Engineering guide
This module provides the dimensions and characteristic values of flat gaskets to DIN 2690, DIN 2691, DIN 2692 and DIN 2697. This series of German standards assigns the matching gasket dimensions — inside diameter, outside diameter and thickness — to every combination of nominal diameter (DN) and nominal pressure (PN), tailored to the sealing face type of the flange (raised face, tongue/groove, male/female).
Beyond the dimensions, the module supplies the gasket parameters required for a flange calculation: minimum and maximum allowable gasket surface pressure, gasket factor, modulus of elasticity with its temperature-dependent alteration rate, and creep factor. If you want to calculate a bolted flange connection — for example to AD 2000-Merkblatt B 7/B 8 (the German AD 2000 pressure vessel code) or DIN EN 1591-1 — these are precisely the values needed to demonstrate tightness in the assembly, test and operating conditions without under- or over-compressing the gasket.
The standards DIN 2690 to 2692 and 2697 have been withdrawn; dimensions of flat gaskets for steel flanges are today governed by DIN EN 1514-1, while gasket parameters are determined per DIN EN 13555 or DIN 28090. For existing plants and re-rating of older flanged joints, however, the old tables remain the authoritative source.
Scope
- Flat gaskets
Typical workflow
Define the flange system and sealing face type
First determine which standard applies: DIN 2690 for flanges with a flat raised face, DIN 2691 for tongue and groove, DIN 2692 for male and female. This fixes the geometric installation situation of the gasket.
Select nominal diameter and nominal pressure
Nominal diameter and nominal pressure address the table entry. The module then returns the gasket's inside diameter, outside diameter and thickness, so that it matches the sealing face of the flange and does not protrude into the flow cross-section.
Record the operating conditions
Operating pressure and operating temperature bound the permissible application range of the gasket material. Via the alteration rate of the modulus of elasticity and the creep factor, temperature influences the long-term behavior of the joint.
Adopt the parameters for the flange calculation
Minimum and maximum load (surface pressure), gasket factor, modulus of elasticity and creep factor are handed over as input values to the actual flange calculation. There it is verified that the bolt forces compress the gasket sufficiently, but not damagingly.
Frequently asked questions
Why is there both a minimum and a maximum allowable gasket surface pressure?
The minimum surface pressure is required for the gasket to conform to the sealing faces and achieve the specified leakage rate; if it is not reached, the joint blows through. The maximum surface pressure protects the gasket from destruction by crushing or extrusion. The bolt forces must lie between both limits in every load case — that is the core of any flange verification.
What are the creep factor and the alteration rate of the modulus of elasticity used for?
Soft gaskets relax under load and temperature: part of the assembly stress is lost over time. The creep factor captures this loss of bolt preload, while the temperature-dependent change of the modulus of elasticity captures the altered spring-back behavior. Both values decide whether the residual surface pressure remaining in operation still exceeds the minimum pressure.
Are the old DIN parameters comparable with the parameters per DIN EN 13555?
Only to a limited extent. The old parameters (such as gasket factors in the style of the classic k-values) are based on different test methods than the leakage-rate-related parameters QMIN(L), QSMAX or PQR per DIN EN 13555 that enter the calculation per DIN EN 1591-1. There is no 1:1 conversion; a calculation by the modern method should use manufacturer parameters per EN 13555.
Which gasket standard applies to new designs today?
The dimensions of flat gaskets for flanges to DIN EN 1092-1 are governed by DIN EN 1514-1. The withdrawn standards DIN 2690 to 2692 and 2697 remain relevant for plants still built with flanges to the old DIN series, since sealing face and gasket dimensions partly differ between the old and the new standards.
Technical content source: LV-Solved-Problems-Content 628d313247e7