Escaping Steam


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Jemma Hyder

Guest
This may appear a minor and somewhat trivial question, but when the funnels started letting steam the noise was awful. Is there any technical way, if he had wanted to, in which Captain Smith could have had them quietened them down?
 

Dan Cherry

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Dec 14, 1999
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Only if he wanted the engines started up again. With the engines shut down, no steam was needed, and with the steam pressure building up in the boilers, this pressure had to be released. Since it couldn't be put through to the engines, it had to go out. Hence the deafening roar of steam roaring from the funnels. Once the boilers were 'cold', the venting stopped, and it would have taken some stoking and time to get the boilers up to where the engines could run at speed again.
 
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Jemma Hyder

Guest
Thanks Dan, Do you have any idea how long the steam would have come off the funnels, do you think it might have died down towards the end?

thanks again

Jemma
 

Dan Cherry

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Dec 14, 1999
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Hello, Jemma,
I don't have an answer for you on how long the steam came off the funnels. Someone who knows what the pressure would have been for an Olympic-class boiler at full steam and how long the steam would take to emit from the pipe vent configuration would be of more help. With no basis to prove otherwise, apparently the steam started venting after the Titanic made her last engine request for stop and continued during the uncovering and preparation of the lifeboats. Around one-half hour, perhaps????
 

Erik Wood

Member
Aug 24, 2000
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When you dump a steam system it doesn't just stop. It trails off. Notice though that on that night just before the lifeboats where lowered the steam venting stopped, no trail off.

I wonder what that could mean??
 
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John Meeks

Guest
Presumably someone shut-off a valve or two, before he 'legged it' up on deck?

I trust the boilers were damped down somewhat before he did this....

Regards,

John M
 
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Alex Twitchen

Guest
Whilst I have little knowledge concerning technical matters relating to steam ships, I have an interest in steam railway locomotives and therefore have some knowledge about the working of safety valves on steam boilers.

I assume (dangerous though that word is!) that steam ship boilers must have been equipped with safety valves which would have opened automatically to vent the excess steam once the engines stopped. These would also have closed again automatically and quite suddenly once the pressure dropped to a 'safe' level. Hence no trailing off.

On another point mentioned above, It would seem to me that to calculate the length of time it would take for the steam to stop it will be necessary to also calculate the rate at which steam is still being generated by the cooling boilers. Certainly in the case of steam locomotives, steam production does not cease as soon as you stop firing and damp down.

No doubt those of you who know far more about ships than I will explain to me the flaws in this theory and I look forward to being educated, however the description of events given above does suggest the working of safety valves to me.

Regards

Alex
 

Erik Wood

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Aug 24, 2000
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I think Alex may have hit upon something in regards to safety valves. What we don't know though is what boiler rooms did the steam come from. I think we could safely assume one of them was Boiler Room 6. Modern ships have safety valves to prevent an over heating boiler or the pressure rising above a certain level.

Hopefully Mark C. who knows a lot about the Olympic Class Liner will be able to help us. Being on the road doesn't enable me to bring my resources with me.
 

Cal Haines

Member
Nov 20, 2000
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Tucson, AZ USA
Alex,

I agree with your post. What's interesting about Titanic is that she had a full head of steam and then stopped abruptly. Scotch boilers do not reduce steam production rapidly, so one would expect the safeties to lift almost immediately. However, Lightoller and others indicate that half an hour or so elapsed from the collision until steam was vented. According to the BOT report, Titanic was fitted with a "silent blow-off", but I haven't been able to find hide nor hair of it elsewhere. It does not appear on the engine room diagram (as best anyone can tell).

Cap'n Erik,

I really don't think that BR#6 had time to blow off steam. According to Barrett and Hendrickson, it flooded very rapidly. It takes time to lift the safeties by hand, and when the lead stoker and the senior engineer beat feet out of the boiler room, I doubt the stokers were far behind. Especially since there was much superstition (unfounded as best I can tell) that the boilers would blow if the boiler room flooded.

We do know that by the time they could get lanterns into BR#5 the water in the boilers was below the glass. That would certainly be a good reason to blow off the boilers in #5. Had Titanic survived, I doubt the boilers in #5 would have been used again until they could be thoroughly inspected.

Cal
 
A

Alex Twitchen

Guest
Capt. Erik, Cal, Tom

Thank you for your responses.

I would have thought that in the event of all engines stopping the safety valves would open fairly quickly upon all of the lit boilers as the engines must have been the main 'consumer' of the steam generated by all of the boilers.

This assumes (not that word again!) that each of the boilers was fitted with a safety valve. If not, I am very glad that I did not spend any time in a boiler room of that period.

Steam railway locomotive boilers were fitted with automatic safety valves from at least the 1820's. The reason being that a steam boiler is basically a sealed vessel with an inlet for cold water and an outlet for steam. Applying heat the vessel causes the water to boil, creating steam. With the outlet closed the steam remains in the vessel gradually pressurising it. The more heat applied the greater the pressure in the vessel. So unless the outlet is opened to allow the steam to escape through the engines (or other steam powered equipment) the pressure in the boiler will keep rising until BANG! A very messy explosion.

The safety valve prevents an explosion by opening automatically when the pressure in the boiler reaches a predetermined maximum safe limit, exhausting the excess steam pressure to the atmosphere.

Again I can only apply my knowledge of steam locomotive boilers to this discussion. Please therefore forgive me if I am wide of the mark, but as the opening of the safety valves would be automatic, I can see no reason why they would not have activated in the flooding boiler rooms just as they would in those that remained dry.

If there were no safety valves, and no other means of venting steam the boilers would have exploded, cold sea water or not.

Although, as I keep saying, I am no expert, I have been 'lurking' on this site for several months now and one thing I picked from another thread somewhere was the possibility that Titanic continued under steam for a period of time after the collision. This may explain the time difference between the collision and the venting of steam. Comments please.

Turning to the condition of the boilers in BR#5, again only applying my knowledge of locomotive boilers, the last thing that you would do with a locomotive boiler if the water was below the glass would be to blow off the boiler.

As the water level in a boiler drops, due to the escape of steam, either throw use in the engines, or via exhausting it is necessary to replenish the boiler via the injectors. Therefore the response to discovering low water levels in locomotive boilers is to open the injectors and not to vent steam. When a boiler runs dry, it cannot generate any more steam, so there is no risk of a pressure explosion. If however, heat is still applied to the boiler this heat will be absorbed entirely by the boiler itself rather than the water and this will cause distortion and eventually destroy the boiler.

I therefore agree with Cal that any boiler that is discovered to have run dry would not be serviceable without thorough inspection.

Capt. Erik the simple answer to your question "Why was it dumped?" is:- to stop the boilers going BANG!

As you cannot stop steam production instantly when you stop the engines the steam has to go somewhere and if left to its own devices it will eventually find a very messy way to escape from the boilers.

In answer to Tom's question, it may well have been possible to exhaust a small amount of the steam through various other pieces of steam operated equipment on board, including the condensers. The boilers however, were primarily designed to supply the huge quantities of steam required by the engines. Therefore even if every other steam consuming piece of equipment on board was working flat out I cannot see that it would have a great deal of impact upon the quantity of excess steam the boilers were generating after the engines were stopped.

Sorry if this post is a bit long winded, but, having been 'lurking' for months, a topic has come up to which I feel I can contribute a little and so I have probably got a little overexcited.

Regards

Alex
 

Erik Wood

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Aug 24, 2000
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Alex,

I am familar with the safety of in which you speak. I think in a different thread some where it was pointed out that the steam could be pushed aft through the condensors so that a big "blow off" like what occured on Titanic wasn't needed.

I do understand that steam production just doesn't stop when you close the dampers. My question is, is why did they find the need to dump it when they did if they could push it back and do a silent blow down??

Maybe my pipe if full of things other then tobacco. But I thought we hinted around this somewhere else. Perhaps Mike can help me. Didn't we discuss the valves in another thread???
 
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Alex Twitchen

Guest
Capt. Erik,

I have found a discussion which may have been the one you are referring to on a thread entitled "What If?" archived 2 March 2002 there are posts on this subject dated Nov 2000. (Sorry I can't work out how to post the address).

I having read the posts on the older thread written by people with a vastly superior knowledge than my own and re-reading the above posts I now think I understand the comments a lot better. Many apologies.

The use of condensers in association with the engines is not something that I had previously considered. It had not occurred to me that it would be necessary to recycle boiler feed water on a ship floating in gallons of the stuff. Thinking about it though, I dread to think what would happen to a boiler fed on neat seawater.

It was suggested on that thread that the condensers were not designed to cope with the vast quantities of high pressure steam in the system when the engines are stopped suddenly from full speed, leading to the pressure in the boilers rising and opening the safety valves.

Could it be therefore that the safety valves, being a last line of defence as it were, vent directly to the atmosphere through the funnels?

I could not find an answer to this on the previous thread.

Thus when the engines stopped there would be a delay until the point is reached where the condensers cannot cope with the build up of steam. The boiler safety valves then open venting the excess steam up the funnels until the rate of steam production reduces to the level where boiler pressure drops. This would cause the safety valves to suddenly close again when the rate of steam production drops back to a level at which the condensers can cope.

This theory seems to fit the observations but does it fit with the technical aspects of Titanic’s design?

I look forward to learning more from you and the other experts on this fascinating web site.

Regards

Alex
 
Oct 28, 2000
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Just to stoke the fires of this conversation--all of the attention here has focused on the boilers. However, we have a couple of other factors that must be considered. One is the evidence that one (or more) bulkheads were in the process of failing. Couple this with the main steam pipes that pierced those bulkheads and you have a new situation. The severing of a main steam pipe would be functionally the same kind of disaster as a hole in a boiler. I also find it curious that the venting of steam seems to have been confined to the boilers in #5 and #6.

-- David G. Brown
 

Erik Wood

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Aug 24, 2000
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Dave you better not be giving away eggs. Dave has a point, something else that will be discussed in September.

Alex said:
quote:

Could it be therefore that the safety valves, being a last line of defence as it were, vent directly to the atmosphere through the funnels?
That makes sense to me. Where is Mark C.????​
 
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Alex Twitchen

Guest
A very interesting point Mr Brown.

A severed main steam pipe would certainly lead to a vast quantity of steam wanting to exit the boiler room rather rapidly and up the funnels has got to be an option.

However, I would have thought that such an escape of steam would tail off as the boilers emptied rather than abruptly stop as mentioned earlier.

Regards

Alex
 
S

Scott R. Andrews

Guest
Alex said:


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quote:
Could it be therefore that the safety valves, being a last line of defence as it were, vent directly to the atmosphere through the funnels?


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All the Best,
Capt. Erik D. Wood


Erik and Alex,

The safety valves atop each boiler were connected to an athwartship manifold pipe running to the centerline of the ship above the boilers. This line of piping was increased in bore at each connection, and terminated at the base of a vertical pipe which passed upward through the boiler casing. The steam escape pipes - one for each boiler room - were run up the fore and aft faces of funnels. (As I mentioned in another thread, the escape pipes on the No. 4 funnel were functional as well, serving to vent exhaust steam from the auxiliaries when it was necessary to operate this machinery in the non-condensing mode, such as in dry-dock.) As Alex states, the safety valves were automatic in normal operation, but hand gear which was operable locally operated at the valves or remotely from the firing aisle below was also fitted (in naval vessels and in later merchant ships, it was common to also provide a means of operating the safeties from the bulkhead deck as well). In regard to Alex's earlier questions, both the automatic safety valves and the manual override of them were manditory requirements from both Lloyd's and the BOT.

I know Cal has been looking at the available drawings for the "silent blow-off" piping without success; I haven't been able to find anything either. Now this is only my opinion, but I don't believe that such as system was intended for handling any large scale dumping of steam, but rather the normal "popping-off" that occured during slow speed manuevering or sudden changes in demand. For one thing piping of the sort of capacity for a wholesale emptying of any one boiler would be large enough to stick out like a sore thumb on the drawings and, for another, dumping such large quantities of steam directly to the condensers would render them ineffective within minutes, making the provision for dumping any really large amounts of steam directly to the condensers pointless.

Regards,

Scott Andrews
 

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