ASME B31T:2015 pdf free download

ASME B31T:2015 pdf free download.Standard Toughness Requirements for Piping.
This Code provides requirements for evaluating the suitability of materials used in piping systems for piping that may be subject to brittle failure due to low- temperature service conditions. While low-temperature service is usually considered to be beloiv ambient temperature, brittle failure can occur at temperatures above ambient temperature for certain combinations of materials, thicknesses, and stress levels. The definition of “lowtemperature service” as used in this Code, therefore. varies widely across the many applications for which piping systems are used. For a building service air line. low temperature may be 0°C (32F), whereas for a cryogenic piping system, it could easily be —185°C (—300°F).’ However, the principles used to evaluate the suitahilit of a piping system as related to service temperature by evaluating the toughness of the material can be applied across a wide temperature range, and this Code has been established to provide uniform guidance in this area. This Code may be invoked in whole or in part by various piping codes and/or specifications and is only mandatory when so invoked.
Suitability of piping systems for low-temperature service is a function of several variables, including material properties, design loadings, and fabrication procedures. The three primary factors that generally control the susceptibility for brittle fracture are material toughness, crack size, and tensile stress level. There are a wide variety of services where low-temperature suitability need not even be considered; however, a screening criterion is necessary to determine this.
One objective of this Code is to provide a simple approach to evaluate whether additional consideration is necessary to evaluate suitability for low-temperature service. This is done by establishing a low-temperature service limit for various materials. Services at or warmer than this limit are not considered low temperature, and additional considerations relative to suitability are not required.
For services colder than this limit, various requirements are provided that, when met, qualify the material for low-temperature services. These requirements include impact testing, qualification of welding and other fabrication procedures, and limiting the design loadings.
This Nonmandatory Appendix provides guidelines for establishing the T-numher group for materials not currently listed in this Code. T-numbers may be assigned to materials listed in any of the B31 piping codes. In establishing the T-number group the committee evaluates the material and the rules governing its use in the Code and gives special consideration to rules governing its use in low-temperature services. If a T-number is being requested for a material, the request should identify the code(s) that list the material and any factors that would influence its toughness or use at low temperatures. Notch toughness data should be provided including test results for the intended design minimum temperature and the range of material thicknesses desired. For welded construction, the notch toughness data shall include the results of the toughness tests required by this Code for weld metal and heat-affected zone for weldments made by the intended weldingprocess.
Based on the material properties and data, a T-numberis developed by
(a) establishing the correct material type (CS, LA, Ss,NI, CI, CU,AL,TI, ZI) following the material type cate-gory used for the allowable stress listing for the material(b) establishing the material minimum temperaturewithout impact testing based on the material type, chem-istry,product form,heat treatment,and the materialnotch toughness data
(c) determining if use of the material should be pro-hibited at temperatures below the temperature associ-ated with the group number
The additional material T-number listing will beincluded in the next revision of this Code. In addition,a Code Case may be issued to provide for interim useof the T-number.