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Stainless steel pipes dramatically cut water leakage rates
Delegates at the 11th Asian Stainless Steel Conference held in Hong Kong this week heard how replacing ageing water pipes with flexible stainless steel piping has saved millions of cubic metres of water and hundreds of millions of dollars.
In a presentation entitled ‘Stainless steel service pipe cuts leakage rates in municipal water distribution’, Dr Nicole Kinsman, Technical Director of the International Molybdenum Association (IMOA) told delegates how 25-30% of water is routinely lost in distribution.
“Ageing steel, lead or plastic pipes are responsible, with problems often going undetected for months or years, meaning that even small leaks can be responsible for large amounts of water loss,” explained Dr Kinsman.
Upgrading these pipes can dramatically reduce water leakage, particularly in the service pipe connecting the water main to a property, where some 95% of leaks are typically found. Corrugated molybdenum-containing stainless steel is an ideal replacement material as it is resistant to corrosion from chlorides in the soil in marine and urban environments. It is also durable and strong, with enough flexibility to protect the pipes from traffic vibration, accidental mechanical damage and even seismic events. The corrugated piping can be simply bent to fit, saving time and money.
In her presentation, Dr Kinsman highlighted the experiences of the cities of Tokyo and Taipei in upgrading their water distribution infrastructure. In Tokyo, the potential for leakage in a network with more than two million connections in one of the most seismically active areas of the world is massive, yet water loss is just over 2%. “The reason is that in the early 1980s, the water authority began a water loss reduction program to replace all the lead service piping in the network with Type 316L stainless steel, and since 1998, with corrugated Type 316L stainless steel pipe,” she explained.
The authority furthermore replaced cast iron pipes with seismic-resistant ductile iron pipe, and introduced a comprehensive leak detection and repair regime to fix leaks very quickly, often before they became apparent. This increased vigilance, coupled with the replacement program, saw Tokyo’s water losses fall by nearly 15 percentage points.
“To put this into context, Tokyo has reduced annual water leakage by over 200 million m3 since the early 1980s. The cost savings associated with the reduced water loss, combined with the savings due to the drop in repair cases, amount to hundreds of million dollars per year for the water authority,” she said.
A similar program to replace service piping and cast iron mains was undertaken in Taipei, after a severe drought in 2002 brought intermittent water supplies to the Taiwanese capital over a 49-day period.
The city was divided into so-called District Metered Areas (DMAs). Leakage rates were analyzed, revealing that 40% of the DMAs were losing half of their water or more before it reached consumers. A detailed analysis of the repair cases showed that while polybutylene pipe accounted for only 3% of the network, it caused 28% of all leaks. Some 80% of all problems occurred in plastic pipes, with the vast majority caused by cracking. As in Tokyo, an enhanced regime of leakage detection and swift repair was introduced.
The ongoing program has replaced 35% of service piping of various materials with corrugated Type 316L stainless steel pipe, as of August 2015. The result is a drop in water loss from 27% in 2003 to 17% in 2014, saving some 146 million m3 of water per year.
“More significantly, a drought more extreme than the 2002 event which precipitated the pipe replacement program occurred in 2014. However, the vast improvement in leakage rates achieved since 2003 meant that there was no interruption to the water supply, in fact more water reached customers even though less was distributed in total,” she explained.
“Water is a fundamental human need which can’t be substituted with anything else. Replacing leaking service piping with molybdenum-containing stainless steel is an investment in the future, which also makes economic and environmental sense in the present day, as these examples clearly demonstrate,” she added.
Notes for editors
IMOA is a non-profit trade association representing the interests of most of the world’s molybdenum producers and converters, as well as consumers and traders.
Molybdenum is added to steels and cast irons to improve strength, toughness, hardenability and weldability for numerous applications in the automotive, shipbuilding, construction, mining, chemical, oil & gas and energy generation industries.
In stainless steels and superalloys, it improves corrosion resistance and high-temperature performance and finds uses in many industrial applications. It is also used in a variety of products from catalysts and lubricants to pigments and paint.
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