INTRODUCTION
An American National Standard is intended as a basis for common practice by the manufacturer,
the user, and the general public. The existence of an American National Standard does not in
itself preclude the manufacture, sale, or use of products not conforming to the standard. Mandatory
conformance is established, for example, by reference to the standard in a code, specification,
sales contract, or public law.
It should be noted, specifically regarding this Standard, that certain requirements reflecting
the general application of valves in a wide variety of services may not be considered to be
appropriate for some valves whose application is known and which may incorporate certain
features found by successful experience to be satisfactory. A specific case in point is that involving
valves developed and used in gas and petroleum product pipelines. Conformance of such valves
to the existing API 6D may by itself be sufficient to satisfy requirements of federal rules and
regulations established by the Department of Transportation, Office of Pipeline Safety Operations.
Another specific case is that involving valves used in instrument systems under an applicable
piping code. Conformance of such valves to the requirements of an existing piping code may by
itself be sufficient to satisfy jurisdictional rules and regulations.
This edition of ASME B16.34 states values in both Metric and U.S. Customary units of measurement.
These systems of units are to be regarded separately. The values stated in each system are
not exact equivalents; therefore each system shall be used independently of the other. Combining
values from the two systems constitutes nonconformance with this Standard.