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7 Flanges7.1 Flanges to European and German Standards 7.1.1 Definitions PN nominal pressure Standard EN 1333 defines PN as an alpha-numeric designation which relates the mechanical and dimensional properties of a pipe system component. The letters PN are followed by a dimensionless whole number, which indirectly correlates with the magnitude of the design pressure, in bar, of the connections at a temperature of 20°C.

DN nominal bore Standard EN ISO 6708 defines DN as an alpha-numeric designation for the size of pipe system components, which is used for reference purposes. The letters DN are followed by a dimensionless whole number, which indirectly correlates with the magnitude of the bore or the outer diameter, in millimetre, of the connections.

Pressure / temperature rating The pressure / temperature rating defines the permissible pressure (surge free) at various temperatures. The relationship is dependent on the nominal pressure rating (PN) and the materials of the flange. The temperature refers to that of the pumped liquid. The pressure / temperature ratings are given in standard flange tables. However the pressure / temperature rating of the flange may not necessarily apply to the entire pipe system. The pressure / temperature rating of fittings, instruments, gaskets and pumps can restrict the pressure / temperature rating of the flange connection. Data from the manufacturer should therefore always be taken into account.

7.1.2 Flanges to European EN, (DIN EN, BS EN) Standards Cast iron flanges to EN 1092-2 The standard covers the following nominal pressure ratings PN 2,5 PN 6 PN 10 PN 16 PN 25 PN 40 Flanges normally raised face type B

Ductile iron (SG) flanges to DIN EN 1092-2 The standard covers the following nominal pressure ratings PN 10 PN 16 PN 25 PN 40 PN 63 Flanges normally raised face type B

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Cast steel flanges to EN 1092-1The standard covers the following nominal pressure ratings PN 6 PN 10 PN 16 PN 25 PN 40 PN 63 PN 100 Flanges normally raised face type B

7.1.3 Flanges to German DIN Standards Cast iron flanges The standard covers the following nominal pressure ratings

PN 2,5 DIN 2530

PN 6 DIN 2531

PN 10 DIN 2532

PN 16 DIN 2533

PN 25 DIN 2534

PN 40 DIN 2535

Flanges normally raised face type C Note! These standards are no longer applicable for new equipment. EN 1092-2 should be used.

Cast steel flangesThe standard covers the following nominal pressure ratings

PN 16 DIN 2543

PN 25 DIN 2544

PN 40 DIN 2545

PN 64 DIN 2546

PN 100 DIN 2547

PN 160 DIN 2548

PN 250 DIN 2549

PN 320 DIN 2550

PN 400 DIN 2551

Flanges normally raised face, PN 16 to PN 40 type C PN 64 to PN 400 type E Note: The standards for PN16 to PN100 are no longer applicable for new

equipment. EN 1092-1 should be used.

7.2 Flanges to American ANSI Standards 7.2.1 Definitions ClassThe flanges are categorised by class. The classes have similar meaning to the European nominal pressure rating, although this term is not used. The figure given after the class refers to a pressure in psig at a given temperature, according to the material, which lies between 65 and 650°C. However for steel flanges to ANSI B 16.5, the class is comparable with nominal pressure rating.

NPSThe expression NPS = nominal pipe size is comparable with the European term nominal bore (DN) NPS is the nominal diameter in inches and is applicable to connecting fittings.

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Pressure / Temperature (P/T) rating The pressure / temperature rating defines the permissible pressure at various temperatures. The relationship is dependent on the pressure class and the materials of the flange and for cast flanges on the nominal pipe size (NPS). The rating is independent of the pumped liquid. The temperature refers to that of the pipe system, although it can be assumed to be the same as that of the pumped liquid. The pressure / temperature ratings are given in standard flange tables. However the pressure / temperature rating of fittings, instruments, gaskets and pumps according to data from the manufacturer should always be taken into account.

7.2.2 Cast iron flanges to ANSI B 16.1The standard covers the following nominal pressure classes

Class 25 ( PN 2,5) 1)

Class 125 ( PN 10) 1)

Class 250 ( PN 25) 1)

Class 800 ( PN 40) 1)

1) These values are not given in Standard ANSI B 16.1, i.e. they are not official and serve only for comparison. Flanges CL.25 and 125FF, CL.250 and 800RF

7.2.3 Cast steel flanges to ANSI B 16.5 The standard covers the following nominal pressure classes

Class150

PN 20 300

PN 50 400

PN 68 600

PN 100 900

PN 150 1500

PN 250 2500

PN 420 Flanges normally raised face type RF

7.3 Flanges to International ISO Standards 7.3.1 Cast iron flanges to ISO 7005-2 The standard covers the following nominal pressure ratings Preferred series (Series 1): PN 10 PN 16 PN 20 PN 50 Optional series (Series 2): PN 2,5 PN 6 PN 25 PN 40

Flanges: Normally raised face type RF Exception: PN 20, without raised face FF (flat face)

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7.3.2 Ductile iron (SG) flanges to ISO 7005-2 The standard covers the following nominal pressure ratings Preferred series (Series 1): PN 10 PN 16 PN 20 PN 50 PN 110 PN 150 PN 260 PN 420 Optional series (Series 2): PN 2,5 PN 6 PN 25 PN 40 Flanges normally raised face type B

7.3.3 Cast steel flanges to ISO 7005-1 The standard covers the following nominal pressure ratings Preferred series (Series 1): PN 10 PN 16 PN 20 PN 50 PN 110 PN 150 PN 260 PN 420 Optional series (Series 2): PN 2,5 PN 6 PN 25 PN 40 Flanges normally raised face type B

7.4 Test pressureAll components of a pump installation which are subject to pressure, i.e. pumps, pipework, fittings etc. must pass a hydrostatic test. This is to confirm the mechanical strength of the component but also primarily the leak tightness. The designated test pressure should generally be applied for a period of 30 minutes. The test pressure is generally set at between 1.3 to 1.5 times the maximum operating pressure, or the maximum permissible operating pressure, or the nominal pressure rating of the flanges. Clean cold water is used for the hydrostatic test.

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