Different types of rigid and flexible pipeline systems are being employed and used by developers throughout the country. This section raises a number of questions on the performance of both systems (durability, strength, maintenance and resistance to jetting, and a number of other areas) and compares how rigid and flexible pipeline alternatives fare.

Rigid pipeline systems (mainly concrete) are designed as structures, flexible alternatives are designed mainly as conduits and will depend mainly on the surrounding bedding to handle and redistribute most of the imposed dead/live loads. It is thought that 5-15% of support for a flexible pipeline system comes from the pipe and around 95-85% comes from the surrounding soil. The nature of materials used for pipes can have a considerable impact on performance. This is explored in this section.

JETTING OF SEWER PIPELINE SYSTEMS
In 2001 a Sewers Jetting Code of Practice was produced by WRc. The code set a number of guidelines, requirements and specifications for use of high pressure jetting. According to the code, concrete pipeline systems currently take a maximum water jetting pressure of 5,000 psi, concrete pipe manufacturers are confident that their products can actually take higher pressure levels. On the other hand, the Code specifies a maximum of 2,600 psi for plastic based pipes. However, new plastic pipe European standards specify a lower maximum jetting pressure of 120 Bar (around 1740 psi)! Read more about this interesting subject.

DEFORMATION OF PIPELINE SYSTEMS Unlike concrete pipeline systems, plastic pipes use a different mechanism to deal with earth movements and dynamic/ static loads imposed on the pipeline as the flexibility of the pipe structure enables it to redistribute the loads through to the surrounding soil. As known, the pipe usually deflects during the process of distributing these loads. Deformation can become progressive throughout the service life of a plastic pipe, reaching alarming levels and leading to the pipes’ failure. A range of information on is provided in this section.

SERVICE LIFE OF PIPELINE SYSTEMS
In 2002 OFWAT estimated that replacing/renovating the UK’s 309,000 km sewerage and drainage network would require £200 billion. The average cost can be considerably high for the larger sewer pipe ranges exceeding 300mm in diameter. With such high stakes, the serviceability and design life of sewerage/drainage pipeline systems is an important topic for the water and sewerage industry. Information from different sources can be found in this section.

FLEXIBLE Vs. RIGID: THE COMPREHENSIVE TABLE
The American Concrete Pipe Association (ACPA) published this table in November 2008. The table identifies the main differences between rigid and flexible pipeline systems.

Coming soon ...

SEWER PIPES AND INHERENT STRENGTH
Inherent strength is one of the main requirements for any infrastructure product. With all ranges of concrete pipeline products designed to strength class 120 (BS 5911: 2004), concrete pipes and manholes now offer the most inherently strong option in the market.