Thursday, 14 April 2016

ENGINE STRAIN COULD EXPLAIN EVERYTHING.

Waratah's twin quadruple expansion engines were complex beasts: 

The enormous weights reciprocating at high speed imposed severe stresses on all parts and imposed great vibrations onto the ship’s hull. Naval acceptance trials, where the engines were driven as hard as possible to demonstrate that the ship reached the required speeds, produced hair raising stories. Not only the noise and heat, but the air filled with water and oil vapor, the intense vibration, the water flung about because some bearings required cooling water hosed upon them, all contributed to a modern vision of Hell.

The engines relied on five steel boilers, combined, having a working pressure of 215 pounds / sq.in. - 43 per boiler. 

It was impossible, 1909, to make cylindrical steel boilers absolutely immune to explosion. In practice everything was done to minimise this risk. In addition to constructing these boilers with the water space divided into sections - preventing general explosion - these boilers needed to be constructed of finest materials and the best of workmanship. Immediately, my thoughts return to:

'Weight is leant to the optimistic opinions of her owners by the
assurances today of Mr. C. S. Richardson , a marine engineering expert ,
who was a passenger to Durban , by the Waratah
on an official mission on behalf of the Geelong Harbour Authorities.'

'He states that it is possible that the steam main pipe is ruptured , and criticises the
steel steam pipes with which the Waratah is fitted instead of copper.'

"The Waratah did have one small repair carried out here, but it was of so insignificant a character that the cost did not exceed 3 pounds 15 shillings.  Mr Booth (of R Booth and Son, engineers, Greyville), who effected the repair, as being the removal of a suction pipe from one of the auxiliary feed pipes, from what is known as the Weirs pump to the heater, which raises the temperature of the condensed water preparatory to its being fed again into the boilers."

"The job was quite a small one, and was needed owing to a fracture which having occurred in the pipe - a copper one - due to a flaw in the metal. This took place some time before the steamer's arrival in Durban, on the voyage from Australia."

Two problems existed in the heat transfer system (including super-heating) which predated Waratah's final voyage. Mr. Richardson criticised the use of steel instead of copper, suggesting that problems with corrosion of steel (along lap joints), exposed to steam and water, could result in fractures and explosions. 

The problems did not stop there with copper used for auxiliary feed pipes found to be flawed - similarly exposing the system to the risk of explosions. Durability and reliability of materials used in this system were crucial to the safe operation of complex steam engines. Flawed metal could be susceptible to unequal expansion, rupturing at random junctures. 

Both the above mentioned short-comings also point to a steamer 'built on the cheap', further confirmed by the overall inadequate power of the system for a steamer of this size and weight. 

Boilers were generally run at a higher pressure than the working pressure of the engines. This was controlled by reducing valves and again another weak link in the system identified if these reducing valves were not constructed of quality materials. 

The engine system of Waratah needed to be pushed, 'pressed' in order to offset the inherent deficiency in power. This over-heating and over-pressurizing could have had catastrophic consequences, particularly if the system had flaws, which it did. If one or more boilers failed (ruptured) due to this over pressure, the rapid release of steam and water could have provided a very potent blast, causing significant damage to surrounding structures, including an over-strained hull. Some of this liquid could have flashed into forceful vapour as the pressure dropped. Rapidly expanding steam bubbles could have thrown large 'slugs' of water, similar to bullets, causing a further dimension of destruction.

In addition to a boiler explosion, there could have been a firebox explosion. Coal fumes could build up in the combustion chamber, and if there was overheating (likely), the coal fumes could volatize until the explosive limit was reached. Such vapours under these circumstances could have exploded. Such an explosion could also have caused the boilers to explode. 

Alternatively, a firebox explosion could have been caused by 'drumming'. Instead of the normal 'roar' of the fire, a rhythmic series of 'thumps' demonstrating that the coal was proceeding through a rapid series of detonations, caused by inappropriate air / fuel mixture ('pressing'), compounding the disaster.

A Waratah watcher Alan Patterson, suggested a scenario which could match the above disastrous sequence of events. If explosions had taken place in the engine room, there is a possibility that in addition to destruction - blowing Waratah's sides out, foundering within minutes - the explosions could have sent flashes of light up through the funnel, creating the phenomena described the crew of the Harlow. The sound of explosions in the engine room might have been absorbed by the surrounding structure and sea water. This might explain why explosions were not heard.

Under normal circumstances, boiler explosions were rare, but in the case of Waratah, her under powered quadruple expansion engines under considerable strain, there is every possibility that this scenario explains the final moments of the flagship, as witnessed by the crew of the Harlow.


  











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