Thin Wall Expansion Joint - Convolution/Collar

Owned by Former user (Deleted)
Dec 11, 2015
3 min read

Convolution Information

Number of Convolutions: Enter the number of convolutions in the expansion joint.

Convolution Height: This is measured in the neutral position from the valley of the convolution to the peak on the same side of the bellows thickness.

Convolution Pitch: The center to center distance between adjacent convolutions. If the convolutions show an off-set angle of the sidewalls in the neutral position, the convolution pitch is the length between two consecutive convolutions when their sidewalls have been made parallel.

Convolution Root Radius: See Figure 26-2 for more information.

Convolution Crest Radius: See Figure 26-2 for more information.

Mean Dia. of Bellows Convolutions: For toroidal bellows, this value is manually entered by the user; for all other bellows types, this value is calculated. For toroidal bellows, see Figure 26-1(c) for more information.

Collar Information

Length: Bellows collar length.

Long Weld Jt. Eff.: The longitudinal weld joint efficiency for the tangent collar. This is determined from Table UW-12.

Thickness: Bellows collar thickness.

Cross Sect. area of all reinf. collars: The cross sectional metal area of all reinforcing collars for toroidal bellows.

Expansion Joint has Reinforcing Collar: Check the box to add a reinforcing collar to a toroidal bellows. Applies to years 2013 and later.

Reinforcing Collar Thickness: This applies to toroidal bellows, years 2013 and later. See Figure 26-1-1 sketch (c) for more information.

Reinforcing Collar Diameter: This applies to toroidal bellows, years 2013 and later. See Figure 26-1-1 sketch (c) for more information.

Reinforcing Collar Overall Length: This applies to toroidal bellows, years 2013 and later. See Figure 26-1-1 sketch (c) for more information.

Long. Weld Jt. Eff. Reinforcing: This is the longitudinal weld joint efficiency for a reinforcing collar on a toroidal bellows.

Collar Material

The collar material and reinforcing collar material both appear in this section.

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.

Density: The material density based on table PRD from Section II, Part D. For those materials that did not have a clear match in this table, every effort was made to assign conservative values. Manually editing this field will sever the connection to the material in the database as indicated by the "Unlisted Material" caption.

Hot Modulus of Elasticity: The material modulus of elasticity based on the TM tables from Section II, Part D. The value shown here is based on the applicable TM table and the design temperature listed for the internal pressure condition. In cases where the temperature listed for the internal pressure condition exceeds the highest temperature entry for this material’s TM table, the value will be zero. There are several materials that do not have clear matches in these tables. When a clear match cannot be found by the software’s assignment criteria, the software will instead retrieve the modulus of elasticity from the external pressure chart assigned to the material. If this attempt also fails, then the value will be zero. This is more common with non-ferrous materials. Manually editing this field will sever the connection to the material in the database as indicated by the “Unlisted Material” caption.

Allowable Stress: 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.