Scraping/ Rack Feed Boring/Abrasive Cleaning –
Scraping is a process that involves the use of spring steel scraper blades that are attached to a winch cable that is drawn back and forth through the pipe to remove particularly hard encrustations that may not be attacked effectively using jetting or other techniques. This method can be used on a wide range of pipe diameters usually from 75 mm to 1,000 mm.
Various types of scraper are available each designed to handle different forms of build-up/encrustation.
Most however do need to have an open pipe to some degree as most do require the installation and use of a winch wire to progress the scraper through the pipe.
Scrapers can take many forms but generally are either in the form of a wire brush, sprung metal teeth or circular rubber sections that are designed to fit snugly inside the pipe diameter being cleaned.
The scraper is moved backward and forwards through the pipe usually with the use of CCTV to observe the state/success of the cleaning operation until the operator is satisfied with the cleanliness of the pipe.
Another form of scraper is the rotating flail which comprises a metal flail on the end of a rotating rod system operated from surface by a rod pulling/pushing machine. The rotating flail dislodges unwanted material from the pipe inner wall. Jetting is then usually used to remove this debris created.
The disadvantage of scraping/ rotating flail works/abrasive cleaning as a technique is that, unless managed very well and undertaken with the minimum of force required to make cleaning happen, severe damage can be caused to pipe being cleaned.
As well as scraper and flail cleaning, there are other forms of abrasive cleaning which involve the use of additives to a water supply or the use of abrasive cleaning materials.
These can be utilised across a range of diameters but in larger diameters are less used than say high pressure water jetting. The techniques may involve the addition of sands or gravels to a water flow which is passed through a pipe. As the additive is stirred by the turbulent flow it abrades against the pipe wall dislodging encrustations and lifting sediments into the water flow. The flow is collected and may be treated to remove detritus with the additive being recycled. The additive may also come in the form of ice which acts in similar fashion to gravel. It does not however need collecting and separating from the waste created as it melts to become part of the final water flow. Detritus is disposed of according to current regulations.
Abrasive cleaning can also be achieved using sand sheets, wire brushes or similar attachments which may be used on the end of a rotating shaft or winch cable. The equipment is passed through the pipe back and forth to affect the cleaning action. Jetting may be utilised to remove waste materials.