Appendix 2 Flange - Load/Bolt Calcs

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Last updated: Dec 28, 2023 by Tiradej Bunyarattaphantu

Last Updated version 2023.12

Bolting Material

Material: A brief description of the component material. When the material selection dialog is used, the default description is based on settings on the Materials-Misc. tab under Tools > Defaults. For example, if the settings are for Spec and Type/Grade and the material is SA-516 Grade 70, this field will show SA-516 Gr. 70. If the settings are instead just for Spec, the field will show SA-516. The field may be edited by the user to say anything without breaking the relationship to the material database; while this flexibility can be very helpful, the user must take care to enter correct information.

Condition: A brief description of the component material. Similar to the "Material" field, the description will default a certain way based on settings on the Materials-Misc. tab under Tools > Defaults when the material selection is used. This field may be edited by the user without breaking the relationship to the material database. As with the “Material” field, the user must take care to enter correct information.

Stress (Hot): The material allowable stress at the temperature listed for the internal pressure condition. When a 3.5:1 safety factor is specified in the vessel screen, this value comes from Section II, Part D (Table 1A for Ferrous Materials, Table 1B for Non-Ferrous Materials, and Table 3 for Bolting). If a 4:1 safety factor is specified, this value is calculated based on the ultimate strength from Table U in Section II, Part D; furthermore, the value is limited to the values listed in the allowable stress tables for yield and creep governed cases. In cases where the temperature listed for the internal pressure condition exceeds the highest temperature entry for this material’s stress line, the value will be zero. Manually editing this field will inform the software that the user is defining the material differently than what is stored in the database and the connection to the material in the database will be severed. This is indicated by the “Unlisted Material” caption.

Stress (Cold): The material allowable stress at 70 °F (20 °C). When a 3.5:1 safety factor is specified in the vessel screen, this value comes from Section II, Part D (Table 1A for Ferrous Materials, Table 1B for Non-Ferrous Materials, and Table 3 for Bolting). If a 4:1 safety factor is specified, this value is calculated based on the ultimate strength from Table U in Section II, Part D; furthermore, the value is limited to the values listed in the allowable stress tables for yield and creep governed cases. Manually editing this field will sever the connection to the material in the database as indicated by the “Unlisted Material” caption.

Load and Bolt Calculations

Is the Bolt Circle > the Flange OD: Select this box for flanges that are designed with slots instead of bolt holes. Per Appendix 2, for flanges such as these, the flange outside diameter is the diameter to the inside of the slots; in this case, the “effective outside diameter” could be less than the bolt circle.

Lock Wm Values to Minimum: Select this box to force the bolt load values, Wm1 and Wm2, to the minimum required in Appendix 2. Clear this box to increase the bolt load values. For cases where flange pairs are used, these values must be manually matched across the two flanges and this box should be cleared.

Number of Bolts: The actual number of bolts, not the number of bolt holes.

Nominal Diameter: The nominal diameter of the bolt. This field will be completed automatically if the Bolt Search is used to select the bolts.

Root Area: The bolt root area based on the smallest diameter on the bolt. This field will automatically be completed if the Bolt Search is used to select the bolts.

Unthreaded Area: The least diameter of any unthreaded portion. ASME PCC-1, Nonmandatory Appendix H contains root areas for common bolt sizes that may be used. This field will automatically be completed if the Bolt Search is used to select the bolts.

Bolt Hole Diameter: The bolt hole diameter, not the bolt circle diameter. This field will fill in automatically if the Bolt Search is used to select the bolts; the value will be determined based on the bolt nominal diameter.

Bolt Size / Threads Per Inch: These fields are completed automatically when a bolt size is selected from the Bolt Search.

Design operating Bolt Load Int. Pressure (Wm1): The internal pressure operating bolt load. This value will calculate to the minimum required by code once all the inputs to do so are made. This value may be increased beyond the minimum when the “Lock Wm Values to Minimum” box is cleared.

Design Seating Bolt Load (Wm2): The gasket seating bolt load. This value will calculate to the minimum required by code once all the inputs to do so are made. This value may be increased beyond the minimum when the “Lock Wm Values to Minimum” box is cleared.

Bolt Circle: The diameter of the circle that passes through the center of each bolt.

Outside Diameter: The flange outside diameter. For cases where slots are used instead of bolt holes, this value will be the diameter to the inside of the slot as referred to in the definition for “Is the Bolt Circle > the Flange OD.”

Nominal Flange Thickness: The flange thickness in the new condition.

Apply Bolt Correction Factor: Select Appendix 2 to determine if a correction factor is applicable per Appendix 2, Section VIII-I. This is ascertained by checking the chord length between the centers of two adjacent bolt holes; if a correction factor is required, the moment on the flange will be multiplied by the correction factor. When Appendix 2 is selected, there is a maximum chord length that cannot be exceeded for the design to pass.