David Pye's series on the Titanic continues with a discussion of the riveters.
Let’s turn our attention to the riveting practice. It was stated that the shipbuilder of Harland and Wolff did not have a full crew of skilled riveters. The opportunity to do the work of riveting was indeed a very haphazard method of joining the steel hull plates together with the shipyard foreman making random choices in hiring the men for the day (skilled if available). Do not lose sight of the fact that not every riveter was at the same skill level.
The pay for doing the job of riveting was based on the number of rivets that were hammered in. The riveter’s pay for riveting the hull plates was based on a piecework rate. The more rivets fitted, the more daily pay. The recommended riveting temperature was given as “cherry red,” or in the range of 1650-1740°F.
However, there are several questions left unanswered. How was the riveting temperature measured? How was the furnace heated? What is considered to be cherry red, and how would the cherry red be determined between two people? I believe that temperature was measured by sight, but not every-one’s eyes are the same. What one person sees as cherry red, another person may not.
Figure 4. A photo of the hull plates being riveted. (Ref. NIST)
In Fig. 5, the furnace appears to be a simple box with a fire, and no temperature control or time control is present. Perhaps the rivet was heated in a charcoal-based fire.
The riveting group itself was made up of two principal riveters: those who would handle the left-hand side of the rivets and those who would manage the right-hand side of the rivets. Another member of each riveting team was a man considered to be what was known as the “holder-on” and a young person whose responsibility was for the heating of the rivets. That young person would place a number of rivet blanks into the furnace. The number of rivets placed into the furnace would depend on the choice made by the young person who was handling the heating of the rivets.
The furnace boy (as young as 14 years old) would put five or six rivets in the fire from his bag of rivets. When the rivet reached the right temperature, he would throw the hot rivet to the holder-on, who put it in the hole and then rammed it through with a back-hammer.
Therefore, some rivets were held at the riveting temperature for a short period of time and other rivets were held at a temperature for a longer period of time. It is not known if there was any quality control of the rivet heating. Obviously, the more the rivets were held in the rivet-heating furnace would mean longer times at whatever temperature the charcoal furnace was set.
It is a well-known metallurgical fact that the higher the austenitizing temperature, the larger the grain structure. How long did the rivet remain at the selected riveting temperature? Once again, this will produce both different grain sizes and different mechanical properties.
It should also be recognized that two material types were utilized for rivet manufacture: wrought iron at the bow and stern of the vessel, and an alloy steel in the approximate center 1/3 of the hull and keel.
Fig. 5. A team of riveters
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