The Pier Pilings Inspection operation is a technique that can be used to visually inspect or search individual or groups of pier pilings. The purpose for this procedure is to maximize the chances of success and ensure that each pier piling is systematically inspected so there is no question that the entire pier area has been completely inspected or searched.

The recommendations for this SOP come from some of the world’s leading experts in the field and have been formulated after many hours of field experience. However, they should be considered a starting point since every possible scenario cannot be anticipated. Be prepared to make adjustments and fine tune the settings to adapt these recommendations to your specific circumstances and environment.

General Concept

The Pier Pilings Inspection consists of two main operations:

1. Inspecting an individual piling circumferentially from surface to seafloor.
   • This can be done in one of two ways:
     1. By inspecting the complete circumference and then changing to different depths as determined by the visibility and length of the piling.
     2. By inspecting using vertical passes spaced circumferentially around the piling.
        • This may be better for pilings that have cross bracing structures.
2. Navigating from piling to piling without putting undue stress on the tether or getting it tangled.

This SOP includes procedures for all of the above approaches.

Applicability

The Pier Pilings Inspection operation is applicable to piers that consist of pilings. Pier wall structures should be searched using the Piling Wall Inspection Standard Operating Procedure.

Prerequisites

Participants in a Pier Pilings Inspection should be familiar with operating a VideoRay Defender running the Greensea Workspace control system. For more information about these products, see our Defender Resources.

Searching for Threats or Hazards

If conducting a Pier Piling Inspection for the purpose of ensuring there are no threats or hazards in the pier area, it may be required to clear an the bottom area around the pilings.

There are two schools of thought about which part to search first, the pier pilings or the bottom.

• If you will be operating from the pier, it is best to clear the pier pilings first to avoid the ROV or tether from contacting a threat device on the pier while searching the bottom. This can prevent accidentally contacting something on the bottom while navigating the ROV to observe the pier pilings.
• If you will be operating from a vessel, it makes more sense to clear the bottom before starting to search the pier. The tether is less likely to contact the pier when operating from a vessel, so clearing the bottom first does not represent a risk of accidentally contacting a threat on the pier.

 Tether management is critical when searching for threats or when operating in an area that may have other vessel traffic. Exercise caution when managing the tether in such situations.

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Vertical Inspection Passes

Vertical passes are most efficient in general, and my be better to use when pilings have cross bracing. The ROV is navigated to the piling and a vertical pass is made with the ROV facing the piling. The distance from the ROV to the piling will depend on the water clarity. The camera should be pointed down slightly for vertical passes that are downward, or up slightly for vertical passes that are upward. At the end of the pass, the ROV is navigated circumferentially to get in position for the next pass, again with the ROV facing the piling. The circumferential distance between passes depends on the size of the piling and the water clarity. The next pass is then made in the opposite direction. This pattern is repeated alternating the directions of the vertical passes until full visual coverage of the piling is completed.

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Circumferential Inspection Passes

Circumferential passes may be more efficient for pilings that have a very large diameter. The ROV is navigated to the piling and a circumferential pass is made with the ROV facing the piling. The ROV is then navigated vertically up or down to position the ROV for next circumferential pass, again while facing the piling. While moving to the level of the next circumferential pass, the camera should be pointed down slightly when descending, or up slightly when ascending. The next circumferential pass is then made in the opposite direction to prevent the tether from getting tangled around the piling. This pattern is repeated until full visual coverage of the piling is completed.

 Circumferential passes are more difficult if the ROV does not include lateral motion capabilities.

 Greensea’s Orbit feature can be used to easily control the circumferential maneuver.

 Using the pattern illustrated below, the tether will lay on the near side of the piling when moving to the next piling. In order to prevent tangles or excess drag, be aware of the tether location as you go around each piling and try to be consistent. This will also help when you return to your deployment point.

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Considerations for the Optimal Navigation Pattern from Piling to Piling

The best pattern to move from piling to piling will depend on the presence and orientation of cross bracing and the numbers of rows and columns of pilings, among other considerations.

Each situation should be examined to determine what pattern will work best. In general, the following guidelines can be used:

• The pattern should run perpendicular to the face of the pier.
• The pattern should run parallel to any cross bracing.
• You should avoid navigating the ROV around pilings when moving from one row or column to another.
• You should avoid navigating the ROV through cross bracing whenever possible.
• If you enter a pattern on or near the surface, you should exit on or near the surface to avoid any unseen cross bracing on which the ROV could get hung up.
• The tether handler should deploy the minimum amount of tether to avoid it getting dragged into the piling structure due to wind or currents.
• Be prepared to follow your tether back to the point of obstruction if you get stuck.

An example pattern that follows the guidelines is shown below. The choice whether to do vertical passes, or circumferential passes on each piling can be decided in the field. In this example, it would be best to use vertical passes. Also, in this case because of the cross bracing, it would be best to only inspect one side of each piling, and then do the other side during the next pass of the pattern. Also note that the tether in the pattern below never crosses completely around the backside of a piling,

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