Editing GWR 3252 Class (section)

===Boilers===
The majority of the class were fitted with [[round-topped firebox]]es of the same diameter as the boiler. The last four were fitted with [[Belpaire firebox]]es, raised a few inches above the boilers.<ref name=OSN29>{{harvnb |Nock |1977 |p=29}}</ref> Eighteen of the Duke class were later rebuilt with domeless tapered boilers and Belpaire fireboxes between October 1906 and January 1909.<ref name=OSN77>{{harvnb |Nock |1977 |p=77}}</ref> They were reclassified as members of the [[GWR 3300 Class|Bulldog Class]]. A further Duke, no. 3273 ''Armorel'', had been fitted with a parallel domeless boiler in February 1902, converting it to a Camel Class locomotive. It was fitted with a Bulldog-type boiler in October 1910.<ref name=OSN77/> By December 1923 all remaining Dukes had been fitted with flush-topped Belpaire fireboxes and domed boilers pressed to {{convert|180|lbf/in2|MPa|abbr=on}}.<ref name=OSNb70>{{harvnb |Nock |1978 |p=70}}</ref> Duke no. 3258, ''King Arthur'', built August 1895, was fitted with a [[superheater]] in December 1896. The rest of the class, with the exception of two locomotives, were fitted with superheaters between August 1911 and September 1946.<ref name=OSNb87>{{harvnb |Nock |1978 |p=87}}</ref> The class had distinctive long smokeboxes, extended to hold a diaphragm plate and net for spark prevention.<ref name=OSN17/>