h2g2 The Hitchhiker's Guide to the Galaxy: Earth Edition

acquintance with wherein you spake,
but that experience with welding and welderers taught me something very similar to your comments.
There are good welders and then there are other people.

I have had no experience with rivets, but I watched with interest the recent re-manufacture of the Statue Of Liberty.

With regard to the Titanic, did it's sister ship have the same sort of rivets?
Was it just bad luck that the Titanic happened to hit the one thing it were vulnerable to?

Hi TR, It was not the rivets that they say caused the problem with the sinking of the Titanic, it was the fact that the ones fitted up near the bow of the ship had to be hit in place by hand, as the machine they had could not get into the confined spaces.
So it was the way they were "flattened over" and the time it took to do that by hand, that caused the weakness.

I know what you meant by good and bad welders, in my experience, where we were doing high standard work all the time, so every weld we did was X-rayed or U/Td, so once you reached 3 repairs, you were off the job, or
had to resit your welding test

In fact that was how we got that saying, "Hollywood Welders" as we called the X-rays "Films" so the saying was, "You are only as good as your last film"
Anyway, thanks for your post, it means a lot when you get feed back
Smudger.

Don't I know it. Sometimes it feels like I'm typing into space.

Then I get the shock of finding a comment on the bottom of my cartoons or column entries... and it doesn't really matter what kind of comment it is...

Shaz tells me that there are a lot of lurker who read our stuff, but don't feel... um... up to approaching the throne... or something like that.

The alternative is something I don't think about.

Hmm. So what kind of rivetting machine did they use on the rest of the ship?
Those hydraulic thingies they show in the old cartoons, with a spade handle on one end and a motion like a jack-hammer?

I shall have to look this up. What size where the rivets and how much thickness of plate did they have to go through?
Wouldnt't the flattening occur on the inward side?
And what sort of alloy were they using for the rivets?

I definitely will go look this up... right now. For some strange reason I am now interested.

Nevermind.

>The programme makers got duplicates of the suspect rivets made by the last British specialist in wrought iron, 57-year-old Chris Topp, who runs forges at Tholthorpe, near York, and Carlton Husthwaite, near Thirsk.

He said yesterday: "I don't know much about the theory the programme is exploring. Personally, I would have thought that running a liner into an iceberg at 27 knots would have been enough to do the damage. I just told them how I would make the rivets – gave them the specifications in metallurgical terms – and they checked against what had been used at the time and said okay."<

http://titanic.marconigraph.com/mgy_tech.html

14. What is the open-hearth method of making steel? Is it a variation on the Bessemer process? Why weren't big ships built before steel mass production?

Steel is iron that has a very exact proportion of carbon mixed into it, making it stronger and less brittle than iron. The Bessemer process was invented in 1855 and was the first practical method for quickly removing impurities (such as silicon, manganese, and carbon) from large quantities of molten iron, thereby allowing for the mass production of steel. This involved pouring molten iron into a large container, called a "converter," where oxidation of the impurities was created by forcing air upwards through the converter. Carbon bonded with the oxygen to form carbon monoxide, which then burnt off at the surface. Silicon and manganese combined with the oxygen to form slag, most of which settled to the bottom of the converter. Steel made using the Bessemer process has a high nitrogen content, is very strong, but brittle at low temperatures. Another, even more efficient process of mass-producing steel was accomplished through the open-hearth process, invented by Siemens in 1856 and first practically applied in 1861, which uses a regenerative furnace to allow wrought-iron scrap to be melted together with cast iron upon the open hearth, instead of within a container. Most British steelworking firms of the early 20th Century using the open-hearth process had acid-lined furnaces, which produced a mild steel with a high content of oxygen, phosphorus and sulphur. It was this type of steel that was used in Titanic, and essentially similar to the steel that would later be used to construct the Queen Mary.

15. How much steel was used on the Titanic and for what? How was the ship riveted together? Were these methods standard for the time? Are they used today?

Over 24,000 tons of steel were used in the building of the hull and superstructure. Almost 1500 tons of that were in rivets (3 million total) alone. As mentioned earlier, both steel and wrought-iron rivets would be used in her construction. The methods used to forge the steel and rivet the ship's structure together were standard in the British shipbuilding industry of the time and would remain so through World War II. Nowadays, riveted structures are rare...welded structures are the norm.

It happens that welding was an emerging technology when Titanic was built. The expansion joints in Titanic were constructed using this new method of joining.

16. Did the builders use inferior steel in Titanic's construction?

The current myth of "inferior steel" evolved from pure hindsight. It is true that the steel provided to Harland & Wolff by Dalzell and D. Colvilles & Co. was produced in acid-lined open-hearth furnaces, which allowed for impurities (such as sulphur and phosphorous) in the steel. These impurities led to low fracture resistance, especially in cold water conditions that reduced ductility (ability of the steel to deform without yielding), by reducing the amount of manganese present to bind to the residual sulphur. With insufficient manganese, the sulphur combined with the iron to form the ferrous sulphide, which created paths of weakness (especially along grain boundaries) along which fractures could propagate. The manganese-sulphur ratio of Titanic's steel recovered from the wreck site has been determined to be 6.8:1, low in comparison to steels produced today that have ratios as high as 200:1. The presence of phosphorous, even in minute quantities, also played a significant role in the initiation of fractures. However, most of steel used by British shipyards during this period was produced using the open-hearth method; in fact, the metallurgy of the steel did not change significantly until after 1947, when wartime experiences prompted closer examination of the elemental properties of steel. At the time of her construction, Titanic's builders used top-quality steel that would remain the industry standard for years to come. To accuse Titanic's builders of using "inferior steel" is unfair, as it would be decades before the minor elements of steel would be more fully understood.

17. Can you explain "microcracking?"

Another factor in the break-up of the ship appears to have been crack propagation along rivet holes. For the Olympic-class ships, the rivet holes were cold punched through the steel plates prior to riveting the plates to the framing. This is an invasive process that creates micro-cracks around the periphery of the rivet holes. In addition, many of Titanic's rivets were hydraulically driven, which created residual compressive stresses that were not relieved, as the cooling of the rivets drew the plate tight against the framing. When the sulphide particles in the steel are subjected to stress, the micro-cracks can coalesce into macro-cracks, which provide pathways for fracture propagation. The British Admiralty subsidised the construction of Lusitania and Mauretania, thereby enabling them to enforce their standing requirement for all rivet holes to be reamed in order to prevent the spread of micro-cracks. After Olympic's collision with H.M.S. Hawke in 1911, Harland & Wolff Naval Architect Edward Wilding noted that cracks had developed in plates that were not located within the immediate impact area. His concern was that the micro-cracks allowed fracturing to propagate and he urged that the Lloyd's Rules for hull surveying requirements be modified to include impact and notched-bar testing. However, even though he recommended that rivet holes be reamed as a precautionary measure, he acknowledged that it was an expensive proposition that would not be cost-effective for steamship companies to implement, given the anticipated loads a steamship might endure during her career.

By 1930, ship classification societies had fully disallowed the cold punching process because of experiences with steamships that were by then getting long in the tooth. Olympic, in particular, suffered greatly from stress crack propagation in her plating, as evidenced in a 1930 hull survey. The Queen Mary used essentially the same steel that the Olympic-class ships used, but she suffers less from crack propagation because her rivet holes were drilled, then reamed.

19. What is meant by "watertight?" How can compartments be watertight if the walls don't extend all the way up?

In the most simplistic terms, the height of two watertight bulkheads is calculated by taking the volume of the compartment that is created between them and assuming that compartment is completely flooded, subtract that volume from the ship's displacement. If the tops of the bulkheads are tall enough to be above the ship's new load-draft line after losing the subject compartment, then water will not rise over the tops. Even if the affected compartment isn't capped by a watertight deck, the bulkheads are still considered to be "watertight," because they can contain the water coming through the opening in the hull within the compartment between them. This is a simplistic summary of the type of calculation that was performed by Titanic's designers when they determined her internal subdivision. Given Titanic's expected operating environment, the height of her bulkheads should have been sufficient. The manner in which a merchant vessel should have been operated meant that the most serious hazard should have been collision with another vessel. Titanic's internal subdivision was well designed for such an eventuality. What Titanic's designers could never reasonably predict was that her crew would steam full speed through a known ice region and risk running into an iceberg.

After the inquires into the Titanic disaster had run their course, the work stoppage on hull 433 was lifted and work begun anew, albeit with major changes in the new ship's design. One of the most significant modifications incorporated was the extension of 5 of the total 15 watertight transverse bulkheads in the centre of the ship all the way up to B deck (the remainder went up to E deck), dissecting much of the First Class accommodation. Even with the increased subdivision, though, Britannic sank in much the same manner as Titanic ‚ with her head pulled down by the loss of buoyancy represented by the flooded compartments, water found its way aft into undamaged compartments through multiple deck and hull openings (of which open portholes played a significant role). Again, a scenario that could not be envisioned by designers laying out a merchant vessel.

well, you got me started...

and I ended up here, after a detour into several websites about the Brittanic...

http://www.allatsea.co.za/unioncastle/arundel.htm

What a long, strange trip it wert.

Thanks!

Wow! TR, A lot of research went into that

Right, the steel plating they used was the top quality they could achieve at that time, including the slag and other impurities

The rivets were made "on site" as you say with a brazier fire, they wee then thrown up to a catcher, who placed them ready for "striking" them into place.

The steel we use these days is a far cry from then, in fact it is mainly due to the chemical formation during furnacing that allows us these days to use much thinner steel than we did when I first started in the industry
In fact I mentioned that earlier where the welds we were making had to be stronger in every way to the "parent metal" also more ductile in tensile strength

In fact the program I watched this on, covered everything you have mentioned, so its a "Goodun" for you to have found all that out
Smudger.