1/700 LPG Carrier

[Neptune]

Well there it is. After sorting out my building mess I decided to go ahead with this one.
So I cancelled the Russian fleet project. Of course I'll keep whatever was finished, but the rest will be thrown away.
My last contract I was on an oddity at sea... The Donau. A sole ship of her class and very special for sure.
She was built in Germany as a Products/chemical/gas carrier in 1984.

I heard from Sean that this info might be interesting, so I'll give it.
Generally you have three very different types of gas carriers:
-LNG (Liquefied Natural Gas, @ -160�C) carriers with a cargo of Methane
-LEG (Liquified Ethane Gas, @ -105�C) carriers with a cargo of Ethane
-LPG (Liquefied Petroleum Gas, @ different temperatures), with cargoes of Propane, Butane, Propylene, Ethylene, Ammonia. Ammonia etc. are in fact chemical gasses, but due to their vapour pressure they are categorised under LPG.

LNG's are like the Excel which I built before. They are generally BIG, with a length of over 250m and a capacity of over 100,000m� . They are very actual. The tanks are made out of wood, with several barriers. The wood is made in boxes filled with Perlite insulation. On the inside the tank is coated with Invar, an extremely thin layer of a metallic substance which doesn't shrink or expand with temperature differences. The strength of the tank is made by the metal exterior. They have generally four big prismatic tanks without a seperation of Port and starboard side due to the tank's structure.
The other type of LNG has these big balls as tanks covered with a heath shield on deck. The balls have some advantages (less cargo surface, less evaporation) but for the same size of ship a prismatic tank ship has a higher cargo capacity.
Inside these ships they cannot reliquefy the cargo, so the cargo evaporates and this gas is sent either to the boiler in the engine room (for steam turbine, or straight to the engine as they now have piston engines which can burn gas) or just vented away.
If they want to cool down the tank they can use a sort of big ventilator to have a faster evaporation taking more energy from the liquid inside the tank.

LEG carriers are a little different as they have a stronger tank structure and are less big. THey are very rare though. Of course they can also take LPG cargoes as their tank can withstand temperatures of -105�C (and LPG is minimal -50�C)

LPG carriers, of which the Donau is an example are much smaller. The biggest, called VLGC (Very Large Gas Carriers) are 230m long and 36m beam with a draft of about 12-13m full load.
The smaller ones, the mid sizers are 150-180m long with a capacity of about 30,000m� and approx 20,000-30,000t.
Tanks are made out of low temperature steel with frames inside and are fully self-sustaining. They hang/inside inside the ship's hull and are supported by wooden blocks.
You can subdivide them into three groups.
-Fully Ref(rigerated), means they carry the cargo at atmospheric pressure and hence temperature of their boiling point.
-Fully Press(urised), means at atmospheric temperature and hence fully pressurised to keep it liquid (these ships are very small as the tanks have to be very strong to withstand the pressure)
-Semi Press/Semi Reg, means they cool down the cargo to about 0�C and keep it at the required pressure to keep it liquid (about 5bar for propane)

The Donau is one of the odd Semi Press ships. The tanks can withstand up to 5 bar, but she can cool down the cargo to carry it fully refrigerated, which she does.
The fully and semi Ref ships can reliquefy the cargo by sucking away the cargo vapours (hence reducing the pressure and creating more evaporation). Then this vapour is compressed, once or twice and expanded creating a sudden cooling. Then this reliquefied stuff is reinjected in the tank.

Here are some pics of the ship and the start of the model. I was onboard when I started the build. I don't have much time right now, so here are some pics. More explanations and pics will follow tomorrow. My next trip will be again on the Donau (normally), so I won't have problems finding reference material. Every modeller's dream I guess (althoug the ship herself must be every modeller's nightmare)

[ASFC]

Like all your scratchbuilt models a very fine model of an unusual subject.

[Dave Wooley]

Great subject and you have a good eye for detail .
Dave Wooley

[Cadman]

Awesome build Roel! Your scratchbuilding skills are greatly improved. It's cool that you are able to reproduce in miniature the ships that you sail on.

Oh and thanks for the technical explanation of tanker types. I tend to get them mixed up from time to time. There is simply not very much coverage of the merchant ships vs warships.

Stay safe out there.

[Neptune]

So let's continue.

The main problem for now is finding the colour Orange in modelpaint. The only orange I find is the Revell glossy paint, but I'm not really keen on using that. Anybody else found orange in another brand? I'm also waiting to get to the city to get some Humbrol red which would be excellently suited for the hull. On Excell I used a glossy paint and I'm not entirly happy with that.

So for the Donau, as you can see the deck is "Russian Red", the hull is brighter red, superstructure white and parts on deck are orange. This odd colour scheme is there because she was built as a products/chemical carrier rather than a gas carrier. Gas carriers often have light grey decks and pipes to decrease the heating of the deck and tanks.

As mentioned the tanks are independent, yet they stick out of the deck partially. On some ships they have two Domes. A Vapour dome situated on the forward part of the tank and a pumpdome situated aft. This is because the ship is more or less always trimmed on the stern, so the liquid will flow aft (easy for discharger when your pumps are there) and the vapour will move up and hence forward (so easier to suck away the vapour with compressors if the vapour dome is forward).
On other ships this is combined. For Donau, the vapour domes are the big circular things you see on the deck (the "tomatoes"), the pumps are mounted behind them but not really in a dome. The Tomatoes are also special for semi-press ships as the shape is dictated by the high pressures. On regular fully ref ships the domes are rectangular.

She also carries three deck tanks, these are normally used to carry small amounts of "cargo" or another cargo to gas in the tanks or cool them down after dry dock or change-over.
For dry dock a ship has to be gas free. That means the tanks have to be fully filled with ambient air and no flammable/toxic gasses should be inside.
A Change-over means you change from one cargo (say Ammonia) to another (say Propane), in between this change you will also be in the ambient phase inside to measure if all the old cargo is really gone.
After the dry dock or change-over you are going for a new cargo, so first you have to dry your tank (to make sure there is no water/moisture left that will freeze the pumps or valves) and then it is gassed in, meaning filled with next cargo gasses at ambient temperature. After that it's cooled down by spraying liquid cargo through a shower in the top of the tank. This liquid evaporates, taking heat from the surrounding vapour and so it is cooling down the tank piece by piece.
Normally a ship has only one or two deck tanks, Donau has three of them.
I was onboard and didn't have any sprue with me. So I had to find another solution. The diameter of these tanks in 1/700 is 4mm and 5mm, so I made a rectangular piece of styrene with this height and hte length of the tank. Then I made some "frames" and glued them on this rectangle. So it's made much like the ship's hull itself.
After that I filled it up with Milliput and sanded it to shape. untill I had the frames coming out. I needed those frames since I don't know if you can glue styrene to milliput. When I had the cilindrical tanks, I still had to attach the supports of these tanks, and that's where the styrene frames play an important role. They were placed where the supports should be, so I could stick the supports on these frames with regular styrene glue.

So here are some more pics. The real thing first, and the reason why this will be a headache!
The green parts in front are the top of the decktanks. The "catwalk" is the path leading from aft to forward on top of the pipes etc. It's a safe way in heavy weather to get somewhere. You can also see the white cabins near the catwalk, which serve to hide from any rain or green water when going forward or working nearby.
The catwalk here is unusually high, same for the pipes. Normally they are only about 2-3m above the deck. On Donau it's about 6-7m because everything has to pass on top of the deckhouse. On other ships the deckhouse is much smaller and the pipes are passing around it.





And the decktanks, one big and two small ones. They are not yet fixed since I'm waiting to find the Orange. Only after that I can really continue with the build. I also put the winches in place now, so everything is ready to start one layer "up" with the pipes and supports (which I intend to make out of PE since styrene is too "big" for this.

[Cadman]

Wow, that's a maze of pipes! I am anxious to see how you replicate this.

[ASFC]

This is going to be something to equal the project those Mare Island blokes are doing in Picture Post thats for sure!

[Dave Wooley]

Stunning photos . But to replicate the pipe work at larger scales is a daunting task but at 1:700 is boardering on wizardry .
Dave Wooley

[Pieter]

Very nice built. I've seen a few similar ships last week when I crossed the Westerschelde last week (forgot my camera , grrrr!) and they are interesting to look at. One suggestion about the piping. They seem to be in the 0.3 to 1 mm range in 1/700 and run in straight angles. I would suggest you use 0.3 to 1mm steel rod for these (should be available in most hobby shops ) as they keep their straight angle once they are bent (unlike brass rod) and they are circular unlike PE. Prime them before you attach them to the ship and use a few layers of relatively thin paint when applying the orange so capillary action will pull the paint around them.

[Neptune]

Actually that range is 0.1 till 0.7. We don't have a 70cm diameter line onboard. Anyhow, I didn't plan to make all the piping 100% accurate. I'm not a wizard you know... I will have a look at that steel rod though, stretched styrene will be trouble to paint and glue without breaking, so something stronger would indeed be advisable.
I'll see how far I can get with accuracy on this one. On previous LPG's I said it was impossible to build them due to the pipes. Insane as I am I decided to build the Donau, with 10x as many pipes....
As for the PE, I'm not planning to make my own PE in the way of the Mare Island project. I'm just going to cut some PE sprues to bits and use these to create the support brackets etc. If I knew how to make accurate PE it would of course be a big help and probably a lot more easier/beautiful. But I'll see. First task is to find good orange paint!

[Timmy C]

Gunze Sangyo makes a glossy primary Orange in both their Mr. Hobby and Aqueous Hobby Colour lines. But like most primary colours, terribly difficult to brushpaint nicely.

[Rob]

Actually that range is 0.1 till 0.7. We don't have a 70cm diameter line onboard. Anyhow, I didn't plan to make all the piping 100% accurate. I'm not a wizard you know... I will have a look at that steel rod though, stretched styrene will be trouble to paint and glue without breaking, so something stronger would indeed be advisable.
I'll see how far I can get with accuracy on this one. On previous LPG's I said it was impossible to build them due to the pipes. Insane as I am I decided to build the Donau, with 10x as many pipes....
As for the PE, I'm not planning to make my own PE in the way of the Mare Island project. I'm just going to cut some PE sprues to bits and use these to create the support brackets etc. If I knew how to make accurate PE it would of course be a big help and probably a lot more easier/beautiful. But I'll see. First task is to find good orange paint!

Hi Roel - I did the pipework on a tanker from scratch. Nowhere near as complex as this lot but you should be ok with brass rod.

Cheers,

Rob k

[Neptune]

Thanks for the advice Rob, will try it for sure.

Currently I'm doing some small stuff. Under the motto: "always go one step further" in my builds, I've now drilled out the anchor winch wheel to mount the "chain" (piece of stretched sprue) inside the wheel and not on top as I did on the Excel. So now it looks a little more "advanced". I'm also painting the deck tanks and will mount them on the deck. I will also paint the winches and do some more detailing work on the foreward part.
I've tried to make a sort of frame to bend in PE, but that didn't work. So I started making more brackets of different sizes. I will then connect these brackets with longitudinal supports (hope that works) and after that I'll paint it and mount it on the deck.
I'm still looking for the orange paint, so I'm being "pushed" towards another build. I'll need Humbrol, so if any of you know where I can get those paints here in Flanders (or the Dutch Province of Zeeland), it would be helpful. For now I've always went to Antwerp, but that's a little too far from my place nowadays...

[Pieter]

't Hobbyhuis in Goes still stocks Humbrol , http://www.hobbyhuis.nl , and that's where my hobby/obsession/whatever started some err....25 years ago (guess I'm getting old). Which puts it just as far from you as Antwerp I think (unless you take the new tunnel) but it can be nice to look at another hobbyshop for a change.

[Neptune]

Yeah I bought my R/C gear there last year, transport for free if you let it arrive in the Netherlands. Through the new tunnel they will be much more expensive than anything from Antwerp (4.60 euro fee to pass that tunnel once and back, would make a total of 9.2 euro just for passing that tunnel, add the fuel and the two cans of paint I need will become very expensive ) I'll see. There is an R/C shop in Ghent, I'll check that one out too somewhere this week.

Here are the pics of the work I did yesterday. Slowly but firmly I'm advancing. Today I found out I have a shortage of PE framing to make all the supports. The forward part is nearly finished with frames, but there is nothing left for the aft part I'm affraid.

Now I also added the pieces of stretched sprue which have to represent the anchor chain and I also started painting the funnel and funnel casing. Sort of looks like a fast progress now .
It's all pretty straight forward, only few new things. I'll take a picture or pictures of the PE frames I'm making too.

[Pieter]

The new tunnel fees ... very deep sigh.......indicate something about the province of Zeeland. Zeeuwen have the same reputation in NL as the Scottish in the UK I'm afraid. Also like the scots they have their own ideas regarding those round traffic signs with a red border and black numbers like "50", "80" and "100" on it. The minimum speed -:). But I digress.....
Very nice anchor winch you're working on. I like the way it's been built up.

Yeah I bought my R/C gear there last year, transport for free if you let it arrive in the Netherlands. Through the new tunnel they will be much more expensive than anything from Antwerp (4.60 euro fee to pass that tunnel once and back, would make a total of 9.2 euro just for passing that tunnel, add the fuel and the two cans of paint I need will become very expensive ) I'll see. There is an R/C shop in Ghent, I'll check that one out too somewhere this week.

[Neptune]

Received the Albion stuff. I sent you a mail from a different adress since I have some trouble with the other one.

Here is some more progress. The PE supports would have been nice, although the glue wasn't holding anything and of course the short supply of PE brackets.
So, result, I decided to go for stretched sprue supports. I compared the size of both and figured out that in one way the stretched sprue is finer than the PE brackets. As you can see I'll have a hell of a job and don't be ashamed to call me a nutcase... I know...
All the drilled holes you can see are for such supports.
In the meanwhile I've finished the anchorwinches, but when I started painting the winches I discovered that I forgot to mount the warping heads.
Bridge structure is not yet fixed since I'm waiting to finish it first. As you can see I've painted the bridge windows with stretched sprue (starts to work after some practice).
Anyways, this is the result so far.
I mounted the PE supports just to show the idea over the forward deck tanks. The sprue supports are already fixed, I'll just have to wait for the paint to continue.

[Neptune]

here is the bridge and an overall view with all the pieces in place. The catwalk are the two PE parts going from aft to forward. I still have to make some additional parts for it though.
I did forget to drill most of hte holes through the tank dome platforms though. So I'll have to do that and be very accurate at it. Aft I still have to drill the holes, so I'll put the platforms in place aft and after that drill the holes. I won't glue them yet though since they have to be a little off the deck. (0.5mm).

[MichelB]

Looks good!

[ASFC]

Ditto