4. Calculation of the screw length

SuCri Module 4 – Bolt Length Calculation in AutoCAD Plant 3D

The Bolt Length Calculation module offers specialized tools for the automatic determination and updating of bolt lengths within a Plant 3D project. The calculation can be performed specifically for a single drawing or in a batch process for an entire project. This is based on a central JSON configuration file in which all relevant formulas, component dimensions, and rounding rules are stored.

A decisive advantage of this module is its flexibility: bolts in the flange connections do not require a predefined length in advance. The calculation engine uses the bolt size as an anchor point to automatically retrieve the correct values for nuts, washers, and length additions from the configuration tables.

In addition, other critical components of the pipe connection are precisely taken into account:

This ensures that even complex connections with different gasket thicknesses are accurately documented in the final result.

Functions and Detailed Configuration

The following sections explain the individual functions, the calculation logic, and the configuration options of the module in detail.

Step 1: 4.1 Commands

The Update function calculates the bolt set lengths for all connection elements in the previously selected drawings and overwrites the corresponding properties in the Data Manager. The results are automatically rounded to the next standard length defined in the configuration.

Step 2: 4.2 Drawing Selection

When executing the "Update" or "Update Exact" commands, a drawing selection dialog box opens. Two basic process modes are available here:

  1. Current Drawing: Processes only the currently open and active drawing.
  2. Project: Allows the selection of individual or all drawings within the current Plant 3D project for efficient batch processing.

Step 3: 4.3 Configuration Data – BoltLengthCalculation.json

The core logic of the engine is based on the file BoltLengthCalculation.json, which is located in the Resources folder of the add-in. This file is divided into six logical sections, which allows for convenient adaptation to different project standards and specifications.

Step 4: 4.4 Calculation Formula

For a standard bolt set, the required length is determined according to the following scheme:

Bolt Length = Sum of connected flange thicknesses + (Nut thickness × Number of nuts) + (Washer thickness × Number of washers) + additional protrusion

Step 5: 4.5 Calculation of Wafer (WF) Type Bolts

Bolts of the "Wafer" type usually pass through two flanges and an intermediate valve body. The calculation specifically takes into account the contribution of the nuts (thickness × quantity), the contribution of the washers, and the exact overall length of the valve body.

Step 6: 4.6 Excel Report

After each length calculation is completed, the system automatically creates a detailed Excel report for checking purposes. The file is saved in the local Documents folder under the naming scheme BoltReport_YYYYMMDD_HHMMSS.xlsx and serves as a binding record of the changes made.

Step 7: 4.7 Updated Properties

Upon successful processing, the following Plant 3D properties are synchronized via the Data Link Manager:

Step 8: 4.8 Example: Reconfiguring Hexagon Bolt to Stud Bolt

If a project change from hexagon bolts to stud bolts or threaded rods is required, the calculation formula can be adjusted via the "Load Data" function. In this scenario, the system automatically adjusts, for example, the number of nuts and the required protrusion of the bolt on both sides.