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Stainless India Magazine

  March 2017
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Stop Water Leaks with Stainless Steel

Stop Water Leaks with Stainless Steel

 
Ramesh R. Gopal *
 

Seen the ghastly seepage marks on the walls of homes of all categories of people? Noticed the mental, physical and monetary agonies of the occupants? Buildings and homes are built to last 60 years or more, but your plumbing is not. Well, this could be a thing of the past if stainless steel plumbing is used. This is because stainless steels are highly corrosion resistant. They are eminently passive (non-reactive) in the full range of potable water chemistries, environmentally friendly and ensure that the quality of water that enters your building is the same that comes out of your tap during the life of the building.

As a result of the excellent corrosion resistance of stainless steels, there is no need for corrosion allowance and this allows thin-walled components to be used. These are lighter, simpler to fabricate and install compared to other materials; and also cost-effective. These properties, and the experience of over five decades in various water works of the world is making stainless steel the preferred material of construction for distribution lines, service lines, potable water treatment and sewage treatment plants.

Read on to see how beneficially this material is used for reducing leakage of water at various stages, conserve the water resources, provide clean drinking water and have long lasting water treatment and distribution plants that require very little maintenance during their lifetime.

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In 1997 the Tamil Nadu Water Supply and Drainage Board (TWAD) took a bold decision and replaced their existing cast iron raw water rising main from the Mettur Dam reservoir with a stainless steel line. They were facing severe problems due to corrosion of the cast iron pipes - namely leakage and pressure drops and expensive repairs/replacements of sections every two or three years. The life of the cast iron line was a little over 20 years. Salem Steel Plant offered the stainless steel option, costing not much over the existing line. A conservative life assurance of 50 years was given, although it could probably go on for many more decades.

Although weight for weight, stainless steel costs about five times that of cast iron, Salem Steel Plant assured TWAD only a moderate increase in cost, near elimination of leakages and repeated expensive repairs, and a substantial reduction in the electrical energy costs for pumping the water up. The design details given below tell you why the installed cost of stainless steel option was to the satisfaction of TWAD officials.

Material

Cast Iron

Stainless Steel

Wall Thickness

13 mm

3 mm

Flow Coefficient

100

150

Service Life

20 yrs

50+ yrs

The wall thickness reduction is because of not having to give corrosion allowance (i.e., not having to add up extra wall thickness in the design to compensate for the anticipated thinning over the years due to erosion or corrosion) and the higher strength of stainless steel. Now, after seven years of service, there has been "zero maintenance" in the line and tremendous savings in electricity bills. TWAD is very happy about the bold step taken years ago (see accompanying photo).

Raw water supply line, Mettur, Salem, Tamil Nadu.

Tokyo plugs leaks with stainless steel service pipe

Tokyo was faced with about 15% water loss because of leaks in the system, including from underground service piping made of lead between the sub-main under the street and the water meter in the Buildings. They have replaced these with stainless steel grade 316 for all the dwellings and this has brought down the overall leakage in the system to 5%. The cost of the stainless steel system was reduced by introducing corrugated pipes, which not only reduced the number of fittings required, but also helped in accommodating the tremors in earthquake-prone Japan (see accompanying photo).

Tokyo's way to conserve water

Waste water treatment plant

In the UK, the Huddersfield Waste Water Treatment Works, which was heavily loaded and able to operate at only 78% of its capacity changed from coated carbon steel traveling distributors to stainless steel. After only two years of operation, maintenance costs had been reduced by 98% and plant availability had increased - equivalent to a 25% increase in plant capacity.

Waste water treatment plant, UK. 98% reduction in maintenance costs; 25% increase in handling capacity. Foreground corroding coated carbon steel distributors; stainless steel in the background.

Slide gates

In water works, leakages and jamming of cast iron (or Ni-Resist) slide gates are a common problem and require heavy maintenance. These problems are easily solved by replacing cast gates with gates made of welded stainless steel plates. The stainless steel gates do not jam when left in position for long periods and when closed, and they seal very well. According to Alabama's Jefferson County in the United States, the stainless steel gates leak only half of the American Water Works Associations recommendations. The best part is they are cheaper than other cast materials because they are so light. They also lead to tremendous cost savings in electricity consumption by the lifting motors.

Stainless steel slide gates have 40% of the market within seven years

"Trenchless" technology to refurbish water mains

In Italy, trenchless technology has been effectively used to refurbish old water mains with stainless steel tubes made of 2.5 to 3 mm thick sheets inserted within them. Using a restricted area instead of a long trench that can disrupt traffic and pedestrians, sections of stainless steel pipes are inserted and joined to the previous one by on-site welding. These new stainless steel water lines eliminate the 40% leakage that was the average for old cast iron pies in most of the European cities. The success of this "trenchless" technology in Turin, Italy, in 1995 is now being used to refurbish water mains throughout Italy. Clean potable water is available now in many towns and cities in Italy without the wasteful leak of 40% of the available water.

Water pipe laying using "trenchless" technology, Turin, Italy

The above are just a few examples of stainless steels can be used effectively by the water industry to contain leakages, provide clean potable water, save on maintenance costs and ensure long lasting infrastructure to the population.

Thin walls, long service life and high expectation of complete recycling at the end-of-life of stainless steel pipe and equipment mean that stainless steels can reduce the material intensity of the water industry. In other words, more of the needs of the society can be met for longer times with less material. This will help to make our society more sustainable.

Having covered the utility of stainless steels for the water industry in general, it is time to discuss stopping leaks in domestic plumbing.

Indoor Plumbing
Stainless steel piping systems have been used for many decades all over the world to handle waters in the highly corrosive environments of the chemical and process industry, pollution control, pharmaceutical, nuclear and food & beverage industries. The invention of simple press-fitting systems for thin-walled pipes has made stainless steel a very cost-effective material for indoor plumbing for potable water. A ½" pipe will have a wall thickness of 0.8 mm compared to 2.8 mm for galvanized steel pipe. These are now being increasingly used to distribute potable water in residential and office buildings, hotels, hospitals and public places in North America, Europe, Asia and Australia

The most important benefit is that stainless steels are unaffected in the full range of potable waters, including soft waters. Other than for bacterial control, they do not demand any water treatment chemicals.

Being buried inside the walls, the material should be corrosion resistant in the environs of brick and mortar. Stainless steels are not at all affected by cement and concrete.

Thin walled piping, easy installation and minimal maintenance during service life (over 60 years), make stainless steels a cost effective option for plumbing. Besides, stainless steels are non-toxic, manufactured from a high proportion of recycled materials and is itself 100% recyclable, which makes them eco-friendly. Because of aesthetic beauty, exposed installations are eye-catching not an eyesore.

Pressfittings, pliers and tube

Wash basins in a hospital

Houses and buildings are designed to last 60-80 years. In general we observe seepage of water and the consequent damage to walls, ceilings and floors within 10-15 years. With stainless steel plumbing, you can be assured of leak-free service during the service life of the building. Thus, it makes good economic sense to use stainless steel at the time of construction. These are also ideal for fountains and watering landscape and parks.

Use stainless steel to stop leaks!

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What are stainless steels?

Stainless steels are a family of iron alloys containing at least 11% chromium. To improve corrosion resistance and the engineering properties, usually nickel (8-12%) and some times molybdenum (2-2.5%) are added. The molybdenum containing alloys resist chlorides to a much greater extent. Though there are over 200 commercial grades of stainless steels, the ones used for the water industry are grades 304 and 316 whose principal alloying contents are given in the table below:

Grades 304 & 316 - Compositions

Grade

Cr

Ni

Mo

304

17-19.5

8-10.5

--

316

16.5-18.5

10-13

2-2.5

* General Manager, Nickel Institute (NI)
Executive Director, Indian Stainless Steel Development Association (ISSDA)

     
 
 
 
         
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