ROV II Gluv Probe Operation Manual

POLATRAKTM ROV II TIP CONTACT

PROBE

GLUV PROBE

Operation Manual

Phone: (713) 983-7117 Fax: (713) 983-8858

10851 Train Court Houston, TX 77041

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DEEPWATER CORROSION SERVICES, INC. ROV II & GLUV PROBE MANUAL

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Table Of Contents

1.1 Dive Spread Installation 1.2 ROV Installation 2.0 Cautionary Notes 3.0 Calibration 4.0 Operation 5.0 Obtaining Pipeline Calibrations for CP

Snake or Pipescan Surveys 6.0 Reference Drawings & Calibration Forms

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1.0 Installation

1.1 Dive Spread

ROV II Tip Contact Probe When used in conjunction with diving operations, it is recommended that a cable is assembled with a SEACON RMG-3FS connector at the subsea end. The most suitable cable in our experience is the 4 conductor armored spiral comms cable that is used by most divers for diver communications. This has two twisted pairs and is very rugged. A connection whip with this connector os provided with the probe and should be soft spliced onto the end of the comms cable. Ensure that the connection is taped back to the armored wire to provide strain relief on the connection. (If required InterResources can provide a complete assembly on a 500 foot long umbilical cable.) The appropriate length of wire should be married into the dive hose leaving 4-6 feet of slack at the diver end and at least 50 feet at the topside end. Always install the dummy plug on the connector when the probe is not attached. The topside end of the wire will be run to the dive control area along with the platform ground cable and any ground from pipeline risers. The connections can be made either to a pair of digital multimeters or to a POLASCAN DUAL READOUT PANEL, available from InterResources. (Wiring hookups are show in section 6.) POLASCAN Gluv-Probe (No Tip Proximity Probe) The Gluv-Probe has the same connector as the ROV II except that the large pin (tip wire) is not used. Note that the probes are interchangeable on the same connector.




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1.2 ROV Installation

The probe is best installed in or on a manipulator but may be attached directly to the ROV frame if there is no manipulator available (this is best when only proximity readings are required). The Gluv-Prove is not recommended for ROV interfacing. The recessed grooves in the probe body may be used to accommodate stainless steel hose clamps for attachment, it is recommended that a safely line is provided as well as some neoprene rubber pads between the probe and the mounting surfaces, this will provide a better attachment and some degree of compliance. The connector on the back of the probe is a SEACON RMG-3FS and is wired as shown in Fig. 1 below.

Fig.1

A male connector on a 6’0” whip is provided to facilitate splicing into the ROV junction box. It is recommended that the two electrode wires are routed in a shielded twisted pair in the ROV umbilical, the tip wire can be connected to a coaxial cable or any other cable that is straignht through to the control van with no breaks. Topside the system can be wired directly into a video annotator (insure that it has an input impedance of at least 10 MegOhm / Volt), or onto either a pair of multimeters or a POLASCAN panel. See attached wiring schematics for hookup options.

PIN 1 CONTACT TIP (TIP) (Blank on Gluv Probe)

PIN 2 ELECTRODE #1 (R1)

PIN 3 ELECTRODE #2 (R2)




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2.0 Cautionary Notes

POLATRAKTM sintered silver chloride reference electrode elements are designed to withstand normal oilfield operations, but they are consumables that have a given operational life, the life of these electrodes can be extended to several seasons if the following care is taken.

• Never allow the electrode elements to be directly shorted to ground or any other metallic object when immersed in seawater.

• Never run the electrode subsea with the underwater connector un-

mated.

• Never read the CP probe with an analog voltmeter, ensure that high input impedance digital equipment is used.

• Never handle the bare reference electrode element (small gray

pellet) with bare or greasy hands.

• Do not use any type of solvent or detergent on the probe, rinse only in fresh water when not in use.

• Never immerse the electrode in anything but fresh water or sea

water.

• Never allow an underwater connector to be immersed unless it is mated or has a sealing dummy plug inserted.

• Never read the electrode on a multimeter scale other than DC

Volts.

• When not in use store the probe in the container provided filled with seawater or tap water. Probe can be stored dry between jobs but should be rinsed in freshwater thoroughly before storage.

• Do not attempt to field repair any wires on the probe or inside the

probe and never attempt to modify the probe tip in any way.




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3.0 Calibration

3.1 General It is imperative to follow calibration procedures precisely and to change electrodes if a probe shows out of calibration. Improperly reported CP readings could cause serious problems to the facility operator and may have to be repeated. The most common cause of problems, particularly on diver surveys, is damage to the cable insulation, this causes an offset in the reading which would usually be interpreted as inadequate protection levels, for this reason both topside and subsea calibrations should be performed before during and after every dive. Note: Oil company calibration specifications must be met, but we strongly advise also using the attached procedures.

3.2 Topside Calibrations (Bucket Calibration)

If probes have been stored for a significant period, and have been allowed to dry out, it may take 1-2 hours of immersion time before the electrodes stabilize.

The attached sheet shows the procedure, ensure that either native seawater or artificial seawater (3% by weight salt) is used. Procedures (forms are included for Cell to Cell, Master Silver/Silver Chloride, and zinc coupon checks). The zinc calibration coupon is provided as standard, but the master silver/silver chloride procedure is recommended). NEVER USE A METALLIC CONTAINER WHEN PERFORMING CALIBRATIONS OR FOR STORAGE.

3.3 Subsea Calibrations

Tow subsea calibration procedures should be followed and the results logged at least once per dive.




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3.3.1 Cell To Cell Calibrations

This procedure checks one cell in the probe against the other, and should be performed with all the cable immersed as it will quickly detect any cable damage.

If dual readouts are used as shown in the wiring diagrams, the cell to cell reading is displayed continuously, this is the recommended procedure. The cells should read within +/- 5 mV DC. If the value drifts outside this range then one of the following has happened:

• Lead wire is damaged exposing copper to seawater. • A connector is not properly made or is leaking. • One cell has failed.

If in the middle of a dive it is possible to complete the dive, however the defective cell should be isolated and the good cell used to finish the dive. The bad cell will normally be the one which displays the most positive potential. So read a potential on the structure with both elements, the most negative cell should be used to complete the dive, and the offset noted. When recovering the umbilical cable from such a dive, monitor the cell to cell value, if the problem is lead wire damage, the value will revert to within +/- 5mV as soon as the damaged area clears the water, in this way the damage can be quickly located and repaired.

3.3.2 Ground Check

This procedure verifies that the platform ground wire and the probe tip will yield the same reading at any point on the main structure. This is particularly important when the probe is being used in proximity mode. The POLASCAN READOUT has a facility to switch between tip and platform ground. To verify the ground, stab the steel structure under survey with the probe and record the value switching grounds from tip to platform, the reading should be identical, if it varies by more than +/ 3 mVDC, check the platform ground connection.




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4.0 Operation

Most oil companies will have their own survey procedures that should be followed. The following guidelines are given as guidance only.

Connect the system as shown on the attached wiring schematics. ROV Wet Check

When interfaced to an ROV, it important to perform a wet check before every dive. Signal errors caused by umbilical power cable interference could introduce reading errors. With the probe wire to the ROV, immerse the system to at least (-) 30 feet, and with the vehicle still in it’s TMS bring up one electrical system at a time and note the potential of the tip (it will vary some depending on immersion time). If there is a problem, the potential will change rapidly or will spike when the circuit is powered. Repeat for all electrical and hydraulic systems. If a problem is detected it should be fixed, usually it’s a poor ground connection or a faulty leaking underwater connector that cause the problem. If the system at fault can be switched off without hindering operation, this is an acceptable option. Offshore Probe Maintenance Changing Electrodes Spare plug-in electrode elements can be provided with the ROV II probe, these elements will also work in the Deep-C-Meter, the CP-Gun and the CP Snake systems. POLASCAN Gluv Probes do not have replaceable elements. If the elements or one element needs to be changed, follow this procedure: 1. Take the probe into a clean inside working area, with a clean grease

free work surface. 2. Locate the assembly drawing at the back of this manual. 3. Remove the head assembly carefully by removing two screws on back

of probe, pull out gently until two electrode connectors are visible. 4. Using an ohm meter measure between the connector pin and the

electrode element to verify which is which. (Do not handle electrode elements).

5. Unplug the bad electrode(s) from connector(s), and discard.




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6. Apply a small smear of silicone grease into the open female connector and insert the new electrode. (Avoid using excess grease, and any grease contact with electrode element.)

7. Check the integrity of the tip wire connector, re-make as necessary. 8. Carefully re-insert the electrodes into the probe body and replace the

head assembly. Recording CP Potentials If wired correctly the CP potentials should have a negative polarity. Accurate readings will be steady and not drifting so long as the probe is not moving. If readings are erratic this is a sign of a connection problem, and the cause should be isolated and fixed. To obtain accurate readings the probe apertures should be within 2“ of the structure surface. The further away the probe is held from the structure area under investigation, the less accurate will be the reading. On offshore structures protected with zinc or aluminum anodes the following potential ranges should be observed. (-) 0.750 - (-) 1.100 Volts On Jacket Members / Pipelines (-) 0.970 - (-) 1.150 Volts On Anodes Readings outside of these ranges should be double-checked. It is possible to see potentials less negative than (-) 0.750 Volts, but this would mean an unprotected structure with large numbers of consumed anodes or a high ratio of low potential anodes.




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5.0 Obtaining Pipeline Calibrations for CP Snake or Pipescan Surveys

AN ROV II Probe is provide as part of both a PIPESCAN and CP SNAKE Survey Spread. Both these systems require a number of calibration points on the pipeline, these are usually measured at anodes or on subsea valve / tie in assemblies. Two readings are required during these calibrations: 1. Close Pipeline Potential (Measured between the probe electrode and

the contact tip) 2. Remote Pipeline Potential (Measured between a remote electrode or

drop cell and the probe contact tip) Note: A POLATRAKTM Model DC-II Drop Cell is also provided with these survey spreads. The remote cell should be deployed over the side of the boat such that it is at least 20 feet from the boat hull and at least 50 feet from the pipeline under survey. Note the close and remote potentials. If an anode is stabbed the remote potential will normally be more positive than the close potential. See Fig. 2 Below

Figure 2. Pipeline Calibration Schematic

Remote DCII Remote DCII Drop CellDrop Cell

Close Electrode R1 in ROV II ProbeClose Electrode R1 in ROV II Probe

•• Calibration stab at anode or on riserCalibration stab at anode or on riser•• Remote is at least 50 feet from pipeRemote is at least 50 feet from pipe

Close vs. Tip (Close vs. Tip (--) 1.080 Volts (True Close ) 1.080 Volts (True Close Potential)Potential)

Remote vs Tip (Remote vs Tip (--) 1.000 Volts (True ) 1.000 Volts (True Remote Potential)Remote Potential)

Close vs Remote (Close vs Remote (--) 0.080 Volts ) 0.080 Volts (Remote Variation (Remote Variation -- Measured & Measured & Calculated)Calculated)

+ -CLOSE

+ -REMOTE




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6.0 Drawings and Calibration Forms

The following drawings and forms are attached for reference: Polatrak ROV II Dive Probe GA Polatrak ROV II Dive Probe Assembly CP Survey Wiring with Optional POLASCAN Panel CP Survey Wiring Schematic with Twin Voltmeter Setup POLASCAN Gluv-Probe Details Calibration Form – Cell to Cell Calibration Form – vs. Zinc Coupon Calibration Form – vs. Master Ag/AgCl Electrode Calibration Form – Pipeline Calibration




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Project No: Pipeline ID: From:Date: Diameter: To:

Operator: Service: Sheet:

Stab At: Anode:Location: X: Flange:

Y: Valve:KP / FP: Coating Defect:

Waypoint No: Riser:

ROV II Probe to Drop Cell Calibration (ROV II Positive): mVClose Potential: mVRemote Potential: mV

Notes:



Waypoint No: Riser:


Notes:



Waypoint No: Riser:


Notes:

Calibration Number:

PIPELINE CALIBRATION RECORD

Calibration Number:

Calibration Number:



ROV II Gluv Probe Operation Manual

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