Deballasting vacuum

Mechanic-H
2nd July 2009, 12:21
I was on the mv King Charles(?) when the hold was being deballasted. Unfortunately the covers were on and the booby hatches were closed. The result was the entire collapse of the hatch covers and most of the comings.
I still have the pictures somewhere.

greektoon
2nd July 2009, 13:39
Cargo holds designed for carriage of ballast are usually fitted with vents on top of the hatch cover panels or off the coamings. They are designed to be opened manually or with float non return vent heads to prevent sea water ingress. In the former case there should be a big notice in the cargo control room and ER conrol room to that effect.

Would be interested to see your photos.

non descript
2nd July 2009, 13:46
A fascinating subject; all too easily done and a wonderful provider of work for not only ship-repairers, but also our friends the legal profession…. The process (of pumping out the ballast with the vents shut) tends to be self fulfilling in terms of creating the perfect seal on the hatch, for the more one pumps out the more airtight the hatch seal becomes.

I am far too polite to mention a certain Greek controlled ship that suffered a curious fate, not dissimilar to that of the Kind Charles… the result was amazing, but seemingly caused by little green men landing their space ship on the #4 Hatch, rather than the crew pulling a vacuum by failing to open the vents…. (Jester) It is quite surprising how much damage a small Martian can do to a hatch just by landing on it in the middle of the night.

greektoon
2nd July 2009, 13:53
Damn Martians!

Satanic Mechanic
2nd July 2009, 13:53
Very good Tonga - I liked that(Jester)

Of course filling tanks without opening (or at least checking) the vents can also be rather interesting.

non descript
2nd July 2009, 13:55
This images is of course NOT the one with the Greek ship... but it gives an idea of the resulting damage when one forgets.

non descript
2nd July 2009, 14:00
Damn Martians!

Well you have to hand it to them; they managed to not only select the only floodable hold to use as a landing place for their silent space craft, but they also got their craft to hit the mathematical centre, where the cross lines from each corner met in the middle of the hatch cover, so the creases almost spelt out the words “Fold here when you pull a Vacuum” – as you say, clever folk these Martians. (==D)

non descript
2nd July 2009, 14:05
The picture as a whole, showing the resulting damage... There are no spaceships left, as this is (i) not the ship but another one, and (ii) the space ship left almost immediately, so no one caught it on camera.

greektoon
2nd July 2009, 14:07
It is true that the terrific forces involved and potential for catastophic damage by over pressurisation or vacuum of cargo / ballast tanks is often not appreciated by ship's crews.

Satanic Mechanic
2nd July 2009, 14:08
The picture as a whole, showing the resulting damage... There are no spaceships left, as this is (i) not the ship but another one, and (ii) the space ship left almost immediately, so no one caught it on camera.


Yup - if that is not proof of extra terrestrial life I don't know what is.

The truth is out there

Satanic Mechanic
2nd July 2009, 14:10
It is true that the terrific forces involved and potential for catastophic damage by over pressurisation or vacuum of cargo / ballast tanks is often not appreciated by ship's crews.

I think it is fair to say that it seldom 'not appreciated' more than once. You don't forget damage like that in a hurry

non descript
2nd July 2009, 14:23
Yup - if that is not proof of extra terrestrial life I don't know what is.

The truth is out there

The Court were kind enough to agree that as the extra-terrestrial life had departed as quickly as they had arrived, no blame should be apportioned to them, as they were clearly unaware that the weight of their spacecraft was not only massively in excess of the permitted load on the steel hatch covers, but almost exactly equivalent to the outwards pressure brought to bear on the panels once about 1000 cubic metres of air had been removed from the floodable hold. If my memory serves me well, the man in the red dressing gown and white wig, was moved to say that in his opinion the Owners and the Charterers should be grateful that the Martians had gone home taking their space module with them, for leaving it behind would have most inconvenient at the very least, and a hazard to the stevedores at the next loading port….let alone the Seaman. (EEK)

Satanic Mechanic
2nd July 2009, 14:29
Slightly related topic, who remembers the RAF harrier that had to do an Emergency landing on a box boat?.

I never found out the full truth, but if the Old Man really did utter those magic words

"Lloyds Open Form"

You really have to take your hat off to him(Thumb)

Skye Sierra
2nd July 2009, 21:05
Slightly related topic, who remembers the RAF harrier that had to do an Emergency landing on a box boat?.

I never found out the full truth, but if the Old Man really did utter those magic words

"Lloyds Open Form"

You really have to take your hat off to him(Thumb)

The Harrier was "ZA176" and the ship was the Spanish Flag "Alraigo". Don't know about the LLoyds open form though - but sounds good. Various quotes put the recovery costs at about £600,000. Cheap at that!!

Roger

Billieboy
2nd July 2009, 23:55
The Harrier was "ZA176" and the ship was the Spanish Flag "Alraigo". Don't know about the LLoyds open form though - but sounds good. Various quotes put the recovery costs at about £600,000. Cheap at that!!

Roger

I remember reading, at the time, that the total costs of the operation were so high that the pilot was told, that the next time he planned to do anything like this, he should eject and let the plane sink. seems that there was too much salt in the engines and airframe, so the whole plane had to be rebuilt.(EEK)

McCloggie
3rd July 2009, 01:25
Very good Tonga - I liked that(Jester)

Of course filling tanks without opening (or at least checking) the vents can also be rather interesting.

Indeed. Bluewater managed to do this on one of their FPSOs (Uisge Gorm) a few years back with predicable results. The ship was taken to Rotterdaam and dry docked where the damaged tanks were cut out/replaced.

The tangled mess of steel had to be seen to be believed!

McC

Billieboy
3rd July 2009, 05:34
Indeed. Bluewater managed to do this on one of their FPSOs (Uisge Gorm) a few years back with predicable results. The ship was taken to Rotterdaam and dry docked where the damaged tanks were cut out/replaced.

The tangled mess of steel had to be seen to be believed!

McC

I seem to remember a stuck p/v valve, (it was said!), on Donax ? causing a little problem. They pulled a split in the bottom of a centre tank which was temporarily plated in Lyme Bay using Cox's gun and bolts, this was for strength reasons not water tightness. Whilst the temporary repairs were on going, a yard was building a new bottom section to suit, this was laid on the blocks after the old stuff had been removed and the ship floated out and back in, on her tank tops. The fit was quite good and the job finished inside the time quoted.(Thumb)

G0SLP
3rd July 2009, 05:59
I joined an almost new LPG/Ethylene carrier in the early 90's where a few weeks previously one of the upper wing ballast tanks had been badly damaged during ballast operations due to the tank air vent having been blocked by a plug of ice during a particularly severe 'cold snap'. Ouch...

Bill Davies
3rd July 2009, 22:35
Countless accidents have been recorded through improper use of p/vs. Some of the bad practices fell into common usage without real understanding.
Ore/Oil carriers were particularly susceptible to damage as so often the mates on board were not really experienced tanker or bulk carrier men.