Ahoy! There M'Hearties. (am I right in thinking that Ahoy is the only word in the English language that should have an explanation mark behind it ? or am I confusing it with Ho! as in Wesward Ho! a rather dreary little collection of shabby bungalows along the coast from Bideford?)
98 35.8' N
101* 21' E
Speed 1.7 kilometers per DAY
Course 156*
Wind SE3 (Gentle breeze)
Sea state less than half a meter ESE'ly swell
Temp (@0400 83*)
WE are in the Gulf of Thailand laying pipe in the chevron field which constitutes a major part of the Thai oil and gas supply. WE expect to be here until late September installing several new [pipe lines and the installing several new platforms connecting the pipe line to the platforms sub sea and installing a new mooring system for an FPSO (and offshore floating, production, storage and offloading facility)
I will try to keep you updated with what we bare doing and how we are doing it for the more technical minded and inquisitive and also make some forays into writing about old tales or new ideas as we go along.
My due of date is April 24th and, as normal, when I am home my updates will be sporadic at best until I join again on June 12th.
Suffice to say that Mrs B and I had a wonderful leave, very busy and productive and full of laughter and we were practically joined at the hip for every second of our 5 and half weeks together.
So today the music is:-
http://www.youtube.com/watch?v=qHPetLms4ZU
So are you wondering how a pipe laying vessel works?
Well how uncanny is that, as I am just about to explain the operation non this vessel.
We are 140 meters long and 40 meters wide. we have a freeboard (the bit above the water line to the main deck) of about 3.5 meters and a draught (the bit below the water line) of about 6.5.
We are self propelled by 6 azimuth thrusters (3 fwd and 3 aft) controlled by a system called dynamic positioning. I am a the Senior Dynamic Positioning Officer on board (I drive the boat) and answer to the Master for marine matters and the barge superintendent for project matters.
WE produce 24,500 kilowatts of power via 6 engines spread evenly between the thrusters, depending on what generator configuration we are using.
The accommodation (that can sleep 395) is on 4 decks and incorporates the galley mess rooms gyms laundries, conference rooms, offices tv lounges etc mainly on the lower deck with the cabins being on the three decks above. Above that lot is the bridge and forward of the bridge is the Heli Deck which is about 30 meters by 40 and makes an ideal place for a walk in the sunshine and breeze with 360* panoramic view of the sea.
It is situated forward and raised up by 10 meters from the main deck and that space is filled with the pipe lining up gear.
The middle longditudinal section of the vessel houses what we call the "firing line" which is in effect a factory production line that the pipe line is created in and travels down on its way to the sea bed.
When laying pipe we have a succession of material barges loaded with pipe come in and tie up to us.
The pipe lengths are loaded onto the port side of the vessel and stacked there and then one at a time they are sent along a series of powered rollers which pulls a "rabbit" through which is a huge wire brush that scours the inside of the pipe to remove any debris.
As the rabbit burrows down the next pipe, the one we are following arrives at the beveling station where the 12.5 meter lengths of pipe are milled and beveled to the correct angle for the weld.
They are then transported by powered rollers to the approach to the firing line.
Here it has a line shot through to the other end (more later) and the end closest to the first welding station is being followed by a bloke with a high temp gas burner bringing the end to a high heat to ensure a good weld.
As the pipe takes its turn at the front of the firing line it is situated on a set of rollers that the number 1 weld station (known as the Bead Stall) can line it up with the previous pipe end,. Meanwhile another bloke with a gas torch is heating up the other end.
The line inside the pipe is attached to the internal clamp and x ray machine crawler and as the pipe in front is sent down the line it pulls the clamp and x ray into the new position.
The internal clamp is moved into position and the Bead Stall crew line u0p the next length of pipe which is then clamped internally to hold it for welding.
Meanwhile at 8 other stations down the length of the firing line the following happens. The first four stations are all welding stations so as each joint goes down the line it is hand welded 4 times.
When on bigger pipe this one is only 16 inch) we use automatic welding bugs that do the weld.
Station 5 is the x ray station where the internal x ray crawler lines it self up with the weld and a negative is applied to the outside. A lead hood is pulled over and ZAP.
The next station is 6 where any repairs are done if it fails the x ray.
the next 7 and 8 are where the external coating is done and the it exits the vessel via the stern through the stinger and down to the sea bed in pone seamless endless continuous process.
At the moment we are managing about 5 joints an hour. On some pipelines when using automatic welding bugs we reach 10 or 12 an hour and can do over 2 kilometers a day.
The whole thing is choreographed by a light system so as each station finishes its work they hit a green light when I have a line of 8 greens on the bridge an alarm sounds and I instigate the move forward of 12.5 meters. This is controlled by the by vessel thrusters and also the tensioner that maintains a tension on the pipeline to prevent it form just falling into the sea. (Aussie Bert is the tensioner operator on my watch he is a bit iof a bushman when home and has already told me many ways of dispatching the most dangerous snakes in the outback. he is abit like Crocodile Dundee with a mustache and flip flops, and is great fun to share a watch with.)
(as an aside on her we also have on the bridge team a Filipino DPO, A Malay Radio Operator, A Singaporean and a Borneo Malay (Sarawk) survey team and an Itallian client rep and an Indian Master with Thai stewrads.) There are afew other nationalities on the other watch. I am midnight to midday and we are 7 hours in front of France time.)
The angle of the pipeline against the depth of water and the correct tension are all finely balanced and the pipeline reaches the seabed about 380 (in this case) meters behind us.
This is worked out by the survey team and the field engineers who also work out what curves we need to lay in the pipe and where and how close to get to obstacles on the seabed that has already been pre-surveyed.
The DP system works out what track the vessel needs to make and what heading changes are needed to get the required pipe line track.
We check this every few hour with an ROV which is an unmanned sub sea robot with cameras and position beacons.
We weld on a lay down head at the end and then using a very powerful winch and the vessels motion we lay the pipe to the seabed. The ROV pops down and cuts the sacrificial sling on the end and then we either bugger of somewhere to do it again or deploy our divers to go and fit a spool piece that connects the pipeline to the nearby platform.
So you now you know when I say we are laying pipe that's what we are up to
Good night and wild dreams
Bentley
The numbers
The longest pipeline I have done on here was 140 kilometers at 2 kilometers a day.
That was a 32 inch gas pipe line and each 12.5 meter length was about 1500 quid.
That was 16.8 million for the pipe itself and @ 250,000 a day for us to lay it = another 16 million.
There would have been all the survey work beforehand and then their is the flotilla of vessels that support us and on and on it goes.
The pipe line would have been in profit within the first 6 months of flowing.
:shock:
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