Loading and Service Conditions
Service conditions are combinations of loads or load sets that occur simultaneously, therefore the piping system must be designed to withstand their combined effects. Occasionally, the service conditions will be specified by the piping design code. Examples are found in the American Society of Mechanical Engineers’ (ASME) Boiler and Pressure Vessel Code, Section III, Nuclear Power Plants Components, Paragraph NCA-2142, where service conditions are defined directly, and the ASME Code for Pressure Piping, ASME B31.1, Power Piping, Paragraph 104.8, where service conditions are specified under the topic of analysis of piping components due to the effects of sustained and occasional loads.
Where service conditions are not specified by a particular code, the designer should review the various loading conditions that the piping system is exposed to and formulate the combinations that must be considered in design. Reference to the most commonly used piping design codes listed in the section ‘‘Use of Codes and Standards in Piping System Design’’ will provide the designer with guidance in setting appropriate design stress limits.