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the voltmeter to the platform. The potential values are displayed on the 

 video monitor. (The French company SESAM, also provides this service from 

 their RCV-225) . 



Marine Growth Clearance 



A water jetting gun with integral pump operates from any depth to provide 

 a high pressure water jet to remove growth. The pump feeds a reaction jet 

 and delivers pressure of up to 351 kg/sq cm (5,000 psi) at a flow rate of 

 38 1. (10 gals) per minute. The gun reportedly cleans to bare metal on an 

 inspection point in seconds. 



Sand Suction 



A suction horn gives the ability to clear sand from around a pipe or similar 

 object on the seabed and allows underside inspection of spool pieces, etc. 



Ultrasonic Measurement 



An ultrasonic wall thickness gauge, developed by Sonarmarine, has a probe 

 held in a manipulator and deployed against the structure. The thickness 

 of the structure is presented on a CRT display and also on digital display 

 or an X-Y plotter. 



Radiographic Inspection 



SMT 2 places an isotope source and a photographic plate around a riser for 

 a specified time and then recovers them. The data is used to detect flaws 

 or cracks in the riser. 



Under the direction of the platform surveyor, the operators of SMT 2 deploy 

 these capabilities at structure locations in accordance with an agreed-to 

 inspection schedule. 



3.1.2 Monitoring 



The distinction between inspection and monitoring was made earlier in this 

 chapter. It is significant to reiterate that more than ninety percent of 

 all tasks now being performed by ROVs fall into these two categories. The 

 primary tools and instrumentation used to monitor various undersea tasks are 

 the depth sensor, and closed circuit TV. The following constitutessome of 

 the work ROVs monitor: 



Grouting operations 



Piling installation 



Structure alignment/orientation checks 



Measure and control of cable length during installation 



Observation of pipeline pull-in procedures 



Pipeline weighting procedures 



The following discussion elaborates on several of these tasks. Monitoring 



of grouting operations consists of straightforward observation of the procedure 



as it is taking place to assure that no more grout than is needed is pumped 



