Engineering task and calculation objective
This module combines the dimensional standard DIN EN 1514-1 for non-metallic flat gaskets with manufacturer data for specific gasket products. Alongside the standardized dimensions — inside and outside diameter, thickness, gasket mean diameter, and effective gasket width — manufacturer-specific characteristic values such as the gasket factor and the alteration rate of the modulus of elasticity are stored, and the actual surface pressure and the expected leakage are evaluated.
The difference from a purely standard-based selection lies in the tightness aspect: while the dimension table only supplies geometry, the actual tightness of a joint depends on the real force-deformation and leakage behavior of the gasket material, which manufacturers document in characteristic-value data sheets (e.g. measured to EN 13555). The module merges both data sources and thus enables a leakage-oriented gasket selection.
In practice, the module is used to find a suitable soft gasket for a flanged joint with a given operating pressure and operating temperature and to check whether the actual compression is sufficient for the required tightness class — for example under requirements of the German TA Luft clean-air regulation or with critical media.
Standard and calculation basis: DIN EN 1514-1: 1997-08 & Herstellerangaben
Calculation workflow
- Define the joint and gasket size: From the nominal diameter DN and nominal pressure PN, the gasket size to DIN EN 1514-1 is determined; inside and outside diameter, thickness, gasket mean diameter, and effective gasket width are thereby fixed.
- Select a gasket product with manufacturer data: For the specific product, the manufacturer data are loaded: allowable surface pressures, gasket factor, temperature-dependent alteration rate of the modulus of elasticity, and leakage characteristics.
- Enter the operating conditions: The operating pressure and operating temperature of the joint are entered; they determine both the required minimum compression for tightness and the allowable material limits at temperature.
- Evaluate actual compression and leakage: From the effective gasket area and the applied force, the actual surface pressure follows; it is compared with the manufacturer data, and from this the expected leakage rate or tightness class is derived.
- Approve or adjust the gasket: If the compression lies outside the allowable window or the leakage exceeds the requirement, the gasket material, thickness, or bolt force is adjusted and the verification repeated.
Input quantities
| Quantity | Symbol | Unit |
|---|---|---|
| _Auswahl | _Auswahl | - |
| Nominal diameter | DN | - |
| Inside diameter | d1 | mm |
| Outside diameter | d2 | mm |
| Thickness of gasket | b | mm |
| Creep factor | PQRi | – |
| Modulus of elasticity | EG | MPa |
| Elasticity alteration rate | K1 | – |
| Maximum load | QSmax Qmax | MPa |
| Minimum load | QSminL QminL | MPa |
| Gasket factor | Q1/P | – |
| Operating temperature | Berechnungstemperatur | °C |
| Operating pressure | p | bar |
| Nominal pressure | PN | - |
| Gasket mean diameter | dD | mm |
| Effective gasket width | bD | mm |
| Modulus of elasticity at 20°C | EG | MPa |
| Thickness of gasket | eGI | mm |
| Minimum compressive stress in gasket | QSminL QminL | MPa |
| Maximum allowable gasket pressure | QSmax Qmax | MPa |
| Thickness of gasket | eGI | mm |
| Additional bending of the gasket | ΔeGc | mm |
| Gasket factor for Qmax G.7.3, (default=0.05) | c1 | – |
| Actual compressive stress | Flächenpressung | MPa |
Worked example
For a flat gasket DN 100, PN 16 to DIN EN 1514-1, the actual surface pressure in the assembly condition is to be determined for the case that the bolts of the joint apply a total force of 150 kN to the gasket — a worked example of a gasket stress calculation.
Given values
| Inside diameter di | 115 mm |
| Outside diameter da | 162 mm |
| Gasket force FG | 150 kN |
Solution
Effective gasket geometry
dG = (115 mm + 162 mm) / 2 = 138.5 mm
bG = (162 mm − 115 mm) / 2 = 23.5 mm
Compressed gasket area
AG = π · dG · bG = π · 138.5 mm · 23.5 mm ≈ 10,225 mm²
Actual surface pressure
σG = FG / AG = 150,000 N / 10,225 mm² ≈ 14.7 N/mm²
This value is compared with the minimum compression specified by the manufacturer for the required leakage class and with the maximum allowable compression of the material.
Result
| Gasket area AG | ≈ 10,225 mm² |
| Actual compression σG | ≈ 14.7 N/mm² |
All values are illustrative. The applicable standard and project-specific boundary conditions remain authoritative.
Frequently asked questions
Why are the standard values of DIN EN 1514-1 not sufficient for a tightness verification?
DIN EN 1514-1 is a dimensional standard — it specifies dimensions but no leakage rates. The sealing behavior depends on the specific material and product and varies considerably between manufacturers. A reliable tightness verification requires measured characteristic values of the product actually used, as published by manufacturers per EN 13555.
What does the leakage class express?
The leakage rate describes the mass flow of the test medium (usually helium or nitrogen), referred to the gasket circumference, at a defined compression and internal pressure. The higher the applied surface pressure, the lower the leakage. Requirements such as the German TA Luft regulation specify limit values from which the required minimum compression is derived.
Which typical mistakes lead to leaking soft gaskets?
The most common causes are insufficient or uneven bolt force during assembly, gaskets that are too thick (more settling and creep loss), over-compression of narrow sealing faces, and neglecting the compression loss due to temperature and relaxation in service. A verification covering all load cases — assembly, test, operation — reveals these effects.