BS 1868: Specifications for Steel check valves (flanged and butt-welding ends) for the petroleum, petrochemical and allied industries

BS 1868: Specifications for Steel check valves (flanged and butt-welding ends) for the petroleum, petrochemical and allied industries

BS 1868 Standard specifies requirements for cast steel check valves or forged steel check valves with flanged or butt-welding ends of the following types:

a) swing, for vertical or horizontal flow (see Figure 1);

b) lift:

i) piston type, for angle or horizontal flow (see Figure 2);

ii) ball type, for angle or horizontal flow (see Figure 3);

iii) ball type, for vertical flow (see Figure 4);

iv) disk type, for vertical flow (see Figure 5).

The terms “vertical”, “horizontal” and “angle” relate to the axes of the body ends.

When swing check valves are used in vertical lines the flow must be in an upward direction. For the purposes of this standard any line with a slope (upward or downward) of 5° or less is deemed to be horizontal. In the case of angle pattern valves the inlet should be vertical.

Definitions

nominal size– the nominal size (DN) is a numerical designation of size that is common to all components in a piping system other than those using valves, fittings, couplings or tubes that are designated by the outside diameter. It is a convenient round number for reference purposes and is normally only loosely related to manufacturing dimensions.

Nominal size

The range of sizes covered in BS 1868 standard is 1/2”-24” (15mm-600mm).

Pressure classification

BS 1868 standard applies to valves of the following class designations:

Classes 150, 300, 400, 600, 900, 1 500 and 2 500.

The numerals in these class designations represent the primary pressure ratings of the valves in pounds force per square inch.

Pressure/temperature ratings

The pressure/temperature ratings applicable to valves covered by this standard shall be in accordance with tables PE 1 to PE 12 as listed in BS 1560-2 for the particular shell material specified. There is, however, a temperature restriction on certain trim materials and soft seal ring (see clause 15 and 20.4).

If valves complying with the requirements of this standard are to be used at service temperatures below – 30 °C, reference should be made to BS 3351. (“Service temperature” refers to the temperature of the fluid in the line