Reliable Foundry Heating without LPG Constraints

Dayalan Karthick, Field Sales Engineer, Weldy, India  

A Foundry with Deep Roots in Madurai, India

The temple city of Madurai in India is home to Aruna Alloy Steels Pvt. Ltd., a foundry whose history began in 1961 as a small-scale industry. Since 1999, the company has focused exclusively on serving the valve industry. 

Today, Aruna Alloy Steels supplies high-performance valve castings ranging from 5 kg to 15,000 kg, with maximum pressure ratings of 5,000 PSI and sizes of up to 72 inches. The company manufactures castings in carbon steel, alloy steel, stainless steel, nickel alloys and copper alloys for the oil, gas, thermal and hydro power, nuclear power and chemical industries. 

With two foundry plants, a production capacity of 5,000 tonnes of steel castings per year and an additional machining facility, Aruna Alloy Steels serves valve manufacturers in domestic and international markets. 

Why LPG Flame Heating Limited the Process 

The quality of a casting begins with the quality of the sand core. Even small traces of residual moisture can lead to blowholes, poor surface finishes and costly casting rejects. 

For Aruna Alloy Steels, consistently drying sand cores with LPG gas torches involved several operational challenges. Fluctuating flame temperatures made uniform heating more difficult and increased the risk of overheating or localized thermal damage. The LPG-based process also required cylinder procurement, transportation, storage and handling. This created additional logistical effort, higher operating costs and a dependency on the availability of gas cylinders. Soot, open flames, gas leakage risks and radiant heat were further factors to consider in daily production. 

As production volumes increased, Aruna Alloy Steels therefore looked for a safer, cleaner and more repeatable solution with precise temperature control. 

Precision Hot Air Replaces Open Flames 

To address these challenges, Aruna Alloy Steels introduced the Weldy HT10000 industrial hot air blower for drying and heating sand cores. 

Safer and Cleaner Working Conditions  

Replacing LPG gas torches removed open flames from the production area, lowered the risk of fire hazards and got rid of gas leakage risks and operator exposure to radiant heat. The electric hot air process therefore eliminated the safety and regulatory concerns associated with LPG cylinder storage and handling. At the same time, the absence of combustion fumes contributed to a cleaner and more comfortable shop-floor environment. 

Lower Costs and Simpler Plant Logistics 

The transition from LPG to electricity simplified plant operations. For this application, gas cylinders no longer needed to be procured, transported, stored or handled. The electric process also reduced maintenance requirements and the manpower associated with LPG handling. 

At Aruna Alloy Steels, the cost comparison showed that hourly heating costs decreased from 136 Indian rupees  with LPG to 84 Indian rupees with the Weldy HT10000, representing savings of approximately 38 percent. 

Reliable Performance for Continuous Foundry Operation 

The Weldy HT10000 is built for continuous industrial operation. Its heavy-duty construction and minimal maintenance requirements ensure reliable performance under demanding foundry conditions. This reliability has made the HT10000 an integral part of the production process at Aruna Alloy Steels, demonstrating how precision hot air technology can modernise a critical foundry application. 

A Step Toward More Sustainable Manufacturing 

The switch to electric hot air also supports the sustainability objectives of Aruna Alloy Steels. Eliminating gas combustion reduced localized carbon emissions and removed combustion fumes from the shop floor. The result is a cleaner working environment for the sand core drying process. 

The Weldy HT10000 has since become an established part of production, combining precise process control with lower operating costs and simpler plant logistics. Its successful use demonstrates how a conventional foundry process can be modernized with a reliable, high-performance electric solution. 

For Weldy, the application marks an important milestone in the Indian foundry industry. It shows that moving away from fossil-fuel-based flame heating is not simply an equipment upgrade, but a strategic investment in quality, safety, efficiency and sustainability.