Codes and standards are technical documents. Some have legal status. They are useful in procuring control valves in that they can be listed by designation, title, and date in purchase specifications. When they are, vendors must adhere to them without the buyer needing to detail their specific requirements in each specification. Besides being educational and informative, codes and industry standards provide an excellent basis for establishing understanding and communication between the buyer and seller. It will be less expensive to get valves designed and built to the requirements of published documents than to develop new documents that cover the same technical details. Manufacturers are familiar with published codes and standards; if they have to expend time examining unfamiliar technical documents to see if their usual products and services can conform to them, extra charges may be applied and exceptions taken. If the standards that a valve supplier adheres to in his standard construction are sufficient, do not ask for more.

A request to a supplier that a valve meet "all applicable industry standards" is too inexplicit. Any necessary standard should be asked for by designation, title, and date.

This chapter will (1) define codes and standards and give general descriptions of them; (2) identify those attributes, requirements, and qualities that are the subjects of the documents; (3) provide at least one specific code or standard by number and title for the most often encountered attributes, requirements, or qualities; and (4) list most of the organizations (and their addresses) that sponsor these documents.

The Valve Manufacturers Association of America (1050 17th Street NW, Suite 701, Washington DC 20036-5503) has published "The Valve Buyer's Standards Guide," which includes a description of some of the standards-writing organizations and the standards they have published that concern valves - including control valves. Every year the American National Standards Institute (ANSI) publishes a catalog of all standards approved by ANSI.

Definitions and Descriptions

Codes are promulgated in document form, written by technical organizations, and accepted by legal jurisdictions as proper interpretations of law. Codes, which are mostly prescriptive, allow little or no flexibility. The National Electric Code (NEC), which is written by the National Fire Protection Association (NFPA), and the Code for Pressure Piping, written by the American Society of Mechanical Engineers (ASME), are United States Codes. Typically, each state's legislature

adopts the codes it wishes followed. The Nuclear Regulatory Commission adopts those codes to which it requires adherence by nuclear facilities. Users planning to obtain and install valves in processes that are subject to code requirements are cautioned to adhere to the code requirements from official documents, which may not be accurately or completely described in this book.

Industry standards are based on engineering fundamentals, experience, and practicality. The industry standards referred to and described in this chapter are those prepared by standards organizations such as ASME, NFPA, the International Society for Measurement and Control (ISA), the Canadian Standards Association (CSA), the International Electrotechnical Commission (IEC-or CEI in French), and so on.

Proprietary "standards" are also written by such entities as chemical companies, petroleum refiners, military organizations, architect engineers, and the like and are used in procurement packages. These may incorporate codes and industry standards, as well as detail other requirements deemed desirable. While these proprietary standards are useful and prevalent, they are not discussed in this chapter. They are useful when a published industry standard or code does not cover some particular requirements. Some topics for control valves that are not yet industry "standardized" are certified prints, packaging, cleaning, painting, coating, and material certification. Each of these may have several levels of adherence. These "standards" are the ones to which valve manufacturers are most likely to take exception or agree to adhere to for an extra charge.

Because codes and industry standards are subject to timely review, revision, reaffirmation, and withdrawal, users are cautioned to confirm the current status of any they choose. It may be permissible to use an obsolete edition of a code or standard if you are ordering additional valves for a plant that will match valves originally ordered when that obsolete edition was current. But if the chosen manufacturer has changed its products to meet the newest edition, it could be more costly to use the old. Generally, the newest edition will be suitable. Standards, or their revisions, still in draft status should not be invoked because they may never be issued or the requirements may change. Most ISA standards that concern control valves are written by ISA committee SP75. Revisions to some of the S75 standards may have had their number changed from that of the previous issues. Any requirements proposed for unissued standards in draft-status form can be stated in purchase documents if desired, omitting any mention of the draft standard.

"Reference standards" are for physical properties. The National Institute of Standards Technology (NIST) is in charge of these standards for the United States. Manufacturers should reference their measuring instruments to NIST standards to provide the required accuracy. The NIST, formerly the National Bureau of Standards, does not write standards; it maintains measurement and calibration standards. You can request that manufacturers perform tests with instruments calibrated to NIST standards.

This chapter may unintentionally omit mention or description of some useful standards and codes in this chapter because they may not have been issued at the time this book went to press, or through oversight.

The "standard" products of some vendors may not meet the requirements of the intended standards. If not, the exceptions should be identified in their offers. It may be that the exceptions they take will be acceptable if satisfactory justification is given. When a vendor is asked to meet requirements that are not one of his standard designs he should show them as extra-price items so their value can be appraised and the requirement perhaps eliminated.

The United States Office of Management and Budget, in its OMB circular No. A-l 19, defines a standard as "a prescribed set of rules, conditions, or requirements concerned with the definition of terms; classification of components; delineation of procedures; specification of dimensions, materials, performance, design, or operations; measurement of quality and quantity in describing materials, products, systems, services, or practices; or description of fit and measurement of size." In its Standards and Practices Department Manual of Procedures the ISA defines a standard as "A document embodying requirements which, if not followed, could directly affect safety, interchangeability, performance, or test results." And it further states: "In general, such requirements should already be widely recognized and used."