page_title: Pipeline video inspection
section_title: Pulling the camera backwards
hierarchical_section_title: Pipeline video inspection / Inspection process / Pulling the camera backwards
caption_attribution_description: English: Glass-plastic composite ("Fiberglass") fish rod, used to fetch ropes through sewer pipes for subsequent pipeline video inspection. Image by User:Leonard G.
context_page_description: Pipeline video inspection is a form of telepresence used to visually inspect the interiors of pipelines, plumbing systems, and storm drains. A common application is for a plumber to determine the condition of small diameter sewer lines and household connection drain pipes.
  Older sewer lines of small diameter, typically 6-inch, are made by the union of a number of short 3 feet sections. The pipe segments may be made of cast iron, with 12 feet to 20 feet sections, but are more often made of vitrified clay pipe, a ceramic material, in 3 feet, 4 feet & 6 feet sections. Each iron or clay segment will have an enlargement on one end to receive the end of the adjacent segment. Roots from trees and vegetation may work into the joins between segments and can be forceful enough to break open a larger opening in terra cotta or corroded cast iron. Eventually a root ball will form that will impede the flow and this may cleaned out by a cutter mechanism or plumber's snake and subsequently inhibited by use of a chemical foam - a rooticide.
  With modern video equipment, the interior of the pipe may be inspected - this is a form of non-destructive testing.
context_section_description: For small diameter pipes there may not be enough room for the tractor mechanism. Instead, a somewhat rigid "fish" is pushed through the pipe and attached to a rope at the access point near the truck. The fish is then pulled to place the rope along the pipe. The rope is then used to pull the inspection pig and cable through the pipe. Detaching the rope, the cable is then used to pull the pig backwards as the pipe is inspected on the monitor (this is the method shown in the illustrations below).
caption: Semi-rigid fish may be pushed through the pipe to fetch a rope
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