The nickel content is insufficient to generate a fully austenitic structure and the resulting combination of ferritic and austenitic structures is called duplex. The combination of high expansion and low thermal conductivity means that precautions must be taken to avoid adverse effects, e.g. during welding use low heat input, dissipate heat by use of copper backing bars and use adequate jigging. This factor must also be considered in components which use a mixture of materials, e.g. a heat exchanger with a mild steel shell and austenitic grade tubes. In response to the growing awareness that our quality of life depends upon protection of our environment, consumers and regulators are directing their resources towards products less harmful to the environment. In use stainless steel is durable and requires a minimum of maintenance, outlasting many competing products and eliminating requirements for additional potentially hazardous materials such as paint, fire protective coatings, cleaners and solvents.
Stainless steel is a valuable scrap material.
Even beer kegs wear out eventually. Power is expensive and modern stainless mills operate close to the theoretical minimum. Despite the very high recycling of old stainless steel products, some stainless steel will find its way to landfills or other disposal sites. In these circumstances no detrimental effect to soil or ground water is expected.