Plastics Pipe Supply

The preponderance of contractual relationships means that the various responsibilities for the final installed quality of a pipe system can sometimes be obscured. Quality is far more easy to assure in the factory situations of polymer and pipe production than it is in the remote and constantly changing situation of site work. Responsibilities for quality can only be assigned by careful contract preparation, cascaded through all stages of the supply chain. Good practice requires the existence of appropriate specifications and standards and the testing and inspection services to implement them. Practical experience dictates that only the acceptance of formalised, strictly applied, QA procedures can ensure that quality standards survive in a cost competitive market. 

There have been two different but equally successful precedents for implementing quality assurance in Europe. In the UK and France, large gas and water utilities were able to create corporate standards to apply through purchase and supply contracts within a customer/contractor relationship with pipe suppliers. In Germany, the proliferation of local authority owned gas and water utilities meant they were too small to impose corporate standards. Instead, the contractual relationship with the larger pipe supply companies was maintained by standards set by third parties such as the German DVGW, supported by independent test houses. 

Even after production, transport and delivery to site there is a responsibility to maintain quality and this applies to the more difficult to supervise tasks of pipe jointing, bedding and backfilling. 

Site procedures need to follow agreed schedules, using approved equipment and conscientious, trained labour. 

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In Section 2.2.5 the general trends in plastic pipe supply over a long period of growth from the late 1960s, were discussed. No attempt was made to analyse the nature of demand that was generating the market. In the light of the discussion of market sectors, how the applications sectors have determined the materials and products that were successful will now be considered with the intention of perceiving the future trends. 

Most trading polymers contain a variety of additives, e.g., plasticisers, lubricants, stabilisers, etc., and it is these additives that promote bacterial attack on the polymer. At the same time, degradation by other routes provides pathways for bacterial attack by creating hydrophilic surfaces. Because many industrial and domestic services are supplied by underground plastic pipes and cables, care must be taken when choosing additives to make sure that the polymer is not vulnerable to attack. 

A water main is to be laid from a water tower to a subdivision that is 2 mi away. The water level in the tower is 150 ft above the ground. The main must supply a maximum of 1000 gpm with a minimum of 5 psig at the discharge end, at a temperature of 65°F. What size commercial steel sch 40 pipe should be used for the water main If plastic pipe (which is hydraulically smooth) were used instead, would this alter the result If so, what diameter of plastic pipe should be used ... 

ISO 14236 2000 Plastics pipes and fittings - Mechanical-joint compression fittings for use with polyethylene pressure pipes in water supply systems ISO 14616 1997 Plastics - Heatshrinkable films of polyethylene, ethylene copolymers and their mixtures - Determination of shrinkage stress and contraction stress ISO 14632 1998 Extruded sheets of polyethylene (PE-HD) - Requirements and test methods... 

Plastic pipes, even when flushed out with the most powerful disinfectants and germicides, have proven to be safe havens for some bacterial strains. Bactena-resistant piping is of major importance in pharmaceutical manufacture, Research is underway to find plastic piping that will reject the adhesion of bacterial slimes. Currently, alloy steels are widely used. The adherence of slimes to plastic pipes permits colonies of bacteria to multiply. A similar problem exists when patients are furnished with plastic implants orprosiheses Hospital water supplies must be continuously monitored. 

PVC or CPVC - Poly Vinyl Chloride-A type of white or light gray plastic pipe sometimes used for water supply lines and waste pipe. ... 

Because of heterogeneity in chlorination, a range of Tg values is often encounterd or observes a broad Tg transition for a given percent chlorine. The important commercial implication of the T g rise upon chlorination is that the polymer can be used in higher temperature applications. Practically, this means that PVC is limited in pipe/plumbing applications to cold water service, whereas CPVC is successfully used for hot water plastic plumbing supply. 

It is not possible to comprehend the true nature of a major industry by simply looking at its current structure and performance. To properly understand why certain forms of organisation exist and what factors determine performance figures it is vital to appreciate the evolution of the industry. The decisions and standards adopted in response to factors pertaining many years ago often result in consequences that continue to influence current technologies. In addition an appreciation of where the industry came from assists in the perception of where it is going next. Therefore we will briefly review the history of plastic pipe production and supply. 

EN 1452 Parts 1 to 7 Plastics piping systems for water supply - unplasticised poly(vinyl chloride) (uPVC). 

EN 1796 Parts 1 to 6 Plastics piping systems for water supply with or without pressure -glass-reinforced thermosetting plastics (GRP) based on polyester resin (UP). 

ISO 14236 2000 Plastics pipes and fittings - Mechanical-joint compression fittings for use with polyethylene (PE) pressure pipes in water supply systems. 

L-E. Janson, Plastic Pipes for Water Supply and Sewage Disposal, Borealis, Stenungsund, Sweden, 1996. 

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