'Docslide.us Pcs 2000 Operators Manual.pdf'

8/20/2019 'Docslide.us Pcs 2000 Operators Manual.pdf'

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DCVG COATING DEFECT

SURVEY EQUIPMENT

PCS-2000

OPERATORS

MANUAL

© This document remains the property of PCS-2000 (Aust) Pty Ltd.No information contained within this document or copies of this document in part or full shall be made and passed

to unauthorised third parties without the written consent of PCS-2000 (Aust) Pty Ltd. _______________________________________________________________________________________________________________________

DEVELOPED & SUPPLIED BY:

PCS-2000 (AUST) PTY LTD 4 Judith Court

Aspendale Gardens Victoria 3195AUSTRALIA

tel : +61 431 807033

fax : +61 3 9532 3963web : www.solcor.com.au


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PCS-2000 Operators Manual Page 1

OPERATORS MANUAL

PREFACE

Thank you for your selection of the PCS-2000 instrument for undertaking Direct Current Voltage

Gradient (DCVG) Coating Defect surveys.

PCS-2000 incorporates the latest corrosion detection and electronics technology into a compact,

international standard unit designed for easy use.

To effectively use PCS-2000 and to keep it in optimum service condition for a long period of

time, follow the operating and maintenance instructions in this manual.


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TABLE OF CONTENTS

Page No

PREFACE..............................................................................................................................1

1.0 COMPONENT GUIDE ..............................................................................................3

1.1 RECEIVER - Figure 1 ............................................................................................3

1.2 PROBES - Figure 2.................................................................................................4

1.3 CURRENT INTERRUPTER - Figure 3 ........... .......................................................6

2.0 OPERATING INSTRUCTIONS.......................... .......................................................7

2.1 Set-Up.....................................................................................................................7

2.2 Survey Procedure....................................................................................................9

2.3 Centering Defects..................................................................................................10

3.0 RECORDING AND INTERPRETATION OF RESULTS ........................................13

3.1 Coating Repair Criteria and Cathodic Protection System Review ..........................16

4.0 CARE AND MAINTENANCE.................................................................................16

4.1 Maintenance..........................................................................................................16

4.2 Procedures ............................................................................................................164.3 Caution .................................................................................................................17

5.0 FAULT FINDINGS..................................................................................................18

6.0 WARRANTY...........................................................................................................19

7.0 EQUIPMENT SET ...................................................................................................20

8.0 OPTIONAL SPARES, EQUIPMENT AND SERVICES ..........................................21

9.0 PATENT PROTECTION..........................................................................................21


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1.0 COMPONENT GUIDE

1.1 RECEIVER - Figure 1

___________________________________________________________________________

Name Function ___________________________________________________________________________

(1) Millivoltmeter Indicates the average steady-state signal voltage measured between the

two probes. Meter has three scales with a centre zero and battery

charge indicator. Scales are + or - 5 / 10 / 20.

(2) Mode Switch Used to turn the instrument ON and OFF and perform a battery test.

(3) Range Selector Used to select the meter range. Ranges are 10 / 20 / 50 / 100 / 200 /

500 / 1000 / 2000 / 5000 mV.

(4) Impedance Used to select the meter impedance. Impedance values are 100 or

1000 megohms.

(5) Strap Post Used to secure neck strap to meter box.

(6) Strap Bracket Used to secure waist strap to meter box.

(7) Probe Socket Used to plug in lead from probe. One located on each side of meter

housing.

(8) Charger Socket Used to plug in lead from battery charger.

___________________________________________________________________________

Figure 1


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1.2 PROBES - Figure 2

___________________________________________________________________________

Name Function ___________________________________________________________________________

(1) Lead Socket Used to plug lead to meter.

(2) Drip Inlet Drip tube inlet. Push tube to lock in. To release tube / plug,

push in outer ring (red) with fingers and withdraw tube / plug.

(3) Foam Grip Soft hand grip for operator.

(4) Electrode Used for potential measurement. Tube contains tap water.

(5) Drip Outflow Apeture Permits flow of water to probe tip.

(6) Removable Plug Holder *Permits replenishment of tap water by unscrewing.‘O’ ring

provides seal.

(7) Porous Plug *Permits electrical contact between half cell and ground.

Removable by unscrewing of two brass fixing screws and

levering out. ‘O’ ring provides seal.

(8) End Cap Used to cover tips when probes are not in use. Prevents

leakage.

(9) Auto Zero Automatically zeroes the meter. Used to maintain needle in

central location when taking readings at defects or when

excessive drift is noted. Activated by momentary thumb

pressure. On right hand probe only.

___________________________________________________________________________

* Notes:

1. Although the video / CD-ROM mentions the use of copper/copper sulphate

(Cu/CuSO4), it is recommended that tap water is used in the test probes.

2. Test Probes - Water can be used in preference to Cu/CuSO4 solution. Recent testresults obtained show that using water provides:

Χ equivalent sensitivity;

Χ easier maintenance;

Χ less risk of damage if spilled on equipment.


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Figure 2


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1.3 CURRENT INTERRUPTER - Figure 3

___________________________________________________________________________

Name Function ___________________________________________________________________________

(1) ON-OFF Switch Used to activate interrupter to set switching cycle.

(2) Signal LED Indicates operation of interrupter with audible switching

sound.

(3) Terminals Used to connect interrupter in series with DC or AC circuit.

Two terminals permit use of banana plug, spade lug or bare

cable connections.

(4) Low Battery Indicator Indicates low battery voltage when illuminated.

(5) Charger Socket Used to plug in lead from charger. Facility also available for

connection of external 12 volt battery using optional

connector lead for extended period of operation.

___________________________________________________________________________

Figure 3


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2.0 OPERATING INSTRUCTIONS

2.1 Set-Up

2.1.1 Fill water bottles in back pack, check adequate levels of tap water (min. 4"/100mm

head) in probes.

2.1.2 Install interrupter in permanent transformer rectifier unit or set-up temporary impressed

current system for signal injection. Normal switching cycle a seconds ON, b seconds

OFF. Positive feeder cable connection to groundbed and negative feeder cable

connection to structure should be confirmed at commencement. See Figure 4.

Figure 4 - Interrupter Set Up to Inject Signal

2.1.3 Output from the system can be turned up without unduly polarising the pipe as current

is only ON for a third of the time. Do not exceed 30 amps DC output. Switchingoutputs greater than 30 amps will damage the interrupter. A separate contractor must be

used in order to switch larger currents.

2.1.4 Where possible adjust current output to give a minimum potential swing of 500 -

600mV from ON to OFF. A swing of 1000 - 2000mV is desirable when testing over

high resistivity ground. 'Shift' of signal strength can be measured using the Pipe-CAMP

meter. One probe being placed on the structure monitoring cable and the other probe on

the ground. The pulsing signal also confirms operation of the equipment.


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2.1.5 Strap on meter, connect cables and drip tubing to probes. See Figures 5, 6 & 7.

Figure 5 - Equipment Set Up

Figure 6 - Confirming Operation of Equipment


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Figure 7 - Drip System Connections

2.1.6 Turn meter ON through automatic battery test. Set impedance to 100 or 1000

megohms. Select 1000 megohms only for testing over bitumen / asphalt surfaces or

where ground is very dry (high resistivity). Set range selector to 100mV for survey to

maintain meter deflections on the scale.

Note: Drip system only require for surveying over high resistance surfaces such as

bitumen, concrete or dry soil/sand.

2.2 Survey Procedure

2.2.1 Measure ON and OFF potentials at all test points, valves and risers to determine signal

strength i.e. difference between ON and OFF readings.

2.2.2 Walk along the pipeline route using probes as walking sticks ensuring that one probe is

in contact with the ground at all times. One probe should always be near the centerline

of the pipeline and the other held laterally by 1-2m. For short durations between steps

both probes must be simultaneously contacting the ground. Where there's no defect, the

needle will register no movement.


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2.2.3 When approaching a coating defect a noticeable swing will be observed on the

voltmeter at the same rate as the interrupter switching cycle. The amplitude of this

swing will increase as the defect is approached and decrease when walking past.Needle swing is directional with probes held in a similar orientation parallel to the

pipeline. Needle swing to right indicates right probe closer to defect and vice versa.

See Note No. 2 under Figure 2.

2.2.4 An auto zero button is fitted at the top of the right hand probe. This button should be

depressed momentarily when the meter needle strays excessively away from the centre

position or to assist when taking readings at defects.

2.2.5 Select a suitable volts scale in order to note amplitude of swings.

2.2.6 If signal strength becomes weak, say 100 - 200mV, consider relocation of signalinjection point to a closer location for increased strength as small defects may be

missed.

2.3 Centering Defects

2.3.1 Whilst traversing along the top of the pipe, maximum amplitude of swing will indicate

approximate location of defect.

2.3.2 At two or three locations, offset from the line by 2 - 4 metres (6 - 13 feet), place probes

along the voltage gradient to obtain a ‘null’ on the meter. A right angle line through the

centre of the probe locations should pass over the defect epi-centre. This geometrical

procedure on opposite sides of the pipeline will locate the exact point above the defect.

See Figures 8 & 9.


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Figure 8 - Locating Defect Centre

2.3.3 Mark defect location by pegging (or alternative) and note location.


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Figure 9 - Voltage Gradients Resulting from Different Types of Defects

2.3.4 With probes spaced approx. 2m (6 feet) apart, measure a succession of potential drops

from the defect epi-centre to remote earth at right angles to the pipeline. This would

typically be 10 - 15m (32 - 49 feet) when increments of potential drop reduce to 1mV.

See Figure 10.

2.3.5 Record summation of potential drop increments to obtain total overline to remote earth

potential drop for relevant defect.


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Figure 10 - Taking of Lateral Readings OL/RE

3.0 RECORDING AND INTERPRETATION OF RESULTS

Signal Strength.

ON and OFF potentials should be measured at all test points, risers, valves and other

pipeline appurtenances. The numerical potential difference is the signal strength.

e.g. ON potential = -1.45 volts

OFF potential = -0.95 voltsSignal strength = 1.45 - 0.95 volts

= 0.5V or 500mV

As the surveyor approaches a coating defect, a pulsing signal is detected by the

voltmeter. See Figure 11.


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Figure 11 - Voltage Gradients around Defects

The electrodes are used in various geometric attitudes and spacings to confirm the

validity of the indication and exact defect location. Probes placed across voltage

gradient lines will indicate voltage deflections cycling at the same rate as the current

interrupter. Probes placed along equi-potential lines will result in the instrument

nulling. Tracing of the voltage gradients will rapidly locate the defect epicentre. The

defect should be marked and a record made. A sample record form is appended.

Signal strengths along a pipeline may be as per Figure 12.

Figure 12


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Estimated signal strength at defect

= 200mV + 1500 (300 - 200) mV

500 + 1500

= 200mV + 75mV= 275mV

A straight line attenuation effect is assumed between test locations to calculate the

signal strength at intermediate defect locations.

Having detected the epi-centre, a series of lateral readings are taken moving away to

remote earth. Lateral readings near the defect will yield maximum voltage differences

where gradients are at a maximum. Whereas readings at remote earth will indicate zero

to 1mV deflections. The summation of these readings is commonly referred to as the

over-the-line to remote earth voltage. The expression "percentage IR" has been adopted

to give an indication of defect size. For instance, if a series of lateral millivolt readings

to remote earth are 25, 15, 6, 4, 3, 1, 1, 0 and the attenuated signal at the location basedon adjacent test point readings is 275mV.

Over-the-line to remote earth voltage = 25 + 15 + 6 + 4 + 3 + 1 + 1mV

= 55mV

Percentage IR = Overline to remote earth voltage x 100%

Signal strength

= 55 x 100%

275

= 20%

Theoretically, this percentage IR is used to predict the reduction in protection

levels ignoring polarisation effect. For example if adjacent test points have 'on'

potentials of -1000mV and it is assumed that the native state potential was: -550mV.

Potential at defect = - Potential -(%IR/100 x potential shift)

= - 1000 - (20/100 x (1000 - 550))

= - 1000 - 90

= - 910mV

In other words, a reduction in protection but still protected. If in fact the defect had a50% IR, the potential would then be -775mV, i.e. under-protection.

There are a number of inherent errors in this technique. Polarisation effects are

overlooked, soils are assumed to be homogenous and potential drops between the

ground surface and defects are not allowed for.


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3.1 Coating Repair Criteria and Cathodic Protection System Review

Reduction in protection will generally be proportional to the amount of poor coating.Thus, any significant coating defects should be repaired. It is good practice to maintain

OFF potentials in the range of -0.85V to -1.15V. Over-protection for some coatings

can be disastrous as a result of hydrogen evolution and formation of alkali.

As a general rule, average to poorly coated pipelines should have coating defects

greater than 15% IR repaired. On well coated pipelines defects greater than 5% IR

should be repaired. As a guidance, 5% IR typically indicates 1.5 in2 /10cm

2 of bare

steel. This varies with resistivity at defect and depth of pipeline.

The cathodic protection system must be adjusted such that all the line is maintained in

a protected range without over-protection.

4.0 CARE AND MAINTENANCE

4.1 Maintenance

4.1.1 *When refilling, avoid spillage of tap water onto top end of probes.

4.1.2 *End caps must be replaced after use immediately to prevent drying out the porous

plug. Caps should contain a small quantity of water prior to being placed over porous

plugs to maintain moisture.

4.1.3 Side connector of shaft for water tube should be plugged after use to avoid fouling with

dirt.

4.2 Procedures

4.2.1 Although the equipment is constructed from robust materials, the meter, probes and

interrupter contain sensitive electronics requiring care in handling and transportation.

Always transport the equipment in the carry cases provided.

4.2.2 Both probes should be secured with sponge and straps at two locations before packing

into tube to avoid vibration damage during transportation.

4.2.3 When testing at test stations/points the range selector should be set at an appropriate

range, say 1000mV.

4.2.4 Ensure that rechargeable batteries in meter and interrupter are kept charged to avoid

delays during surveying. Use only charger supplied. Make sure that the correct voltage

supply is used i.e. 110V or 240V.


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4.2.5 Current at transformer rectifier to be interrupted MUST NOT exceed 30A. When 30A

or more, switching via a contractor is required. Switching of currents of 20A or less

will increase the relay life.

4.2.6 Static spike must be used at all times.

4.2.7 Static spike seats between two 'O' rings on the porous plug holder.

4.2.8 During surveying do not forcefully jab at the ground with the probes.

4.3 Caution

4.3.1 Protect the meter and interrupter from rain. Do not immerse probes in water.

Electronics components are housed in the probes.

4.3.2 Electrical connector sockets to be kept free from dirt.

4.3.3 *Absorbent paper / cloth should be placed around probes prior to filling probe with

water to catch any spillage which would contaminate the electronics.

4.3.4 The porous plugs at the ends of the probes will wear and will require replacement.

Remove brass fixing screws and lever out using pliers or grips.

4.3.5 Ensure that during unscrewing porous plug for refilling or replacement, the adjoining

end piece is held and not the transparent electrode.

4.3.6 Sharp side blows to the shaft must be avoided.

4.3.7 Water should be emptied from electrodes when equipment is not in use.

4.3.8 Avoid stretching or tugging cables.

4.3.9 Backpack bottles should be emptied of water and double capped after use.

4.3.10 Only fill bottles with clean water to avoid blockage of tubing.

4.3.11 Sponge tips must be kept moist at all times to avoid hardening up. Retain in sealed

bag.

* See Note No. 2 under Figure 2.


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WARNING: Only qualified and experienced personnel should undertake connections toAC and DC circuits. Exposed live cables are hazardous.

DO NOT clean the equipment with solvents as permanent damage may occur. If cleaning is

necessary, only use a damp cloth.

5.0 FAULT FINDINGS

PROBLEM POSSIBLE REASON ACTION

Insufficient current output Χ Increase current output.

Χ Disconnect off other lines

not under test.

Χ Change groundbed location.

Testing on pipeline

appurtenance which is

resistively connected to the

pipeline.

Test at different location.

Large defect at test location. Test at different location.

Low Signal Strength

Short to foreign structure. Locate short and isolate.

Low Battery Indication Batteries require recharging. Put on charge.

Existence of large defects. Increase current output or

relocate groundbed.

Short to foreign structure Locate and isolate.

Testing over high resistance

ground

Χ Change meter range.

Χ Use water drip system.

Χ Increase water drip rate of

Χ If over bitumen place

Major Loss of Signal

Test point resistivity

connected to pipeline.

Test at different location.

Unable to Centre Defect Long defect such as scratch

or split.

Trace voltage gradients by

placing one probe overline and

other laterally spaced to obtain

equi-voltage gradients.

See Figure 8 in Section 2.3.2.


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PROBLEM POSSIBLE REASON ACTION

Several defects closely

spaced in a line.

As above.

Poor connections between

meter and probes.

Check cabling and connections.

Signal to line removed. Check signal injection location

and interrupter.

Low Battery. Charge.

Unable to Obtain any

Readings

Low level of water. Replenish.

Erratic Deflections of

Meter.

Improper contact due to

humidity at contact points.

Ensure all contact points and

connections are perfectly dry

and free from moisture.

6.0 WARRANTY

Equipment carries a 12 month warranty against defective materials and workmanship from

date of shipment. PCS-2000 (Aust) Pty Ltd is not liable for damages resulting from

instrument failure. Goods must be returned to manufacturer with freight pre-paid by client.

The warranty becomes void if internals of the equipment are tampered with by unapproved

personnel unless specifically advised in writing by PCS-2000 (Aust) Pty Ltd.


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7.0 EQUIPMENT SET

A full set of PCS-2000 equipment consists of:

1. PCS-2000 receiver.

2. One pair of probes, cables and one auto zero switch.

3. PCS-2000 current interrupter.

4. Battery charger.

5. Backpack containing one pair of water bottles.

6. Two pairs of connecting drip tubes (one spare pair).

7. 50 defect location markers and holster.

8. Sponge and wood probe tips and fixing screws for testing over concrete and

asphalt/bitumen.

9. Receiver harness.

10. CD-ROM.

11. Operators manual.

12. Carry case and probe tube.


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8.0 OPTIONAL SPARES, EQUIPMENT AND SERVICES

The following are available as optional items:

1. Cables

2. Replacement tips

3. Synchronous interrupters

4. Results plotting program

9.0 PATENT PROTECTION

Worldwide patent protection under the International Patent Co-operation Treaty has been

registered.

PCS-2000 (AUST) PTY LTD

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