Control valves

Desuperheaters

4.8.3

<374 °C ASME 150, ASME 300, ASME 600, ASME 900, ASME 1500 + PN16, PN25, PN40, PN63 and PN100 Slip-on

374 - 425 °C ASME 150, ASME 300, ASME 600, ASME 900, ASME 1500 + PN16, PN25, PN40, PN63 and PN100 Weld neck

375 - 570 °C ASME 150, ASME 300, ASME 600, ASME 900, ASME 1500 Weld neck (Slip-on N/A)

Component

Mechanical design temperature

up to and including 425 °C

Mechanical design temperature

above 425 °C up to and including 570 °C

Pipe ASTM A106 Grade B ASTM A335 P11

Flanges ASTM A105N ASTM A182 F11

Spray nozzle ASTM A182 F316L ASTM A182 F11

Nozzle holder ASTM A350 LF2N ASTM A182 F11

Available types

Spray type desuperheaters

A simple type of in-line desuperheater with cooling water injected into the centre of the unit via an atomizing nozzle sprayed in the

direction of the steam flow. Spirax Sarco spray type desuperheaters are available in two options:-

1. Spray nozzle desuperheater (SND)

The assembly is designed for mounting on a suitable flanged branch on the steam pipework. A thermal sleeve installed downstream

of the unit is recommended.

Steam flow

Simple spray nozzle type desuperheater (SND)

Applications:

-

Relatively constant load handling duties.

-

Retrofitting a desuperheater to an existing steam line (steam line and thermal sleeve by others).

-

Large steam lines where an STD could be cost prohibitive.

Mechanical design temperature and flange rating

Materials

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TI-P475-01 CH Issue 3

Direct Contact Desuperheaters