Plastic pipe system peak performance techniques

Plastic pipe system peak performance techniques

Efficient and reliable pipe systems are vital to everyday life and can be produced from a variety of materials ranging from the traditional metal, concrete and clay to plastics. 

With a number of potential risks in creating - and maintaining - sustainable pipe systems it is essential to consider the diverse range of elements involved throughout the process. From product design to material testing to failure investigation, construction installers, engineering consultants, facilities management, insurance companies as well as solicitors all need to be aware of the demands of the application and the pipe system specifications. 

Commercial use

Plastic pipe systems are used in many industrial sectors such as utilities, civil, infrastructure, energy systems, building and construction. Service and utility installations include potable water, water heating, sprinklers or compressed air. Civil applications include underground installations such as sewerage and land drainage, while energy applications include oil and gas pipelines. 

Major installations can consist of kilometres of pipe and potentially thousands of fittings, therefore it is essential to select the right system for the application. To avoid the high costs associated with failure the application should dictate the type of pipe system required.

Performance characteristics

Plastics are used commercially for pipes; systems based on materials such as UPVC, CPVC, PE, PEX, PP, ABS, Polybutylene, PVDF and GRP represent over 90% of plastic pipe systems sold today. Each material offers a different set of performance characteristics to fit a specific application.

Plastic pipe systems consist of extruded pipes in a range of diameters and injection moulded fittings. Size varies as does form – such as tees, elbows, adapters and sleeves. Pipes are cut to length and coupled with fittings, which creates a network. Joints are prepared for systems in a variety of ways including solvent cement and heat welding techniques.

The durability of a thermoplastic pipe system is dependent on factors such as time, temperature and applied stress. These will affect the long term behavior of the material and influence product life therefore it is vital to consider long term material properties at the design stage of an installation project. This together with appropriate system selection at the same stage is important to ensure reliability over the product life-cycle.

Legislation performance requirements

There are many adopted standards and codes of practice related to pipe systems to ensure both conformity and safety. For pipes to meet the performance requirements of a given standard they will need to be marked by the manufacturer as defined in the standard. There may also be specifications which define the quality and type of material and workmanship upon which a contract is based. Specifications will identify important characteristics along with applicable standards, for example, ISO, ASTM, UL etc.

Installation variables

Another important consideration for a successful plastic pipe system is the installation process. It is during installation that many potential problems can occur. Manufacturers do provide general instructions and guidelines for installation design but variables of each specific installation must also be considered for it to be successful. Poor quality solvent cement jointing, insufficient provision for thermal expansion or inadequate fixed supports are just some installation issues that can lead to stresses on the system as well as influence system performance and potentially lead to failure.

Failure

The consequences of system failure can vary dramatically depending on the final application and location. Catastrophic industrial installation failures can result in significant associated damage and financial loss.

Failures often fall into four main categories:

  • Manufacturing - faults in the original pipe or fittings 
  • Workmanship - faulty installation / engineering 
  • Environmental - contamination effects or solvent cement effects 
  • Operational - system operating outside of design criteria, in either storage or post installation.

Testing and expert support

Typically performance testing within pipe standards involves:

  • Appearance
  • Dimensions
  • Resistance to internal pressure
  • Impact resistance
  • Tensile strength
  • Vicat softening temperature
  • Longitudinal reversion
  • Thermal stability.

Performance testing within fitting standards involves appearance, dimensions and resistance to internal pressure.

The extensive material and product testing laboratory capabilities available through Smithers assist companies in the evaluation and characterisation of extruded pipe and injection moulded fittings with a wide range of services related to plastic pipes, fittings and seals from concept to disposal. This includes material characterisation and product testing. 

Our team of polymer consultants have a fundamental understanding of polymer behavior, how polymer products and parts perform in-service, extensive experience of failure modes and a practical appreciation of design and processing. This enables us to offer a wide ranging service to support companies in the high performance of plastic pipe systems.

Find out more about our pipe failure testing facilities.