Polyethylene for smaller diameters, ductile iron for larger ones. Don't use fiberglass, steel or concrete for water supply. Longevity is the main criteria along with ease of use. The ability to make 'under-pressure' connections is also important.
Bioriented PVC (PVC-O) is most probably the best alternative. It combines the advantages of PVC (low cost, ease of installation, chemical resistance) with the ductile behaviour of HDPE. External diameters used to be limited to DN400 mm but now DN800 mm and even bigger are available and installed.
The selection of pipe material is a careful decision to be made after considering design criteria, soil parameters, effect of corrosion, hydrodynamic effects such as water hammer, type of jointing, water quality to be conveyed, capacity intended to be conveyed, environmental statutes, project life cycle cost inclusive of its operation & maintenance, being some of them. Having said this the availability of materials and the skill levels of pipe laying technicians paramount vital importance. Generally for sizes till 450 mm PE is a good choice and for larger diameters PE although will be good would be more expensive. DI can be used for larger sizes subject to terrain and other soil parameters. It has to be noted that metallic pipes are subject to corrosion, non metallic pipes such as concrete, asbestos cement, are prone to joint dislocation due to soil migration. GRP pipes if selected has to be carefully designed to account for strain corrosion and delamination by selection of proper resin/glass mix ratio and good manufacturing practice which does not allow delamination and cracking due to soil loads. PE pipes are temperature sensitive and care needs to be exercised while laying them in oil contaminated soils. You may go through the published edition of Malaysian Water Association recommendations which considers almost all practical considerations for an optimized choice.
Hello, I see you have had lots of informative answers to your question. In addition to the answers provided I would also suggest you consider the internal aspects of the pipe and the corrosivity of your water supply. Ideally, your system should be designed to minimise low turnover especially at the extremity of your distribution system as this is where you will notice the more significant deterioration over time. Kind Regards Helen
Pipes made from Polyethylene (PE) is a cost effective answer for a number of piping problems in Metropolitan, Municipal, Industrial, Underwater, Mining, Landfill Gas extraction, Cable duct and agricultural applications. It has been tested and proven effective for underground, above ground, surface, under water as well as floating pipe applications.
Polyethylene pipes both High Density (HDPE) and Medium Density (MDPE) can carry potable water, wastewater, slurries, chemicals, hazardous wastes, cables and compressed gases as well as oils. Polyethylene pipes have a long and successful service experience to the gas oil, mining and water utility industries. PE pipes have the lowest repair frequency per Kilometer of pipe per year compared with all other pipe materials used for urban water and gas distribution.
Sir, As Carlos mentions below there is no specific rule in choosing the pipe material. It depends on availability and economics. Bear in mind the availability of this pipe material for operation and maintenance. Concrete pipe is brittle and fragile, heavy and hence need to be handled cautiously. It could have high operation costs. Concrete mixed with Asbestos Cement should not be used because on environmental and health impacts. Ductile iron pipes are the best but are costly. HDPE pipes are mid-way but need to be buried as sunlight (UV) would have an impact on it. I suggest that for the same pipe diameter you carry out a cost analysis on the available pipe materials in your village/country. Cost to include operation costs also.
Por la experiencia, que tengo en la comercialización de tuberÃas de Asbesto Cemento, PVC y HDPE estructurales y lisa; debo mencionarles que no existe el mejor material; lo que se debe hacer es conocer si las caracterÃsticas técnicas que ofrece el material, soporta las solicitudes del terreno en el cual se van a instalar. En su momento todos los materiales han cumplido solicitudes de instalación pero las garantÃas de funcionamiento, hermeticidad y resistencia a cargas externas son las que al final deciden si es el mejor para las conidiciones en las cuales seran instaladas y van a ser operadas. Hoy dÃa las tuberÃas de Polietileno de Alta Densidad con sus uniones de termofusión y/o electrofusión son la mejor alternativa.
Not necessarily. MDPE and HDPE pipes can now be manufactured with a diameter of 2500 - 3000mm. Therefore any size from around 20mm upwards may be used for water. E.g. here is a nice example of 1200m SDR 11 PE pipe from Agru as used in a project in Australia http://www.agru.at/en/solutions/agruline/water-supply-system-for-water-storage/
Further to my earlier comments: the main problem with rigid pipes is the joints - especially concrete and very especially pre-stressed concrete (the disaster I mentioned earlier). With PE the jointing is by fusion welding and this is purported to be stronger than the pipe itself.
if you are talking about preserving water quality and if price is not an issue, a composite pipe with a ceramic lining. glass lining is good too. great for transmission. check it out. you will find that this will be the future for developed countries.
The decision of the best pipe to use in a water supply network depends on a lot of factors, such as:
- Diameter
- Working pressure and Working flow
- type of lands (mechanical and chemical point of view)
- Operational availability for repairs
- Durability
- Environmental issues
- Reliability
and etc.
You should choose the factors that have the greatest weight in the decision. According with your question, Environmental issues have a high weight, so you must chose accordingly; pipes made of material that is 100% biodegradable and such a material that doesn't contaminate soils and the water.
If you are considering to use a concrete pipe, most probably we are talking of a water transmission main with a big diameter. For concrete pipes, you have a some choices to consider. LCP, PCCP, BWP, etc. for reliability and Durability you should chose a PCCP Pipe (Prestressed concrete cylinder Pipe).
In terms of maitainence programs, you have a innovative technologie for PCCP pipe monitoring: Without dewatering the system, you can introduce an optical fibre inside the pipe "SoundPrint AFO Pipeline Monitoring" that continuous real-time structural monitoring PCCP pipelines. This is a technology used to detect and locate wire breaks in a PCCP pipe as they occur, wire breaks are the mains indicator that this pipe type will eventually fail.
Assessing the condition of buried infrastructure can be challenging and difficult to predict. Traditional belief dictates the condition of the pipe is directly associated with its age, however extensive field work shows this is not always the case and actually 70% to 90% of the replaced pipe still have remaining useful life.
So for maitanance procudures, you should ponderate a important factor: is this pipe material easy to access in the future? We know that leaks are also a strong indicator of pipe failure, even the smallest ones. Pressure pipes typically do not deteriorate or fail systematically along their full length. Rather, pipe condition is usually related to localized problems. It is known that more than 90% of pipelines are in good condition leaving less than 4% of requiring renewal. By determining the actual condition of pipelines, utilities can avoid the unnecessary replacement of pipelines with remaining useful life while improving the reliability of their system by avoiding pipe failures and reducing water loss.
If we are considering a big diameter (DN>400), consider Steel, PCCP or Ductile Iron Pipes. These kind of pipes have a strong mechanical resistance, they support water hammer and highest pressures, with very high secutrity factors.
Ask the pipe manufacturers their opinion, and put all those arguments on the balance of decision, weighing those that are most important to you.
Polyethylene (PE) pipes are best suited for long life times (dependent upon the conditions, >100years). Low maintenance, lightweight, flexibility, leak free systems and ease of installation are key characteristics. Most importantly PE pipes are corrosion free. Depending on the diameter, very long lengths can be supplied minimising the need for jointing. If jointing is required, this can easily be done through butt fusion welding or by using electrofusion fittings. This modular approach also gives the opportunity to to easily tap off the main flow pipe if required. New modern PE 100 products such as "crack resistant" grades may also be used in grounds where imported back fill is not required. As indicated previously, good quality PE resin suppliers and pipe manufacturers comply with various national and international standards to ensure products that are fit for purpose. As a minimum, ISO 4427 gives more details. As a rough guide, a good quality PE 100 SDR11 pipe can transport water safely at 16 bar (safety factor included), based on an ambient temperature of 20°C for 50 years.
Recently we have completed a project name"Dhaka Water Supply Sector Development Project" where we upgraded our pipeline (water supply network) approximately 3000 KM. We used HDPE material pipe and set the pipes by trench less technology. The specification are as below
1.1 Materials Requirements 1.1.1 Pipe materials and jointing Pipe materials to be used for the project works shall conform to the standards described in this Requirements. If any material, not covered in these requirements, is required to be used, it shall conform to relevant International Standards or requirements specified by the Project Manager. Three types of materials are expected to be used by the Contractors for DWSSDP namely High Density Polyethylene (HDPE) pipes, un-plasticized polyvinyl chloride (uPVC) pipes and Ductile Iron (DI) pipes depending on the field situation and requirements as described in this section. HDPE pipes will be used for trenchless technologies for pipe replacement and pipe extension, uPVC pipes may be used in case of conventional trenching methods. All pipes and fittings are intended to be used in Dhaka City Area for drinking water supply under pressure at normal temperature. The materials must be suitable for operation in the tropical climatic conditions that prevail in Bangladesh. Ambient temperatures are up to 50°C and humidity up to 95% at 35°C. The pipes and fittings shall be manufactured specially for surface installation in tropical humid climates with a prevailing water temperature of 35°C. Heavy rainfall and significant flooding usually occurs in Bangladesh during rainy season; dry and dusty conditions prevail for rest of the year. All pipes and fittings shall be new and unused. The Contractor shall notify the Project Manager of his proposed sources of materials prior to delivery and submit test results of the said pipe type and dimension according to test method specified in this section. After arrival to the site, all materials shall be subjected to an acceptance test prior to their immediate use. Test samples to be taken out before installation shall be taken out together with the Project Manger or his representative. The cost of sampling / testing shall be borne by the Contractor. If any sample does not conform to the prescribed tests and quality, the batch of pipes and / or fittings shall be rejected by the Project Manager or his representative and such materials shall be removed from the site by the Contractor at his own cost. Such rejected materials shall not be made acceptable by any modifications. Jointing for pipes and fittings / specials shall be done in accordance with the relevant Specifications depending on type of pipes being used. 1.1.2 High Density Polyethylene (HDPE) Pipes Standards ï‚· The materials from which the pipes are made shall be in accordance with ISO 4427-1; ï‚· All High Density Polyethylene (HDPE) Pipes (PE 100) shall conform to the standard of ISO 4427-2: 2007(E) of PN 10 nominal pressure and SDR 17 Mean outside diameter shall be in accordance with ISO 11922-1: 1997 (grade B for sizes ≤630) and the maximum out of roundness (quality) shall be in accordance with ISO 11922-1: 1997 (grade N for sizes ≤630). Mean outside diameter and the maximum out of roundness for different diameter of the above mentioned series of PE 100 pipes (provided in the table given below); ï‚· The pipe shall be coiled such that localized deformation, e.g. buckling and kinking, is prevented. Minimum internal diameter of the coil shall be not less than 18 x nominal diameter; ï‚· The length of straight pipes and coils depends on the field requirement for the trenchless technology and minimum internal diameter of the coil. Contractor should supply the pipes accordingly; ï‚· The wall thickness for different diameter of the above mentioned series of PE 100 pipes should be in accordance of the table given below; ï‚· Dimension of the pipes shall be measured in accordance with the ISO 3126; ï‚· All testing at factory to be done in accordance with the provision in the relevant code/ specification. Nominal outside diameter (mm) Mean outside diameter (mm) Maximum out of roundness (mm) Nominal wall thickness (mm) SDR 17 (S 8) PE 100 (PN 10) dem, min dem, max emin emax 75 75 75.5 1.6 4.5 5.1 110 110 110.7 2.2 6.6 7.4 160 160 161 3.2 9.5 10.6 200 200 201.2 4.0 11.9 13.2 225 225 226.4 4.5 13.4 14.9 280 280 281.7 9.8 16.6 18.4 315 315 316.9 11.1 18.7 20.7 355 355 357.2 12.5 21.1 23.4 400 400 402.4 14.0 23.7 26.2 450 450 452.7 15.6 26.7 29.5 Markings of pipes and fittings: All pipes shall be permanently and legibly marked in such a way that the marking does not initiate cracks or other types of failure and such that normal storage, weathering, handling, installation and use do not affect the legibility of the marking. If printing is used, the colour of the printed information shall differ from the basic colour of the product. The marking shall be such that it is legible without magnification. The frequency of marking being not less than once per meter. The size of marking shall be at least 10 mm height. The marking shall show the followings in order as stated below: ï‚· The Manufacturer's name or Trademark and the text: "DWSSDP-2009, DWASA" (in bold letters) shall be marked on the surface of each pipe; ï‚· The number of ISO Specification i.e. ISO 4427-2: 2007 (pipes), ISO 4427-3: 2007 (fittings); ï‚· The designation of the pipe maternal e.g. PE 100; ï‚· The fitting material and name of fitting e.g. HDPE Nipple; ï‚· The nominal outside diameter, SDR series and Pressure (in bold letters) e.g. 200 mm, SDR 17, PN 10; ï‚· Production period (date or code) e.g. 0310. This looks like: (Trademark name or symbol), DWSSDP-2009, DWASA HDPE, ISO 4427-2: 1996, 200 mm, SDR 17; 0310 1.1.3 Jointing of HDPE Pipes and Fittings Butt Fusion Jointing Equipment Butt fusion jointing equipment shall be certified in accordance with ISO 12176-1. Only fully automatic Computerized Numerical Control (CNC) machines or computerized microprocessor based machines shall be used. Manual or Semi Automatic CNC machines are not allowed. Butt Fusion requirements Butt Fusion jointing shall be carried out in accordance with ISO 11413. Testing of such joints shall be in accordance with ISO 13953. Joints: When PE pipes are assembled to each other or components, joints shall be in accordance with ISO 4427: 2007. HDPE Pipes (PE 100) may be required to be joined by butt fusion (100 mm Ø or above) or using electro fusion fitting mixing different pipe material, the joint should conform to the requirement specified in the relevant code. Only pipes and fittings of the same material type, size and rating shall be butt welded, e.g. PE 100 pipes should not currently be welded to PE 80 pipes; PN 12.5 pipe should not be welded to PN 10 pipe or fitting. The most widely used method for joining individual lengths of PE pipe and PE fittings is by heat fusion of the pipe butt ends. Quality butt fusion joints may be produced by using trained operators and quality butt fusion machines in good condition. Anyway fusion and other standard practices like mechanical fittings (compression fittings, flanged joints etc.) as appropriate are to be followed depending on each joining situation the Contractor may encounter. Care should be taken to ensure that all pipe jointing is adopted in accordance with the manufacturer’s recommendations. Fittings: The Contractor may use following three types of fittings made from polyethylene (PE) for piping systems as per ISO 4427-3: 2007. ï‚· Spigot Fittings: Spigot fittings are injection moulded fittings and / or fitting which are assembled using butt fusion joints. The dimensions of spigot fittings up to and including nominal size 63 shall conform to the requirements of ISO Standards; ï‚· Electro-fusion Fittings: Electro-fusion fittings shall be injection moulded fittings made of PE but incorporating integral heating element(s) to enable fusion with PE pipes. Installation shall be carried out in accordance with ISO 11414; ï‚· Mechanical Joints and Fittings: The materials and constituent elements used in making the fitting (including elastomers, greases and any metal parts) shall be as resistant to the external and internal environments as the other elements of the piping system and shall have a life expectancy under the following conditions as least equal to that of the PE pipe conforming to ISO Standard. The requirements for the level of material performance for non-polyethylene parts shall be at least as stringent as that of the PE pipe systems. All mechanical joints and fittings shall be of approved types designed specifically for PE pipe system and shall conform to the requirements specified in the following table. The fittings shall be supplied with all necessary coupling rings, nuts, bolts, washers, rubber rings / sealing gaskets and restrainers / stiffeners.
You can visit Bangladesh to see this success project.
Having looked at many systems across the world, I have seen many successes and even a few disasters. Obviously there are aspects which relate to the size of the system and the larger the pipes get then the more complex the solution. I have seen steel, cast iron, ductile iron, galvanized iron/steel, uPVC, concrete, fiberglass, MDPE and HDPE (and even brick gravity aqueducts).
For the larger pipelines ductile iron is preferred as it has the durability of cast iron with some of the flexibility of steel. Never use steel unless it is very well protected both inside and out.
The UK went to MDPE for distribution systems many years ago but the world-wide preference has been for HDPE. uPVC can present problems if there are sudden pressure changes whereas PE is more able to withstand such conditions and is easier to use on-site. In Russia, I found a supplier making fiberglass distribution pipes which required the system be taken down for 24 hours whilst a simple connection was made. PE can be connected to under pressure with no shutdown.