Engineering task and calculation objective
This module determines the dimensions of bracket supports (support lugs) to DIN 28083 for vertical process equipment. Starting from the actual cylinder diameter, the corresponding standard cylinder outside diameter per DIN 28001 is determined and from it the matching nominal bracket size with its standardized geometry. These dimensions are the input data for the load-bearing verification of the vessel wall as carried out per AD 2000-Merkblatt S 3/4 of the German AD 2000 pressure vessel code.
Bracket supports introduce the equipment weight locally into steelwork or a concrete floor and thereby generate local bending and membrane stresses in the cylindrical wall. Which bracket size may be assigned to a given vessel diameter therefore depends not only on geometry, but on the bracket load, stability and strength of the vessel wall — the standard supplies the designs and dimensions, while the stress verification decides on admissibility.
The module also supports the practical boundary conditions of vessel fabrication: standardized designs with and without reinforcing plate, and the version for insulated vessels in which the bracket penetrates the insulation layer.
Standard and calculation basis: DIN 28083:2017-11
Calculation workflow
- Assign the cylinder diameter: The actual cylinder diameter is entered; the module assigns to it the standard cylinder outside diameter per DIN 28001. This fixes the curvature of the contact surface to which the bracket is matched.
- Record the wall thickness: The shell wall thickness is needed because it governs the local load-bearing capacity of the shell at the load introduction point and helps narrow down the sensible bracket size.
- Select the nominal bracket size: The nominal bracket size is chosen from the standard series. The module returns the associated geometry — contact height, projection, plate thicknesses and, where applicable, the dimensions of the reinforcing plate — as specified by DIN 28083.
- Hand over to the strength verification: With the bracket dimensions, the support force per bracket and the wall data, the verification of local load introduction per AD 2000-Merkblatt S 3/4 is carried out: allowable local stresses in the cylindrical wall taking internal pressure and supplementary loads into account.
Input quantities
| Quantity | Symbol | Unit |
|---|---|---|
| Nominal size of the bracket | PN (1 - 8) | - |
| Nominal cylinder diameter (acc. DIN 28 001) | Da | mm |
| Distances | z1 = a3·sinα = z2 = a4·cosα = | mm |
| Distances | z1 = a3·sinα = z2 = a4·cosα = | mm |
| Shell wall thickness | se | mm |
| Actual cylinder diameter | D0 | mm |
Calculated results
| Quantity | Symbol | Unit |
|---|---|---|
| hv | hv | mm |
| bv | bv | mm |
| sa | sa | mm |
| ta | ta | mm |
| ba | ba | mm |
| e | e | mm |
| ss | ss | mm |
| Length of the substitute web plate | ls | mm |
| Width of the substitute web plate | bs | mm |
| Angle of inclination (ligament) | α | ° |
| ts | ts | mm |
| hs | hs | mm |
| Eccentricity of the web plate | as | mm |
| Tabelle | Tabelle | mm |
| Tabelle | Tabelle | mm |
| Tabelle | Tabelle | mm |
| Tabelle | Tabelle | mm |
| Tabelle | Tabelle | mm |
| Tabelle | Tabelle | mm |
| Tabelle | Tabelle | mm |
| Tabelle | Tabelle | mm |
| Tabelle | Tabelle | mm |
| hp | hp | mm |
| Tabelle | Tabelle | mm |
Frequently asked questions
Does DIN 28083 also specify the load capacity of the bracket?
No. The standard standardizes designs and dimensions. The allowable load only follows from the verification of the load introduction into the vessel wall (AD 2000 S 3/4 or equivalent methods such as those of the WRC bulletins) and from the strength of the bracket plates and welds themselves. The same bracket size can be admissible on a thick-walled vessel and inadmissible on a thin-walled one.
When is a reinforcing plate under the bracket required?
When the local stresses from the bracket load exceed the allowable values of the unreinforced wall — typically for thin-walled vessels, large support forces or additional moments from eccentric load introduction. The reinforcing plate enlarges the effective load introduction area and reduces the bending stresses in the shell; its dimensions are assigned to the bracket sizes in the standard.
How many brackets are usually arranged and how is the load distributed?
Two, three or four brackets around the circumference are customary. For a statically determinate support (three brackets), the total load is assumed to be evenly distributed; with four or more supports, erection tolerances and foundation settlements can lead to uneven load distribution, which must be accounted for in the verification by an uneven-distribution assumption.
What must be considered for insulated vessels?
The bracket must penetrate the insulation without unnecessarily enlarging thermal bridges and without the supporting structure crushing the insulation. DIN 28083 provides versions with correspondingly enlarged projection for this; the additional eccentricity of the load introduction increases the moment on the vessel wall and must be considered in the verification.