scope:

SCOPE AND ORGANIZATION OF PTCs

Most ASME PTCs are applicable to a specified type of equipment defined by the respective code. There may be several subcategories of equipment covered by a single code. Types of equipment for which PTCs apply can be classified into five broad categories as follows:

(a) electrical or mechanical power producing

(b) combustion and heat transfer

(c) fluid handling

(d) emission control

(e) other equipment

The quantities that characterize performance are defined in each code for the equipment within its scope. Absolute performance characteristics determined by adherence to a PTC can be evaluated compared to design or predicted characteristics, to previous test results, or they can be used to benchmark or ascertain performance at a particular time.

Some PTCs are written as general documents for reference in support of the equipment PTCs. These can be considered technical reference material for the equipment codes; three types of reference codes exist.

The first type covers instrumentation used in the measurement of thermodynamic or process fluid parameters, such as pressure, temperature, flow, and steam quality, as well as how to analyze the uncertainties associated with measurement of all primary parameters to develop overall test uncertainty. Such individual codes referring to process or thermodynamic quantities are known as PTC Instruments and Apparatus Supplements. They are supplementary to the information on mandatory instrumentation requirements contained in the equipment codes. Instrumentation information in equipment test codes supersedes the information given in these supplements, but otherwise these supplements should be incorporated by reference in equipment test codes where deemed appropriate by the committee.

The second type covers miscellaneous general information and currently consists of ASME PTC 1, General Instructions, and ASME PTC 2, Definitions and Values. ASME PTC 2 contains standards for terms, units, values of constants, and technical nomenclature.

The third type addresses the measurement of phenomena closely associated with the equipment performance, such as emissions.

Figures 1-2-1 and 1-2-2 show the organization of ASME PTC categories.