Lap seam boiler constrction, ex-Proposed New-Builds

The very earliest materials were very poor and loco lives of sometimes as little as two years are recorded. Things started to improve about 1835, but they were still dealing with wrought iron rather than steel. Construction techniques were another issue: boilers, for instance, were built from four longitudinal plates lap riveted together. The boiler might have looked circular but wasn't quite so, and each time it was steamed, the pressure would force it into a true circle, only for it to regain its natural shape on cooling. This constant flexing led to fatigue cracking and many a boiler explosion.

Crank axle failures were far from uncommon, and the double frame with one set of frames outside and a second layer inside the wheels provided an axlebox each side of the wheel, in the hope that these would keep the wheels of the broken axle on the rails and prevent a disastrous derailment.

 

I was just looking at a drawing of Crampton's 'London' for the LNWR, its boiler had transverse stays to the barrel which was oval in section. Other unusual design features were the driving axle spring hangers, the rear ones fixed to the frames in the usual manner but the front ones fixed to the sides of the firebox. Also the grate was longer than the firebox, extending beyond it fore and aft so part of it was beneath the footplate. Despite all that the accounts are that it went well, running at speeds in the 70s, even if it didn't reach the 100 that the designer claimed it would be capable of!

 

I'd quite forgotten about the oval boiler section. The solution identified by Blodge for the new double fairlie boiler (a half-way-house between the present parallel FR/Hunslet design and the original Spooner 'wagon top' design) might suggest something practical, if anyone decided they just had to have an authentic LNWR Crampton.

A working 5in gauge model, sold recently, clearly doesn't feature an oval boiler.... can't say I blame the builder!
http://prestonservices.co.uk/item/5-gauge-crampton-4-2-0-steam-locomotive/

It's worth noting that the outer firebox of the FR 'England' locos forms a load bearing part of the chassis, with frames attached, fore and aft, by rivetted brackets. The objective in this case being the same as that permeating Crampton's thinking, i.e. to keep the centre of gravity as low as possible. The brackets for the rear frames are clearly visible on the photo (from Glenn Williams's public Facebook page) of "Welsh Pony's" original boiler and the positioning of the front section evident from the photo of the new boiler in position on the chassis.
https://m.facebook.com/story.php?story_fbid=10213497411452464&id=1316613558&__tn__=C-R

 

Indeed the original boilers fitted to the L&MR pair Lion [Thunderbolt of Titfield Thunderbolt fame] and Tiger were oval shaped. The idea being to keep the centre of gravity low down. Rather than being a vertical oval boiler, they were fitted with a horizontal oval boiler. Which in turn reminds me that the L&NWR's Cornwalls' original boiler was fitted below the single driving axle, again in an attempt to keep the centre of gravity low to the ground.

 

My, we have diverged tangentially from the subject originally at hand... ;-)

 

Lap seamed barrels of course remained standard on almost all traction-engines into the 1930s, although from the 1870s they were generally prohibited on railway locos (although there are aways exceptions to these sort of rules - I know of a 1921 built standard gauge loco boiler with a lap seam - and it's in ticket today)

 

I thought that whereas Adams did not use lap seams, his successor, Drummond, did.

PH

 

It's quite possible (I know little about either!) - the boiler I'm thinking of is on something else.

 

My fault! And what I said was wrong too !

 

Quite possibly, but it's a lot more interesting than what anyone would put on their letter to Santa before sending it up the chimney!

 

BS 931 1951 allowed lap joints for pressures up to 130 psi but the 1961 revision reduced this to 70 psi and diameters no greater than 30". The standard does require the provision of witness slots, though. This doesn't prevent such boilers being built and I know of one traction engine owner who insisted on his replacement boiler being an exact copy of the original, lap seam included. Your firm even built it! Before your time, though.

 

Are we still diverting from the original post subject??

 

Yes
(See Post 669)

PH

 

That being the case, can we please move this (most interesting) discussion to a dedicated thread on lap seams?

 

Oh! dear,

PH

 

Stops you wibbling all over the new-build thread for five bloomin' minutes! ;-)

 

It needed to have a degree of substance to it which has now been removed.

 

There was at least one SG loco built later than that with a lap seam boiler - Warwickshire (Manning Wardle 2047/1926). The boiler was condemned in 1989 but can still be seen in the yard at Bridgnorth.

The locomotive is currently being overhauled and will have a new boiler built. (Thread drift back into new builds starts here....)

https://www.svrwiki.com/2047_Warwickshire

 

That's manning's all over - lovely little things, but very much creatures of the 1870s, and never really modernized.

Funnily enough, I've the drawing for Warwickshire's new boiler on my desk at work at the moment...