Coatings & Linings
Internal Cement Mortar Lining (BFSC)
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The method of application of the blast furnace slag cement (BFSC) lining is described below:
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Cement mortar lining provides a physical barrier to the water and thus protects the pipe from corrosion and subsequent tuberculation.
Cement linings in iron pipes create a balanced pH environment at the pipe wall that prevents corrosion occurring.
The ground blast furnace slag content reduces the amount of soluble alkaline material in the mortar.
The blast furnace slag reacts with the free lime in the mortar to produce compounds with cementitious properties, reducing the level of alkaline materials able to leach out into the water.
It improves hydraulic flow characteristics:
- Centrifugally applied cement mortar linings are smooth, which results in high flow coefficients (provide a higher Hazen William’s ‘C’ value of 140) and reduces frictional head loss and pumping costs
- Additional vibration enables optimum compaction.
- After spinning, the lining is cured for a sufficient time in a controlled atmosphere.
- Process control ensures a controlled uniform thickness of mortar throughout the pipe.
- The seal coat reduces the interaction between the water and cement. If the water is soft and aggressive or if there is high ‘residence’ time, it has been found that leaching from uncoated cement linings can in the certain conditions result in an undesirable rise in pH.
- In gravity distribution networks, it helps to maintain enough residual pressure at tapping points.
- Cement mortar linings help to maintain the same flow area and coefficient of friction over a long period of time.
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Protection Mechanism of Zinc / Zinc Aluminium Coatings
1. Zinc coating provides a stable protection layer:-
In a Zinc coated pipe, the metallic Zinc in contact with corrosive soil slowly turns into a layer of zinc corrosion products, such as zinc oxides, carbonates, oxychlorides etc. which results in stable, dense, impervious, adherent layer which occupies almost exactly the same volume as the initially porous Zinc metal layer and uniformly covers the surface.
2. Self healing of damage:-

Zinc Aluminium
How does it work?
Coating Thickness
Epoxy Finishing Layer
- Increased ability to cope with transportation, site handling and installation
- Scrape tests fail to expose bare metal