ASME B31T-2015 pdf download

ASME B31T-2015 pdf download.Standard Toughness Requirements for Piping.
Since the nominal thicknesses in Table I-i of Mandatory Appendix I are generally derived based on uniform increments of temperature, the table does not contain uniform increments of thickness. 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 on some other factor, those factors are given in the notes listed in column 3 of Table 3.1-1.
3.4 Low-Temperature Service Limit (Column 4 of Table 3.1-1)
Column 4, the first temperature column in Table 3.1-1, is the low-temperature service limit. If the design minimum temperature is equal to or warmer than this value, then low-temperature requirements do not apply. Materials within a group may be used at this temperature or temperatures warmer than this limit without imposing any of the requirements of this Code. This limit considers material properties and the influence of fabrication processes on the material properties.
3.5 Material Requirements for Low-Temperature Service (Columns 5 and 6 of Table 3.1-1)
Column 5 lists the minimum permitted temperature of the material. When a temperature is listed, this is the design minimum temperature permitted for the material group regardless of impact testing or any other requirements except as permitted by column 18, where the applied stress is limited to 30% of the allowable.
Column 6 is the minimum temperature without impact testing for the material. If the design minimum temperature is equal to or warmer than this value, the material does not require impact testing. If the design minimum temperature is colder than this value, impact testing of the material in accordance with section 3 is required. For carbon steels, this limit might vary with material thickness (T-number groups CS A, CS B, CS C, and CS D) or with stress levels. Additional rows are provided in the table for thickness variations. Interpolation between thicknesses is permitted. Figures and a table for the curves of the variation of temperature with thickness are provided in Mandatory Appendix I and these may he used as an alternative to the values in Table 3.1-1. Permitted temperatures with stress limits are provided for by using columns 10 through 18 instead of column 6 as discussed in para. 3.6 below.
3.6 Design Requirements for Low-Temperature Service (Columns 10—18 of Table 3.1-1)
3.6.1 Minimum Material Temperature Without Impact Testing.
(h) The specimens shall be removed from a location as near as practical to a depth midway between the surface and center thickness. The coupons for heat- affected zone impact specimens shall he taken transverse to the axis of the weld and etched to define the heat- affected zone. The notch of the CVN specimen shall be cut approximately normal to the material surface in such a manner as to include as much heat-affected zone as possible in the resulting fracture. Where the material thickness permits, the axis of a specimen may be inclined to allow the root of the notch to align parallel to the fusion line. When a grain-refining heat treatment is not performed on welds made by the electroslag or electrogas welding process, the notch for the impact specimens shall be located in the grain-coarsened region.
(c) For the comparison of heat-affected zone values with base material values, CVN specimens shall be removed from the unaffected base material at approximately the same distance from the base material surface as the heat-affected zone specimens. The axis of the unaffected base material specimens shall be parallel to the axis of the heat-affected zone specimens, and the axis of the notch shall be normal to the surface of the base material.
3.7.2.3 Test Requirements. The impact test
requirements and acceptance standards for the weld metal used for welding procedure qualification shall be the same as specified in section 4 for the base material to be welded or repaired. Retests in accordance with the provisions of para. 4.5.4 are permitted. Where two materials are to be joined by welding and have different fracture tou gli ii ess requirements, the test requirements and acceptance standards of either material may be used for the weld metal unless otherwise specified by the code referencing this Code.
For Charpy V-notch tests of the heat-affected zone, three Charpy V-notch specimens representing the heat- affected zone material and three representing the unaffected base material shall be tested at the design minimum temperature of the base material. Test acceptance criteria are as follows:
(a) The Charpy V-notch impact tests of the unaffected base material shall meet the requirements of this Code. If the average lateral expansion values of the three HAZ specimens are equal to or greater than the average value for the unaffected base material CVN specimens, the qualification test shall be considered acceptable, and the values and testing temperature shall be recorded on the Welding Procedure Qualification Record (PQR).