Plastic pipework
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.
Plastic pipework is used for the conveyance of drinking water, waste water, chemicals, heating fluid and cooling fluids, foodstuffs, ultra-pure liquids, slurries, gases, compressed air, irrigation, plastic pressure pipe systems, and vacuum system applications.
Structured-wall pipes and fittings are products which have an optimized design with regard to material usage to achieve the physical, mechanical and performance requirements.
[5] Chlorinated polyvinyl chloride (CPVC) is resistant to many acids, bases, salts, paraffinic hydrocarbons, halogens and alcohols.
Due to its greater temperature threshold and chemical resistance, CPVC is one of the main recommended material choices in residential, commercial, and industrial water and liquid transport.
Continuous development of the material has enhanced its performance, leading to rapidly increasing usage by major water and gas utility companies throughout the world.
Also for PE pipe material, several studies demonstrated the long track record with expected lifetime of more than 50 years.
Its strength at temperatures ranging from below freezing up to almost boiling makes it an ideal pipe material for hot and cold water installations, radiator and under floor heating, de-icing and ceiling cooling applications[9] Polyethylene of Raised Temperature (RT) or PE-RT expands the traditional properties of polyethylene.
Enhanced strength at high temperatures are thus made possible through special molecular design and manufacturing process control.
Its resistance to low or high temperatures makes PE-RT ideal for a broad range of hot and cold water pipe applications.
A good performance at operating temperature range from up to 60 °C (140 °F) (continuous) makes this material suitable for in-house discharge systems for soil & waste.
A special PP grade with high temperature behaviour up to 90 °C (194 °F) (short-term) makes that material a good choice for in-house warm water supply.
[10] Polyvinylidene difluoride (PVDF) is a fairly non-reactive, thermoplastic fluoropolymer with excellent chemical and thermal resistance for plastic pipework uses.
PVDF piping is used most in the chemical process industry due to its ability to plumb aggressive, corrosive solutions.
PVDF pipe also sees common use in high purity applications, semi-conductor fabrication, electronics / electricity, pharmaceutical developments, and nuclear waste processing.
Dissimilar from other common thermoplastic pipes, (uPVC, CPVC, PE, PP), PVDF does not exhibit sensitivity to UV light or ozone oxidative damage, approving it for long term outdoor uses.
Due to its long-term strength characteristics, high stiffness and cost effectiveness, uPVC systems account for a large proportion of plastic piping installations and some estimations put it that greater than 2,000,000 miles (3,200,000 km) of uPVC pipe are currently in service across applications.
One variant called OPVC, or PVCO, represents an important landmark in the history of plastic pipe technology.
This molecular-oriented bi-axial high performance version combines higher strength with extra impact resistance.
Recent investigations at the German KRV and the Dutch TNO have confirmed that uPVC water pressure pipes, when installed correctly have a useful life span of over 100 years.
The measured failure times as a function of the stresses in the pipe wall has been demonstrated in so-called Regression Curves.
[13] Some reasons why plastic piping systems may fail are poor product bonding/gluing during installation and naturally-occurring physical damage, such as from tree root infiltration.
[citation needed] Basically, the pipe follows the soil movement or settlement of the backfill, as technicians call it.
[citation needed] The thermoplastic behavior of the pipe material is such that the induced stresses are relaxing to a low level.
This means that when a rigid pipe is subject to excessive loading, it will reach the limit for stress values more quickly and break.
[citation needed] It can therefore be concluded that the flexibility of plastic pipes offers an extra dimension of safety.
