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IAPMO PS 51-2020
Expansion Joints and Flexible Expansion Joints for DWV Piping Systems
1.1 Scope This Standard covers plastic, elastomeric, and metallic expansion joints and flexible expansion joints intended for use in drain, waste, and vent systems and specifies requirements for materials, physical characteristics, performance testing, and markings. 1.2 Alternative Materials The requirements of this Standard are not intended to prevent the use of alternative materials or methods of construction provided such alternatives meet the intent and requirements of this Standard. 1.3 Terminology In this Standard, (a) “shall” is used to express a requirement, i.e., a provision that the user is obliged to satisfy to comply with the Standard; (b) “should” is used to express a recommendation, but not a requirement; (c) “may” is used to express an option or something permissible within the scope of the Standard; and (d) “can” is used to express a possibility or a capability. Notes accompanying sections of the Standard do not specify requirements or alternative requirements; their purpose is to separate explanatory or informative material from the text. Notes to tables and figures are considered part of the table or figure and can be written as requirements. 1.4 Units of Measurement SI units are the primary units of record in global commerce. In this Standard, the inch/pound units are shown in parentheses. The values stated in each measurement system are equivalent in application, but each unit system is to be used independently. All references to gallons are to U.S. gallons.
International Association of Plumbing and Mechanical Officials [iapmo]