April 7, 2023 PMI Revision 00 1

Turbine pressure survey

April 7, 2023 PMI Revision 00 2

Pressure survey• Objective

– It gives a very useful indication of the internal condition of a turbine.

• Method– During acceptance test pressure at each tapping

point at full load is recoded and plotted on a graph.

– It can be compared at later date. If there is no deterioration, then the slope at full load will remain unchanged.

April 7, 2023 PMI Revision 00 3

150

100

75

0

Pressure B

ar

T.S

.V.

Impulse stage

1st Reaction

HP

exhaust

6 Heater.

IP Inlet

5 Heater

Dearator

LP

Inlet

Tapping points

Basic Turbine pressure survey diagram

Optimum 200 MW

April 7, 2023 PMI Revision 00 4

150

100

75

0

Pressure B

ar

T.S

.V.

Impulse stage

1st Reaction

HP

exhaust

6 Heater.

IP Inlet

5 Heater

Dearator

LP

Inlet

Tapping points

Turbine pressure survey diagram- effect of load change

Optimum 200 MW150 MW

April 7, 2023 PMI Revision 00 5

150

100

75

0

Pressure B

ar

T.S

.V.

Impulse stage

1st Reaction

HP

exhaust

6 Heater.

IP Inlet

5 Heater

Dearator

LP

Inlet

Tapping points

Turbine pressure survey diagram- effect of Internal wear

Optimum 200 MW

150 MW

April 7, 2023 PMI Revision 00 6

150

100

75

0

Pressure B

ar

T.S

.V.

Impulse stage

1st Reaction

HP

exhaust

6 Heater.

IP Inlet

5 Heater

Dearator

LP

Inlet

Tapping points

Turbine pressure survey diagram- effect of Internal restriction

Optimum 200 MW

April 7, 2023 PMI Revision 00 7

150

100

75

0

Pressure B

ar

T.S

.V.

Impulse stage

1st Reaction

HP

exhaust

6 Heater.

IP Inlet

5 Heater

Dearator

LP

Inlet

Tapping points

Turbine pressure survey diagram- effect of Heater outage

Optimum 200 MW

April 7, 2023 PMI Revision 00 8

Observation• If on a st. line but above the optimum line for a

particular load indicates– General wear throughout.– Worn diaphragm seals/ blade tip seals.

• If on a st. line but having kink in the pressure line, it indicates– Restriction to flow.

• If silica deposition is there then LP inlet pr.will show a high trend.

April 7, 2023 PMI Revision 00 9

THANK YOU