product support 030605

HopkinsonsINDEX

2 Weir Valves & Controls First choice for process protection WVC-HOP001-R0

Weir Valves & Controls 4

The Hopkinson Story 6 - 17

Company Milestones 18

Boiler Mountings & Valves 18

Parallel Slide Gate Valves(a) Operating & Design Features 19 - 20(b) Product Application 20(c) Hopkinsons Product Range & Features 20(d) Valve Construction 20

(i) Back Seating(ii) Packing Under Pressure(iii) Seats & Discs

(e) Comparison of Parallel Slide Valve with Wedge Gate 22 - 25(i) Seating Principles(ii) Thermal Binding(iii) Ease of Maintenance

(f) Optional End Connections 26(g) Bolted Bonnets 26(h) Stuffing Box Design 26 - 28

(i) Exfoliated Graphite Packing(ii) Upgrading of Conventional Glands & Pressure Seal Bonnets(iii) Water Sealed Glands

(i) High pressure Parallel Slide Gate Valves 28 - 33(i) Pressure Seal Bonnets(ii) Venturi Bore Design(iii) Follower Eye(iv) Seat Velocities(v) Product Ratings(vi) Relationship Between Nom. Pipe Size & Valve Seat Diameter (vii) Vee Port Outlet Seats(viii)Steam Purging with Venturi Valve Design(ix) Process, Petrochemical & Nuclear Market

Bypass Valves(a) Application 33(b) Method of Operating 34

Equalising Bypass Valves & Devices(a) Hydraulic Lock 35(b) Balanced Spindle Valves 35 - 36(c) Equalising Pipes & Applications 36(d) Over Pressure 36 - 37(e) Alternative Equalising Devices 37(f) Equalising Bypass 37 - 38

Types of Main Valve Operation 38 - 42

Check & Non-Return Valves(a) Swing Check Valves 43(b) Low & High Pressure Variants 44(c) Feedwater Check Valves 44(d) Vertical Lift Check Valves 45(e) Comparitive Disc Movements (Vertical Lift & Swing Check) 45(f) Stop Check Valves (Stop & Non-Return Valves) 45(g) Tilting Disc Check Valves 46 - 47(h) Bled Steam (Extraction Steam) Non-Return Valves 48 - 53

(i) Features of Hopkinson Design(ii) Valve Application(iii) Competition

3Weir Valves & Controls First choice for process protection

Hopkinsons INDEX

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Reheater Isolation Devices 53 - 56

Drain & Blowdown Valves(a) Comparison of Types 56 - 58

(i) Wedge Gate Valve(ii) Globe Valve(iii) Ball Valve(iv) Parallel Slide Gate Valve

(b) Rack & Pinion Blowdown Valves 58 - 59(c) Uniflow Drain Valves 59(d) High Performance Parallel Slide Gate Valves 60

Water Gauges (Water Level Indicators)(a) ‘Absolute’ Type 60 - 61(b) Plate Glass Type 61(c) ‘Bulls Eye’ Type 62(d) Try Valves 62

ASME Section 1 Safety Valves(a) Definition of Safety Valve Types & Terms 63

(i) Safety Valve(ii) Relief valve(iii) Safety Relief Valve(iv) Set Pressure(v) Simmer(vi) Lift(vii) Rated Capacity(viii)Accumulation(ix) Overpressure(x) Blowdown

(b) Hopkinsons Product Range & Ratings 64 - 66(i) Features & Benefits(ii) Principal Competitors

(c) Hopkinsons Steam Test Facility 67(d) Safety Valve Mounting 67(e) Hydrostatic Testing 68 - 69

(i) Hopkinsons Products(ii) Competitors

(f) Servo Loaded Direct Acting Safety Valves 69(g) Anti Simmer Devices 69 - 70

Feed Water Heaters 71

Feed Water Heater Bypass Systems(a) Electrically Operated Gate Valves 72(b) Spring Loaded Bypass Valves 72 - 73(c) Competitors 73(d) Atwood & Morrill 3-Way Valves 73 - 74(e) Medium operated 2-Way Changeover Valves 75

Combined Cycle Power Plant System

Fossil Fuel Power Plant System


HopkinsonsPRODUCT SUPPORT MANUAL

3-way valvesCheck valvesGate valvesGlobe valves

Control butterfly valvesIsolation butterfly valvesHigh performancebutterfly valvesTriple offset butterfly valves

Globe control valvesTurbine bypass valvesChoke valvesDesuperheatersSevere service valvesControl valve actuators

Pipeline surge absorbersPulsation dampersThermal expansioncompensators

Check valvesGate valvesGlobe valvesReheat isolation devicesSafety valves

Side entry ball valvesTop entry ball valvesSubsea ball valvesRotary gate valvesIntegrated systems

Spring-loaded safetyrelief valvesPilot operated safetyrelief valvesTwo-way change-over valvesThermal relief valvesTank blanketing system

Pilot operated nuclearsafety valves

Triple offset butterfly valves

Weir Valves & Controls The key to the success of Weir Valves & Controls isour capability to deliver engineering solutions thatadd value to the customer’s process. We offer a totalpackage of products to meet end-to-end projectrequirements. Using our own analysis andconfiguration system, we will design and deliver theoptimum valves and controls solution to protect thevalue of the production process.

A rigorous programme of information managementmeans that the division is able to take a moreanticipatory role in defining the future needs andexpectations of the market by fully utilising theorganisation's critical resources to provide wholeprocess isolation and control valve solutions for theglobal Energy sector.

With a comprehensive range of engineered valveproducts Weir Valves & Controls have developed anextensive global installed base and expertise acrossa wide range of industry sectors:

• Power Generation• General Industrial• Oil & Gas Production• Refining• Petrochemical• Chemical• Pulp & Paper• Desalination


Hopkinsons PRODUCT SUPPORT MANUAL

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Quality assuranceWeir Valves & Controls operates qualityprogrammes to cover the full scope of theiractivities. Comprehensive quality systems havebeen developed to serve the power, oil and gas andindustrial markets which they serve.

The company holds approvals to:

• ASME Section III ‘N’, ‘NPT’, ‘NV’

• ASME Section I ‘V’

• ASME Section VIII code UV

• BS EN ISO 9001:1994

• NF EN ISO 9001

• API Q1 TO API LICENCES API 6D (6D-0182) and API 6A (6A-0445)

• API 526

• TUV - AD MERKBLATT WRD HP 0

The Quality systems have been approved for thesupply of products to meet the requirements of thePressure Equipment Directive (PED) andcompliance modules A,D1,H,B&D have beenapplied in categories I through IV respectively.

The company is committed to compliance withlegislation and has an established environment andhealth and safety policy.

An ongoing commitment to customer care is metthrough the process of continuous improvementand the further development of our systems andprocesses towards meeting ISO 9001:2000.

Valve testing facilitiesAll pressure containing items are hydrostaticallytested, seat leakage tested and functionally tested.In addition, gas, packing emission, cryogenic andadvanced functional testing can be arranged.

Material testing facilities• Non-destructive examination by radiography,

ultrasonics, magnetic particle and liquid penetrant.

• Chemical analysis by computer controlled directreading emission spectrometer.

• Mechanical testing for tensile properties at ambientand elevated temperatures, bend and hardnesstesting. Charpy testing at ambient, elevated andsub-zero temperatures.

Further technical information can be obtained fromour Web site: http://www.weirvalve.com

HopkinsonsWeir Valves and Controls manufacture HopkinsonsValves and Boiler Mountings for use on steamraising plant of any size and type.

Hopkinsons brand products, renowned for longand dependable service life, can be seen oninstallations ranging from shell boilers for heatingand process steam up to the highest capacity unitson electricity generating stations.

In the nuclear power industry, the Hopkinsonname is synonymous with expertise in the designand production of safety related items such as fastoperating main steam and main feed isolationvalves.

The Hopkinson range of products also includesvalves for isolation, regulation, pressure relief,instrumentation and drain and specific plantprotection duties on the new generation ofCombined Cycle Gas Turbine Power Stations.

6A-04456D-0182


HopkinsonsTHE HOPKINSON STORY

Britannia Works, Huddersfield, UK, the headquarters and mainfactory of Hopkinsons Limited.

The Early History of ValvesThe history of the development of valves containsvery little recorded information, and cannot besaid to have shown much progress beyond themost primitive stages until the beginning of the19th century.

As far back as about 230 B.C., Philon of Byzantiumdescribed arrangements for drawing wine fromcasks, corresponding to present-day faucets forremoving beer from barrels, and even mentioned asimple design of a two-way-cock. The Romansmade use of the elementary types of valves,probably for controlling water in pipes, andamong those preserved is a bronze plug cockdiscovered in the Palace of Tiberius in Capri (builtA.D. 39). This type of valve continued to be usedwith little variation until the advent of steam as amotive power, when the screw-down stop valveand weight-loaded safety valve were developed.

The apparent absence of progress in valve designfor two thousand years is obviously due to the factthat man had not yet appreciated the uses ofsteam as a source of power, and such valves aswere required called for no particular technicalskill in design and construction. The crudewooden plug valve (illustrated), dating from thelate 17th century, was probably quite adequate forthe very unexacting duties which it had toperform.

With the development of steam power, however,the importance of valves as a means of promotingefficiency and safety began to be appreciated byengineers. It is at this stage, in the early decades ofthe 19th century, that the Hopkinsons story began.

Elm wood stop valve

Bronze plug cock

Roman stop cock

opposition to the introduction of machinery in thetextile industry.

However, Joseph Hopkinson believed inengineering and in the future of steam. Hisengineering interest obviously knew no bounds,he even patented an improved design of steelstiffener for ladies corsets!

Despite the hostile climate he started business in1843 in an upstairs room in Huddersfield. But evenas early as 1835 he was involved in tests toestablish the relative strength of the copper tubesin a boiler. From this evidence it can be assumedthat he was one of those engineers earnestlyinvolved with the early introduction of steampower to the textile mills of Huddersfield anddistrict.

By 1845 the business was firmly established inlarger premises, two converted cottages, inLockwood, Huddersfield. So, ‘HopkinsonsHuddersfield’ seen on valves in virtually everycountry in the world, was born.

Identifying the Market

Right from the outset Joseph Hopkinson identifiedhis market. Indeed he left a hair-raising account ofwhat many boilers and boiler mountings were likewhen he began to design and manufacture valves.

The crude equipment installed, and the light-hearted manner in which boilers were looked aftercaused numerous serious accidents. Frequentcases arose where boiler attendants, ignorant ofthe consequences, tied-down the weight lever ofthe safety valve in order to gain an increase insteam pressure - often with disastrous results.

In fact it was not until there was an increasedsense of responsibility, fostered by the various‘Steam Users’ Associations, and backed by reliableboiler mountings, that the boilerhouse explosionbecame a rarity.


Hopkinsons THE HOPKINSON STORY

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Views of Hopkinsons Cottage Workshop.

Typical of the devastation caused by a boiler explosion

The Hopkinson StoryToday Hopkinsons Limited is located in a 16 acre(7 hectare) factory and office complex inHuddersfield employing approx. 500 people. Itsbusiness is that of a world leader in themanufacture of valves, for power generation, theOil & Gas industries and process andpetrochemical applications. Behind these facts is aremarkable story of inventive genius, enterpriseand dedication to quality that has earned the firmits unique international reputation over the yearssince 1843.

That story began at a time when there were stillmen in the prime of life who had fought at theBattle of Waterloo and before Huddersfield had arailway link with the commercial world.

Opposition to Mechanisation

Huddersfield and its neighbourhood were stillaffected by the Plug Riots of 1842 (so-calledbecause men drew the plugs from factory boilers)that showed the continuing bitter



A Haystack boiler of the 1840’sNote the crude repair patches (right)

Hopkinsons Compound Safety ValveSafety Indicator & Alarm

Early Mountings

Those were the days of the Haystack and WagonBoilers, simple, crude designs which remained ingeneral use in industry until nearly the middle ofthe century. Arrangements for safety and controlwere likewise crude - where in fact they existed.

The earliest method of ascertaining the level ofwater in a boiler was by holes through the boilershell each containing a wooden bung which couldbe withdrawn by the attendant to check if thewater or steam issued from the hole. A morerefined method followed in the form of twopetcocks or taps situated one above and onebelow the normal water level. Here again theattendant had to physically open the taps to checkfor the presence of fluid.

The breakthrough came with the addition of aglass tube to connect the outlets of the taps, soproviding a continuous indication of the waterlevel. This formed the basis of today’s tubularwater gauge.

A means of boiler pressure indication wasintroduced by adapting the mercurial ‘U’ tube ormanometer gauge with a wooden rod resting onthe mercury and moving over a scale.

Better Designs

Subsequently the primitive boiler designs werereplaced by other and better types, such as thesingle-flued, or Cornish boiler, designed to sustainrelatively high pressures, and originally introducedby Richard Trevethick in 1812. In due course thatwas succeeded by the Yorkshire and then the well-known Lancashire boiler, while the locomotivetype of boiler was also instrumental in affectingthe trend of design of boiler equipment,particularly in regard to spring safety valves, asopposed to lever or weight controlled valves.

Creating the Business - and it’s Symbol

It follows that when J. Hopkinson & Co. beganoperations in 1843 there was a genuine need forthe design and construction of safety boilermountings. In this regard the company adoptedas its trademark the stool, or saddle, which wasriveted to the boiler shell, and on which the safetyboiler mountings were mounted.

One of the first major successes of the companywas the Compound Safety Valve, which proved tobe an outstanding invention for preventing boilerexplosions. Moreover its later development, theDuad Safety Valve, became a standard fitting forLancashire boilers and can still be seen in servicetoday. The Compound design was among theproducts exhibited by the company at the GreatInternational Exhibition in 1851 when it received amedal and certificate signed by H.R.H. Albert, thePrince Consort.



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A 60 horse-power balanced horizontal condensing steam engine

Challenging Words

Not frightened to put his money where his mouthwas Mr. Hopkinson published an advertisement in1852 headlined “Important Invention! Steamboiler explosions rendered impossible”. The copyexplained the features of Hopkinson’s New PatentCompound Safety Valve and at the end carried thebold statement:

“£200 REWARD is hereby offered, and will be paidby the Inventor, to any person who shalldemonstrate the possibility of exploding a boilerfrom pressure of steam or deficiency of water, iffitted with the New Patent Compound SafetyValve, provided that the Boiler operated upon isequal to its ordinary working pressure”.

Needless to say £200 in those days of goldenguineas was no mean sum and clearly confirmedthe firm’s confidence in its product just as indeedit does today.

Moreover the early Steam Users Association -which were later to become the boiler insurancecompanies we know today - offered a 10 per centreduction in premium if a boiler was fitted with aHopkinson’s Compound Safety Valve.

With these early developments, and the expansionof the firm to new premises in Leeds Road, thepattern was set whereby the history ofHopkinsons was to become that of the wholeprogress of valve design and manufacture.

In 1854 the Hopkinson’s type water gauge madeits appearance, together with a mercurial typesteam pressure gauge. Similarly, the companyintroduced a patented ‘Economical Self-CleansingBoiler’ which was claimed to work with perfectsafety at a pressure of 100 Ib/in2 - a remarkableinnovation in a decade in which anything inexcess of 40 Ib/in2 was considered a highpressure.

Three years later - in 1857 - the company’scatalogue stated “the patent transverse boiler maybe used at 200 Ib/in2 or 250 Ib/in2 with greatersafety than the best of the ordinary boilers at 70Ib/in2”. Actually there was considerablecorrespondence in the Manchester Guardian onthe definition of high pressure, which closed withthe view that it was 50 Ib/in2!



Mr. Hopkinson with his steam engine indicator.

Scale model beam engine

Hopkinsons on the Indicator

At about this time - and with more than ten yearsresearch and development behind it - thecompany introduced the Hopkinson’s SteamEngine Indicator, which was an improvement onJames Watt’s invention. Put in Joseph Hopkinson’sown words:

“What the Stethoscope is to the Physician, theIndicator is to the Engineer - revealing the secretworking of the inner system, and detecting minutederangement’s in parts obscurely situated”.

His method of selling his Indicator is interesting initself. Very simple he used his own Indicator toimprove the efficiency of the engine by re-settingthe valve timings. If he did not improve thehorsepower by 10 per cent, then no fee wascharged. If he succeeded, he was paid sevenshillings and sixpence ‘per horse’ plus 25 per centof the cost of the coal saved over two years.

This development of the Indicator was followed bythe publication of a book ‘Hopkinsons on theIndicator’, which contained a great deal ofadditional information on the management ofsteam engines and boilers. At once this book wasrecognised as making an important practicalcontribution to the existing knowledge on thesubject, and it ran into many editions.

It was not, however, entirely well received. Therewas apparently a critical review of it in TheEngineer and as the Editor failed to publish JosephHopkinson’s reply, he wrote again to the Editorstating:

“You publish a scurrilous article, which you call areview of my book - the third edition - from whichit is quite evident that the subject is one withwhich you are altogether at sea, and undoubtedlyhave a less knowledge than most operativeengineers.

“Your cowardly conduct in this matter, refusingme a reply, and then withholding my property,deserves the highest censure, nay, more, such achastisement as I shall take the liberty of givingyou for your cowardice, viz., a horse whipping”.

There is no record of whether he carried out histhreat, but it is indicative of the blunt andforthright manner of the man. Certainly he wasnot backward in coming forward and - like Brunel- was a first-class publicist. There is a reproductionof him with his “new design in valve setting” withthe copy which stated:

“The prosperity of England depends upon thesuccess of her manufacturers, and the amount ofsuccess that is accomplished in all practicalsciences depends solely upon having the rightman in the right place to arrange and conductthem”.



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A drawing of theHopkinsons PSV

Deadweight SV

‘Accessible’ Check Feed Valve

Originally the valves were made in cast iron andgunmetal, and were designed for pressure up to200 Ib/in2. By the late 1890’s they were beingoffered in cast steel - capable of with-standinggreater mechanical stresses in the pipeline thancast iron - and suitable for steam pressures up to250 Ib/in2. Today however, they may cope withsuperheated steam at pressures of 4,350 Ib/in2 attemperatures of 1085˚F (300 bar at 585˚C), or,boiler feed water at 6,250 Ib/in2 at 500˚F (431 barat 260˚C).

1889 saw the production of the ‘Accessible’ CheckFeed Valve, which was designed to enable thevalve and seat to be examined while the boiler wasunder steam. That was followed by the ‘Absolute’Water Gauge, which was fully automatic in bothgauge arms, thus preventing the escape of steamand water in the event of breakage of the gaugeglass.

With these new products and sustained growth, inMarch 1894 the firm was converted into a privatelimited company with a capital of £40,000 andtrading under the name of J. Hopkinson & Co Ltd.

The next milestone came in 1903 when - stillinnovating - the firm introduced the Hopkinson’sCentre-Pressure Valve, primarily designed as aturbine stop valve. This unit comprised two mainvalves and a leak-off-device - all automaticallycontrolled in sequence. Advantages of the design -mainly that the master valve never had to close oropen against full pressure - were quickly realisedin the power industry, and soon added new lustreto Hopkinson’s reputation.

Even more significant, 1903 was the year when thesite was prepared for the present Britannia Worksin Birkby as, despite extensions, the Viaduct Streetworks was too small to handle the constantlyexpanding volume of orders. The reason Birkbywas chosen was because at that time the site wasin a designated Industrial area and the companywas to have had a railway line, but in the event itdid not materialise.

In this regard it is interesting to note that while in1890 the number of employees totalled about 120,the new works employed some 600, a figurepractically trebled before the Second World War.



A Hopkinsons venturi parallel slide valve.

The venturi parallel slide valve.

Hopkinson & Ferranti

Back to 1904 and a association betweenHopkinsons and another Great British innovator,Dr. Sebastian Z. de Ferranti, the pioneer of electricpower. It was he who, looking at the drawings ofthe Hopkinson’s Parallel Slide Valve and also at thedrawing of a Venturi flow meter, had the idea ofcombining the features of one with the other. Hetherefore adapted the design of a Hopkinsonsvalve to incorporate a converging inlet and adiverging outlet flow passage similar to that of aVenturi meter. This concept was developed andthe result was the Hopkinsons-Ferranti Stop Valve,which made one more significant advance in thevalve industry.

The general features, still as valid today as then,were similar to those of the parallel slide valve butembodied the Venturi principle. Owing to thereduced bore, the valve travel and fittings areproportionately smaller, the load area is less thancorresponding sizes of full-bore valves andoperation of the valve is therefore easier.

Underlying this development is the story thatFerranti originally offered his idea to theHopkinson then running the business for a lumpsum of £10,000. However he was told that theidea had no particular future, but that Hopkinsonswas prepared to take up the patent on a royaltybasis.

In the course of further negotiations the pricedropped from £10,000 to £5,000 to £2,000, butstill Mr. Hopkinson insisted on an agreement on aroyalty basis only. Ultimately Ferranti agreed - andcollected some £64,000 over the course of the lifeof that patent.

But hindsight is of little use, and as it was, thesustained overall progress of Hopkinsons meantthat its interests soon extended internationally.

By 1910 the firm had depots and showrooms inthirty cities around the world and, to catch the eyeof the relaxed industrialist, there was even ashowroom on the pier at the North of England’smost popular seaside resort, Blackpool!

Naturally the First World War years 1914-18 hadprofound effect on the firm insofar as manyemployees joined the services and production wasconcentrated on essential war materials.

A year later in 1920, a new private company wasformed with a capital of £600, 000.



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Throughout its history the company has produced valves to meetthe highest pressure and temperature requirements of the powerindustry.

This graph illustrates the upward trend in water tube boilerpressures to the middle of this Century. Since then, however, UKelectricity generating station practice has remained virtually levelat 2,400lb/in2 (165.5 bar).

Stateside Testimonial

Hopkinsons technical excellence was still beingrecognised far from home as indicated by a notefrom the American Prime Movers CommitteeReport given at the National Electric LightAssociation convention in Chicago in 1921.

“The ‘Hopkinson’s’ English valve has been used inthis country on high pressure superheated steamwork with marked success...The success of thesevalves is due to the very careful design of body,grade of materials used throughout, and goodworkmanship”.

Proud of its success and anxious to increasebusiness even more the private company exhibitedat the British Empire Exhibition at Wembley in1924. This event coincided with the firmcelebrating eighty years in business so a “MonsterExcursion” - as the paper dubbed it - wasorganised by the company. In brief, 1,300employees and their relatives were taken fromHuddersfield to London on a free, all expensespaid, visit to the Exhibition.

In 1926 the firm became public company, with acapital of £700,000 and with the title, HopkinsonsLimited.

Other examples of the success achieved byHopkinson’s designers and engineers on the shopfloor are numerous. To take one example in 1930Hopkinsons were asked to supply a 10 in. centre -pressure turbine stop valve for an experimentalturbine installation at the Delray No. 3 PowerStation of the Detroit Edison Company, USA.

This valve was required to operate at 415 Ib/in2

maximum pressure and 1,000˚F, a temperaturepreviously unapproached in power stationoperation. The arduous operating conditionsnecessitated the use of special steels for the bodyand lid. As a result the order gave Hopkinsons yetanother ‘first’ and heralded the company as amanufacturer of alloy steel valves.

Six years later, in 1936, Hopkinsons producedvalves for Brimsdown ‘A’ Power Station North ofLondon. Here the safety valves had pressure of2130 Ib/in2, and pressure at the turbine stop valvewas 1950 Ib/in2 with a working temperature of930˚F.

Year of Installation

Op

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Pre

ssu

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b/I

n2

Bar

War Work

A few years later Britain was involved in theSecond World War when the efficiency andcontinuous operation of the power stations andvital industrial plants were essential. Since these inturn depended on the reliability of boilermountings and valves, Hopkinson’s products weregiven the highest priority. Actually for some timeprior to September 1939 the firm had substantialorders for equipment for the new power andprocess installations in Government factoriesthroughout the country, in addition to extensionsto electricity generating stations which thenacquired a new urgency.

Furthermore there was the extra production forthe war effort in the form of components forarmaments, aircraft, tanks and even assemblies for‘Asdic’ submarine detection instruments.

Britain Rebuilds

Post war nationalisation of Britain’s electricityindustry brought in considerable orders forHopkinsons when the new authority commenceda national plan for the modernisation of existingplant and the construction of additional powerstations. Once more, the company’s expertise wascalled upon to provide the best in the design andmanufacture of valves and associated products tomeet this challenge.

In fact, as the industry’s expansion programcontinued, Hopkinsons supplied practically two-thirds of the valve requirements and over a third ofthe sootblower systems for the fifty 500 MWelectricity generating units built in the 1960’s.



High investment in the machine shop.

The internationally recognised ‘N’ code

Going Nuclear

Perhaps the most notable innovation in the powerindustry’s history has been the introduction ofnuclear power, and beginning with the worlds firstindustrial scale nuclear power station opened atCalder Hall England in 1956. Hopkinsons hassupplied both conventional and purpose designedvalves for all the UK’s commercial andexperimental nuclear reactors.

On the international scene too, Hopkinsons isrecognised as an authority on valves essential tothe safe operation of nuclear power stations. Themain steam safety valves, main steam and mainfeedwater isolation valves made for PWR(pressurised water reactor) type nuclear powerstations in the USA, Europe and Asia are notableexamples. Valves for controlling heavy water havebeen supplied for the primary heat transfersystems of Canadian ‘CANDU’ type reactors.

Drilling valve bodies in ‘F’ bay.



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A main steam isolation valve

Butterfly valves molded in GRP material

X-Stream TrimControl Valve

Referring again to the Venturi parallel slide typemain steam and main feedwater valves for nuclearpower stations, at which they fulfil a requirementfor the safe shutdown of the nuclear reactor in anemergency situation. The incredible fast closingspeed of these 30in. (750mm) valves - a mere twoseconds for full operation - contrasts sharply withthe five minutes or more which would be neededfor the manual operation of a much smaller valveat the beginning of the century.

The above and other examples quoted throughoutthis publication indicate the results of the constantresearch and development work by the companyand, in parallel the capital investment in newbuildings, plant and equipment.

Continuing Development

The Weir Group vigorously encourages andsupports product innovation by membercompanies, of Weir Valves & Controls.

Hopkinson’s products continue their leadership ofthe high integrity valve industry by constantresearch and development. The use of highlydeveloped materials - ceramics, plastics, carbonand graphite and new metallic alloys - arecontributing to improvements in valve design. Themain aims are valves having lower weight, higherstrength, smaller components and longer servicelife, all advantageous to the valve user in reducingpower plant construction and running costs.



Company MilestonesCompound Safety Valve patented 1852

Steam Engine Indicator improvements patented 1857

Deadweight Safety Valve introduced 1870

Parallel Slide Gate Valve patented 1881

Steel valves introduced 1890’s

Hopkinsons-Ferranti (Venturi Flow) Stop Valve patented 1904

Steel foundry opened 1912

Electrically operated valves introduced 1920’s

Public company floated, Hopkinsons Ltd 1926

Alloy Steel valves for 1,000˚F duty produced 1930

Sootblowers added to product range 1938

Valves for world’s first industrial scale nuclearpower station, UK 1956

Supplied two-thirds of valves etc. for UK’s 25 newpower stations 1960’s

Main Steam Isolation Valves for PWR nuclearpower stations 1970

Repair & Servicing subsidiary opens in Cardiff 1981

Autotork Electric Actuator/Controls subsidiary launched 1987

Blakeborough Controls Valves incorporated inHopkinsons range 1988

Hopkinsons Ltd bought by Weir Group 1989

Oil & Gas Industry pipeline valves range announced 1993

Acquisition of Batley Valve 1996

Acquisition of Sebim Group 1998

Acquisition of Flowguard 1999

Formation of Weir Valves & Controls 2002

IntroductionMost valves on a power station can beconveniently listed in two groups,

1. For safety

2. For control (A few belong to both groups)

Group 1. Includes Safety Valves, Water Gauges, Non-return Valves and automatic Isolating Valves.

Group 2. Includes Feed Valves, Blown Down Valves, Drain Valves and all the various kinds of Stop Valves.

The following pages are intended to helpnewcomers to steam engineering to becomefamiliar with the many types of Hopkinson’s Valvesand Boiler Mountings they are likely to comeacross in the course of their work.

Weir Valves and Controls Salesmen, Agents andRepresentatives will also benefit from a greaterunderstanding of the various products and theirapplications, enabling them to provide a betterservice to their customers.

Boiler Mountings & ValvesIn the complex equipment of a modern steam,generating plant, the boiler mountings andauxiliary valves rank among the most importantitems, as the safety and smooth working of thewhole plant depends to a great extent on theirsuitability and correct design.

The casual observer would hardly notice themountings and valves, as they are usually almostindistinguishable under a thick covering oflagging. Many of them - such as Re-heaterIsolation Devices - are placed in remote positions,well away from the firing floor. Some are soinsignificant in size that one might easily assumethat their design, construction and duties werematters of little consequence.

The power plant engineer however quickly findsout the value of these fittings. He appreciates thenecessity of obtaining first class equipment,installing it correctly and maintaining it properly.He soon learns that one faulty valve can cause themost exasperating and costly shutdowns, and thata leaky valve can waste an extraordinary amountof expensive steam.

When it is remembered that in a large steamgenerating plant there are hundreds of items ofequipment that come within the category ofmountings and valves, the responsibility placed onthese fittings will be fully appreciated.


Hopkinsons PARALLEL SLIDE GATE VALVES

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Parallel Slide Gate ValvesThe Parallel Slide Gate Valve (PSGV) in its variousforms, accounts for some 65% of the total numberof valves manufactured annually under theHopkinson name.

First introduced in 1881 the basic design principleon which the valve operates has remainedunchanged to the present day.

Before examining this important design of valveand its various applications, we should firstconsider basic valve construction and operation.

TYPICAL HOPKINSON’S PARALLEL SLIDE GATE VALVES FORA WIDE RANGE OF APPLICATIONS.

Figure 1

600# Bolted Bonnet Valvewith Flanged End Connections.

Small BoreForged Steel Valve

1000# Class Valve incorporatingPressure Seal Bonnet

with Butt Weld End Connections.

(a) obturating(direct thrust)

rotating

sliding

(b) pinching

There are only two ways of controlling the flow ofliquids and gases and all valves, whatever theircomplexity might be are based on one of thesefundamental principles.

Fig1. Shows a simple tank from which water isflowing from an outlet near the bottom. In orderto control the flow, one can either place a fingeragainst the pipe (diagram a) or alternatively, if thepipe is flexible it can be “pinched” (diagram b).

These illustrations represent the two basicprinciples of valve construction, although the firstprinciple is developed in three ways, representingthe different means by which the stopper can bepresented to the pipe end, or seating.

If you can think of another practical way you willhave invented a new type of valve!!

Advantages Disadvantages

Globe Smaller sizes have best shut-off Very high pressure drop (∆ p) through valve and rapidand regulating characteristics. wear of seating faces. Larger High Pressure sizes require

massive actuators.

Conical Quick acting, straight through Difficult to combine tight shut-off with ease of operation.Plug flow.

Ball Quick acting, straight through Unsuitable for regulating duties whichflow, easy operation. can cause damage to the ball surface.

Butterfly Quick acting, good regulating Unsuitable for very high pressures andcharacteristics. temperatures.Compact.

Gate Straight through flow, Wedge gate type unsuitable for varying temperature low ∆p. applications. Parallel slide design unsuitable for low ∆ p

conditions.

Pinch Glandless, positive shut off Pressure and temperature limited by diaphragmon dirty fluids. material.Lends itself to linings such asglass, rubber etc.


HopkinsonsPARALLEL SLIDE GATE VALVES

Figure 2

How does it operate?

Nominally parallel seat faces

Self aligning discs

Closure takes place atoutlet only

Inlet disc lifts fromseat face

FLOW

Figure 3

Larger sizes &higher pressuresfitted with gearssometimes need asmany turns of thehandwheel, as agate valve.

The first & simplest way of moving the stopper isby a direct thrust on to the seating. This we call theobturating movement and is the basis of the globevalve. The word “globe” being based on the shapeof the first valves of this type which were like asphere or globe.

The second method of motivation is to rotate thestopper, which is the basis of the plug cock, aprinciple dating back to early Roman Times.

The third way is to move the stopper across theface of the seating which is the basis of the gatevalve (Both Parallel Slide & Wedge Type).

All diaphragm valves are based on thepinching/squeezing action.

To summarise, here then we have the fourprincipal methods of valve closure:-

1. OBTURATING - Globe Valve

2. ROTATING - Ball Valve, Plug Cock Butterfly Valve.

3. SLIDING - Wedge Gate, through Conduit Gate,

Parallel Slide Line Blind.

4. PINCHING - Diaphragm Valve

Each has its own particular characteristics,advantages and disadvantages.

The Hopkinson’s Parallel Slide Gate Valve bydefinition falls into category 3.

product support 030605

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