Page 553 - The ROV Manual - A User Guide for Remotely Operated Vehicles 2nd edition

550 CHAPTER 20 Tooling and Sensor Deployment
FIGURE 20.19
(a) Skid-mounted 5000 psi (345 bar) water blaster pump and (b) cavitation cleaning wand
(Courtesy (a) Seanic and (b) Cavidyne.)
user of air versus water is the substantial reduction in kinetic reaction of air versus water (i.e., the reactionary “kick” of the water jet is much more forceful than with air due to the difference in density between the two cleaning agents).
This approach, which utilizes water (salt or fresh) at low pressure and high volume, in combina- tion with a specially designed delivery device to produce high-energy cavitation, provides a much safer underwater cleaning system. This quickly and effectively removes unwanted marine growth from underwater structures, allowing the use of much lower pressures than preexisting high-pressure water technology. Cavitation is more efficient and effective than traditional water blasters and elimi- nates the dangers associated with the use of high-pressure water. Cavitation units clean steel, con- crete, wood, rubber, fiberglass, fabric, etc. without damaging existing surfaces or surface coatings.
Similar to skid-mounted tooling is the skid-mounted “sensor pod” or “survey skid” (Figure 20.20). Often, the sensor is not able to be mounted to the main body of the vehicle (e.g., a pipe camera that must see the sides as well as the top of a pipe while the vehicle flies over, or rides upon, the top of the pipe due to the reach angle necessary for viewing or for the proximity to electrical (or acoustic) noise. In Figure 20.20, the sensors are mounted at the end of telescoping poles (or manipulator arms) to achieve the proper offset.
20.2.2 Tooling deployment unit
Described within Category 3 of ISO 13628-8 ROV tooling configurations is the modular TDU interfaced with the ROV’s frame (very similar to an underslung skid, but mounted to the front, rear, or side of the vehicle). As shown in Section 19.7.3 of this manual, docking points are provided for subsea interface on either side of the TDU with the actual tool slung below the docking points.