Piping
Flange gasket dimensions
In short
For a pipe and a pressure rating, the calculation reads the gasket dimensions from the tables: EN 1514-1 type IBC flat gasket (PN 6 to 40) or ASME B16.21 (class 150 to 600), ASME B16.20 spiral wound gasket (class 150 to 2500) with centering ring and inner ring. Seating width: b = (d2 − d1) / 2.
Calculation
Example calculated with the tool’s default values.
Inputs
- Gasket
- Flat EN 1514-1 (PN)
- Nominal pressure
- PN 16
- Pipe
- DN100 · 114.3 × 3.6 mm
Results
- Gasket OD
- 162.0 mm
Worked example
Every value in this section belongs to the example, calculated with the tool’s default values.
Other results of the example
- Gasket ID
- 115.0 mm
- Seating width
- 23.5 mm
- Flange: raised face diameter
- 158.0 mm
- Flange: bolt circle diameter
- 180.0 mm
- Thickness: to be stated on the order (EN 1514-1 § 5.4.1), e.g. “s = 2 mm”.
Step-by-step calculation
Table lookup
EN 1514-1 PN 16 DN 100
d1 115.0 ; d2 162.0
Seating width
b = (d2 − d1) / 2
(162.0 − 115.0) / 2 = 23.5 mm
EN 1514-1 PN 16: full series
| DN | ID (mm) | OD (mm) |
|---|---|---|
| 10 | 18 | 46 |
| 15 | 22 | 51 |
| 20 | 27 | 61 |
| 25 | 34 | 71 |
| 32 | 43 | 82 |
| 40 | 49 | 92 |
| 50 | 61 | 107 |
| 65 | 77 | 127 |
| 80 | 89 | 142 |
| 100 | 115 | 162 |
| 125 | 141 | 192 |
| 150 | 169 | 218 |
| 200 | 220 | 273 |
| 250 | 273 | 329 |
| 300 | 324 | 384 |
| 350 | 356 | 444 |
| 400 | 407 | 495 |
| 450 | 458 | 555 |
| 500 | 508 | 617 |
| 600 | 610 | 734 |
| 700 | 712 | 804 |
| 800 | 813 | 911 |
How to use it
- Pick the gasket type: EN 1514-1 flat (PN), ASME B16.21 flat or ASME B16.20 spiral wound (class).
- Pick the nominal pressure or the flange class.
- Pick the pipe: its outside diameter selects the DN or NPS.
- Read the gasket diameters, then the raised face and bolt circle of the mating flange.
- Give the thickness on the order: the table does not set it for a flat gasket.
Frequently asked questions
What are the gasket dimensions for DN 100 PN 16?
EN 1514-1 type IBC, PN 16 DN 100 (pipe OD 114.3): inside diameter d1 = 115 mm, outside diameter d2 = 162 mm, seating width (162 − 115) / 2 = 23.5 mm. The mating EN 1092-1 flange has a 158 mm raised face and a 180 mm bolt circle. Thickness is given on the order, for example s = 2 mm.
What are the spiral wound gasket dimensions for class 150 NPS 4?
ASME B16.20: inner ring ID 106.4 mm, winding from 127.0 to 149.4 mm, 4.45 mm thick, centering ring OD 174.8 mm. Rings are 2.97 to 3.33 mm thick. The mating ASME B16.5 flange has a 157.2 mm raised face.
Is a PN 40 gasket bigger than a PN 16 one?
For DN 100, yes: in PN 40, d2 = 168 mm (flange raised face 162 mm, bolt circle 190 mm), against 162 mm in PN 10 and PN 16. The inside diameter stays 115 mm. The full series of the chosen PN is shown under the result.
When is an inner ring required on a spiral wound gasket?
Per ASME B16.20 § 3.2.5: always with PTFE filler, and in class 900 from NPS 24, class 1500 from NPS 12, class 2500 from NPS 4. Otherwise it is supplied by default with graphite unless the order says otherwise. The calculation flags it.
What thickness for a flat gasket?
The tables give the diameters, not the thickness: it depends on the gasket material and is given on the order (EN 1514-1 § 5.4.1, for example s = 2 mm). For ASME B16.21, 1/16 in (1.6 mm) and 1/8 in (3.2 mm) are common.
Limits
Indicative results. Dimensions of new gaskets, read from published tables (Zickwolff, Gore, Garlock); for a form other than IBC or a specific gasket, the maker’s datasheet prevails. No tightening torque or seating stress: they depend on the gasket and the bolting.
Sources
- EN 1514-1:2024, forme IBC : Zickwolff (DN 10 à 500) = Gore (DN 10 à 800) = Garlock Europe p. 5 (DN 600 à 800) ; consultés le 10/11/2026 (link)
- Gore, Gasket dimensions according to EN 1514-1 : Tableau IBC, PN 2,5 à 40 (link)
- EN 1092-1:2018 (bride) : Portée de joint et cercle de perçage : voir Brides et boulonnerie (link)