ASME B31T:2021 pdf download

ASME B31T:2021 pdf download.Standard Toughness Requirements for Piping
1.1 Scope
This Standard provides requirements forevaluatingthe suitability of materials used in piping systems for piping that may be subject to brittle failure due to low-tempera- ture service conditions.
1.2 Units of Measure
This Standard states values in both International System (SI, also known as metric) and U.S. Customary (USC) units. Within the text, the USC units are shown in parentheses or in separate tables. The values stated in each system are not exact equivalents; therefore, each system of units should be used independently of the other. When separate equations are provided for SI and USC units, those equations shall be executed using variables in the units associated with the specific equation. The result obtained from execution of these equations may be converted to other units. When necessary to convert from one system ofunits to another, conversion should be made by rounding the values to the number ofsignificantdigits ofimplied preci- sion in the starting value butnotless than four significant digits for use in calculations.
2 GLOSSARY
CVN: the abbreviation for Charpy V-notch. design minimum temperature: the lowest component temperature expected in service. fullydeoxidizedsteel:steelthathas beendeoxidized,either bythe addition ofstrongdeoxidizingagents orbyvacuum 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 code, standard, or specification referencing this Standard. governing thickness: thethickness usedindeterminingthe low-temperature service limit of T-number groups CS A, CS B, CS C, and CS D in Table 3.1-1. Unless defined differ- ently in the code, standard, or specification referencing this Standard, this thickness is the nominal thickness of the component or, for blind flanges and line blanks, 1 / 4 of the total thickness, where the total thickness is the thickness of the blind flange or line blank, including the thickness of the facing(s), if applicable. lower critical temperature: the temperature at which the first phase change occurs when heating a metal. low-temperature service limit: the design minimum temperature at which additional requirements for low- temperature service do not apply. NDTtemperature: the nil ductilitytransition temperature. 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 ofsimilar mate- rials with similar low-temperature requirements. The number consists of the material type and 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 ofmaterials with similarrequirements. 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 ð21Þ Material Groupings (Column 1 of Table 3.1-1) Listed materials are assigned T-number groups 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 in Mandatory Appendix III.) In determining the applicable T-number group for a material from Table 3.2-1, consideration shall be given to the material specification, grade, and any other variables as established in the notes. The table separates the materials into types (carbon steels, low-alloy steels, etc.), and the group number is represen- tative of the low-temperature service limit for the mate- rial; however, the low-temperature service limitmayvary based on the design and fabrication requirements.