4.4 Calculation formula

Calculation of Bolt Length in Smap3D Piping

In Smap3D Piping, the determination of the required length of bolt sets in piping systems is carried out fully automatically. The precise calculation of bolt length is an essential prerequisite for error-free material planning and ensures the technical safety of flange connections in your 3D model.

The Standard Calculation Formula

For a standard bolt set, the sum of all component thicknesses within the connection forms the calculation basis. The total length of the bolts is composed of the following components:

• Sum of the connected flange thicknesses
• (Nut thickness × number of nuts used)
• (Washer thickness × number of washers)
• (Additional length × number of additional parts)
• Thread depth (protrusion after the last nut)
• Valve flange thickness × number of valves (if connected directly to a valve)
• Connection offset × number of connections (if connected to an equipment nozzle)
• Gasket thickness × number of gaskets (if gaskets are present in the model)
• Stub-end offset × number of stub-ends (if present)

Influence of gasket thickness:
Consider a flange connection with a 2 mm thick gasket compared to an identical connection with a 10 mm thick gasket. In this case, there is a difference of 8 mm in the calculated bolt length. Different gasket thicknesses in the 3D model thus flow directly into the results of the bill of materials.

Special Features for Loose Flange Connections

In connections with loose flange pairs, the flange offset of the connected stub-end is additionally included in the calculation. If a stub-end has a flange offset of 10 mm, for example, the calculated bolt lengths will be correspondingly larger than for a comparable welding neck flange connection.

To ensure that this value is correctly taken into account, the multiplier STUBEND must be defined in the configuration and the flange offset must be stored in the corresponding component (stub-end).

Rounding to Predefined Standard Lengths

The calculated result initially represents a theoretical value. This is then rounded to an available standard length from the RoundLength table. Two different logics can be applied here:

• Rounding Up (UP): The system selects the next available length from the table that is equal to or greater than the calculated theoretical value.
• Rounding Down (DOWN): The system selects the next smaller available length from the table.

When using the Update Exact function, no rounding to table values takes place. If the calculated length exceeds the maximum available standard length in the database, the component is marked with the status Fail in the report.