Cast Iron Pipe Manufacturer Eliminates Rework & Saves US$40,000 per Month
Cast Iron Pipe Manufacturer Eliminates Rework & Saves US$40,000 per Month
Problem:
A high-production foundry which manufactures cast iron products from recycled materials, needed to efficiently cool cast iron soil pipe from 350° to 100°F (177°C to 38°C) after dipping the pipe in hot asphalt. The asphalt coating, which acts as a corrosion inhibitor and fills in the porosity of the pipe, was chosen as a solvent-free coating but caused surface imperfections as it cooled on the pipe surface. Though the asphalt was an acceptable “green” alternative to previously used coatings, the surface flaws were unacceptable to customers and resulted in a significant number of returned products.
Cooling by immersion in a water bath was tried first but caused blistering of the asphalt coating. Ambient air cooling gave a better finish but took much longer and required manual rotation of the large pipes to prevent bumps from forming where drips of asphalt cooled and hardened on the surface of the pipe. Both solutions resulted in excessive manual labor and overtime expense.
Solutions:
Spraying Systems Co.’s solution was a simple cooling station comprised of two rows of six 1/4J air atomizing nozzles mounted 30” (762 mm) above the pipe to provide even coverage of the 4’ x 10’ (1.2m x 3m) area. Based on the specific heat of the cast iron and the pipe mass, a heat balance calculation provided the theoretical water flow and nozzle quantity required to complete the cooling in the desired time. Air atomizing nozzles are used because they provide nearly 100% evaporation, maximize cooling and resist plugging even when used with recycled water.
Results:
The cooling system has dramatically improved the foundry’s production, eliminating US$40,000 in monthly rework and overtime expense. This savings resulted in a payback of less than two weeks. In addition, the cooling system advances one of the company’s green initiatives.
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