Exclusive: Rostfrei Make Zincalume Steel Silos

[caption id="attachment_2912" align="aligncenter" width="1014"] Picture: Rostfrei Steels[/caption] Rostfrei Steels Pvt. Ltd. is a well-known name in India for large liquid storage tanks and grain storage silos. Rostfrei Steel Pvt. Ltd. is an ISO 9001 company and is operational since 2004. Since 2004 Rostfrei Steels has completed more than 8000 installations worldwide in approx. 25 countries. Being an Indian company the major objective of Rostfrei Steels was to find a very effective grain storage solution for tropical and sub-tropical regions of India and another objective was to find a cost effective solution for Paddy (Unshelled Rice) storage since India is second largest country in Rice Production and paddy is difficult grain to store in metallic silos due to its high silica content. Finally, the search ended with Zincalume Steel Silos grade AZ-150 and Colorbond Steel Silos (AZ-200). Both these steels perform better in tropical and sub-tropical regions and are very good for storage of abrasive, high moisture and fragile grains like paddy. Moreover Zincalume steel and Colorbond Steel Silos performs far better than conventional GI Steel silos in India like climates. Colorbond Steels has advantage that one can choose any color to match existing color theme of customer’s factory, however Zincalume steel silos are more cost effective. Zincalume Steel ZINCALUME Steel like Galvanised steel is a metal coated steel but it has Alloy coating of 55% aluminium, 43.4% zinc and 1.6% silicon which is carried out at 600 Deg C. Zincalume is the best material for long-term storage of grains as it has Excellent Thermal Reflectivity, Better Corrosion Resistant, Lightweight and Stronger than conventional Galvanised steel material. Problems associated with GI Steel Silos The biggest problem is that the average service life of GI Steel Silos is very less in tropical and subtropical regions. GI Steel have metal coating of 99.7% Zinc over mild steel base metal which is carried out at 450 Deg C. Zinc Coating saves mild steel from getting corroded by providing galvanic protection. Zinc, however reacts with atmospheric oxygen in the presence of humidity and form Zinc Oxide. Zinc protects base metal mild steel by gradually sacrificing itself, which means by converting itself to Zinc Oxide. Eventually with the passage of time whole of zinc coating gets sacrificed and base metal mild steel is exposed and thereafter corrosion of base metal is very fast. Since zinc reacts with atmospheric oxygen only in the presence of humidity in the air.  Wherever the humidity is more the reaction is fast and wherever it is less reaction is slow.  Warmer air has more capability to retain moisture and colder air has less capability to retain moisture. Hence GI performs better in colder climates than in warmer climates hence more popular in countries where the climatic is colder most of the time. In tropical and sub-tropical regions since the air is warm and humid, GI does not perform to its expectations. Average Service Life of of GI Steel silos in tropical and sub-tropical regions is as mentioned in the table below; Graph below displays how GI performs in Rural, Sub-urban, Temperate Marine and Tropical Marine atmospheres Rostfrei Make Zincalume Silos solves the corrosion problems ZINCALUME Steel has Alloy coating of 55% aluminium, 43.4% zinc and 1.6% silicon by weight. Since Aluminium is a lighter metal hence volumetrically it occupies approximately 80% of the volume, and hence aluminium helps to protect zinc coming directly in contact with atmospheric humidity and oxygen. Thus, Zincalume has double protection - Barrier protection of Aluminium and Galvanic protection of Zinc.  Aluminium is protecting Zinc and Zinc is further protecting Base metal. Advantages of Rostfrei Make Zincalume Steel Silos Zincalume Steel Silos provide following benefits that no other grain silo can provide so efficiently

• Uniform Alloy Coating: ZINCALUME Steel has Alloy coating of 55% aluminium, 43.4% zinc and 1.6% silicon. Since it is carried out at much higher temperature i.e. 600 Deg C, hence this alloy coating is much more uniform and strong.
• Durability: Zincalume steel has very good Corrosion Resistant Properties and can withstand Salt Spray Test of 2000 hours. If we compare it with GI grade G115 (350 GSM), we can easily conclude that it is four times better than GI 115 grade as GI 115 can withstand a salt spray test of only 500 hours.
• Excellent Thermal Reflectivity: This is the biggest advantage of Zincalume Steel Silos as this aspect is directly linked to quality of grains. Zincalume Steel Silos has Excellent Thermal Reflectivity of Solar Heat and due to this property of Zincalume steel, Zincalume Steel absorb only 4-5% heat as against GI Silos that absorbs 22% to 26% solar heat which is 5-6 times the heat absorbed by Zincalume Steel. High heat absorption by GI silo increases the average temperature inside silo, which ultimately results in quality deterioration of grains. Thus, grains due to high thermal heat reflectivity stay approximately 4 deg cooler in Zincalume Steels silos that is a big saving in operation cost. Cooler grains require lesser aeration, lesser fumigation and are less prone to infestation problems.
• Scratch Resistant: Rostfrei Make ZINCALUME steel is coated with specially developed passivation and resin coating as separate layers that improves its scratch resistance qualities. Scratch resistant Zincalume Steel can handle abrasive grains like Paddy (unhulled rice) that has approximately 80% to 90% silica content.
• Long Lasting Lustre: Special treatment provided to Zincalume Steel reduces the rate of oxidation and resultant discoloration (Darkening) of Zincalume steels hence look newer for longer time. GI Steel silos become dull grey in color within 2 years of operation and thereafter starts absorbing 26% of solar heat, which either discolors the grains or make them brittle. Brittle grains breaks and generate grain dust while conveying and discolored grains result in quality problems. In Zincalume steel silos this kind of problems are very minimum.
• Service Life: ZINCALUME Silos provides up to 2 to 3 times the service life of Galvanised steel silos of same coating thickness. Average Life of Zincalume Silo is approximately 40-50 years as against 20 to 23 years of Galvanised steel silos having same coating thickness
• Warranty: Tata BlueScope company that manufacture Zincalume Steel extends 20 years warranty against perforation by weathering from the date of installation in neutral environment. Rostfrei manufacture silos only with Tata Bluescope manufactured ZINCALUME steel silos and forthwith extends the same warranty to its customers

Other Advantage Besides above, there are some more advantages that makes a grain manager more enthusiastic about Zincalume silos Due to excellent thermal heat reflectivity, the heat absorption inside a Zincalume Steel silos is very less, hence there is lesser moisture migration. Aeration cost also decreases, as grains are cooler. Cooler grains means lesser fumigation thus savings on fumigation cost. Cooler grains also mean much lesser yellowing, and discoloration problems. Since Zincalume is corrosion resistant, grain managers can also store high moisture grains for shorter durations without many problems. Finally due to its long lasting lustre your silos look newer for much longer time. -By PK Bhardwaj, Expert Grain Storage, Handling and Processing, Vice President-Grain Management, Rostfrei Steels Pvt. Ltd. India.