Plastic pipework: Difference between revisions

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{{short description|Tubular section or hollow cylinder made of plastic}}

[[File:Polyethylene Pipe lengths.jpg|thumb|343x343px|Plastic Pipepipe lengths manufactured in Australia by [[extruding]] [[High-density polyethylene|HDPE]] material.]]

'''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 [[Pipe (fluid conveyance)|pipes]] are far stiffer per unit weight than solid members.

'''Plastic pipework''' is used for the conveyance of [[drinking water]], [[Wastewater|waste water]], [[chemical]]s, heating fluid and [[Coolant|cooling fluids]], [[foodstuff]]s, ultra-pure liquids, [[Slurry|slurries]], [[gas]]es, [[compressed air]], [[irrigation]], [[plastic pressure pipe systems]], and [[vacuum system application]]sapplications.

== Types ==

There are three basic types of plastic pipespipe:

===Solid wall pipe===

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*[[Sewerage|Sewer]] applications: High [[chemical resistance]]

Plastic pipes are capable of fulfilling the specific requirement for each application. They do so over a long lifetime and with reliability and safety.<ref>{{Cite webnews|url=https://www.acu-tech.com.au/about-us/why-use-hdpe/|title=Why Use HDPE - What is HDPE Pipe?|website=Acu-Tech Piping Systems|language=en-AU|access-date=2019-01-04}}</ref> The key success factor is achieved by maintaining consistently high quality levels. For plastic pipe products, these levels are defined by the different standards. Two aspects are fundamentally important for the performance of plastic pipes: flexibility and long lifetime.<ref>{{Cite web|url = http://www.teppfa.eu/why-use-plastic-pipe-systems/|title = Why use Plastic Pipe Systems|last = TEPPFA, The European Plastic Pipes and Fittings Association}}</ref>

==Materials used==

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=== HDPE (high-density polyethylene) ===

[[High-density polyethylene]] (HDPE) - HDPE pipe is strong, flexible and light weight. It has a zero leak rate when fused together.<ref>{{cite webnews|url=https://isco-pipe.com/pipe/|title=HDPE Pipe|newspaper=Isco Industries |access-date=16 March 2021}}</ref>

===PB-1 (polybutylene) ===

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===PVDF (polyvinylidene difluoride)===

[[Polyvinylidene difluoride]] (PVDF) is a fairly non-reactive, [[thermoplastic]] [[fluoropolymer]] with excellent chemical and thermal resistance for plastic pipework uses. PVDF resin is produced through polymerization of the [[vinylidene fluoride]] monomer. The PVDF resin is then used to make PVDF pipe as well as many other products.

Industries and applications select PVDF pipe due to its inert, durable qualities. 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.

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===Pipe system failure===

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.

Plastic pipes were also found to fail more often during dry, hot summers.<ref>{{Cite webjournal|url=https://www.nature.com/articles/s41598-023-33548-7|title=Assessment of the impacts of climate change on water supply system pipe failures|date=2023 |doi=10.1038/s41598-023-33548-7 |last1=Fan |first1=Xudong |last2=Zhang |first2=Xijin |last3=Yu |first3=Allen |last4=Speitel |first4=Matthew |last5=Yu |first5=Xiong |journal=Scientific Reports |volume=13 |page=7349 |bibcode=2023NatSR..13.7349F |pmc=10163270 }}</ref>

=== Flexibility ===

Plastic Pipes are classified by their [[stiffness|ring stiffness]]. The preferred stiffness classes as described in several product standards are: SN2, SN4, SN8 and SN16, where SN is Nominal Stiffness (kN/m2). Stiffness of pipes is important if they are to withstand external loadings during installation. The higher the figure, the stiffer the pipe.{{cn|date=October 2024}}

After correct installation, pipe deflection remains limited but it will continue to some extent for a while. In relation to the soil in which it is embedded, the plastic pipe behaves in a 'flexible' way. This means that further deflection in time depends on the settlement of the soil around the pipe.{{cn|date=October 2024}}

Basically, the pipe follows the soil movement or settlement of the backfill, as technicians call it. This means that good installation of pipes will result in good soil settlement. Further deflection will remain limited.{{cn|date=October 2024}}

For flexible pipes, the soil loading is distributed and supported by the surrounding soil. Stresses and strains caused by the deflection of the pipe will occur within the pipe wall. However, the induced stresses will never exceed the allowed limit values.{{cn|date=October 2024}}

The thermoplastic behavior of the pipe material is such that the induced stresses are relaxing to a low level. It has to be noted that inducedInduced strains are far below the allowable levels.{{cn|date=October 2024}}

This flexible behaviour means that the pipe will not fail. It will exhibit only more deflection while keeping its function without breaking.{{cn|date=October 2024}}

However, rigid pipes by their very nature are not flexible and will not follow ground movements. They will bear all the ground loadings, whatever the soil settlement. This means that when a rigid pipe is subject to excessive loading, it will reach the limit for stress values more quickly and break.{{cn|date=October 2024}}

It can therefore be concluded that the flexibility of plastic pipes offers an extra dimension of safety. Buried Pipes need flexibility.<ref>{{Cite web|url = http://www.teppfa.eu/why-use-plastic-pipe-systems/|title = Why use Plastic pipe systems|last = TEPPFA, The European Plastic Pipes and Fittings Association}}</ref>