BR Standard class 6 No. 72010 'Hengist' and Clan Discussion Thread

I've seen several examples of new replacement boiler plate corroding faster than the old plate that they have been welded to. The only plausible explanation I have heard is that the older plates had more impurities in them (such as nitrogen) and these acted as a corrosion inhibiter. Modern steels have much better quality control.

 

Is it corroding faster than the bit it replaced though?

There will have been a reason that previous bit of boiler was replaced, and not the bit that wasn't replaced

 

I heard the same but in this case one of the main impurities in older steels mentioned was copper. It would be interesting to see some research into this.
FWIW the Marshall engine I used to own is still running around with its original box and barrel and will be 100 next year - no patches or building up either. I can't see any engine with a modern steel box doing this.
Ray.

 

I agree. Turning the question around, what might be the downside be from having a protective film between the faces? If none, slap it on.

 

Although the surfaces may not have been coated with oil or grease when assembled I'm sure, in most engineering works, the parts would have had sufficient oil on them to prevent overnight rusting during manufacture. Unless the parts were degreased prior to assembly, by riveting or bolting, this layer would have provided good protection within tight, accurate, jointed faces.

 

When Tornado was having its middle cylinder rebored it was necessary to remove the front buffer beam assembly and rust was found between the components. "Wet Assembly" is common in the aviation industry and so this has been used for the assembly of frame plates and stretchers of 2007. It is all there in the construction section.

 

Having two "dry" surfaces joined together makes good environment for crevice corrosion.
Of all the riveted joints I have seen (narrow gauge locos, carriages and wagons, 100-140years old) I have never seen dry surfaces. On carriages and wagons most often linseed oil was used, it dries and work well. On locomotives primer seems to have been the standard.

 

Different industry but exposed to the elements on structural steel we mated with wet paint to prevent corrosion. We also ground sharp edges as you can guarantee paint thickness on sharp corners.

Sent from my SM-T820 using Tapatalk

 

Different industry; this is what matters.
The two original locomotives of the Talyllyn Railway were rebuilt and restored in the 1950s and 60s. Talyllyn was rebuilt in 1957/58 by Gibbons Brothers. Dolgoch left the railway in the Summer of 1954 and did not return to Wharf Station until 1963. The engine went to Hunt Bros of Oldbury and it was stripped for inspection. The frames were found to be in a reasonable condition but the boiler was another matter; it was life expired. It was also observed that there were no intermediate frame stretchers. The original boiler was, in due course, sent to the Hunslet Engine Co. which in 1958 delivered a new boiler which was essentially a replica of the old one.
When Talyllyn was rebuilt a new boiler was also supplied which incorporated the use of the original firebox. This boiler was not a faithful replica of the original. It was of welded construction and made no use of flanged plates. It was also 1" larger in diameter than the original.
Both of the original locomotives have upward extensions of the motion brackets and these reach to the boiler. When Talyllyn was rebuilt the new boiler ended up resting on the upper corners of the motion brackets but was not secured to it. Dolgoch was moved to Gibbons Bros early in 1962. Gibbons found some brackets attached to the boiler and these were removed as being superfluous. They repeated the same mistake that had been made on No. 1.
The two Fletcher, Jennings locomotives were built with the boilers as structural members of these engines. Those extended motion brackets fastened to brackets on the boilers. Both rebuilds suffered the consequences of inadequate frame stiffness.
Gibbons Bros. had an engineering works but they were not a railway engineering works. Small details, in the event not so small, in truth very significant were outside the range of their experience. It took many years to get the two originals to a dependable and satisfactory state. This is not to be read as a criticism of Gibbons, these were very early preservation days but there are lessons here. Lack of attention to what an outsider sees as an insignificant detail can prove to be very costly.

 

Fascinating reading, which explains a fair amount of the 'issues' reported when both Fletcher Jennings locos returned from rebuilding, but ...

Query: re:No.1. The actual firebox, or it's design? I've seen comments concerning the 'forlorn and rusty object which was Talyllyn' (i.e. between 1945-57) from several sources stating that the dangerous condition of the the loco's firebox was one of the more visible reasons it expired when it did.

 

Flipping the coin over,the last Marshall that I worked on was new in 1882 and within 8 years was just being used as a countershaft for a gas engine because the side of the firebox had rotted through.

 

No. 1 hadt a bulge on the outside of the firebox finally which points to the stays, presumably if they broke rather than tore out of the copper the inner firebox may well have been reusable - and copper was particularly expensive after the war until the mid 1970s. L T C Rolt comments on its state as the Preservation Society found it in “Railway Adventure”.

 

https://www.theclanproject.org/Clan_News.php

This week you can get an idea of the full length of the engine as the frame extensions have been fitted. The dragbox will have to come out again as we're not happy with the fit against the rear face of the frame extensions. A light skim in the machine shop should do the job.

Ian

 

Those extensions look a lot bigger when on.
So when they are done is that the full extent of the frame?

 

With regard to the debate around painting of jointing surfaces, this seems to be one of those engineering areas where there are conflicting views. If you think mechanical engineering has these debates, try working with software developers! A lot of developers view their code as their "art" and getting them to use standardised coding methods is an ongoing battle. I have the scars to prove it!

We've taken a lot of advice and have talked to 3 ex Crewe works employees, one of which used to be an inspector. We also have access to the original Crewe works "Method of Frame and Cylinder Construction and Assembly - Crewe - Class 7 and 6 BR engines".

Bikermike - almost! The hind beam still has to go on with the 2 rubbing plates so that will push it back another couple of inches. The central Intermediate Rubbing Block will probably add another 4"

 

Many many thanks for these fascinating updates every one a learning curve for us "amateurs".

 

Concerning several aspects of this superb project, I'm getting the distinct impression the same applies to the "professionals" too. Quite how far our movement has come since those forlorn chalked messages on doomed (and not so doomed) locos, half a century ago, never ceases to amaze me.

 

Yes, its definitely a leaning curve for us. Take for example today as I seem to learn something new every day. I've been puzzled by 70013 having a globe type oilbox for the pony truck (or trailing truck bolster)



Whereas 71000 just has a cork plug in the plate



I'm currently converting the 1951 instruction manual for BR Standard Locomotives into a Word document. We can then use this as the basis for 72010's instruction manual. The 71000 arrangement is the system described in the manual - so why was the oil box added to 70013?

 

Could the oil box have been added by a running shed to increase the amount of oil to the bearing - or reduce the number of times it had to be oiled?
It is really interesting to see the steady growth of the engine with these regular updates.

 

If so, from where did they obtain it? By the time of the 'standards', I couldn't imagine any new component being designed, manufactured and fitted without the OK from higher up.