When selecting materials the designer must be aware of those quasi-legal parameters against which his choice will be evaluated. He will initially generate a specification for his product: this will list comprehensively the technical and environmental requirements of the product for which materials must be found. Standards are then usually set up, defining technical performance limitations of candidate materials, processes and engineering practices, and will be used to validate final choices.

Specifications and standards are vital to successful industrial activity at all stages between product design and point of sale, where the customer's view of and expectations from his purchase have been moulded by what standards led him to expect.

Types of standards

Value standards are those which society expects to apply to the community as a whole: they include, for example, standards for clean water, regulation of emitted toxic gases and of radioactivity from industry. Davis (1984) has produced a review of UK environmental specifications in the last 25 years.

Regulatory standards may be developed by an industry to serve its own needs or image, or they may be imposed as mandatory by a Government Department. Examples are Health and Safety practices, and the control of industrial liquid effluent compositions.

Our present interest is specifically with materials and methods standards, which define achievable, and hence expected, performance parameters and the associated testing methods.