Engineering task and calculation objective
This module provides the dimension tables for welding flanges on vessels and process equipment to DIN 28036, the German standard for apparatus flanges. For each nominal diameter it delivers the complete flange geometry: inside and outside diameter, flange thickness, bolt circle diameter, number of bolts, bolt size and bolt hole diameter, plus the sealing face dimensions — from the flat raised face to tongue/groove (Forms C/D) and male/female (Forms E/F). The flange weight is output as well.
Decisive for pressure equipment design is the pressure-temperature rating: for the selected flange, the module states the nominal pressure and the allowable pressures as a function of operating temperature, up to the maximum allowable operating pressure at the associated limit temperature. This makes it possible to check, without an individual calculation, whether a standardized apparatus flange is adequate for the intended operating conditions.
Apparatus flanges to DIN 28036 are used in vessel and equipment fabrication wherever manholes, nozzles and equipment connections are to be executed with standardized weldable flanges; they complement the piping flanges to DIN EN 1092-1 with vessel-specific sizes.
Standard and calculation basis: DIN 28 036: 2005-06
Calculation workflow
- Select nominal diameter and sealing face type: First, the nominal diameter and the desired sealing face type are chosen: flat raised face, tongue (Form C) and groove (Form D), or male (Form E) and female (Form F). The module returns the associated diameters of the raised face, tongue, groove or male/female faces.
- Read off the flange and bolt geometry: For the selected flange, the inside diameter, outside diameter, flange thickness, bolt circle diameter, number of bolts, thread size and bolt hole diameter are output — the basis for the mating design, gasket selection and bolt procurement.
- Check the pressure-temperature rating: Based on the operating temperature, the allowable pressure of the flange is determined and compared with the required operating pressure. What governs is the allowable pressure at design temperature, not the nominal pressure at room temperature.
- Add weight and bill of materials data: The output flange weight feeds into weight estimation, transport planning and costing; together with the bolt data it forms the complete bill-of-materials item of the joint.
Input quantities
| Quantity | Symbol | Unit |
|---|---|---|
| Nominal diameter | DN | – |
| Outside diameter | D | mm |
| Bolt circle diameter | K | mm |
| Flange thickness | C1 | mm |
| Bolt size | M | – |
| Number of bolts | n | - |
| Diameter of bolt hole | L | mm |
| Inside diameter | B1 | mm |
| Operating temperature | (≤ 300°C) T | °C |
| Gasket outside diameter | d1 | mm |
| Outside diameter (Form C tongue or E male) | x | mm |
| Inside diameter of C tongue | w | mm |
| Outside diameter (D groove or F female) | y | mm |
| Inside diameter of D groove | z | mm |
| Flange weight | G | kg |
Calculated results
| Quantity | Symbol | Unit |
|---|---|---|
| at max. allowable operating temperature | TS | °C |
| Max. allowable operating pressure | PS | bar |
| Nominal pressure | (20°C) PN | bar |
| All.press. | PS120 | bar |
| All.press. | PS200 | bar |
| All.press. | PS250 | bar |
| All.press. | PS300 | bar |
Frequently asked questions
How do apparatus flanges to DIN 28036 differ from piping flanges to DIN EN 1092-1?
DIN 28036 is tailored to vessel and equipment fabrication: the series are based on apparatus nominal sizes and typical vessel connections, and the standard contains the sealing face types customary in equipment fabrication, including tongue/groove and male/female. DIN EN 1092-1 covers the general piping program. Mating dimensions can be compatible, but need not be — at interfaces between the two standard worlds, bolt circle, number of bolts and raised face must be checked case by case.
Does the pressure-temperature rating replace a flange calculation?
For flanges operated within the standardized rating, yes — the tabulated values cover the verification, provided that material, gasket and bolts conform to the standard. As soon as supplementary loads act (piping forces and moments, large nozzle loads), special gaskets are used, or the operating point lies outside the rating, an analytical investigation per AD 2000 B 7/B 8 or DIN EN 1591-1 is required.
When do you choose tongue/groove instead of a flat raised face?
Tongue/groove (Forms C/D) confines the gasket mechanically: it cannot be blown out and the surface pressure is concentrated on a defined narrow area. This is advantageous at higher pressures, with hazardous media and in vacuum service. The drawbacks are more elaborate machining and the fixed pairing of the flange halves. Male/female (Forms E/F) is the self-centering intermediate solution with confinement on one side.
Why can't I simply take the nominal pressure as the allowable operating pressure?
The nominal pressure PN is a classification quantity at reference temperature. As temperature rises, the strength values of the flange material decrease, and the allowable pressure drops accordingly. The module therefore outputs the allowable pressures staged over temperature; the value at the highest occurring design temperature always governs.