Abstract： ASME B31T:2015 pdf download.Standard Toughness Requirements for Piping. The curve used to generate columns 10 through 17 is provided in Mandatory Appendix 11 and may be used as an alternative to columns 10 through 17. Column 18 lists the mi...

ASME B31T:2015 pdf download.Standard Toughness Requirements for Piping.

The curve used to generate columns 10 through 17 is provided in Mandatory Appendix 11 and may be used as an alternative to columns 10 through 17.

Column 18 lists the minimum low-temperature service limit achievable by limiting stresses to less than 10% of the tensile strength (i.e., SR S 0.3) and may be used without any additional low-temperature service requirements. At these stress levels, the design

margin is considered adequate to prevent a brittle fracture failure mode. The low-temperature service limit listed in column 18 may be used in lieu of that listed in column 4 when the stress ratio 5 0.3.

3.6.2 Stress Ratio. The stress ratio is defined as the maximum of the following:

(a) nominal pressure stress (based on minimum pipe wall thickness less allowances) divided by the allowable stress at the design

minimum temperature.

(b) for piping components with pressure ratings, the pressure for the condition under consideration divided by the pressure rating at the design minimum temperature.

(c) combined longitudinal stress due to pressure. dead weight, and displacement strain (stress intensification factors are not

included in this calculation) divided by the allowable stress at the design minimum temperature. In calculating longitudinal stress, the forces and moments in the piping system shall be calculated using nominal dimensions, and the stresses shall be calculated

using section properties based on the nominal dimensions less corrosion, erosion, and mechanical allowances.

In determining the stress ratio, the loadings coincident with the metal temperature under consideration may be used in lieu of

maximum design values, Where there are several low-temperature design conditions, each shall be evaluated to determine the stress

ratio.

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