ASME B31T:2018 pdf free download

ASME B31T:2018 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 below ambient temperature. brittle failure can occur at temperatures above ambient temperature for certain combinations of materials, thicknesses, and stress levels. The definition of “low-temperature service as used in this Code, therefore, varies widely across the many applications for which piping systems are used. Fora building service airline, low temperature may be 0°C (32°F), whereas for a cryogenic piping system, it could easily be —18S°C (.300DF).I However, the principles used to evaluate the suitability 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.
(d) The procedure qualification shall simulate the maximum percent surface strain, employing a bending process similar to that used in the fabrication of the material or by direct tension on the specimen.
(e) Sufficient CVN test specimens shall be taken from each of the three heats of material to establish a transition curve showing both the upper and lower shelves. On each of the three heats, tests consisting of three impact specimens shall be conducted at a minimum of five different temperatures distributed throughout the transition region. The upper and lower shelves may be established by the use of one test specimen for each shelf. Depending on the product form, it may be necessary to plot the transition curves using both lateral expansion and energy level data.
Using the results of the impact test data from each of three heats, taken both before and after straining, determine either of the following:
(1) the maximum change in nil ductility transition (NUT) temperatuie along with (-a) or (-b)
(-a) the maximum change of lateral expansion and energy at the temperature under consideration
(-b) the maximum change of temperature at the lateral expansion and energy levels under consideration
(2) when lateral expansion Is the acceptance criterion, either the maximum change in temperature ii’ tht’ maximum change in lateral expansion
3.7.3.3 Acceptance CriterIa. To be acceptable, the formed material used in production shall have impact properties before forming sufficient to compensate for the maximum loss of impact properties due to the qualified forming processes used. A new procedure qualltication test is required when any of the changes in (a), (b). or (c) are made.
(a) The actual postweld heat treatment time at temperature is warmer than previously qualified unless the material is P-No. 1 and the thickness is less than 50 mm (2 In.). If the material is not postweld heat treated, the procedure shall be qualified without postweld heat treatment
(b) The maximum calculated strain of the material exceeds the previously qualified strain by more than 0,5%.
(c) Preheat over 120°C (250°F) is used in the forming or bending operation but is not followed by a subsequent postweld heat treatment.