A standard is a set of "how to" instructions for designers, manufacturers, and/or users of the equipment covered. It can run from a few paragraphs to hundreds of pages. Standards are considered voluntary because they serve as guidelines only, without the force of law. Organizations such as ASME that develop standards can publish them, and can certify manufacturers and provide stamps for manufacturers to place on products that are built in accordance with the requirements of the relevant standard, but they cannot force anyone to follow their standards.

Standards are effective because they serve as a common language, defining quality and establishing safety criteria. Costs are lower if procedures are standardized, and training is simplified. Consumers also accept products more readily when they have been manufactured according to some accepted standard.

Figure 1 shows a plot of boiler explosions versus years since the Code was introduced.



Standards do, however, take on the force of law when they are adopted as a means of meeting regulatory requirements or when they are cited in contractual agreements between suppliers and purchasers. Adoption of voluntary standards by government agencies has been steadily increasing since the enactment in 1996 of the National Technology Transfer and Advancement Act, which mandated federal agencies to adopt voluntary consensus standards in lieu of developing their own standards for both regulatory and procurement purposes, unless technically impractical to do so.

There are two kinds of standards; performance standards, which specify what a product is supposed to accomplish, and design standards (also referred to as prescriptive standards), which detail the composition of a product and how it is to be made. Usually, performance standards are preferred over design standards, because they allow greater flexibility in product design and development, and they foster innovation. In reality, most standards contain aspects of both performance and prescriptive standards.