Ductile iron and galvanised iron pipes are two of the most common types of pipe used worldwide. These two materials have unique features that distinguish them from others, and current technology and techniques have resulted in the development of upgraded versions of these pipes. These are used in a variety of industries, households, and sewage systems. This paper examines the distinctions between ductile iron pipes and galvanised iron pipes, as well as how these differences affect their use in pipelines and sewage systems.
History of GI Pipes
Scientists originally explored galvanization in the 1770s, about 60 years before it was fully implemented in the 1830s. In 1937, French engineer Stanislaus Tranquille Modeste Sorel received the first patent for the technology and began producing it shortly after. By the 1850s, European manufacturers were producing galvanised steel across the continent. The United States quickly followed, building its first factory in the 1870s.
Steel elements are immersed in a molten zinc bath to produce galvanised steel pipe. This is also known as hot-dip galvanization or galvanization. In this procedure, the two metals are chemically linked to one another and will never separate, resulting in more durable and long-lasting steel.
History of DI Pipes
In 1948, the first ductile iron pipe was produced as an experiment by the American Cast Iron Pipe Company. Years of refinement in metallurgical, casting, and quality control procedures followed. With the first shipment in 1955, the ductile iron pipes were finally introduced into the market.After 1955, Ductile iron pipes were recognised as a pipe with all the desirable features of cast iron plus added ductility and strength.Ductile iron pipes have proven themselves to be nearly maintenance-free pipe material, and it is now employed in the transportation of potable water, sewage, slurries, and process chemicals.
Advantages and Disadvantages of GI Pipes
Galvanised Iron Pipes are essentially Mild Steel (MS) Pipes that have been galvanised, or coated with a layer of zinc. The zinc coating helps in preventing rust on the pipe. GI Pipes are commonly used in plumbing (both domestic and industrial) and a variety of other applications.
Difference Between Galvanised Pipe and Ductile Iron
|Galvanised Iron pipes Vs Ductile Iron pipes|
|Galvanised pipes are pipes made of iron coated with a zinc layer.||Ductile iron is a type of cast iron made by adding graphite.|
|Galvanised pipes are made of iron and zinc.||Ductile iron is produced with iron, graphite, and silicon along with some other elements in trace amounts.|
|Galvanised pipes are made by coating zinc on the iron surface.||Ductile iron is made by adding graphite as nodular inclusions into iron.|
|Galvanised pipes are protected from rusting by galvanising them.||Ductile cast iron has enhanced ductility, high impact strength, etc.|
Ductile iron is made up of the following elements: 3.2 to 3.6 per cent carbon, 2.2 to 2.8 per cent silicon, 0.1 to 0.2 per cent manganese, 0.03 to 0.04 per cent magnesium, 0.005 to 0.04 per cent phosphorus, 0.005 to 0.02 per cent sulphur, less than 0.4 per cent copper, and the remainder (around 94 per cent) iron (Dey, 2020). Additionally, tin or copper can be added to boost ductile iron strength at the cost of ductility. The corrosion resistance of ductile iron can be enhanced by adding chromium and nickel. Additionally, to improve oxidation resistance, aluminium can be used for Silicon.
Galvanised steel is composed of metal alloys such as carbon or plain-carbon steel. Carbon steel is created by combining two elements: iron and carbon. Manganese, silicon, and copper are other metals that may be included in this alloy. They typically constitute less than 0.60 per cent of the alloy, implying that their impact on the alloy’s characteristics is insignificant.
Galvanised steel corrodes with time, and it is very challenging to tell if it has corroded by looking at the pipes from the outside. The pipes rust from the inside out, resulting in poor structural qualities, leaks and collapses. They will also form calcium deposits within the pipe. Calcium buildup in these pipes can eventually cause them to become partially blocked, resulting in poor water pressure and rusty water.
Ductile iron is more flexible and corrosion-resistant than Galvanised iron pipes due to its unique composition. Graphite in ductile iron forms spherical nodules rather than the flakes observed in grey iron. This spherical shape provides structural stability to the iron, preventing fracture development and boosting ductility (flexibility). Ductile iron pipes are manufactured with 130 or 200 gm/m2 external metallic zinc coating and 2nd part Bitumen coating or epoxy coating to increase protection against corrosion. Polyethene sleeves may be applied during installation to enhance protection in an aggressive environment. The corrosion rate of ductile iron pipes is around 0.005 per year, and because it is so low, these pipes are almost corrosion-free.
According to piping professionals, galvanised iron pipes should ideally be replaced instead of having them maintained, which can be expensive given that these pipes don’t last very long. As the life expectancy is around 40 to 50 years, galvanised pipes frequently cause low water pressure, leaks, and un-potable water. If these pipes aren’t repaired immediately, washing them on the exterior can eliminate rust for the time being. However, if the rust is severe or inside the pipe, plumbing experts can be contacted to remove it.
DI pipes on the other hand require very minimal maintenance due to their increased longevity. Impact failure or bursting due to a crack or water hammer is extremely rare with an expected life of 100 years. As ductile iron pipes can last more than a decade, the frequency of damage is very low.
While Ductile Iron pipes are virtually maintenance-free, they are also very cost-effective thanks to their reduced pumping and tapping costs.
As demand for depleting resources rises, sustainability issues arise in every business. Both business owners and their consumers are looking for sustainable products and practices that will not harm the environment. Galvanised steel has a long history of being environmentally friendly. In contrast to many other metal treatment techniques available today, the alloys used to create galvanised iron pipes are easily reclaimed and reused.
Because the main components for the process, zinc and steel, are natural items, production produces less waste and harm than other kinds of synthetic manufacturing. Zinc, in particular, is plentiful, ranking 24th among all elements on Earth. When it comes to hot-dip galvanised steel, there is no need to be concerned about limited resources. Galvanised steel, unlike other products that require rare earth minerals for corrosion treatment, uses only easily available components. The ubiquitous availability also avoids the need for long shipping routes, which add to the carbon impact of production (Why galvanizing is sustainable – Galvanizers Association, 2016).
When it comes to ductile iron pipes they are also completely environmentally friendly. Ductile Iron Pipes are made from recycled steel and iron scraps. Having as much as 98% recycled content, Ductile Iron Pipe is itself 100% recyclable, and decades of extensive use have demonstrated it presents no adverse health risks. Pumping through a Ductile Iron Pipe instead of PVC can save about 40% of energy consumption. This also means less CO2 production and an overall fall in carbon emissions. A ductile iron pipe is not vulnerable to pollutants creeping their way into drinking water, but a plastic pipe is, which can contaminate the water. A plastic pipe was linked to 98 % of permeation occurrences in a study conducted by the EPA. Toxic substances cannot find their way into drinking water if ductile iron pipes are used.
TATA Ductura: Your Brand of Choice
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Monitoring of Metal Temperature for Casting
Strict Control of Metal Temperature for Casting – Surface Quality, devoid of cracks, cuts and netting patterns enabling full protection against corrosion.
Chemical, metallographic and dimensional properties
The chemical, metallographic, and dimensional properties of these materials give them resistance to leakages and high ductility and impact resistance.
Quality of External Coating Uniform Zinc and Bitumen/Epoxy
Quality of External Coating Uniform zinc and Bitumen/Epoxy external coating ensures corrosion-free existence for the pipe’s life
Internal grinding of cement mortar lining
A smooth and uniform thickness of the pipes’ internal lining is achieved by grinding the cement mortar lining internally.
Extra-long type socket design
The Socket Design is extra-long and provides a strong grip which prevents disjointing of pipes.
Cut and chamfered spigot end for smooth entry
Spigot finish – For each pipe, the Spigot end is cut and chamfered to make it smooth for entry and devoid of all sharp edges.
Uniform thickness, roundness and straightness
True Dimensions – Strict control of roundness, Straightness, Uniform Wall thickness, Socket and Spigot dimensions.
This paper described a complete comparison between ductile iron pipes and galvanised iron pipes. The key difference between these two pipes lay in their preparation, and the resulting resistances and metal properties they received from these processes. Moreover, we saw that DI pipes are much superior to GI pipes in every way possible, which makes them an ideal choice for both domestic and industrial applications.