Tores mailbox VIIC and VIIC/41 operation and technical details

[tore]

Simon.
You have probably seen it, but anyhow below is the drawing of the emergency ventvalve fitted directly on the ballast saddletank. The intricate coolingpipe arrangement for the group exhaust valves follows this evening my time, I believe the explanation and solution of the cooling water shut of valve has been found just minor details remains.
Tore.

[SnakeDoc]

Hi Tore,

The fuel/ballast tanks no 2 port and starboard have a residual venting. The venting of the fuel/ballast tanks are usually operated from the controlroom. In the fuel mode the ballasttanks 2 and 4 port and starboard are separated by gatevalves operated from deck. However the venting ducts have an emergency shut valve Right at the merger of the ventduct and the saddletank. The philosophy is that in case of damage to the ventingducts you should shut the the emergency vent valves to save the buoyancy of the saddletanks. The same philosophy must be valid for the residue venting as well, but I have found no mentioning in the literature of these emergency valves in the aft part of fuel/ ballast tanks 2 port and starboard. My conclusion is nevertheless: the purple elaborate and important valves are the emergency shut off valves for the residual venting duct of the fuel/ballasttanks 2 port and starboard. As a proof I show a picture of the emergency shut of valves for ballast/fuel tanks 4 port and starboard operated from the controlroom, as you see they are identical only the handle is removed.

I like your explanation very much. Here is another photo of the emergency vent of the Tauchbunker 4:



What wonders me, is that on the "vent diagram" (http://uboatarchive.net/U-570Plate16.htm) the residual air vent duct has no emergency vents. Also, in the description of the Tauchanlagethere is said:

An den Austritten der Entl

[tore]

Maciek.
I agree with you, the gate valve is probably fairly close to the ballasttank anyhow. As you have evidence in the original Tauchanlage text I believe we now finally have come to the final correct arrangement.
Tore

[tore]

Simon.
The last and may be most complex item on this topic is probably the group exhaust coolingwater piping. The system sketches gives the impression that the internal coolingwater system is subjected to full seawaterpressure which is an impossibility. Based upon limited available sketches and photos I have have made the following proposal: It is a shut of seavalve fitted on the group exhaust valve housing at the side of the double walled drainspace. On the u historia photo of the group exhaust valve,  it is the biggest valve having pipeconnection marked 6. The double walled cast steel group exhaust valvehousing  can for sure  take the max seawaterpressure. All the other items in the internal coolingwater system you want to have behind this shut off valve. The more flanges packings and stuffingboxes which are subjected to exessive pressure the more risk you have for serious or even fatal leakages. The  valve housing consist of 3 parts, the main housing, the endcover and an exhaust manifold transmissionflange. The latter two have to be cooled as well and as they should be behind the main seavalve, it would require some unusual pipings. On the sketch below you see my proposal, the only pipe I have not been able to get confirmed is the top pipebend for the coolingwater from the exhaust manifold to the transmission flange.
As so many times before the real execution deviates a bit from the systems sketches, they just show the principle, not the execution. I have to finish off with my reservation: this is a proposal.
Tore

[NZSnowman]

Simon.
The last and may be most complex item on this topic is probably the group exhaust coolingwater piping. The system sketches gives the impression that the internal coolingwater system is subjected to full seawaterpressure which is an impossibility. Based upon limited available sketches and photos I have have made the following proposal: It is a shut of seavalve fitted on the group exhaust valve housing at the side of the double walled drainspace. On the u historia photo of the group exhaust valve,  it is the biggest valve having pipeconnection marked 6. The double walled cast steel group exhaust valvehousing  can for sure  take the max seawaterpressure. All the other items in the internal coolingwater system you want to have behind this shut off valve. The more flanges packings and stuffingboxes which are subjected to exessive pressure the more risk you have for serious or even fatal leakages. The  valve housing consist of 3 parts, the main housing, the endcover and an exhaust manifold transmissionflange. The latter two have to be cooled as well and as they should be behind the main seavalve, it would require some unusual pipings. On the sketch below you see my proposal, the only pipe I have not been able to get confirmed is the top pipebend for the coolingwater from the exhaust manifold to the transmission flange.
As so many times before the real execution deviates a bit from the systems sketches, they just show the principle, not the execution. I have to finish off with my reservation: this is a proposal.
Tore

Q. Tore, From your group exhaust coolingpipes a.jpg drawing you have drain line (Red) inboard and the crossover line (Orange) outboard (Top Drawing). This were a reason why have done it this way? As I would had imagine it was the other way, with the crossover line inboard and the drain outboard, as would used the minimum amount of pipe (Bottom Drawing).


Fig. 1. Cross-section with pipe layout.

[NZSnowman]

'T' handles hatches within the floor plating

Tore, look what I found today, you can see the handle


U-166 (http://www.mille-sabords.com/forum/index.php?showtopic=40300&st=175)

[NZSnowman]

Tore, slowly checking and updating the piping (colours piping).

[tore]

Simon
Coolingwater group exhaust valve drain.
If you look right down at the side of the E-room door I believe you find a drain collecting funnel for the drainpipes that`s why I put the drain inboards.
Tore

[tore]

Simaon.
T handles.
Very good, you realize of course the engines are not GWs.
Tore

[tore]

Simon.
Group exhaustvalve housing.
Very good you made a drawing of this item. If you check the u historia photo I believe you shall see the transferflange from the exhaustmanifold, having a smaller diameter than the inlet to the housing. A transfer piece consisting of two flanges having different diameter and a cooling waterspace in between is causing the complication. I have taken the liberty to mess up your nice drawing in order to explain what I mean. see the drawings below.
Tore

[tore]

Simon.
Group exhaustvalves.
Having received further pictures I have to revise my last theory slightly. The revised system drawing is shown below. I guess there is a small detail which may be a bit unclear, I don`t believe there is a connection at the crossing point, engine coolingwater pipe and the pipe to the drain- crossover selector cock. In fact on the photo the pipe is not shown, I am sure it is there but as a separate pipe going somewhere else. Otherwise I hope the sketch is self explaining.
I have again messed up your nice drawing in an attempt to show the complete arrangement. Most of the changes are based on photos and drawings. Otherwise the system is following basic requirements like keeping pipes, flanges, packing and stuffingboxes which are not pressureproof behind the main overboard seavalve. Further the coolingwater should go from low inlet to high outlet. The main coolingwater outlet from the engine is shown being a fairly large pipe, the full amount of coolingwater can not flow through the narrow coolingspaces of the transmission flange and end cover. They are cooled in series and the pipes are much smaller as shown, howewer the only connection not confirmed by documents is  the small pipe branch off from the main cooling waterpipe ( or exhaustmanifold) to the transmission flange. I have indicated two possibilities on the drawing. The system is elaborate and many pipes are stacked on top and behind each other, this is not easy to draw. The collection of valve and pipeoutlets, drains and vents is really cramped in the aft bulkheadarea  and would require another study I guess.
Tore

[OldNoob]

I am just blown away by the technical knowledge of the contributers on this forum.
I bet with everyones combined knowledge here we could actually build a real U-boat!
All we would need is a wealthy, slightly off,  financier like the gentleman building Titanic II, and lots of young muscle

Seriously though, just amazed by the information and knowledge contributed on this forum.

[TopherVIIC]

I am just blown away by the technical knowledge of the contributers on this forum.
I bet with everyones combined knowledge here we could actually build a real U-boat!
All we would need is a wealthy, slightly off,  financier like the gentleman building Titanic II, and lots of young muscle

Seriously though, just amazed by the information and knowledge contributed on this forum.

OldNoob,
I am not only blown away by the assembled  tech knowledge, but by the forensic  extrapolation we have been able to do with a truly limited set of input. There are only so many plans, so many period photos, only so many boats, and 1 Pajama-wearing Tore!

[tore]

Hi guys.
I have been through this before, graduating 60 years back as lieutenant (E) on Royal Navy's engineering training course on A,F, S and U classes of submarines in UK, coming home realizing I got a VIIC 41 totally different, with no contact with the germans and practically no drawings. One advantage to present days though, you was on board and could crawl,follow pipes and look at the items. Howewer the testing that your assumptions was right or wrong was slightly more exciting than experiencing the evaluation of my present days assumptions on this thread today.
Tore

[NZSnowman]

Tore, here the remaining of the engine exhaust, how does it look?