ASME B31T:2010 pdf download

ASME B31T:2010 pdf download.Standard Toughness Requirements for Piping
2 GLOSSARY
CVN: abbreviation for Charpy V-notch. design minimum temperature: the lowest component tem- perature expected in service. fully deoxidized steel: steel that has been deoxidized either by the addition of strong deoxidizing agents or by vac- uum treatment, to reduce the oxygen content to such a level that no reaction occurs between the carbon and oxygen during solidification. Also known as killed steel. Steels that are not fully deoxidized include rimmed, semi-killed, and capped steels. Limitations on the use of steels that are not fully deoxidized may be imposed by the applicable piping code or specification. low-temperature service limit: the design minimum tem- perature where additional requirements for low- temperature service do not apply.lower critical temperature: the temperature at which the first phase change occurs when heating a metal. NDTtemperature: the nilductilitytransitiontemperature. stress ratio: the ratio of the design stress to an allowable stress. (See para. 3.6.2.) T-number: a number assigned to a group of similar mate- rials with similar low-temperature requirements. The number consists of the material type, a temperature characteristic, and possibly a suffix.
3 LOW-TEMPERATURE RANGES AND REQUIREMENTS
3.1 Low-Temperature Service Requirements Low-temperature service requirements are contained in Table 3.1-1. These requirements are established for T-number groups of materials with similar require- ments. In addition to T-number group, in some cases requirements are dependent on thickness and/or other characteristics as listed in Table 3.1-1. 3.2 Material Groupings (Column 1 of Table 3.1-1) Material T-number groups for each covered material specification are provided in Table 3.2-1. (In addition, a table sorted by material type and T-number group that lists all materials in each T-number group is provided inMandatory Appendix III.) In determining the applica- ble T-numbergroup fora material fromthe table, consid- eration shall be given to the material specification, grade, and any other variables as established in the notes. The table separates the materials into types (car- bon steel, low alloy steel, etc.), and the group number is representative of the low-temperature service limit for the material; however, the low-temperature service limit may vary based on the design and fabrication requirements. Low-temperature service limits shall be determined from Table 3.1-1. An “(A)” in the T-number group [e.g., CS −20(A)] indicates that materials of that group may not be used at temperatures colder than the group number [e.g., −20°F (−29°C).3.3 Nominal Thickness and Notes (Columns 2 and 3 of Table 3.1-1) For material T-number groups where the low- temperature suitability varies significantly according to the thickness, a thickness is listed in column 2 of Table 3.1-1. Note that the thickness is the nominal thick- ness as defined in the code or specification referencing this Standard. The variation based on thickness applies to carbon steel T-number groups CS A, CS B, CS C, and CS D where Table 3.1-1 lists thickness at each 10°F increment. When it is desired to refine the influence of the thickness, Mandatory Appendix I provides the continuous curves and tables that can be used at inter- mediate values or greater thickness. Since the nominal thicknesses in Table I-1 of Mandatory Appendix I are generally derived based on uniform increments of tem- perature, the tables do not contain uniform increments ofthickness. Again, the continuous curves in Mandatory Appendix I should be consulted for the precise values. For material T-number groups where the low- temperature suitability is dependent upon some other factor, those factors are given in the notes listed in col- umn 3 of Table 3.1-1.