Pipe cleaning is commonly performed by a technique known as sewer jetting. Sewer jetting is the application of streams of high pressure water for use within pipes for cleaning & debris removal. Water at the correct high pressure can cut roots, dissolve blockages, emulsify grease and soaps while spray washing pipe wall surfaces. As part of the jetting process, the water from the nozzle can also wash away accumulated dirt or debris on the bottom of the pipe at the same time.
For sewer jetting, a jetting nozzle is attached to the end of a length of high pressure hose with the other end connected to a high pressure water pump. Jetting nozzles have small precision machined orifices or jets to restrict water flow from the jetting pump thus causing high pressure to build within hose. As the pressurized water is expelled from the nozzle jets it reverts from pressure to velocity (speed) creating thrust that allows the nozzle to pull the jetting hose. With the system pressurized, high pressure jetting hose coiled on a hydraulic powered hose reel (up to 500′) is released by the operator who controls the travel speed and distance of the nozzle up the pipe.
Pressurized water expelled from the nozzle jets cleans debris, removes pipe blockages or roots from the inside of the pipe while traveling through the pipe. Optimum cleaning is achieved when the hose is being rewound onto the hydraulic reel. During this action, water from the nozzle jets effectively forms a curtain or wall of high pressure water that forces (or rakes) the debris downstream. Sewer jetting technology can be applied to clean all size pipe diameters with the appropriate size of high pressure jetting unit.
The majority of pipes that need to be cleaned & maintained and/or potential applications for high pressure jetting units are:
Sanitary or Mainline Sewers: located under streets and roads that connect building laterals to a municipal wastewater treatment plant for treatment. Wastewater flows freely through sewers via gravity. Sewers are connected at various intervals by manholes (maintenance access point) that in some applications will allow for a change of direction of wastewater flow.
Municipal sewers can range in size from pipes as small as 6 inches, increasing in diameter as more & more laterals connect to the system. Sewer blockages can form as a result of root infiltration, food grease buildup, soap residue buildup, dirt and debris accumulation. Blockages can also occur from pipe failure or collapse that will require excavation to correct. Private sanitary wastewater collection systems of similar construction can be found on privately owned property connecting buildings in apartment and office complexes, universities or other large campus-type facilities that ultimately discharge into a municipal wastewater systems.
Laterals – Pipes that connect building drainage systems to municipal sewers, considered to be part of the property and the responsibility of the property owner. Typically, laterals are 4″ & 6″ diameter pipes that connect directly to municipal sewer pipelines, but can be larger for commercial or industrial buildings. Lateral blockages can form as a result of root infiltration, food grease buildup, soap residue buildup, dirt and debris accumulation. Blockages can also occur from pipe failure or collapse that will require excavation to correct.
Drains – Drainage pipes are located under or within buildings, considered the be part of the property and the responsibility of the property owner. Drains in buildings can range in sizes from 2″ to 6″ diameters (typically) that normally contain “Tees” or “Elbows” for wastewater directional changes. Drain blockages can form as a result of food grease buildup, soap residue buildup, dirt and debris accumulation.
Storm Drains – pipes that are limited to the collections and control of rainwater. Rainwater can be collected and directly diverted to streams or rivers without passing through a water treatment plant. Storm drain blockages can form as a result of root infiltration, silt, dirt and debris accumulation. Blockages can also occur from pipe failure or collapse that will require excavation to correct.
Process Pipe & Conduits – Pipes of all diameters & lengths used in manufacturing plants, chemical plants & food processing facilities that transports liquids other that sanitary wastewater or rainwater. Blockages in process pipelines can be caused by many factors related to the process, each individual application occurrence will have unique factors to be dealt with on a case-by-case basis. Hard scale mineral buildups found inside of pipes will reduce overall pipe flow capacity.
High-pressure water at the correct pressure can remove any scale buildup no matter how irregular without damage to the original pipe. All of the above types of pipe systems are susceptible to blockages and thus inconvenient backups or potential economic loss. Blockages can occur from the buildup of debris over a period of time, ingress of root infiltration or from foreign debris introduced into the pipeline (accidentally or maliciously). No matter what type of debris that is the cause of a blockage; high pressure jetting is the preferred method of re-establishing water flow.
High pressure jetting not only removes a blockage but washes away all debris found within a pipe. Using high-pressure water is faster and less physically labor intensive than use of a mechanical rodding or cable machine. High-pressure jetting units maintain constant working pressure and cleaning power at the nozzle end. Mechanical machines will lose cutting and torque power as rod or cable distances increase within pipelines from the point of entry.
High pressure jetting has another advantage over cable or rodding machines. Where access is difficult, a lightweight, flexible jet hose is a safer and more practical solution. Pipelines that are suspended from ceilings or catwalks are easily cleaned using a high pressure jetting hose rather than a heavy, cumbersome mechanical drain cleaning machine. Cleaning vertical stacks or vents is easier with a high pressure jetting unit and lightweight jetting hose than with heavy drain cleaning cables or rods.
Over the past 70 years sewer & drain lines have been installed with little or no attention paid to routine pipeline maintenance. The “bury and forget” or “out of sight, out of mind” attitudes toward sewer lines has now led to a growing maintenance and rehabilitation industry. With increased collection system integrity & environmental concerns, inspection of wastewater collection systems has become a major market application for high pressure jetting units.
Pre-cleaning of sewer and drain pipelines with high-pressure water prior to televised inspection (CCTV) surveys for determination of pipeline structural integrity is now a recognized standard operating procedure. Cleaning and CCTV inspection of laterals and pipes under buildings for structural defects is also growing in demand, especially at the time of property transfers.