In the early eighties and speaking generally, the only internal pipeline inspection was either performed by the sewer inspection companies, who’d be inspecting mainly dry sewer pipe sections over short distances; typically not exceeding 150m and who stop when the pipe became surcharged to the point where the camera would become submerged as well as the oil industry support companies who run ‘intelligent pigs’ though the oil pipes to assess weld integrity, pipe wall thickness and symptom in order to assess pipeline longevity and safe operating pressure.
At the moment the lake companies who had been largely oblivious to the internal condition of their pipelines, adits, aqueducts and tunnels were start to have concerns in regards to the integrity of their assets, most of which was constructed during the Victorian times or even more recently in early fifties coupled with never been inspected and were unsuccessfully attempting to find companies and/or equipment that could accomplish such surveys.
Sometimes these were in a position to de-water the pipelines and if large enough diameter, they’d send a confined space team into carry out a visual survey; such surveys were obviously fraught with potential dangers, such as ones included the possibility of collapse, flooding and the accumulation of toxic gasses.
De-watering was included with its own pair of potential risks for the structural integrity with the concrete, tunnelled and brick constructed pipelines; in many cases, small leaks produced by displaced joints, erosion and localised damage etc. enabled the leaking water to find a path from the ground well as over a number of years, earth could be beaten up from throughout the pipe, often leading to large water filled voids forming across the not in the pipeline.
The newly de-watered pipeline which will often be partially dependent on your head water from the pipeline (trying to push the walls out), to maintain its structural integrity, could suddenly encounter several a lot of water outside the pipeline (looking to push the walls in), creating localised parts of external high pressure, which would often cause pipe failure and localised collapse, causing subsidence with the ground higher than the pipeline manifesting as holes in your yard that could appear ‘over-night’.
At about this time around there were an escalating demand through the Water Companies for you divers up water filled pipes equipped with CCTV cameras, to survey as far for their nerve or umbilical length would permit.
Inside a very short period of time the HSE Diving Executive, showed an enthusiastic interest in the safety aspect of sticking divers up pipes and very quickly an excursion selection of around 30m as a maximum was considered safe, providing that the mandatory safety precautions were in place.
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