WATER JET CONFERENCE - Waterjet Technology Association

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ABRASIVE INJECTION USAGE IN THE UNITED KINGDOM. N.J. Griffiths M.A. Cantab. Sheldon Industrial Equipment,, Birmingham, England. ABSTRACT: This paper follows the development of systems using high pressure water and abrasives from the early 1960's when the technique was purely used for cleaning vehicles, metal panels and some buildings as a contracting tool; to continuously running systems with wear resistant components. It explores the possibilities of factory bared installations for process industries and covers special equipment for abrasive cleaning of pipes and metal cutting systems for use in hazardous environments. INTRODUCTION AND HISTORICAL BACKGROUND: In the early/mid 1960's water jetting was becoming recognized as a useful tool for industrial cleaning and descaling, as well as an efficient method of drain cleaning and unblocking. However, because of the pressure limitation of existing pumps and ancillaries, particularly hose [maximum pressure usually 5 - 8000 psi], a method of enhancing the cleaning power of the water jet was sought, and the answer appeared to be the addition of abrasives into the water jet stream. The early sand guns were usually of the form shown in Figure 2. While being a form of jet pump and efficiently conveying abrasive and accelerating it, they suffered from very rapid wear on the central abrasive passage, the angled water jets in the spool and the gas pipe extension. ABRASIVE FEED. The earliest sand guns had a hose from the sand gun which was led to a second operator having a bag of abrasive, into which the hose was fed. Unless this second operator was very careful as to how he skimmed the hose over the surface of the abrasive, he tended to have an intermittent feed, ranging from no abrasive to an excess, which clogged the hose and gun. This led obviously to very intermittent cleaning performance. The next stage in the development of an abrasive feed system, was the introduction of hoppers with variable orifices [see Fig.1] at the bottom, to change feed rate. These still suffered from blockages from damp abrasive and from water flowing back from the gun and clogging feed lines with wet abrasive. Pressurization of the hopper improved matters [especially when being used under water], but what was needed was a positive abrasive feed system which could be separately controlled, independent from the high pressure gun. This could alter abrasive feed rate, and be switched off separately to enable feed lines to be sucked clear of residual abrasive. CONCRETE CUTTING GUNS. The earliest attempts of the use of high pressure water as a cutting tool was for enhanced cutting of concrete, where the addition of abrasive could cut [be it slowly] the reinforcing bars. While the earliest attempts at such cutting systems were rather crude and subject to very rapid wear, they showed the potential of what water and abrasive could do, and most cutting heads are a development from this early equipment. 455
SLURRY FEEDS. In order to get around the problem of clogging and the need to feed dry abrasive, there has been considerable development of wet slurry systems. However, these in themselves had further problems in that there is the need for a wear resistant feed pump, the abrasive has a tendency to settle out in feed lines and the mixture must be kept agitated. However, the main disadvantage is that under similar operating parameters a slurry system can be 50% less efficient than with a dry feed system. This is almost entirely due to the fact that it is very nearly impossible to feed slurry with greater than 50% by volume of abrasive. Thus, nearly half the power of the water jet is being used to accelerate water, which has next to no cleaning effect. The following graph (Figure 3) illustrates the relationship between abrasive feed and cleaning rate for typical wet and dry feed systems. While most abrasive devices are of the type described previously, other devices have been used. They all work on the principle of the velocity of the water jet creating a venturi to entrain the abrasive and accomplish mixing. ENGINEERING CONSIDERATIONS OF CLEANING HEADS: Abrasive cleaning heads must have the following characteristics in order to be usefully employed : 1. Maximum cleaning speed for minimum abrasive usage. 2. Maximum band width to translate into slow linear speed when held on the end of a gun. 3. Minimum wear of internals, in order to be used reliably for long periods of time. 4. Easy replacement of wearing parts, as these must Often be replaced on site under difficult conditions. 5. Light weight when used manually to reduce operator fatigue. Because early sand guns were made from normal steels it was found in practice, that spools and discharge pipes were lasting less than 2 hours. Wear on these units occurred in three main areas 1. Abrasive passage in centre of spool due to high velocity within venturi system. 2. Water jets wear outwards so that they no longer intersect at a fixed point, so they quickly wear through discharge tube. 3. Discharge tubes normally made from @" gas pipe wear out at best in approximately 2 hours. In order to minimize wear, modern cleaning heads are of a different design (Figure 5). RESISTANT MATERIALS: BARREL LIFE. While normal steel barrel life of 1-2 hours is satisfactory in a contracting hand held situation it is impractiacal in a continuous blasting operation or process machine. It was necessary to design a wear resistant outlet tube (Figure 6). Trials carried out early in the 1970's showed that the cleaning rate was proportional to the amount of abrasive up to a certain point. [see Fig 4] As the amount of abrasive increased beyond this point the performance began to tail off. This was because the abrasive head could entrain more abrasive than it could accelerate to optional velocity. At the same time, it was found that 456
Page 1 and 2:
Proceedings of the Second U.S. WATE
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Visualization of the Central Core o
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A Status Report on the Conceptual D
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SESSION 7 - CIVIL & INDUSTRIAL Chai
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Cutting Hard Rock With Abrasive-Ent
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frictional and piping component rel
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R = a1 ⋅ A1 A2 a2 I = 2H o Q o
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attenuation of the output. The tran
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Figure 1. Branch System Modulator F
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Figure 5. Modulation Response for B
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Figure 9. Modulation response for s
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can be used for any form of input.
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with a cylindrical shape to the jet
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m/s. The range of power found from
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Figure 3. Power vs nozzle diameter
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Figure 5. Frequency vs length of th
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NAME: Gerald Zink COMPANY: StoneAge
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modulatornozzle assembly. The ordin
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DISCUSSION OF FLUID MECHANICS The i
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This process serves to protect the
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For test purposes, these concrete b
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REFERENCES CITED 1. Barker, C. R.,
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FIGURE 4. INNER CORE OF PERCUSSIVE
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FIGURE 9. EXAMPLE OF HIGH-PRESSURE
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NAME: John E. Wolgamott COMPANY: St
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THE FOCUSED SHOCK TECHNlQUE FORPROD
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The reflected wave is thus also cyl
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neglected. The introduction of a co
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DISCUSSION NAME: George Savanick CO
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H’ mean shape factor Hj theoretic
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Required streamline curvature at th
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2 x 2 ≅ ( e − 2 p + w)/k2 (2-8)
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eliminating 2 n r 2 from equations
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approximation to the actual flow si
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skin friction coefficient but are c
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where: (H) = A1H 3 + A2H 2 + A3H +
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effect (< 0.5%) on coefficients of
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TABLE 5 Rei x 10 5 β 3 4 5 6 Po Po
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TABLE 6 D(mm) d o(mm) L t(mm) L f(m
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expanding rather than contracting a
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25. Weber, H.E., 1978, Boundary lay
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Figure 5. Wall velocity distributio
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Figure 9. Effect of nozzle design o
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Figure 12. CA+T Design Philosophy.
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Figure 16. Effect of inlet b 1 cond
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Figure 20. Relaminarization at nozz
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Figure 24. Pressure decay data. 88
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VISUALIZATION OF THE CENTRAL CORE O
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DISCUSSION Although employing the i
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5. Lambert, J. H., 1760, Photometri
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Figure 6. Spectral sensitivity curv
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NAME: W.C. Cooley COMPANY: Terraspa
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INTRODUCTION Pulsed liquid jets sho
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y=X ∨ P A dy = p p A p 2 (L c y=0
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Using equation (15), the value of X
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Thus about the first 10% of the dri
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Many design cases, including those
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surface spall occurred, resulting i
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Figure 3. Chamber pressure at pisto
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Figure 7. Effect of nozzle area rat
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Figure 11. Extrusion device schemat
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Figure 15. Typical chamber pressure
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DISCUSSION NAME: W. C. Cooley COMPA
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material which are, in turn, affect
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the water jet. This method was not
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where h is the depth of penetration
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obtained during this phase of the i
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observed that the smallest depth of
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Figure 2. Idealized Relationships b
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Figure 6. Penetration as a Function
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DEVELOPMENT OF VARIABLE DELIVERY TR
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THE STRUCTURE AND FUNCTION OF THE P
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The injection pressure can be contr
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ACKNOWLEDGEMENTS The authors gratef
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Figure 4. Theoretical required powe
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Figure 9. Variation of efficiency w
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THE "SKIPJACK" SEWER CLEANING NOZZL
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HYDRO-BLASTING SAFETY C.W. Adaway,
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Remember, your Hydro-Blasting work
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horizontal, sometimes vertical, and
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Figure 2. Safety Gear Figure 3. Tub
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DEVELOPMENTS IN CLEANING COKE OVEN
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causing chain breakages and the scr
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was encountered, then the rotation
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(C) Capital Expenditure: Material i
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Figure 9. Swivel coupling Figure 10
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OPTIMIZING JET CUTTING POWER FOR TU
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PRESSURE DROP (psi) ELEMENT Cv @10
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power output. Undersized nozzles re
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Subscripts n - Nozzle p - Pump t -
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Figure 1. Cutting effect as a funct
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CONSIDERATIONS IN THE COMPARISON OF
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pressure can be lowered to perhaps
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Figure 2: Fan jet issuing from a no
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DISCUSSION NAME: John Griffiths COM
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where Q = Flow rate - gpm D = Jet O
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Again, not limited to Newtonian flu
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REFERENCES 1. Brown, R.W. and Loper
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Table 2. Jet Cleaning Speeds and ot
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ANSWER: The utilization of the stat
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complexity and short component life
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Figure 4, for ap values ranging fro
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Decontamination Methods for rapidly
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a. “PULSER” b.”ORGAN-PIPE”
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Figure 5 - Removal rate for various
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DISCUSSION NAME: David A. Summers C
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DRILLING BORE HOLES IN COAL MINES U
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pile could not be judged as represe
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DISCUSSION NAME: David Summers COMP
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HYDRAULIC MINING EXPERIMENTS IN AN
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The monitor was fed pressurized wat
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The IH rig was considered to be sup
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REFERENCES 1. Okhrimenki, V. A., A.
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Figure 2. Jet cutting sandstone at
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Figure 5. Schematic plan view of In
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Figure 7. Suction Box. 226
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USE OF HIGH PRESSURE WATER JETS FOR
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flame torch to cut this block, redu
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the order of 360 rpm. Under these c
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Figure 3. Slot cut by jet at 11 o s
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JET-MINER SURFACE AND IN-SEAM TRIAL
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The hydraulic drive of the haulage
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The surface trials had have the obj
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Figure 2. Experimental version. Fig
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Figure. 7 Jet-Miner prototype Figur
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SOME PATTERNS OF TECHNOLOGY TRANSFE
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Development of High Pressure_Techno
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configurations, the design of an op
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and public sectors. After a haitus
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Souder, W.E. and Evans, R.J., "The
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Figure 5. Technological achievement
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Table 3. Perceived disadvantages of
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already been, or is being applied w
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Using the requirements profile and
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ant hose combination, a guiding sys
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HYDRAULIC MINING TESTS Site selecti
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SAFETY All operations were carried
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TABLE V. Categories of Jet Mining D
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Figure 2. Generalized geologic prof
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SECONDARY FRAGMENTATION WITH WATER
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do possess a maximum point (Fig. 8)
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Figure 4. Rossin-Rammler plot. Figu
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Figure 8. Non-dimensional plot for
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HYDRAULIC COAL MINING SYSTEM Typica
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Figure 4. (From ref. 1) DISCUSSION
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INTRODUCTION Developing an unique t
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The coefficients "b " in Eq. (1) ca
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By the end of 1982, a total of more
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Figure 4. Cutting ability of swing-
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Figure 10. An operating performance
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for an abrasive, the abrasive parti
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the particles, while at slower spee
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to break away the remaining segment
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Table 1. Concrete saw technology. T
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NAME: Tom Brunsing COMPANY: Foster-
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FEASIBILITY STUDY OF CUTTING SOME M
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hydraulic power required to cut thr
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pressure was varied from 103 to 310
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2.1 Heading and gutting fresh cod f
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Figure 5. The cuts surface of a blo
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Figure 17. Cuts made across the cla
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JET NOTCHING USED IN THE CONSTRUCTI
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Bottom notch diameter was determine
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σ H = in-situ stress in the horizo
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Figure 3. Final block displacement.
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Figure 8. Comparison of Slurry Pump
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THE FURTHER DEVELOPMENT OF AN UNDER
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use taps or hydrants. To achieve th
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supply line. It was determined that
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The rotating head requires major mo
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Figure 4. System field test set-up
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Figure 10. Bentonite drilled clay s
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MECHANICAL TOOLS Cutting Tool Energ
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Ψ = cos −1 ⎧ ⎪ ⎪ ⎨ ⎪
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mode also contributes to chip flush
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NAME: Simon Johnson COMPANY: Newcas
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ROLLER TOOLS COMBINED WITH HIGH-PRE
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Various designs and applications ar
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Figure 1. Full-face tunneling machi
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Figure 11. roadway profile cutting
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Figure 19. High-pressure water jet
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DESIGN AND OPERATION OF TWO LARGE-S
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The hydraulic system for the thrust
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Results of Trial Tests As part of m
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cutting rates, degree of bit wear,
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Overall approximate Weight: Basic M
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Figure 5. 3 ft. diameter laboratory
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nozzle diameter and cutting speed w
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2. Cutting Speed The influence of c
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energy it effects an increase in me
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Tip angle (degrees) 87 Off-set angl
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Figure 5. Figure 6. Figure 7 Figure
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Figure 17. Figure 18. Figure 19. Fi
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SCHEMES OF COAL MASSIF BREAKAGE BY
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out thoroughly an efficient scheme
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Research analysis has proved that t
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DEPENDENCE OF POWER INDICES OF COMB
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The experiments have shown how the
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K Ay = coefficient correcting for f
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Figure 1. Schemes of combined break
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Figure 5. Dependence of specific en
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Figure 12. Percentage of grade R -6
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Figure 1. Particle size analysis. T
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NAME: Dr. Henkel COMPANY: Bergbau-F
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presented. This study, of course, i
Page 412 and 413: identifying a general trend for the
Page 414 and 415: Effect of Abrasive Hardness, Shape
Page 416 and 417: In some situations, especially in c
Page 418 and 419: Figure 1. Abrasive waterjet nozzles
Page 420 and 421: Figure 8. Effect of standoff distan
Page 422 and 423: Figure 13. Abrasive waterjet cuts i
Page 424 and 425: CUTTING WITH ABRASIVE WATERJETS M.
Page 426 and 427: 3.3 Abrasive Feed Systems For abras
Page 428 and 429: Because of the large number of infl
Page 430 and 431: due to wear. Although actual operat
Page 432 and 433: from this new technology. Table 2 l
Page 434 and 435: Table 1. materials cut by abrasive
Page 436 and 437: Figure 1. Abrasive waterjet nozzles
Page 438 and 439: a) kerfs in mild steel b) S.S. 15.5
Page 440 and 441: a) circle cutting in glass b) lamin
Page 442 and 443: DISCUSSION NAME: Andrew F. Conn COM
Page 444 and 445: CUTTING HARD ROCK WITH ABRASIVE-ENT
Page 446 and 447: slurry nozzle. Testing at water pre
Page 448 and 449: DISCUSSION OF TEST RESULTS Jet Conf
Page 450 and 451: materials. The flexibility in nozzl
Page 452 and 453: pressure can be wiped out if diffic
Page 454 and 455: 9. Maurer, W.C., and Heilheckler, J
Page 456 and 457: Figure 5. Effect of abrasive feed r
Page 458 and 459: Figure 9. Accumulated depth of mult
Page 460 and 461: Figure 13. Close-up view of quartzi
Page 464 and 465: sudden changes in the feed rate eff
Page 466 and 467: or the abrasive must be manually to
Page 468 and 469: clog; there not being sufficient ar
Page 470 and 471: CODE OF PRACTICE FOR THE USE OF ABR
Page 472 and 473: Figure 5. Water abrasive cleaning h
Page 474 and 475: Figure 15. 360 0 abrasive pipe clea
Page 476 and 477: ECONOMIC CONSIDERATIONS IN WATER JE
Page 478 and 479: Other criteria to be considered in
Page 480 and 481: 3 MANUAL METHODS OF JET CLEANING &
Page 482 and 483: contractor with old, unsafe, equipm
Page 484 and 485: Figure 1. Showing the increased cos
Page 486 and 487: Figure 8. Automatic tube bundle cle
Page 488 and 489: ackground to the subsequent coopera
Page 490 and 491: The molecules of SUPER-WATER posses
Page 492 and 493: shaken just before use. SUPERWATER
Page 494: 26. Bednarz, L.P., "Effects of Poly
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