GLOUCESTERSHIRE'S CHEMICAL ROMANCE
|Although I normally only buy
models of vehicles built by the Gloucester
Railway Carriage and Wagon Company this particular item - B738 in the Dapol range - was acquired
for use on Capital Works not only because of its
evocative late Victorian design but because it
represented a little known realm of Gloucestershire
Until the 1880s most liquid chemicals - such as the oily tar processed by distillers such as William Butler and Company - would have been carried in tins, casks, jars or carboys aboard open or covered railway wagons but by then the British chemical industry had grown to such proportions that dedicated wagons were needed. Privately owned tank wagons also flourished because British railway companies were exempted from providing rolling stock for cargo that might cause contamination under the "common carrier" obligations written into their various Acts of Parliament.
|WILLIAM BUTLER & COMPANY (BRISTOL) LIMITED WAGON 64|
|Butlers fleet number 64 would have
travelled widely to collect raw materials recovered from
gas works and charcoal and coke plants and from the
South-West and West Midlands and the design is one
closely associated with Charles Roberts of Wakefield.
Built by the West Yorkshire firm until 1946, it comprises
a riveted rectangular tank located directly on a wooden
frame ( accurately represented in the Dapol model I am
pleased to say!) between simple heavy duty baulk ends
held together with longitudinal tie rods. Later variants
also featured steel bands over the tanks which located
into brackets on the solebars.
The rectangular shape of Butlers fleet number 64 was dictated by metal sheet initially being only available in flat plates which were bolted together to form boxes. However, square joints proved to be a point of weakness, not least because liquid loads have a tendency to slosh into corners and impose a high shock load. Indeed, highly inflammable liquid fumes could exceed their flash points in a rectangular tank wagon and ignite in the same way that a diesel engine burns fuel! Similarly, the large liquid surface area inherent in a rectangular tank allows fuel to slosh from side to side, making the wagon unstable without the addition of internal baffles which add to the cost of both initial building and maintenance.
For this reason, rectangular tank wagons fell out of favour after 1927 by which time rolling plate technology had advanced enough for cylindrical tank barrels to be bolted or riveted together. In a full horizontal cylinder the fuel has a relatively small surface and so has little lateral movement.
|STRAIGHT LINES AND CURVES|
|An alternative - and slightly
safer although more expensive - design involved making
the sides and top of the tank from a single sheet of
curved metal with the ends rivetted to an internal L
shaped stiffening member. One such example - with a 5
-6-0 ton tate weight for a 7 ton load - was built by the
Gloucester Railway Carriage and Wagon Company Limited in
the late Nineteenth Century for Liverpool naptha
processors C. Kurtz & Son. Rather worryingly for such
a volatile cargo, the brakes on Kurtz fleet number 1
applied only to one axle!
Interestingly, C. Kurtz & Son provided a link between the Gloucester Railway Carriage and Wagon Company Limited and the earliest days of passenger railways as the bright yellow lead chromate pigment for the paint used on George Stephenson's "Rocket" and the Liverpool & Manchester Railway's First Class carriages had been introduced to Britain in 1800 by a German chemist called Kurtz, who set up a factory in Manchester. The colour had been popularised for horse drawn coaches by Princess Charlotte and was still in vogue in the 1830s.
|THE RESIDUE THAT'S GOOD FOR YOU|
|When coal gas was widely
introduced for lighting and heating in the early years of
the 19th Century - after being invented by Scotsman
William Murdoch in 1794 - there was some public concern
about the oily black by-product 'coal tar' - seven and a
half gallons of which were produced for every ton of coal
used to make coal gas - that was often simply dumped into
the local rivers.
With the water content reduced however, coal tar was found suitable as a protective 'paint' on buildings. Rammed earth cottages, for example, had a black strip of tar around the base of their whitewashed walls where the rain might cause most damage.
However, in 1838, two years before the arrival of modern edge railways in Gloucestershire, John Bethell of Bristol patented tar-based creosote as a timber preservative. Although initially designed to protect ship's timbers, Isambard Kingdom Brunel realised that the new preservative treatment could be used to treat the longitudinal timbers of the broad gauge "baulk road" track of the Great Western Railway that he was directing construction of between London and Bristol.
Brunel took out a licence with John Bethell for use of his patent and also took Bethell's technical advice in the erection of a tar distillery on the site of an earlier copper works at Crews Hole, Bristol - then a part of Gloucestershire.
William Butler - previously employed by Brunel on the broad gauge Bristol and Exeter Railway - was appointed as manager of the new tar distillery and - following a devastating fire in 1863 - bought the business himself under the name of William Butler & Co Ltd.
Coal gas tar, despite its unappealing appearance and smell, actually consists on a range of valuable materials that can be separated by distillation. In the early days creosote and pitch ( representing about 60% of the original coal tar collected ) were the only saleable products. The solid but fusible coal-tar pitch found a market as a binder for unusable small coal or 'duff' and anthracite dust, producing a first-class fuel briquette. As a result, by the early 20th century Britain was exporting large quantities of pitch to Germany for this purpose.
Soon though, producing the more elusive, volatile - and valuable - tar distillate of naptha became the main objective of the tar distillers. As a solvent of latex, naptha - comprising only 5% of coal tar - was used to make rubberised goods, fuel for 'oil lamps' and could be burned in special chambers to recover the carbon rich 'lamp black' that was used for making electric carbons, printing inks, shoe-blacking, patent leather and other goods. However, lamp black's most important use after the 1930's was in motor car tyres. Rubber tyres are actually about one third carbon, which makes the rubber much more hard wearing and accounts for their black colour.
By the 1860s the lighter fractions of coal tar were being further distilled to obtain benzene, toluene and naphthaline and - overall - products of coal tar have a staggering range of applications.
The ammoniacal liquor provides liquid ammonia, sulphate of ammonia, sulphur and ingredients for wool scouring, soap, detergents and explosives. Sulphuric acid is produced which is used in galvanising and for motor car battery acid. Carbolic oil contains phenols and cresols, the former are used in adhesives and aspirin the latter in sheep dips, tanning fluids and weed killers. Carbolic oil also contains Xylenols used in anticeptics and disinfectants.
Benzole is used in perfumes and provides benzene used in petrol and for making nylon. toluene used for food sweeteners and TNT as well as the all important aniline dyes, and xylene, used in printing inks, paints and varnishes. Naphthaline oil is used in mothballs and also contains naphthaline used for disinfectants, antiseptics, fire lighters and dyes as well as phthalic anhydride used in disinfectants, antiseptics and plastics. The lighter oils in the naphthas are used for brake linings, lubricants, photo chemicals and linoleum flooring. Creosote oil is used as a wood preservative and in aviation fuel and fuel oil. Anthracene oil is used as a spray for fruit trees, in the manufacture of dyes and as an additive for road tar. The residual pitch is used for making road tar, rust preventative coatings and for roofing felt.
|IN HIGH SPIRITS|
|Three models on Barnhill Model Railway Club's EM gauge Kingsfield layout show the evolution of railway tank wagons designed to carry Class A inflammable liquids such as petrol. All three Esso marked vehicles use the cradle method of supporting the cylindrical tank but the older pattern wagon on the left - with the blue edged oval logo - has the crossed wire ropes used until the mid 1920s. The wagon on the right - with large blue corporate lettering edged in red - is in the light buff livery with red lining stipulated from 1902 to March 1939 while the wagon in the centre of the rake has the overall silver used from 1945 onwards. Although out of shot, these Class A wagons were correctly coupled to low sided wagons to distance them within a train from both locomotive and guards van.|
|A further refinement of the Class A two axle format is seen here on Mike Briggs & Nick Barnett's 00 gauge Marcroft layout displayed at the Cheltenham GWR Modeller's Group Exhibition in aid of CLIC Sargeant in April 2007. Seen here in the company of wagons built to carry grain, cement and coal, the British Petroleum tank wagon carries its yellow, white and green trademark on a grey background and has its two midships ladders curved inside the loading gauge and only reaching down to the solebars.|
|While rectangular tanks sufficed
for the bulk transport of coal tar, the more volatile
products of coal tar - and crude oil - including required
petroleum, creosote, ammoniacal liquor, acids and dyes,
required cylindrical tank wagons of more advanced design
that were introduced from the start of the 20th Century.
However, these did not become commonplace until the
arrival of specialised rail-connected reception
facilities during the 1920s.
The main challenge of cylindrical tank wagon design was securing the tank to the frame. The Railway Clearing House produced various drawings to illustrate its recommended methods of fixing, but while these were broadly adopted they were not compulsory and any method could be used which was acceptable to HM Inspector of Railways.
For many years timber was widely used, both for the underframe and the tank mounting by either the saddle or cradle method. In the saddle method, the tank was carried on four transverse bolsters ( or saddles ) while in the cradle method the cylindrical tank was carried on two longitudinal members. Angle iron end stanchions and wooden - or steel and wooden - horizontal beams held the tank longitudinally and the beams were stayed to the underframe by steel rods. The tank was finally secured by holding-down bands and crossed wire ropes.
From the mid 1920s the wire ropes on cylindrical tank wagons were discontinued and a horizontal tie rod was introduced between the stanchion beams. Later on various bracket mounting techniques and welding were adopted which ultimately led to the monocoque bogie-mounted 100 ton oil wagons that run on Britain's railways in the 21st Century.
Since 1902 however cylindrical tanks mounted on metal underframes have been compulsory for Class A - the most highly inflammable - liquids and from 1905 these had to be both filled and drained from the top of the cylinder. Furthermore, 1902 regulations stipulated that cylindrical tank wagons for Class A liquids were to be painted light stone ( later formalised as 1930 British Standard 358 Light Buff ) with a six inch wide Post Office Red (BS 538 ) band along the centre line and bear the following inscription in bold characters:
NO LIGHT TO BE BROUGHT NEAR THIS TANK. THE COVER AND ALL OTHER INLETS AND OUTLETS MUST BE KEPT SECURELY FASTENED WHEN NOT IN USE, WHETHER THE TANK BE FULL OR EMPTY
In March 1939, after pressure from owners, the Railway Clearing House indicated that the tops of the frame and the tanks should be painted aluminium with the red band on the end of the tank and a little way down each side, thus leaving more room for lettering and trademarks. However, this scheme was short lived for after trials with the Royal Air Force it was withdrawn in 1941 and a livery less conspicuous from the air was introduced. This was matt dark lead grey for the tops of the frame and above.
After 1945 the aluminium scheme was reintroduced, but the red band was dropped although the inscription was retained.
|Rob Owst's 00 gauge
Pallet Lane layout displayed at the Cheltenham GWR Modeller's Group Exhibition
in aid of CLIC Sargeant in October 2008 meanwhile featured 1963 vintage
anchor mounted tank wagons in Shell / BP markings. The
cylindrical tanks themselves fill the width of the
loading gauge, forcing the curved access ladders to the
ends of the wagons, which are of a longer - more stable -
wheelbase than the earlier chassis type vehicles. Also
noticeable on the weathered barrels above their metal
skirts is the appearance of ISO type "Hazchem"
warning and description labels for hazardous cargoes. The
gross laden weight of these wagons would have been 45
The Royal Dutch Shell Group was founded in February 1907 when the Royal Dutch Petroleum Company ( formed in 1890 ) and the UK's Shell Transport and Trading Company Ltd ( established in 1897 ) merged their operations, a move driven by the need to compete globally with the then predominant American Standard Oil company.
During the First World War - which saw internal combustion engines challenge the slower, less flexible railway systems of both sides - Shell was the main supplier of fuel to the British Expeditionary Force, sole supplier of aviation fuel and provided 80 % of the British Army's TNT. In addition it volunteered all its ships to the British Admiralty although its holdings in Romania were destroyed and those in Russia confiscated by the Bolsheviks after 1917. However, proposals to merge Shell with truly British concerns such as the Anglo-Persian Oil Company or Burmah Oil came to nothing.
During World War II Shell's Dutch head office moved to Curacao in the Caribbean while Shell's U.S. refineries produced fuel for the Allied air forces.
|THE ASHPHALT JUNGLE|
|This 0 gauge wagon - seen
on Duncan Croser's Lynton Road layout displayed at Cheltenham GWR Modeller's Group Exhibition
in aid of CLIC Sargeant in October 2008- was made from the JPL kit and
represents a wagon built by Cravens of Sheffield in 1927
with twin tank barrels, each mounted on two wooden
saddles. As such it makes an interesting contrast to the
alternative arrangement of two parallel tanks running the
full length of the chassis. Very similar in format to the
tank wagons used by railway companies to supply
compressed coal gas to carriages within trains and
outlying depots, these "long but thin" twin
tank wagons were sometimes used to carry petroleum but
more often small consignments of more than one grade of
The wagon being shunted at Lynton Road station however was registered with the Great Western Railway for carrying any one of six grades of fuel oil, ranging from Number One Grade ( domestic central heating oil ) through Number Two Grade ( diesel engine road vehicle fuel ) to industrial heating and residual, heavy and high wax content crude oils. The steam heating pipes are visible on the left hand end and the letters APOC stand for Anglo Persian Oil Company.
The Anglo Persian Oil Company was founded in 1909 after eight years of exploration in the Iranian desert by wealthy Englishman William Knox D'Arcy. In the face of rising costs, difficult terrain and an uncertain political situation, oil was struck in the south west of Iran in 1908. The new company then promised secure supplies of oil to Winston Churchill, then First Lord of the Admiralty, in exchange for an injection of £ 2 000 000 of new capital. With the British government as a controlling interest, APOC explored for new oil reserves in Canada, South America, Africa, Australasia and Europe after World War I before being renamed the Anglo-Iranian Oil Company in 1935.
During World War II the oilfields of Iran were threatened by German advances both in North Africa ( halted by the 1942 British victory at El Alamein ) and in Russia. Despite Nazi access to Romanian oil in November 1940, one aim of Hitler's Operation Barbarossa in 1941 was to capture the oilfields of the Caucasus - just north of Iran. However, this aim was to be frustrated by the siege of Stalingrad and the Nazi's unsustainable efforts to take the city on the River Volga.
In 1951 meanwhile Iran nationalised what was then Britain's largest single overseas investment and in 1954 Anglo-Iranian was rebranded as British Petroleum, which went on to explore for oil in Kuwait, Libya, Iraq, the North Sea and Prudhoe Bay, Alaska. Despite establishing the biggest oilfield in the United States however the British government sold its last company shares in 1987 and BP , like other oil companies, is now investing heavily in hydrogen power and other renewable energies. At least one of the Cravens built twin tank wagons however survived into the 1970s under Lubricating Products ownership.
|Cylindrical tank wagon 7 in the overall black of Dick Lubricants was outshopped from Charles Roberts of Wakefield in June 1930. The 17' 41/2" by 6' 41/2" diameter barrel - split into two equal compartments for the carriage of different load types in the same journey - had horizontal tie bars above the longitudonal cradle but no wire ropes to hold it down. W.B. Dick & Co Ltd had offices at Grosvenor Gardens, London, SW1.|
|Another Charles Roberts built wagon cradle-type two axle tank wagon, this time in Imperial Chemical Industries markings The 24 inch diameter white star indicates that this wagon can run in goods trains up to 35 mph and the overall dark blue scheme denotes a Class B wagon - cleared for transporting any oil except petrol.|
|Although at first glance a long way from the 100 ton bogie tank wagons introduced from 1969, Esso wagon 2686 - preserved on the Severn Valley Railway as a water carrier for fire fighting - has its 4 000 gallon liquid vessel anchored to the underframe by two fabricated steel saddles on either side of a riveted cradle carrying the oval worksplate depicted below. Unlike the 1902-1905 pattern cylindrical tank wagons there are no end stanchions, horizontal beams, tie bars or wire ropes. It has a 35 ton gross laden weight.|
|Although the Gloucester Railway Carriage and Wagon Company produced relatively few tank wagons in its century long history, Esso 2686 was built just west of the Wye at the yards of The Fairfield Shipbuilding and Engineering Company of Chepstow, Monmouthshire in 1949.|
|Having featured Esso wagons in both
Class A and B categories, mention must be made of arguably the most
famous tank wagon ever to appear as a 4mm scale injection moulded kit.
First marketed by Airfix, Esso Class B
wagon 3300 is now sold under the Dapol banner. In
comparison with some of the other designs discussed above
this wagon has a simple yet elegant twin-saddle
attachment between cylinder and chassis although the 22'
6" cylinder noticeably stops short of the full
length of the chassis ( 27' 9 3/4" over buffers )
and is far enough inside the loading gauge to permit
sub-solebar length ladders to be attached amidships.
Other visible refinements include roller bearing axle
boxes and two brake blocks acting on each wheel. The
latter were applied either by manual lever during
shunting or by twin vacuum cylinders as part of a vacuum
brake fitted train. Like later airbraked monocoque tank
wagons, the buffers were either hydraulic or pneumatic.
The two stars are also a clue that this 15' wheelbase Class B wagon was designed with the post 1955 Modernised British Railways in mind and intended to be run at over 45 mph without frequent inspection stops during transit. Such special treatment was made necessary by the general age and obsolescent design of Britain's tank wagon fleets, which had not been Nationalised along with the rest of British Railway in 1948.
In 1956 the Esso Petroleum Company Limited approached British Railways to design a maximum capacity four wheeled tank wagon within the existing 35 ton gross laden weight limit and more than 800 examples of this pattern were constructed by various builders to carry both Class A and B liquids. Load discharges were to be controlled by an internal rod and plug operated by a handwheel on top of the tank barrel, some 12' 6" above rail level. The same wagon design was also built for operators such as TSL in the early 1950s by Powell Duffryn of Cardiff, later to absorb the remains of the Gloucester Railway Carriage and Wagon Company.
In the case of Esso's Class B variants the loads would have included diesel fuel and kerosenes with steam coils fitted to assist the offloading of heavy fuel oils. An alternative way of heating tar ( also known as bitumen ashphalt ) from its room temperature solid state to fluid aboard post Second World War wagons was by means of flame tubes. These would be set low on the wagon ends and end in a chimney at the top, the heat being provided at the discharge location by means of a gas lance.
Indeed, one of my earliest memories of visiting the East Somerset Railway at Cranmore was walking toward the steam locomotives saved by David Shepherd past lines of what looked like petrol tankers that had been set on fire! Luckily the "SUKO" ( short for Shell UK Oil ) wagons did not explode but just wafted warm tar as they prepared for bottom discharge of their loads - possibly sourced from Californian crude oil or the tar sands of Trinidad.
Unlike Class A tank wagons, Class B vehicles were permitted to be coupled next to guards vans and locomotives without any intervening barrier vehicle.
|When, around 1900, gas works
started using carburated water gas to heat their retorts,
thereby achieving a higher temperature and great
economies for the gas works, this drove off more of the
valuable fractions and reduced the quality of the tar
passed to the distillers.
Despite this, William Butler & Co Ltd became a very successful and innovative company and in 1952 separated their tar distillation and other businesses with the formation of Bristol and West Tar Distillers, in which the Southwestern Gas Board took a 25% stake.
Then in 1962 the Gas Board became sole owners of this company, and in 1964 Butlers moved all their operations away from Crews Hole and Silverthorne Lane to a new base at the Rockingham Works at Avonmouth where they continued to operate under the name of Butlers Chemicals Ltd.
By 1972 Butlers Chemicals Ltd was predominantly a supplier of fuel rather than chemicals and so the name changed again to Butler Oil Products prior to a takeover by Fina in 1988 and another name change to Total Butler in 2001. In 2008, Total Butler - with its fleet of distinctive red and white road tanker lorries - is the only British oil supplier to hold a Royal warrant.
Back at Crews Hole the Gas Board continued to operate the tar works to treat the crude tar generated from the production of town gas. However the introduction of natural methane North Sea Gas took away this source of tar, although it was still being produced by the coke works linked to the steel industry in South Wales. A means of getting rid of this waste product was still required.
On 1st April 1970 the ownership of Bristol and West Tar Distillers changed hands for the last time when it became owned by the British Steel Corporation (BSC). The contraction of the steel industry in the late 1970s reduced the need for tar distillation and so the Crews Hole works closed in 1981 as BSC reduced the number of tar plants that they operated.