A pipe-in-pipe system [1] is a form of plumbing where all water pipes are running inside another pipe. Its purpose is to ensure that any leaks in the innermost pipe will not leak into the building structure and can be detected, as well as make for easier change of any internal pipes with leakage without opening the walls.
A pipe-in-pipe system consists of four main components: an inner pipe, an outer pipe, wall boxes, and a distribution cabinet. [2]
In Norway, domestic plumbing based on pipe-in-pipe systems (known as: rør-i-rør system) was introduced in 1995, and has since become a legal requirement in all new houses being built. Due to experience with water damages with many traditional copper pipes in Norway between 1970 and 1995, new requirements came in 1997 stating that water pipes should be easily accessible for replacement after installation. [3] These requirements have since lead to the current de facto requirement for pipe-in-pipe plumbing.
During normal operation, the water flows through the inner water pipe, which is enclosed by the outer goods pipe. The plumbing leads back to a centrally located distribution cabinet where the pipes to all tapping points of the home are gathered in one place. In the event of any damage and leakage to the internal pipes, the external pipes must ensure that the water leak is safely diverted to the distribution cabinet where it is made visible for inspection before it is lead to a room with drains in the floor. It can be advantageous to install a water leak sensor and connect it to an automatic water stop valve which closes the water supply. In the event of visible leaks, there must also be an easily accessible manual main shut-off valve which must stop water supply to all pipes. [4]
Due to the way pipe-in-pipe systems are installed using flexible internal and external pipes, it is possible to pull out and replace the water pipes without having to open up walls. To ensure this, it is important that the outer pipes are clamped properly and securely so that they remain attached to the building structure, while also not being damaged. This is an absolutely crucial factor for how easy it is to change the water pipes, and the clamping rings used should be attached near wall boxes and distribution cabinets.
In addition to proper clamping of the external pipes to the building structure, proper clamping of the distributors inside the distribution cabinet is also important to avoid water hammers when taps are closed rapidly. Pipe-in-pipe systems may be more susceptible or vulnerable to water hammers,[ citation needed ] and are therefore recommended to be used together with soft closing water taps.
A valve is a device or natural object that regulates, directs or controls the flow of a fluid by opening, closing, or partially obstructing various passageways. Valves are technically fittings, but are usually discussed as a separate category. In an open valve, fluid flows in a direction from higher pressure to lower pressure. The word is derived from the Latin valva, the moving part of a door, in turn from volvere, to turn, roll.
Plumbing is any system that conveys fluids for a wide range of applications. Plumbing uses pipes, valves, plumbing fixtures, tanks, and other apparatuses to convey fluids. Heating and cooling (HVAC), waste removal, and potable water delivery are among the most common uses for plumbing, but it is not limited to these applications. The word derives from the Latin for lead, plumbum, as the first effective pipes used in the Roman era were lead pipes.
A gasket is a mechanical seal which fills the space between two or more mating surfaces, generally to prevent leakage from or into the joined objects while under compression. It is a deformable material that is used to create a static seal and maintain that seal under various operating conditions in a mechanical assembly.
Hydraulic shock is a pressure surge or wave caused when a fluid in motion, usually a liquid but sometimes also a gas is forced to stop or change direction suddenly; a momentum change. This phenomenon commonly occurs when a valve closes suddenly at an end of a pipeline system, and a pressure wave propagates in the pipe.
A tap is a valve controlling the release of a liquid or gas.
A plumbing fixture is an exchangeable device which can be connected to a plumbing system to deliver and drain water.
Within industry, piping is a system of pipes used to convey fluids from one location to another. The engineering discipline of piping design studies the efficient transport of fluid.
In modern plumbing, a drain-waste-vent is a system that allows air to enter the plumbing system to maintain proper air pressure to enable the removal of sewage and greywater from a dwelling. Drain refers to water produced at fixtures such as sinks, and showers; waste refers to water from toilets. As the water runs down, proper venting is required to allow water to flow freely, and avoid a vacuum from being created. As the water runs down air must be allowed into the waste pipe either through a roof vent (external), or an internal vent.
A compression fitting is a fitting used in plumbing and electrical conduit systems to join two tubes or thin-walled pipes together. In instances where two pipes made of dissimilar materials are to be joined, the fittings will be made of one or more compatible materials appropriate for the connection. Compression fittings for attaching tubing (piping) commonly have ferrules in them, and are sometimes referred to as flareless fittings. There are also flare fittings that do not require ferrules/olives.
In pipeline transportation, pigging is the practice of using pipeline inspection gauges or gadgets, devices generally referred to as pigs or scrapers, to perform various maintenance operations. This is done without stopping the flow of the product in the pipeline.
An air gap, as related to the plumbing trade, is the unobstructed vertical space between the water outlet and the flood level of a fixture. Air gaps of appropriate design are legally required by water health and safety regulations in many countries. An air gap is the simplest form of a backflow prevention device.
Cross-linked polyethylene, commonly abbreviated PEX, XPE or XLPE, is a form of polyethylene with cross-links. It is used predominantly in building services pipework systems, hydronic radiant heating and cooling systems, domestic water piping, insulation for high tension electrical cables, and baby play mats. It is also used for natural gas and offshore oil applications, chemical transportation, and transportation of sewage and slurries. PEX is an alternative to polyvinyl chloride (PVC), chlorinated polyvinyl chloride (CPVC) or copper tubing for use as residential water pipes.
A pipe is a tubular section or hollow cylinder, usually but not necessarily of circular cross-section, used mainly to convey substances which can flow — liquids and gases (fluids), slurries, powders and masses of small solids. It can also be used for structural applications; hollow pipe is far stiffer per unit weight than solid members.
A fitting or adapter is used in pipe systems to connect straight sections of pipe or tube, adapt to different sizes or shapes, and for other purposes such as regulating fluid flow. These fittings are used in plumbing to manipulate the conveyance of water, gas, or liquid waste in domestic or commercial environments, within a system of pipes or tubes.
Plastic pipe is a tubular section, or hollow cylinder, made of plastic. It is usually, but not necessarily, of circular cross-section, used mainly to convey substances which can flow—liquids and gases (fluids), slurries, powders and masses of small solids. It can also be used for structural applications; hollow pipes are far stiffer per unit weight than solid members.
A pipe support or pipe hanger is a designed element that transfer the load from a pipe to the supporting structures. The load includes the weight of the pipe proper, the content that the pipe carries, all the pipe fittings attached to pipe, and the pipe covering such as insulation. The four main functions of a pipe support are to anchor, guide, absorb shock, and support a specified load. Pipe supports used in high or low temperature applications may contain insulation materials. The overall design configuration of a pipe support assembly is dependent on the loading and operating conditions.
Copper tubing is most often used for heating systems and as a refrigerant line in HVAC systems. Copper tubing is slowly being replaced by PEX tubing in hot and cold water applications. There are two basic types of copper tubing, soft copper and rigid copper. Copper tubing is joined using flare connection, compression connection, pressed connection, or solder. Copper offers a high level of corrosion resistance but is becoming very costly.
An anti-dribble valve is a component of a fuel injection system used for diesel engines. Its main function is to provide precise timing of fuel injection, particularly at the end of the injection time. If fuel was allowed to 'dribble' after the main phase of injection, this fuel would be too late for good combustion and so would be only partially burned as visible exhaust soot.
A gas cabinet is a metallic enclosure which is used to provide local exhaust ventilation system for virtually all of the gases used or generated in the semiconductor, solar, MEMS, NANO, solar PV, manufacturing and other advanced technologies.
A water distribution system is a part of water supply network with components that carry potable water from a centralized treatment plant or wells to consumers to satisfy residential, commercial, industrial and fire fighting requirements.