Great Western Boilers

I've been wondering recently - I am aware that the GWR had 'standard' boilers, with the idea that they would be interchangeable not only within a class, but within all classes which used that size of boiler. I'm also aware that some 'standard' boiler sizes were only to be found on one class!

I was wondering if someone could provide a reasonably definitive list as to what went on what?

 

Its a very big subject unfortunately: there were something like 30 types that were reasonably capable of being called standards...
Some of the key ones still in use in BR days...

Parallel
N Class - Dukes and Dukedoogs, but had been on various 2-2-2s and 2-4-0s
P Class - Dean Goods, 57xx, eventual fit to most pre grouping pannier tanks, many others
Std 21 - 54/64/74

Tapered
Std 1 - Most 4-6-0s except Manor, Castle, King and County, 28s
Std 2 - Many 2-6-2 tanks, some 4-4-0s, 56s, absorbed
Std 4 - std 2 length, std 1 diameter, some 4-4-0s (inc City), 43s, 42s, 72s, absorbed
Std 5 - 44s and 45s
Std 7 - just 47xx, but much used in paper exercises. Similar to standard 1 but much bigger diameter and longer firebox
Std 8 - Castles - Std 7 was too heavy: its a smaller diameter version
Std 10 - shorter version of Std 2, designed for absorbed, later 2251, 94s, 15s.
Std 12 - King - longer version of Std 7 with even longer firebox

I suppose P Class, and Std 1, 2, 4 are the ones that are about in any numbers now.
Worth noting that although each class of boiler was interchangeable there were many differences in detail design over the years, tube arrangements, especialy for superheating being the most obvious.

 

That's just the sort of answer I was hoping for, thanks Jimc! What boiler did Manors carry?

 

Add:
Std 14 - Manor
Std 15 - County
Std 19 - similar to 2301 class but with sloping foundation ring for absorbed locos eg ex MSWJR 2-6-0
Std 21 - 54xx/64xx/74xx

Std 1 - add Star, Saint
Std 4 - add 3150

Can't remember re 14xx/58xx/16xx straight away

Only Std 7 & 19 are extinct types from the above.

 

I presume No.7 will be re-created when the new 47xx is built.
I understand the large prairies, 41xx, 51xx, 61xx, 81xx, carried the No.2 boiler, if that is the case WSR's 9351 has a No.2 boiler instead of the normal No.4 boiler for a GW Mogul.

 

From page 9 of "Churchward Locomotives" by Haresnape & Swain:

4-4-0 County, 2-6-0, 4-4-2T County Tank, 4-4-4T (not built) 2-6-2T -3150, 2-8-0T - 42xx, 2-8-2T - 72xx - Standard Boiler 4.

4-6-0 - Saint, 4-6-0 - Grange (originally envisaged by Churchward) 2-8-0 47xx (as first built), 2-8-0 - 28xx & Collett 2884, 4-6-0 Hall and Modified Hall - Standard Boiler 1.

2-8-0 - 47xx - Standard Boiler 7.

4-6-0 - County - Standard Boiler 15 (very similar to LMS 8F boiler - as we shall see when Didcot finishes its project!)

Kings, Castles and Manors as already described in previous posts.

Purely for interest, 2807's boiler is No8270 which was fitted in 1960. The boiler was constructed in the 1920s, which makes it rather younger than the rest of 2807. This boiler also found itself running on 6848 "Toddington Grange" at one time - how's that for coincidence! (2807's tender is quite "young" too being of 1919 vintage!)

 

The Std 14 boiler on the Manor was a definite odd man out. Mid way between a Std 2 and a Std 4 in diameter and mid way between a Std 1 and a Std 2/4 in length. They must have been really struggling with the weight budget.
They knew they needed more steam than the Std 4 could produce since a big motivation for the new 4-6-0s was that the 43s tended to run short on steam hauling big loads at higher speeds than a normal freight train (source Cook, Swindon Steam).

 

Bulldogs normally had Std 2 boilers. I understand there were plans for a batch of Bulldogs with the Std 4, but in the end it didn't happen.
I think only 6'8 wheel 4-4-0s had Std 4 boilers: Counties, Cities, those Atbaras that were rebuilt to City spec and, temporarily, some Badmintons.
Some Bulldogs temporarily carried the smaller Std 3 boiler (effectively a shorter barrelled Std 2) in the 1930s when there were good spare Std 3s after the 36xx 2-4-2Ts were withdrawn.

 

Just wondering, the lists above miss out Std 6, what would this have been?

 

If my guess as to its identity is correct there was one and only one Std 6 boiler built. It had the same barrel diameters as the Std7, but much longer (far too long in fact), and a wide firebox, and when it needed heavy repairs they scrapped the loco it was on instead...

 

A certain failed Pacific?

 

Sorry if the GWR fans think that this is provocative, but looking through the RCTS series on GW engines, I have always had the impression that there are so many GW standard boilers and so many more variations possible that there were, effectively, no standards at all. This isn't to say that the manufacturing standards weren't high, the opposite is certainly the case, but that the GWR's loco engineers just didn't keep the tight grip on the number of variations that they ought to have had. This must have increased costs in the workshops and engine sheds to the detriment of the shareholders.

Regards

 

I think you're right Orion, and that is coming from someone with a definite softspot for the GW. Standard in a lot of cases seems to have been a misnomer.

 

If you look at the history of surviving boilers then its clear that the policy of having interchangeable boilers to speed up overhauls worked, and boilers could readily be swapped between classes. Some boiler types had very long lives - the P Class, for instance, was, I think, in production between 1884 and 1950 and naturally over that time much was learned and many improvements were made: I doubt that, interchangeable though they might be, the 1884 boiler was really much like the 1950 one: history does, after all, tell us that the ultimate P Class boilers were very good steam generators indeed. There was certainly a policy of continuous improvement in the detail design.

I think you'd need to be much more expert than I am on engineering methods and techniques to comment on whether, for instance, there was a significant increase in costs by having boilers in existance with different tube arrangements. I suspect that maybe there wasn't such a degree of automation that this was a major problem. There's an interesting example in Cook's book Swindon Steam about giving a Saint which had particularly thoroughly bored out cylinders a new set of pistons which were the largest size they could fit, and were the equivalent of half worn, because pistons were cheap and cylinders were expensive, so it worked out as cost-effective. I think you'd have to be an extraordinarily competent and expert researcher to be able to evaluate decisions like that at this distance.

The other big factor was the grouping. The GWR inherited some 700 locomotives from just about every possible manufacturer, amongst which 5 constituted quite a large class. There was a huge program of reboilering so that as many of these locos as possible acquired boilers that could be interchanged for maintenance. Stds 9, 10, 11 were designed as new standard boilers for absorbed classes.

One thing you can be sure of though: I'd much rather have been a GWR shareholder than an LMS or LNER one!

 

It was perhaps Churchward, more than any other Great Western CME, who pursued standardisation and circumstances meant that this standardisation was bound to be adversely affected, witness the 8F style of boiler for the 4-6-0 County, an LMS design boiler (almost) simply because the LMS 8F was chosen for war production and built at Swindon amongst other places. Churchward didn't really want to build the Great Bear but the directors demanded it, hence a one-off boiler and so on. From my relatively limited knowledge of Stanier and Gresley designs it does seem to me that they too pursued standardisation as much as they could.

 

The Hawkesworth County boiler is certainly an odd one.I know almost exactly nothing about boiler construction, but I've gathered that things called flanging blocks are required, and that these seem to be very expensive items. Presumably the ones for the 8F boilers had been paid for by the Ministry of Defence and were on hand and effectively free...

I wonder if, like the Manor, its a question of weight budget again... Presumably the aim was to have a more powerful fast MT loco than the Hall, and it was reckoned that a bigger boiler was required. The Castle boiler is a good bit bigger than the Std 15 on the County, and as a County was nearly as heavy as a Castle anyway (why I wonder!) presumably that would have made the loco too heavy. I wonder if a higher pressure No1 would have been just as good, but the Std 15 did have quite a lot more grate area than the Std 1 and I've read that coal consumption per quare foot of grate gets above a critical factor then efficiency decreases significantly.

Still, you must consider that whilst I have a reasonable collection of reference books, my knowledge of the serious engineering is minimal, and this is very ill informed speculation so beware...

 

two different series of loco both nuimbered in the 15xx range. The earlier ones were 0-6-0pt too and had all been scrapped when the later ones were built post WW2