ASME Section II part D-Guide to allowable stress tables

What is in ASME Section IID

BPVC Section II-Materials-Part D-Properties-(Customary) or BPVC-IID (Customary) – 2021 is the part 4 of the ASME Section II series. Part D Section is a “Service Section” for reference by the BPVC construction Sections providing tables of material properties including allowable, design, tensile and yield stress values, physical properties and external pressure charts and tables. Part D facilitates ready identification of materials to specific Sections of the Boiler and Pressure Vessel Code. Part D contains appendices which contain criteria for establishing allowable stress, the bases for establishing external pressure charts, and information required for approval of new materials.

The information and restrictions provided in the notes found throughout the various stress tables in Sub part 1 of Section II, Part D are mandatory. These notes are organized as follows:

EXX:   defining onset of values based on successful experience in service

GXX:   general requirements

HXX:   heat treatment requirements

SXX:   size requirements

TXX:    defining onset of time-dependent behaviour

WXX:   welding requirements

In Tables 1A, 2A and 5A, the information in Nominal Composition column is non-mandatory and is for information only. However, these nominal compositions are primary sorting used in these tables. Also, the information in the Alloy Designation/ UNS Number column is non-mandatory for specifications for which a grade or types is provided. For specifications for which no grade or type is listed, the UNS Number is mandatory.

When provided, the information in columns for Product Form, Specification Number, Type/ Grade, Class/ Condition/ Temper, and External Pressure Chart Number is mandatory.

The information in P-Number and Group Number columns is also mandatory; however, the primary source for this information is Table QW/ QB-422 in ASME Section IX. When there is a conflict between the P-Number and Group Number information in these stress tables and that in Section IX, the numbers in Section IX shall govern.

The information in the Minimum Tensile Strength, Minimum Yield Strength, and Size/ Thickness dimensions columns is also mandatory; however, the primary source for this information is the material specifications in ASME Section II, Parts A and B. These values are a primary basis for establishing the allowable stress and design stress intensities. When there is a conflict between the tensile and yield strength values in the stress tables and those in the material specifications in Section II, Parts A and B, the minimum tensile and yield strength values in Parts A and B shall govern.

The information in the Applicability and Maximum Temperature Limits columns is mandatory. The temperature to which allowable stress or design stress intensity values are listed is not necessarily the temperature to which use is permitted by a particular construction code. Different construction codes often have different use temperature limits for the same material and condition. Further, values may be listed in the stress tables at temperatures above the maximum use temperature limit. These stress values are provided to permit interpolation to be used to determine the allowable stress or design stress intensity at temperatures below the next lowest temperatures for which stress values are listed and the maximum use temperature limit listed in these columns

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