Inside cement mortar lining of the ductile iron pipes doesn't only ensure observation of the hygienic requirements at potable water transportation, but also improves the hydraulic propetries of the ductile iron pipelines.
Roughness factor (according to COLEBROOK formula) of the inner surface of the ductile iron pipe with inside cement-mortar lining is K - 0,03 for every single pipe. It is recommended to take K - 0,1 for DN 80-250 mm.; K - 0,08 for DN 300-700 mm.; K - 0, 05 for DN 700-1000 mm. for calculations when deigning pipeline systems out of ductile iron so that all friction losses in the assembled pipeline system are considered. that means that ductile iron pipes with inside cement-mortar lining permit to reduce hydraulic losses through friction in the pipeline to a considerable extent and correspond to all the modern energy conservation requirements.
Besides, big flow section of ductile iron pipes compared to polyethylene pipes (with the equal value of nominal bore DN), makes possible a considerable pumping cost reduction of the transported liquid.
The clear opening comparison between ductile iron and polyethylene pipes
Ductile Iron pipes Svobodny Sokol,
Polyethylene Pipes PE-100 SDR 17,
ALL Union State Standard 18599-2001
|Ratio of ductile iron pipe clear opening to PE clear opening
Wall thickness with cement-mortar lining,
Wall thickness, mm
Internal diameter, mm
Ductile iron pipe and PE pipe clear passage area comparison DN 100 mm
With the same nominal diameter of ductile iron pipe and PE pipe the clear opening of the ductile iron pipe with inside cement-mortar lining is 30 % bigger than polyethylene one. in diameter range 80 - 1000 mm respectively.
Unique properties of ductile irone provide pipelines with:
- no corrosion in conjunction with high mechanical properties and functional features of spigot and socket connections;
- high safety margin compared to other pipeline sysems (Сmar <3,0);
- cold resistance (impact strength of ductile iron pipes does not change in the range from +20 Co to -60 Co)
Ductile iron pipes have less failure compared to pipelines of other materials.
Numerous tests have proven that along with the estimated permissible load ductile iron pipes have sufficient reserve reliability. It is ideal for complicated laying conditions.
Number of failure per every 100 km of water pipelines.
Water lines oservation of West Germany 1999 (Information given by Deutcher Verein des Gas Und Wasserfaches - German Water and Gas Providing Unity )
German Water and Gas Providing Unity gives the water pipe failure statistics (according to analyses more than 360 water service organizations, more than 126 000 km of potable water lines and about 5 million square km. of pipelines connected with living housing sector).
According to the statistics, ductile iron pipes have the least percentage of failure.
The data Pipe failure as a result of earthquakes in Japan, India and the USA (per 100 km)
Spreading of water pipelines on the example of some earthquake prone areas of Japan, China, India and the USA (depend on pipe material)
The statistics of pipeline failure during earthquakes on the territory of the USA, China and India 1989 - 2009 shows that ducile iron pipes in earthquake prone areas having the longest spreading have suffered less than other pipelines (4,4 failure per 100 km) from earthquakes more than 7 points Richter scale
Moscow water pipeline failure statistics is practically the same(water lines spreading is more than 10 000 km; steel pipelines are 72%; 26% made of iron(1450 km - ductile iron); 2% polyethylene and concrete pipes)
- Maximum allowable rate
- Expectable pressure to break the pipe
- Counted pressure to break the pipe
Ductile iron pipes and fittings have high margin level relating to maximum allowable pressure.
The pressure level to break the pipe is more than maximum allowable rate.
Sources of information:
- Japan Water Works Association « Damage to water Pipelines at the 1995 Hyogoken-Nanbu Earthquake».
- Iain Tromans Department of Civil and Environmental Engineering Imperial College of Science, Technology and Medicine London,« Behaviour of buried water supply pipelines in earthquake zones», January 2004.
- Kuraoka S., Rainer J.H.«Damage to water distribution system caused by the 1995 HyogoKen Nanbu earthquake» Canadian Journal of Civil Engineering, 23, (3), pp. 665-677, June 01, 1996.
- M. Nakano, S. Katagiri and S. Takada «Anexperimental study on the antiseismic performance of a U-PVC water supply pipeline with enlarged expansion joints» ASIAN JOURNAL OF CIVIL ENGINEERING (BUILDING AND HOUSING) VOL. 10, NO. 5 (2009).
- Eidinger, J. M. (1998). «Water Distribution System.» The Loma Prieta, California, Earthquake of October 17, 1989.
- Anil Kkumar Sinha, Senior Technical Advisor, Asian Disaster Reduction Center «THE GUJARAT EARTHQUAKE 2001».
- V. Thiruppugazh, Joint Chief Executive Officer Gujarat State Disaster Management Authority, India «WHAT HAS CHANGED AFTER GUJARAT EARTHQUAKE 2001».
- «DAMAGE BEHAVIOR OF LARGE-DIAMETER BURIED STEEL PIPELINES UNDER FAULT MOVEMENTS» LIU Ai-wen(1) , HU Yu-xian(1) , LI Xiaojun(1) , ZHAO Fen-xin(1) , TAKADA Shiro(2) (1. Institute of Geophysics, China Earthquake Administration, Beijing 100081, China; 2. Kobe University, Japan).
Ductile Iron Pipelines with inside cement-mortar lining quarantee high quality of transported water that meet all the requirements of hygienic safety (water PH up to 12,0).
Ductile iron pipeline systems are impermeable for hydrocarbons and chemical substances that can be found in environing soils.
Complete recycling of the pipes after the service.
High Economic Efficiency
Minimal time to compensate money spend on installation ductile iron waterline.
Ductile iron price decreases relating to PE pipe prices with the diameter increasing.
Economic effect during the stage of installation appears because of the absence of necessity to use power station, high-quality staff or special technical machines. Ductile iron pipes can be layed in the soil directly without preparing channel from sand. Simple and easy process of assembling ductile iron joint pipelines even when the temperature is below the zero temperature provides a high speed of assembling.
This is temporary reduce of the expenses, that in different cases has real cost of money.
Reducing the money spent on water line service
According to the statistics of the international and Russian scientific researches ductile iron water lines are admitted to be the most reliable pipes to be installed.
The expected faultless service life of ductile iron pipeline systems:
- In water supply networks under the condition of soil corrosion, stray current and absence of cathodic protection is 80 to 100 years;
Corrosion resisting prperties of ductile iron pipes are 5-10 times higher than steel pipes.
- In sewage networks with hydrogen sulphure it reaches 50 - 60 years.
|Total corrosion, mm/year
|Steam and hot water pipelines
|Petroleum containing liquids
Power costs, special equipment and highly qualified stuff during the ductile iron pipe installation process are not required.
Laying directly in the ground of 8-10 meters deep without bed preparation is possible.
Installation works during negative temperatures are allowed without any risks