You are correct, Robby. A great deal of nonsense and pontification has been written about the bunker fire in Titanic's bunkers.Regarding the issue of damage that the fire in Stokehold No. 9/Coal Bunker W (forward, starboard side coal bunker of No. 5 Boiler Room) may have caused to Watertight Bulkhead E between Boiler Rooms 5 & 6 I'm of the opinion that very little in the way of damage was sustained. Over the past year I've picked up a part time hobby of blacksmithing and have learned a little about the physical properties of metal especially when exposed to high heat. Mild Steel was used to form the shell plating which essentially made up the hull, bulkheads and subcompartmental partitions that formed rooms like the Coal Bunkers. Mild Steel has a very low carbon content. Steel with high concentrations of carbon is desirable because it's stronger and harder than mild steel. However, during the forging process steel alloys with higher carbon particle content has to be put through a heat treatment known as annealing . This is a process of allowing high carbon steel to slowly cool over several hours until room temperature once removed from the forge. If one where to remove a bar of high carbon steel from the forge and then suddenly quench it in water or even allow it to cool to room temperature with no annealing process it would become as brittle as glass. Since mild steel was used in the construction of Titanic's hull, bulkheads, and miscellaneous partitions there was no danger of brittling. You can heat and quench and heat and quench and heat and quench mild steel multiple times and it really doesn't cause the sorts of structural weaknesses many have speculated about Bulkhead E. Sure you can heat mild steel or any type of steel to white hot temperatures for too long and totally ruin the metal, but those conditions weren't reached.
I feel beyond a shadow of doubt that the wave of "green foam" and whatever else witnessed by 2nd Engineer Harvey and Fireman Fred Barrett in No. 5 Boiler Room as they were attempting to attach a set of non-collapsible "wandering hoses" to the bilge or ballast pump located at the central aft end of that compartment was Coal Bunker W's hatch door finally giving way. The immense pressure from the rising seawater of which it wasn't designed to hold back simply blew open allowing the flooded coal bunker to violently rush out into the main Boiler Room area of the compartment. The event was enough to cause both men to drop what they were doing and make their way up the escape ladder. In retrospect, probably the best thing to have done would have been to allow the ingress to pour through the open hatch door onto the Tank Top where it could then easily have been pumped out by the compartment's dedicated bilge pump previously mentioned. There were no drains to allow the ingress of seawater collecting in Coal Bunker W (or any Coal Bunker for that matter) from emptying into the main part of the Boiler Room where it could have been removed. Having said this it wouldn't have mattered one bit to the survival of Titanic.
BELOW: The situation at the time of final evacuation of No. 5 Boiler Room around 1:15 AMish...
View attachment 44962
For a start off, it was caused by spontaneous combustion...a process which does not happen instantly but is due to chemical reaction which takes place over a number of days. Here is the process:
Oxidation occurs when oxygen reacts with coal.
"The oxidation process produces heat. If the heat is dissipated, the temperature of the coal will not increase.
If the heat is not dissipated, then the temperature of the coal will increase.
At higher temperatures the oxidation reaction proceeds at a higher rate.
Eventually a temperature is reached at which ignition of the coal occurs. "
Ignition does not necessarily mean "bursting into flames". That will only happen if there is additional free oxygen. In 99% of cases, ignition occurs deep within the heap and is simply a hot glow. The trick is to keep air from it as long as possible.
The first sign of SC is usually localized heat. If the heating continues, the steel will eventually glow to a dull red colour. However, heat dissipates due to conduction by the surrounding steel-work, the hot -spot remains local and the steel temperature seldom gets above 649 C. Since Steel does not change it's molecular structure until it reaches 724 C, only localised distortion will take place. The danger from IC is not failure of the steel but ignition of adjacent inflammable materials such as cargo or more coal.
SC could never have been located, as has been suggested, at the shell plating...side of the bunker. Simply because any heat generated in the coal would have been carried away by a great heat exchanger called the ocean.
The daft notion that a black smear on the external surface of the hull was evidence of the fire is just that...daft. The claim was that a black smear on the outer hull was proof of the fire. The position of the smear in question was too high and to far forward and was probably a shoulder contact with a fender in the dry dock.
The top of the coal heap in the full bunker piled against WT Bulkhead "K" was at the water level in way of frame No.41... midway between funnels 1 & 2 Any SC fire in that heap started after the coal was loaded and would have been at a much lower level. It would not have started until the boilers were fired up and the bunker space started to heat up
I have seen many ideas on these pages but don't seem to remember anyone asking how the fire in the bunker space was originally discovered.
As I pointed out above, localized heat from an SC fire would turn steel cherry red. Since an SC by its very nature is buried, the only way it could have been discovered was by a very obvious smell of smouldering coal and a localised area of heat above the coal surface. This would not have been detected immediately but several days after the bunker was filled and the boilers were fired up.
As for distortion?
As I pointed out, the heat from an SC in a ship compartment... if occurring against a steel bulkhead...will dissipate by means of conduction. The effect on the structure depends on the structure itself.
The WT Bulkhead of a ship is very heavily strengthened by an increase in the plate thickness at its base and by closely spaced, heavy steel frames extending from top to bottom. In this instance the thinner parts...bulkhead plating... would heat up quicker and expand between the heavier frame. The result would be a bulge in the bulkhead plating between the frames... a "ding" as it was known as.