Which standard applies
The main standard for steel flanges in Russia and the CIS is GOST 33259-2015. It replaced GOST 12815, 12820 and 12821, used to design pipelines for decades. Older designs still use the former designations — the correspondence is shown below.
Main flange types
| Type | Name | Where it is used |
|---|---|---|
| 01 | Slip-on plate flange | Low pressures and temperatures: water, air, heating networks |
| 02 | Lap joint flange on a weld ring | Where the flange must rotate during assembly, expensive pipe materials |
| 05 | Blind flange | Closing pipe ends and nozzles |
| 11 | Weld neck flange | High pressures and temperatures, critical pipelines |
Sealing faces
The sealing face design must match on both flanges of a joint and suit the gasket.
| Design per GOST 33259 | Name | Former GOST 12815 |
|---|---|---|
| B | Raised face | 1 |
| C / D | Male / female | 2 / 3 |
| E / F | Tongue / groove | 4 / 5 |
| J | Ring-type joint for oval gasket | 7 |
The most common is design B. Male–female and tongue–groove pairs hold the gasket more securely and are used at higher pressures and for hazardous media. Design J is for high pressures with a metal ring gasket.
How to choose a flange
- DN and PN — per the pipeline and maximum pressure including testing.
- Type — per pressure, temperature and assembly method.
- Face design — per the mating flange, valve or equipment.
- Material — per medium and minimum temperature: carbon steel St20, low-alloy 09G2S for the North, stainless 12Kh18N10T for aggressive media.
- Gasket and bolting — per pressure, temperature and medium.
We will select GOST flanges, gaskets and bolting for your pipeline.
Pipeline componentsFAQ
How does a plate flange differ from a weld neck flange?
Can flanges with different sealing faces be joined?
What is design B?
Which steel to choose for the North?
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