Restarting Titanic's Engines

[Dave Gittins]

There's a bit of evidence that, after the collision, Titanic's engines were stopped and then briefly run again. (I know, it's all very vague)

A little bird in what passes for my brain keeps telling me that somewhere I've heard a perfectly sane reason for this. I can't place the source. It may have come during a recent excursion on a steam tugboat. (Lucky me!)

I'm sure somebody explained that when a reciprocating steam engine stops, it is necessary to see that all the steam is cleared from the cylinders. If it condenses in them, bad things happen when the engine is restarted.

Would any expert like to comment on the idea that this may explain why the engines would briefly be turned over after the sudden stop?

 

[Samuel Halpern]

There are small valves called cylinder drains to let the water out as it forms in the cylinders. When steam enters a cold engine, much more of the steam will condense until the valve chests, valves, cylinders and pistons heat up to the temperature of the steam. That will make a lot of water in the cylinders. If that water is not removed, it could great damage to the engine. The cylinder drain cocks at each end are opened to let the water out until the engine gets up to working temperature. These are also opened when the engine is stopped.

In starting a reciprocating engine, it may be that the piston valve for the high pressure cylinder was in a lap position when the engine stopped turning last. In that case, the engineer can open bypass valves to let a little high pressure steam into the valve chests of the other cylinders to get the engine moving. Once the engine is turning, the bypass valve is closed to stop wasting high-pressure steam in low and intermediate-pressure cylinders.

To get an idea of what it takes to start up one of these multiple expansion reciprocating engines, here are the steps taken from an old US Navy operations manual (http://www.usstexasbb35.com/history_of_steam_engine.htm):
-Inspect engine and auxiliaries for security of holding down bolts, tie rod nuts, keepers, set screws, split pins, and oiling gear, etc.
-Remove bearing gaskets and temporary covers. Clean piston and valve rods of all oil and dirt.
-Jack engine at least one complete turn. (this was done by a 15 horse power electric motor attached to a gear and later removed prior to starting).
-Disconnect Jacking gear.
-Open main injection and discharge valves.
-Start independently driven main circulating and air pumps.
-If these auxiliaries are direct connected, start the auxiliary means of circulating water and pumping channel ways.
-Crack air cocks on the condenser to insure against its becoming air bound.
-When sufficient vacuum is formed, turn auxiliary exhaust not being used elsewhere and drains not needed for feed heating into the main condenser.
-Open full and then close main and maneuvering throttles and by-pass valves.
-Drain main steam separators.
-Open main line stop from upper station.
-Open main engine cylinder, valve chest, throttle, and jacket drains.
-Start warming up main engine by one of the methods previously described. As the steam pressure rises, manipulate the throttle and by-pass valves so as to prevent too much pressure in the engine.
-Open steam and exhaust root valves to reversing engine.
-Warm up and drain reversing engine and throw the links over every few minutes.
-If so fitted, try out hand-reversing gear.
-Turn steam on throttle balance if so fitted.
-Put pressure on water service.
-See circulating water on water-cooled surfaces such as guides, thrust, and main bearings, and inspect for leaks.
-Run links out to maximum cut-off.
-Slack stern glands enough to allow a trickle of water to come through.
-With gravity lubrication, remove oil cup covers and blow out oil lines with steam or air, fill oil manifolds and inspect the wicks.
-With forced lubrication system, test out the system by starting lubricating and cooling pumps and inspect to see that there are no leaks or closed valves and that all the bearings are getting oil at the proper pressure. Shift and clean the basket strainers several times before getting underway.
-See that the splash casing and oil deflectors are in place and secured.
-Assemble hand oiling gear, including rod swabs.
-Assemble emergency tools and wrenches.
-See that all tools and loose gear are secure for sea.
-Close by-pass valves.
-Rock engines, with the links and throttle to work out water.
-About 15 minutes before the time set for getting underway get permission from the engineer officer of the deck to try the engines.
-With gravity lubrication, hand oil all around.
-Try engines, making not more than two turns each way before reversing so as to get no way on the ship. While turning over slowly see that all moving parts operate properly.
-Turn steam on gland seals and see that the drains are open.
-Build up vacuum, minus 14 psi.

 

[Steffen Reichel]

Well, I knew those drain valves as 'drain cocks' because valves were large types, usually used to adjust pressure and pass-through, not only as a 'cutt-off'. While cocks are smaller, those little ventiles only knew two possitions: Open und Close.
Usualy cocks were lever operated, lever angle 90° Close, 0° open. Also there were spring loaded cocks, like grease cocks, which blocked steam from steam engines to enter the oil and grease lines.
And there were several 'drain cocks' in steam engines. Spring loaded, self opening 'drain cocks' were commonly found on auxillary engines, like steam propeller water pumps or steam driven air compressors.
So my question for this is:
Did Titanics huge main engine got self opening drains, or were that automatically opening and closing drain valves, or were there manually operated drain valves mounted? In railroad steam engines, most cylinder drain valves were manually operated, but I've seen in marine engines self-opening drain cocks, which were closed be steam pressure entering the HP chest and forcing a control valve to close, thus closing all drain valves.
I've never seen spring loaded drain valves on any common engine, only toy or modell engines got such drain valves...


BTW: The starting valves... Dear Samuel Halpern,
all compound engines, usually all triple or quadruple expansion engines I found had starting valves. Only a few require a starting possition, like 5° after top lap possition HP cylinder, but most steam engines with a direction and expansion control linkage had starting valves. Self operating valves, like Maffei, Brown and DEMAG were found, als linkage controlled starting valves. Linkage controlled starting valves opened, if the linkage was forced to full steam, around 80%. In common operation, even if all ahead was commanded, the linkage was not set to more than 75%. This means 75% of the piston ways steam could enter the cylinder, making only around 10-20% way expansion power, thus putting nearly full boiler pressure and boiler load onto the piston. Very cruel power output, but not very economical. So 80% was only a possition to start the engines. Here starting valves were opened, letting about 25% HP steam to lower pressure valve chests, like IP and LP cylinder, making them do the first motion, after the first round, or first half round, the engineer will adjust the linkage, 'pulling back' to approximately 60%, forcing the linkage controled starting valves to close.

Also I found procedures, which could be used to preheat the cylinders:
Starting valves were opened, by forching the linkage to 80% (starting valves open) or manually schedule. Then main steam valve was opened to preheat possition, so only little steam entered the engine, to less to force it move, and the steam was exhausted throught the drain valves.
During this process, the linkage was inspected, and set two up to five times from full ahead to full astern, making the preheating steam entering both sides of the piston and preheat the engine.
Large engines also had speciall preheating valves, which are used to avoid much condensing of the steam during the first time of motion, and aviod water hammer damage.

 

[Aly Jones]

How long did it take for the Titanic to start moving after the command of full steam ahead at the start of her maidan voyage?
(Meaning when the first lots of coal are place in the boiler's)

example- Seconds, Mintues or Hours.

 

[Samuel Halpern]

Alyson, if you are asking how long did it take from when a boiler was first lit up to when enough steam pressure is built up so it could be put "on line" to the engines, then you are talking about 12 hours, give or take a bit.

 

[Aly Jones]

12 HOURS to start up Titanic. So if captain Smith wanted to sail at 12.00 midday,he would have to send the command *Full steam ahead* at 12.00 midnight?

 

[Michael H. Standart]

>>So if captain Smith wanted to sail at 12.00 midday,he would have to send the command *Full steam ahead* at 12.00 midnight?<<

Not quite.

What happened was that at a specific time before getting underway, the boilers would be lit off and the fires built up. The water takes a lot of time to reach the temperature at which it would flash into steam. The idea was to build up a full head of steam so you could run the engines.

I'm not sure how much water the boilers could hold, but it took quite a bit of time to absorb enough thermal energy to boil.

 

[Aly Jones]

Ok Michael. All this as been done,all the boiler's have been lit and there is enough steam and water.When Captain Smith order's *full steam ahead* How long would it take for Titanic to start taking off?

Seconds,Minutes or Hours?

 

[Michael H. Standart]

>>How long would it take for Titanic to start taking off?<<

She starts moving from the time the engines had steam supplied to them, which is to say almost immidiately. There would have been a time lag of several seconds because steamships don't have direct throttle control, but the engineers were plenty fast enough to make things happen.

 

[muzza]

Being an ex Navy steam engineer it takes anywhere from 4-8 hours to start up a steam ship from cold, firstly you need to slowly raise steam in the boilers as you are doing that you warm through your steam systems- main steam lines, drains and aux systems. Once the systems are hot and expanded correctly the main engines are normally tested at a low ahead and astern rpm to ensure all is ok then the engines are ready to go and the full head of steam could be applied at anything from then basically. The engines have drains on the cylinders which would be left cracked open and the engines would have a very and I mean very small amount of steam admitted the propellers would only be turning a few rpm if that this keeps the engines ready to go or evenly heated and expanded so they can go at a moments notice reciprocating are easy steam turbines are even move critical they cannot sit stationary for more than a few minutes at operating temperature otherwise you will have problems with the turbine shaft as it will bow and bend or as it is correctly termed hog and sag.

 

[lemarlù]

The engines have drains on the cylinders which would be left cracked open and the engines would have a very and I mean very small amount of steam admitted the propellers would only be turning a few rpm if that this keeps the engines ready to go or evenly heated and expanded so they can go at a moments notice reciprocating are easy steam turbines are even move critical they cannot sit stationary for more than a few minutes at operating temperature otherwise you will have problems with the turbine shaft as it will bow and bend or as it is correctly termed hog and sag.

That's the reason why, I think, the Titanic was fitted with a low-pressure turbine at the center. Just to keep a minimum steam flow alive when sitting at the docks and obviously take extra speed from it when sailing. It's my opinion though.

 

[Doug Criner]

I believe you are misinformed. The center turbine only operated when the two wing recipts were at least half speed. It would not have been operated otherwise.

 

[Michael H. Standart]

>>Just to keep a minimum steam flow alive when sitting at the docks...<<

There would be no need of a turbine to do that. Steam service would have been plumbed to wherever it was needed on the ship independently of anything to do with propulsion.

 

[Jim Currie]

Most ships had a 'donkey' boiler for port operations. Steam was neaded to drive auxhiliary machinery such as feed,sanitary, bilge, ballast and FW pumps as well as mooring and cargo winches. Many ships had 'turning gear' which was engaged in port to turn the main engines a few revolutions and ensure them free and operationg smoothly for when needed.

The Turbine was only used for ahead movement and when the main engine rpm exceeded 50. See Sam Halpern's extensive work on this subject.

 

[lemarlù]

I believe you are misinformed. The center turbine only operated when the two wing recipts were at least half speed. It would not have been operated otherwise.

Interesting. Didn't know how it worked exactly.

There would be no need of a turbine to do that. Steam service would have been plumbed to wherever it was needed on the ship independently of anything to do with propulsion.

Yeah, if used like I said, it should have been a useless waste of space inside the engine rooms indeed. And just to let the steam go somewhere.

Many ships had 'turning gear' which was engaged in port to turn the main engines a few revolutions and ensure them free and operationg smoothly for when needed.

I had a similar idea. That's why in my mind I believed a bit of steam was admitted to the turbine, also for this purpose.But it was my mistake.