, both with capacity of 27.5 billion m3 (970 billion cu ft) of natural gas per year. Pipes have a diameter of 1,220 mm (48 in), a wall thickness of 26.8 to 41 mm (other specification 38 mm (1.50 in)) and a working pressure of 220 bar (22 MPa; 3,200 psi). I would like to see the reciprocating pump that could shove a pig down that line!

When laid the pipelines would have been full of air at more or less atmospheric pressure. That air has to be displaced before gas is introduced or there would be an explosive mix in the pipeline. This is done by introducing a train of 'pigs', typically plastic spheres full of glycol and pressurised to be a snug fit in the pipe. A couple of these with methanol between them, to mop up any residual moisture, followed by a sizeable volume of inert gas, such as nitrogen, then another couple of 'pigs', all pushed along by the gradual introduction of natural gas. Liquids are captured in 'slug catchers' for treatment and disposal. The air and nitrogen are vented off and the gas goes to the customer.

Pigging is a normal and, in some cases, a frequent operation to remove liquids from gas pipelines and to coat the inside of the pipeline with corrosion inhibitors.

There are also 'gauging pigs' to measure the how round the pipeline is. I've known pipelines gone oval under road crossings. There are 'intelligent pigs' which measure wall thickness and determine the integrity of all the welded joints. All pushed along by the gas flow.

It is going to take a LOT of pigging to purge Nordstreams 1 & 2 of all the nice corrosive seawater which will rush in once all the gas has vented off.

Yes....but when the maintenance gang take over it is a different story . And the inspection pigs are capable of being placed with a bit more precision.

 

[Beneteau381]

How's that going to work if the pipeline isn't in use?

The person at the far end, russia? put a pig in the launcher, open the valve and start the triplex pump and pump it along with sea water.

 

[Porthandbuoy]

Yes....but when the maintenance gang take over it is a different story . And the inspection pigs are capable of being placed with a bit more precision.

I kep it at Pigging 101

 

[Beneteau381]

There are suggestions that the pipes will be written off due to corrosive sea water inside causing rust.

We used to use seawater as the medium to push pigs, its not an issue

 

[Beneteau381]

Makes you wonder if they sent some pigs down the pipe with explosives on them and then blew the pipes open from within. Either way I would imagine it will take years to make them live again if gas export was ever re established to the EU.

what i said

 

[Bilgediver]

what i said

So did I back at #22 Great minds

 

[boomerangben]

We used to use seawater as the medium to push pigs, its not an issue

I’m not sure they would use seawater in a 1200km 48” pipeline - that’s one heck of a lot of treated water to get rid of at one end or the other (nearly 1.5 million tonnes) I’ve only been involved in relatively short small dia pipelines so not sure how they would do this monster although Porthandbuoy seem to have a good insight

 

[boomerangben]

The person at the far end, russia? put a pig in the launcher, open the valve and start the triplex pump and pump it along with sea water.

Only if someone opens a valve at the other end…

 

[Beneteau381]

I’m not sure they would use seawater in a 1200km 48” pipeline - that’s one heck of a lot of treated water to get rid of at one end or the other (nearly 1.5 million tonnes) I’ve only been involved in relatively short small dia pipelines so not sure how they would do this monster although Porthandbuoy seem to have a good insight

Last one I did was in the late 80s, offshore Angola, 20 kms as it turned out. The engineer that installed the pipe line wasnt very good at counting! A very small supply boat tied off the well protector, a dowell schlumberger engineer in his orange coveralls, a triplex pump and counter and a suction pipe chucked over the side. Hours of boredom as the triplex pumped away, the boss on shore calling on the radio, should be here now, are you sure youve launched it! Hilarious!

 

[jamie N]

Many hours of my life have been spent watching a pig-receiver, with the 'other end' calling up and asking "Any sign of the dye yet?"
"No:........can't be long though"
With a guide base cementing job, the calculation was to work out the theoretical requirement, triple it, then start pumping it, frequently making a 'car park' around the guide base!