SST 500/700
Single-stage Steam Turbines

The API 611- and API 612-compliant single-stage steam turbine (SST) is a versatile,
rugged steam turbine typically specified by the refining, petrochemical, food
processing, steel, and other industries as an economical and reliable mechanical
drive for lube oil pumps, process pumps, feed water pumps, fans, compressors, and
generators.

Horizontal, Axial Split Casing
The axial split design allows the upper half of the casing to be removed for easier
access to internal parts inspection and replacement. The sturdy metal-to-metal joint
sealing casing design meets ASME section VIII and NEMA stress level standards
compliant with API 612 requirements.

Overspeed Trip System

t 4 tIndustrial-type babbitt-lined journal bearings

The SST safety valve and trip system work independently of the governor. They use
a piloted venturi-type mechanical trip valve and provide positive closure to shut off
steam to the turbine in the event of overspeed. The valve can be reset against full
steam pressure.

t 5 tHigh-capacity thrust bearing for positive rotor
location

Trip and Throttle Valve (optional)

t 1 tHigh-efficiency blading
t 2 tKeyed and shrunk wheel on shaft
t 3 tUnique, angle-type carbon-ring packing

t 6 tNonsparking, bolt-type overspeed trip
t 7 tSpeed governor
t 8 tOil rings
t 9 tTrip lever
t 0 tGovernor valve stem
1
t 1 t tationary, replaceable, nonsparking
1 S
labyrinth bearing-case oil seals

The trip and throttle valve functions as a quick-closing valve (manual or automatic)
that is actuated by the overspeed governor, a mechanical safety trip, or the optional
electronic trip actuators. It also functions as a manually operated throttle valve for
bringing the steam turbine up to speed (standard supply on SST 700LP). Choose
from a Dresser-rand mechanical trip and throttle valve, or a Dresser-Rand Gimpel™
oil-operated trip and throttle valve.

t 2 tOil rings
1

Governors

1
t 3 Internal oil reservoir

11

Exhaust
12

1
2
3

13

4

The Woodward Class A TG governor is standard equipment on
all SST models as a self-contained, hydraulic powered governor
for high output and accurate speed control. Alternate governing
systems are supplied as necessary based on operating conditions or when specified by the client.

Rotors, Bearings, and Seals
Two rows of single-disc, Curtis forged wheels are shrunk and
keyed to the shaft to prevent wheel movement relative to the
shaft throughout the steam turbine speed range. Solid rotor
designs are available as an option for high-speed applications.

5
6
7

8

Journal bearings are split at the horizontal center line for easy
access and replacement without removing the rotor. Bearings
are bronze-backed and babbitt-lined for improved operating life.
Standard oil ring or optional pressure lubrication can be used as
required. Anti-friction ball bearings also are available for quick
start applications or where mist-oil lubrication is specified.

9

10
Inlet