5. CHAINS AND ENVIRONMENTS Most chain is made of metal or engineered plastic, which may be impacted by the conditions under which the chain is operated. For example, the tem- perature or the amount of dust in the air can affect the chain. When you select a chain for your application, you have to take into account the environment in which the chain is operated. In this chapter, we will explain problems that may develop when operating a chain under certain conditions, and how to deal with them.
5.1 STEEL CHAINS
5.1.1 Use of Steel Chains in High Temperatures When heat-treated chains are run in temperatures higher than their temper- ing limits, the following problems may occur: • Increased wear due to decreased hardness. • Improper lubrication due to lubricant deterioration or carbonization. • Stiff joints and increased wear due to oxide scale formation. • Decrease in strength. To prevent lubricant deterioration at high temperatures, use a special lubri- cant. Table 5.1 shows the transmission capability of power transmission roller chains with high-temperature lubricant. Check the manufacturer’s catalog for additional information. When chains are used in temperatures above 250˚C, pay special attention to the composition and heat-treatment of the chain. The most popular type of chain for high temperature is SS specification, which is made of 304 stainless steel, and has a maximum working temperature of 650˚C at low speeds. However, to maintain an adequate safety margin at a high temperature like this, we suggest you use NS-specification chain. NS chain is made of 316 stain- less steel, which contains molybdenum and less carbon. NS specification has worked at low speed in environments up to 700˚C. If your operation runs at temperatures higher than 400˚C, consult the manu- facturer before making your chain selection. Production methods and materials may be specially adapted for your application.
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