wtil-NO--768 C OtiF- 9603 - 7 NO9705199 Norske Sivilingeniorers Forening

OIL FIELD CHEMICALS 7th international symposium

17-20 MARCH 1996 Dr Holms Hotel Geilo, Norway

Electrical Scale Elimination Technology

9

LECTURER: A G Hunton, Humber Technical Services, UK

Reproduction is prohibited unless permission from NIF or the Author DISCLAIMER

Portions of this document may be illegible in electronic image products. Images are produced from the best available original document ELECTRONIC SCALE ELIMINATION TECHNOLOGY

by

Alan G Hunton, B.Sc., M.LW.Soc.

Humber Technical Services and technical adviser to Scalewatcher UK Ltd.

SUMMARY

The useof magnetic and electric fields for the purpose of preventing deposition of mineral salts and reducing corrosion in flowlines has been reported in the literature for about one hundred years (1,18). The technology has developed only slowly on account of unreliableperformance and no credible proven mechanism to explain the claimed effects. However, potential cost benefits to the end-user and the need for better environmental protection has renewed interest in the subject. During the last fifteen years a technology has been developed which uses the fieldsgenerated by electronic circuitry in order to achieve positive results. Working in the audio frequency range these devices appear to affect the nucleation processes although there is still no basic understanding of the fundamental mechanisms.

Case histories and results from independent laboratory studies do seem to confirm that electronic and magnetic devices can influence the deposition of carbonate and other scaling minerals.

A review of scientific literature is presented relating to the use of magnets and electronic devices for scale prevention. Operational features of the electronic devices are presented as well as information on the scope of application. Potential advantages of electronic devices are described and a number of case histories are given from differing industrial sectors.

1

wfwwm of im document s awiED On LITERATURE REVIEW: ELECTRONIC AND MAGNETIC DEVICES.

Water conditioning devices have had a controversial history. Welder (1) reviewed the early devices offered to the consumer during the period 1865 to 1954, claimed for scale and corrosion control. The earliest products were based on electric or electrolytic fieldbehaviour and were sold on the basis of corrosion control. The use of magnets became more prevalent after about 1925. At this time reports of scale prevention and scale removal were also more common.

With no basis for understanding how their devices worked, marketing strategies used by some vendors became exaggerated and included claims such as " being rendered electrochemically neutral' and that devices 'probably scared the so that they never dared unite to form scale': such statements ensured the technology was not taken too seriously by industrialists or academics. Indeed, even today there has still been no consistent, long-term and widespread use of a single device reported in the reputable literature. Early academic studies on the effects of applied fields gave mixed results; Eliassen and Uhlig (2,3) reported in 1958 that a series of experiments on failed to show any improvement in scale control in the presence of magnetic or electrolytic devices.

Despite some negative results there continues to be a significant number of positive claims from other academic workers. Donaldson(4) describes benefits of magnetic treatment of and reports the descaling effects also noted by many industrial users. Gehr(6) notes significant changes in water properties for calcium sulphate solutions in the presence of a strong . It is claimed that statistically significant changes in surface tension and solution viscosity were observed.

It is interesting to note that laboratory experiments utilising once-through systems generally failed to give significant results, e g. Hasson and Bramson(5) whereas those utilising recirculating rigs showed greater effects(6). Baker and Judd(10) also note the importance of recirculating or flowing systems to obtain enhanced results. A further experimental difficulty stems from the fact that early devices and some that are still available today are based on an intrusive design. The disturbance in flow pattern caused by the device itself and the potential for increased internal corrosion are factors that could have influenced accurate monitoring of that system.

Donaldson has shown that magnetic fields can result in changes in mineral growth characteristics such as particle size, crystal morphology, solubility and he also notes changes to zeta potential(7). Calcium carbonate crystals were generally larger in an applied field but, curiously, those of calcium sulphate were reported smaller. In a separate study Donaldson(13) reports evidence that barium sulphate particles were apparently smaller after exposure to applied fields but suggests this is due to reduced aggregation of fundamental particles. Chibowski(8) also found differences in zeta potential and surface free energy using radiofrequency derived electric fields. Higashitani(9) found reduced nucleation frequency of CaCOs particles by magnetic fields although growth rate was accelerated.

Pandolfo(l 1) reports that in the presence of magnetic fields, CaCOs crystallises in the form of aragonite (an unstable form at normal temperatures) at high flow rates and that the ratio of aragonite to is affected by ferrous or ferric ions. A possible mechanistic role of was also explored by Herzog and Katz(12) who showed that trace concentrations of ferrous ions would inhibit the growth of calcite but not aragonite. No relationship between scale prevention, applied field and ferrous concentration has yet been reported .

There is considerable evidence that particle size and growth characteristics are affected by applied fields underspecific conditions but the results reported do not always show a consistent pattern. Curiously, Higashitani(9) found that in the two brine system Na2S04 + CaCh, it is only the NazSCk component water which needs to be 'magnetised' in order to achieve a change in absorbance due to CaS04 precipitation. He also reports on the 'memory effect'; the apparent ability of the conditioned water to retain the properties of scale prevention for many hours or even days after passing through the device. Further he reports that incompatible brines such as NaiSCM and CaCb brine solutions, can be separately 'magnetised', then stored and still inhibit scale when mixed to induce supersaturation, 120 hours later. Other workers also report similar effects.

Scale deposition experiments by Ellingsen(15) indicate that rate of scaling varies with field strength, levelof supersaturation, TDS and pH. Ellingsen did not find significantflow rate dependency but most workers note that flow rate is critical for magnetic devices and in addition a minimum magnetic field strength is needed before beneficial effects are observed. These latter two observations are of considerable consequence when we compare claims for the performance of magnetic and electronic devices. Recent work at Cranfield University and also Portsmouth University has demonstrated the reduced deposition of carbonates in the presence of an electronic device.

Contradictory claims are commonplace. For example a scan of the scientific literature shows that there are about equal number of claims that devices cause increased corrosion as there are that they reduce corrosion. By comparison, vendors literature either gives no information or claims

3 ScalevR7/c7/cr Scalen-.jfcfer Early products claims and potential benefits

1870- el ectroiytic / electromagnet devices used to prevent • prevent hardness scale * environmentally friendly. formation. corrosion. * complete/partial chemicals replacement. • remove or soften existing 1925- deposits. * performance synergism permanent magnets used for scale prevention. • reduce bacterial Induced with chemicals. corrosion. * almost maintenance free. • ...... and other * very lowrunning cost. no single device has evolved that has achieved miscellaneous benefits long-term, widespread use with consistent performance proven throughcontrolled monitoring.

Scalevp.jteAcr Scalew-i7fcter Historical problems Donaldson and Grimes (Brunei u> have shown applied fields.... x results often Inconsistent x poor reproducibility between'similar'installations. result in x no fundamental mechanism proposed to explain the V changes In particle size observations /claims. V changes in crystallinity x technology not highly regarded by scientific community, V changes In crystal morphology x technology underfunded, V changes in solubility x no predictive tool developed, •/ changes In rate of precipitation x end-user not confident V changes in surface charges

ScalOHWc/tfr SC&ld»'<7tcher

Other workers (s.fl. sennas) Scale deposition tests with magnets have shown that applied fields.... cublished laboratory work shows scaling rate varies: result in v changes In aragonite proportion ■* magnet field strength V changes In zeta potential •* supersaturation v changes in surface free energy ■» IDS v 'memory effects •* pH ■* flowrate and report ■* flow configuration (once through/recirculating effect ■f role of Fe2+ ions (e.g. Herzog) for laboratory rigs)

but....data is not always reproduced in different laboratories. N.B. variance, laboratory results and field clavned resute

4 i 3C8&8*\ifcbcr Sca!e-.:Y/K(;;.'T Permanent Magnets types of applied field device

(1) Wrap - round bar magnets - early technology ✓ Permanent Magnets

V Electronic Induction Coil (Scalewatcher) Wrap - round types essentially an assembly of bar magnets, linked •/ Electromagnets and wrapped around pipe. Field not focused. term 'applied fields' is better than 'magnetic fields'.

ScatevrafcjW Sea I e-.: v r

Permanent Magnets Industrial scope of electronic devices (2) So called 'ceramic' magnets are more powerful, containrare earth metals. Can be supplied as successful applications claimed in..... pup joints in varying sizes. Field focused. * water heaters * cooling towers » shell, tube and plate heat exchangers » bottle washing plant * chemical process plant standard magnet, -4000 gauss various materials » dairy industry thread or * oil industry C0UP* ln6 device non-intrusive * swimming pool maintenance

Scalewwte/K?/- Scalenw/,-/*?.r Electronic - Induction Coil

a) current direction b)

•Scalsweteheierpelent system requlree current dlreeHon tochengewlthfrequency varying 100-5000Hz iruim

5 corrosion benefits. Intending users should be cautious regarding vendors information and case 9 histories.

Applied field devices are claimedto give benefits other than scale control. In the oil industry there are vendors references to the successful control of wax deposition in pipelines (from wet crude) and improvements to oily water separation, although no credible laboratory evidence is offered that supports the field observations. Lazarenko(20) found that the strength, density and frost resistance of concrete was improved if the process water was magnetically treated. Lin and Yotvat(21), working in Jerusalem, Israel, found that the yield of fruit and vegetables and the output of livestock was increased and other workers have reported similar observations in the presence of magnetic fields (no explanation provided).

DEVELOPMENT OF ELECTRONIC SCALE PREVENTION DEVICES.

Much of the literature cited above refers to the use and performance features of magnets, electromagnets and electrolytic devices. Perhaps as a consequence to the variable results achieved using these devices, other technologies have emerged. Electronic devices are characterised by a solenoid coil or coils wrapped around a pipe and a signal generator which supplies current to the coil. Induced magnetic and electric fields within the pipe are then claimed to influence the mineral precipitation processes.

A patent describing an early version of such a device (16) advised a coil or ring fitted internally within the flowing fluidand which produced a fixed magnetic field strength. Apart from the obvious installation problems, the fixed fieldresulted in flow rate dependency. In 1985 a Belgium patent described an external coil device in which only one end of the coil was connected to a low voltage signal generator: this arrangement has the disadvantage that high frequency (interference) signals are generated. More recently devices have been offered and patented that incorporate the more advantageous arrangement of external coils with a return coil to the generator unit. Various coil arrangements and signal outputs are described and claimed to have advantages.

One commercially successful device has been patented by De Baat Doelman(14). An energising signal is produced, of which the frequency is continuously changed within the audio range. The pulse shaped current creates an induced electric field, concentric around the axis of the pipe. Typically the frequency varies within the range 100-5000 Hz. As a consequence to this arrangement, any particle that moves within the field experiences an induced electric field and a Lorenz' type force of approximately equal magnitude, irrespective of flowrate. Tests at a University in America have confirmed that the induced (electric) field is unchanged

6 irrespective of flow rate. Residual magnetic fieldshave been measured and found to be below 1 gauss. The technology described by De Baat Doelman represents an attempt to overcome one major disadvantage of permanent magnet devices, viz. that they work well only within a certain flow rate "window' and that at higher and lower flows the performance drops to zero.

The potential to adjust power, frequency and coil configuration on site enables performance to be optimised with no downtime and no pipe replacement. Further perceived advantages of electronic devices are given in appendix 2.

Other electronic devices are commercially available. Operating principles differ from that described above. Some rely on simple AC or DC currents and so may be expected to show flow rate dependency: others function by means of a double coil arrangement or an open coil.

Effects on system variables for the device of De Baat Doelman(14) are described below.

Effect of Pipe Material.

Performance differences between steel pipe and non-conducting materials such as glass or plastic might be expected butevidence from applications on steel pipe suggests this is insignificant. It is found that the magnetic field from an electronic device of De Baat Doelman (14) is concentrated in the pipewall for steelpipe. Measurements of the induced electric field along the central axis of pipe in a flowing brine did, however show that a significant induced field existed, irrespective of pipe material although the value of that field for the steel pipe was somewhat lower(17). Only lead pipe has been shown to be unsuitable.

It is concluded that the nature of the pipe material could influence the performance of non-intrusive magnets and electronic devices. An implied advantage of electronic units is that the input current can be adjusted to compensate for these effects (compare permanent magnet).

Effect of Pipe Size

Any type of device could potentially be engineered to fit pipe sizes of 10 to 1250 mm+. The necessary weight of permanent magnets to fit very large pipe sizes and associated installation difficulties effectively sets an engineering upper limit to their application. No such difficulty exists with non-intrusive induction coil systems. There is evidence from the field these devices can be

7 effective on large pipe diameters (see case histories, CH 1-3), although as the diameter increases the power outputfrom the device should be increased to compensate for higher self induction and resistance of the coil. The relationship between diameter and power is determined empirically.

Effect on Flow Rate.

For a given pipe diameter, no flow rate dependency has yet been observed. This is believed to be a feature of the frequency modulation technology. In at least one system (CH 1, appendix 1) a water flowline on an offshore oil platform was characterised by very high Reynolds numbers, indicative of turbulent flow. At the other end of the flow spectrum, units are claimed to be effective on quiet flows. Laboratory work has shown that an induced electric field is formed even in zero flow. The positive effects are apparent for a significant distance downstream and persist for some time after the fluidspass through the applied field. However, once the treated water is transferred from the pipe system into a static vessel (or a kettle, for example) scale prevention is possible for a limited period only. Devices are not recommended to be fitted to the inlet to storage vessels with long residence times.

Effect of Hardness, IDS and Supersaturation.

Tap in the UK have typical calcium contents 60 - 250 mg/1, TDS restricted normally to lOOOmg/1 and pH in the range 5.5 to 8.5. Electronic devices are generally effective for prevention of hardness scale from such waters in water heaters, pipes etc. (CHS). No detailed scientific study has explored the performance features of electronic devices (or magnets) as a function of these variables and as each variable is extended to the limits found in industrial process waters. Case history information (CHI ) demonstrates efficiency at high hardness (Ca=3900mg/1) and high TDS. It is found empirically that as the TDS (conductivity) increases the power output should be increased in order to optimise performance. If the correct electronic unitselection is made it is possible to achieve good inhibition performance at very high TDS (CH2).

Currently it is not possible to predict in advance the result of installation of electronic (or magnetic) devices to industrial process streams. The relationship between hardness, TDS, other water property variables and limescale deposition is exceedingly complex and a systematic research effort is required to gain the necessary data. The degree of supersaturation is expected to be a key parameter for any future prediction tool.

8 Memory Effect and Scale Removal.

Anecdotal evidence from the field shows that scale prevention effects persist for considerable distances downstream and for extended periods of time. An electronic device fitted to the riser of a large dairy farm successfully prevented limescale throughout the house and also in multiple feeder lines to bell-waterers and nipple drinkers. Furthermore the user reports that existing limescale was removed over a period of two months. Working with permanent magnets Higashitani(9) describes laboratory evidence of similar effects.

There are other case histories apparently claiming scale removal (usually calcium carbonate) from fouled pipework downstream of the point of installation of electronic devices. Even where scale is not removed it is common for users to report a change in form to a softer (amorphous) deposit which can then be discharged easily by physical means. The incidence of success in removing scale from flowlines carrying mains quality water is reasonably high.

Effects on Sulphate Scales.

The effects of electronic devices on barium or strontium sulphate scale formation are not yet described but Donaldson has shown positive results on barium sulphate using magnets. Research by De Baat Doelman(17) has demonstrated that electronic devices can reduce by calcium sulphate (as gypsum).

Distilled water containing 1000 mg/1 CaS04 was recirculated through a test section of a rig for various periods of time. Controlled experiments were run using the same water with and without a device fitted to the rig. The weight of scale deposited in the test section is shown in the appropriate figure.

POSSIBLE MECHANISMS.

The fundamental interactions between applied fields and precipitating substances are not understood despite the fact that many workers have studied the subject. The current scientific literature describes the macro effects which are themselves the consequence of the fundamental interactions. The amount of energy that is introduced by an solenoid coil is very small (the consumption of the device of De Baat Doelman is one order of magnitude less than a cordless telephone) and if we wish to study the induced fields, scientific tools are needed of high precision which do not interfere with the interactions that we want to measure. The

9 atomic force microscope (AFM), capable of examininggrowth patterns on surfaces at the highest resolution is a tool that may demonstrate some of the key interactions and is being used by workers in Japan.

Possible mechanisms that are invoked include structural changes to water molecules (for example breakage of hydrogen bonds and cation hydration alterations), enhancement of homogeneous nucleation and a role for iron colloids providing sites for heterogeneous nucleation in the mobile phase. Until appropriate observations are made we can only form judgements about the mechanisms.

We know that in order to form a scale deposit three conditions must be met;

1. Solutionmust be supersaturated. 2. Nucleation sites must be available at the pipe surface. 3. Contact / residence time is adequate.

To prevent scale it is necessary to remove at least one of the deposition pre-conditions. Clearly contact time is not a factor: this is the same in the presence and absence of a device. To be effective any device must therefore affect either the supersaturation value or the nucleation process. Supersaturation is unlikely to be reduced as a direct result of the application of a applied field (such little energy is introduced that we may have to rewrite the laws of thermodynamics!) nor is it likely that the device would affect the availability of heterogeneous pipewall nucleation sites.

It is postulated that the direct effect of the electronic device described above is on the nucleation process and in particular to enhance initial nucleation within the bulk fluid flow through the creation of new nucleation sites. Crystal growth then occurs at these points of nucleation and not at the pipewall. Suspended solids increase with a corresponding dropin the level of solution supersaturation (see figures). Several workers, including Busch(19) favour this approach. The increase in suspended solids immediately downstream of the position of a device and an increase in C02 evolution have recently been claimed to have been measured in controlled experimentation (unpublished information). It is not claimedthat the overall production of solids (precipitated) is greater that the production of scale solids in the absence of a device and the converse could be true. ScaS&Mtclw Solids production along pipe carrying Solids production along pipe carrying supersaturated brine (1) supersaturated brine (2)

* Without Scatomtchor

scale deposited

ewwenedw

Scalewwicto- Solids production along pipe carrying supersaturated brine (3) CaS04 scale in recirculating system

Change In supwsatumtion 77 mg CeS04 in test section

hours make-up loti water w*h

Scalen-tf/cZtfr Lorenz force Possible Mechanisms

The force that electric and magnetic fields exert • changes to the structure of water (breakage cfH-bonds on a moving charged particle and deformationcf hydration shield). » enhancement of nucleatlon (increased molecular collisions). * role of cotioktal Iron (change in pH ~> Increase F=qE+q(VxB) precipitation). % lorenz force effects (charge dlstrtoution). force magnetic field vector charge particle velocity clues: many workershave reported that applied fields give electric field vector * significant Increase In pH * reductionIn surface tension * Increase in suspended Solids permanent magnet - 4000 gauss, electronic device <0.1 gauss

11 A Lorenz force F, is experienced by charged particles that flow through a field.

F = qE + q (V x B) where q is the charge on the particle, E is the electric field vector, v is the particle velocity and B the magnetic fieldvector. It is postulated that it is this Lorenz force that initiates the fundamental interactions. Note that the flow dependancy of magnetic devices could be explained by the velocity parameter, V, and E = 0 and by further analogy the flow non-dependancy of electronic devices could be explained by the fact that the second term approaches zero. Electronic devices operate at very small residual magnetic fields whereas magnets need high field strength (>1000 gauss) for optimum performance. This suggests that the key feature is the value of the Lorenz' force which acts on the charged particles rather that the individual magnetic and electric field vectors.

Another mechanism suggested by more than one 'academic' worker invokes changes to cation hydration following breakage of hydrogen bonds by the field (it is unclear if the energy available from the Lorenz' force is adequate to fully support this possibility).

As a consequence to the enhanced nucleation and precipitation of scaling minerals, it is further postulated that in favourable situations previously supersaturated solutions can become locally undersaturated (downstream) thus disturbing the equilibrium of existing scale deposits which can slowly re-dissolve. This would explain the many reported observation of scale removal downstream of the point of installation.

FAILURES.

Any balanced presentation should make reference to the failures as well as successes. The work of Eliassen (2) and a review by Cowan and Weintritt(18) provides much evidence of failure of devices. Cowan correctly states that successes claimedfor many devices have in fact been due to some other concurrent change that took place within the system. Failures in industry are more common than in domestic situations. High suspended solids, high TDS, high pH, sudden pressure change and irregular flow regimes are parameters sometimes associated with failures.

A contributory reason for failure is that many vendors have a poor understanding of the scope and limitations of their devices. Previous success in treating mains water problems leads to false claims that the same product can resolve industrial problems with waters of very different qualities. Devices are claimed in vendors literature to 100% replace chemicals. Without qualification this is unlikely to be true and may lead to failure: the two technologies should be

12 seen as complimentary with overall cost and environmental benefits to the end-user, rather than mutually exclusive.

CONCLUSIONS

Electronic scale prevention and scale removal has been demonstrated in the field and in the laboratory. Simple mains and potable waters can be treated to reduce or eliminate timescale with high probability of success. Industrial waters of much higher hardness and TDS, with calcium carbonate and calcium sulphate mineral supersaturation have been successfully treated. Significant replacement of chemicals is possible in many instances. The flexibility of the electronic device technology suggests significant advantages over the more established use of magnets.

Electronic devices and magnetic devices give very similar results in field installations and early indications are that performance similarities are found in the laboratory. The operating principles of the two types of device cannot be the same however as magnets require a minimum (large) magnetic field strength and they are effective within limits of flow rate.

Much work still needs to be done to understand the fundamental interactions, to define the scope and application limits and to build a predictive tool for the end-user. Vendors are in general small companies with limitedresources for R&D. Other sources of sponsorship are needed so that industry can benefit from the undoubted potential for environmental and cost improvements that is offered by this technology.

The combined use of a 'physical water treatment device1 and conventional scale control chemistry mav well give optimum performance and would be an intriguing subject for study (perhaps funded by a chemical company??).

The author wishes to thank Scalewatcher UK Ltd. and Scalewatcher International Ltd. for their help in preparation of this document.

REFERENCES.

1. Welder, B.Q. and Partridge, E.P.1 Practical performance of water conditioning devices,' I&EC, Vol 46, 5, p 954-970,1954. 2. Eliassen, R and Uhlig, H,' So called Electrical and Catalytic Treatment of Water for Boilers,' JAWWA, Vol 44, p 576 - 582, July 1952. 3. Eliassen, R et al, "Experimental performance of Miracle Water Conditioners', JAWWA, Vol 50, p 13371-1385, 1958. 4. Donaldson, J.D, New Scientist, 117, 1988. 5. Hasson, D and Bramson, D, 'Effectiveness of magnetic water treatment in suppressing CaC03 scale deposition1, Ind Eng Chem Process Des Dev, 24, p 588-592,1985. 6. Gehr, R. et al, 'Reduction of soluble mineral concentrations in CaS04 saturated water using a magnetic field',Water Resources 29, p 933-940, 1995. 7. Donaldson, J.D., The magnetic treatment of fluids in scale prevention', Conference; Advances in Solving Oilfield Scaling Problems, Aberdeen, October 1992. 8. Chibowski, E., et al, Colloidsand Surfaces A: Physiochemical and Engineering Aspects 92, p 79-85,1994. 9. Higashitani, K., et al, 'Effects of a magnetic field on the formation of CaC03 particles', J. Colloid and Interface Science, 156, p 90-95,1993. 10. Baker, J.S and Judd, S.J., Cranfield University, unpublished information. 11. Pandolfo, L., et al, La Chimica e L'Industria, 69, p 88-89,1987. 12. Herzog, R.E., Katz, J.L., et al, 'Magnetic water treatment: The effect of Iron on calcium carbonate nucleation and growth', Langmuir, 5, p 861-867,1989. 13. Donaldson, J.D., and Grimes, S.M., 'Magnetic treatment of fluids for barium sulphate scaling prevention', PSTI Technical Bulletin, 1, p 13-16,1991. 14. De Baat Doelman, J., U.S. Patent 5,074,998, 'Apparatus for treating liquid to prevent and/or remove scale deposits', 1991. 15. Ellingsen, F T., and Kristiansen, H., Vatten, 35, p 309-315, 1979. 16. Vermeiren, U.S. Patent 2,596,743,1952. 17. De Baat Doelman, J., Scalewatcher unpublished report, 1994. 18. Water - Formed Scale Deposits', Cowan and Weintritt, page 300-306, Gulf Publishing Company, Houston. 19. Busch, K. W , et al, 'Studies of a water treatment device that uses magnetic fields', Corrosion, Vol 42, 4, p211-221,1986. 20. Lazarenko, L.N., and Zhuravlev, PD, 'Influenceof magnetic water treatment conditions on the quality of concrete', Sov. surf Engng. appl. Electrochem (eng) 1,101-105 (1985). 21. Lin, I.J., and Yotvat, J., 'Electro-magnetic treatment of drinking and irrgation water' Wat. Irrig. Rev., 8, 16-18 (1989).

14 Appendix 1 - Case Histories.

Case History CHI: Offshore Oil Platform: Water Treatment Plant: Flowlines and a treatment plant for oily water (flotation unit) were fouled by CaCOs and minor iron oxides despite scale inhibitor use. A Scalewatcher unit was fitted to 10" GPR inlet, carrying 8000 1/min. of brine. Scale inhibitor plus device were used together for 2 months, then chemical used reduced to zero. Inspection of the system after 6 months showed that Bowlines and flotation unit were practically free of scale. Partial water analysis: pH= 7.0, Ca= 3900 mg/1, HCO3=220 mg/1, Mg=670 mg/1, Na=44000 mg/1, C$=78000 mg/1. Temp=50°C. Pressure=1.05 bar. Analysis similar over 24 month period.

Case History CH2: Brine in large Base Chemical Manufacturing Plant: Process stream was a salt brine containing a low but significant level of hardness (CaCOs + Mg(OH)2). This caused fouling of individual plant 6" lines and common 14" manifold. Not inhibited butcleaned every 6 weeks by acid. The quantity of scale that had accumulated could be calculated. After fitting a Scalewatcher units to a test 6" line it was found that the quantity of scale accumulating per 6 week period was 10% of that previously recorded. Partial water analysis: pH=9, NaCl=200000 mg/1, Ca hardness =5-15 mg/1, Mg hardness= 10-20 mg/1, Temp=60°C. Flow=50001/min.

Case History CH3: Source cooling water in (paper) mill: Cooling water from a hard water aquifer was previously fouling a heat exchanger unit. Performance was then monitored with polycarboxylate inhibitor plus Scalewatcher unit fitted to 12" steel inlet line carrying 4000 1/min water. System then clean. Chemical dose reduced to zero. After 2 months inspection showed only trace scale. Partial water analysis: pH=7.5, Hardness (CaCOs)=300 mg/I, IDS <1000 mg/1, Temp= 70-80°C, Pressure=l bar, suspended solids absent.

15 Appendix. 2 - List of perceived advantages of \$ca\ewatcher\ electronic units compared to alternative devices.

Advantages of electronic units compared to magnets

• Easily installed • Environmentally safe • Non intrusive no restriction to flow no risk of corrosion due to installation no need to cut / weld pipe sections • Not flow rate dependant no upper limit: viz. comparison magnetic systems • No restriction on pipe size (magnets are limited) sizes from 15mm to over 1250mm are fitted • No requirement for in-line filter • Evaluation (trial) units available for industrial users • Lightweight • Available in intrinsically safe housing sealed to EP55. [IP66 available]. can be configured for offshore oil platform locations • Conforms to EEC standards - complies with IEC335 • Can be used safely on drinking water supplies • Audio and visual malfunction alarms • Support from technical service department • Guaranteed 3 years by manufacturer

Note that this specific list may not apply to all electronic devices available on tire market.

16