The Steam and Water Analysis System (SWAS) is critical for monitoring the purity of boiler feedwater and steam in thermal power plants to prevent corrosion in steam-related equipment. It involves stages of sample extraction, transport, conditioning, and analysis, ensuring accurate measurements of various parameters such as pH and conductivity. Without a SWAS, power plants face higher risks of shutdowns due to impurities, making it essential for optimal operation and maintenance.

1. Steamand Water AnalysisSystem(SWAS) –CorrosionControl inBoiler&Turbine
To monitorand control the purityof boilerfeedwaterSteamandwateranalysissystem (SWAS)
designed.
Steam and water analysis system (SWAS) is a system that is used to analyse and display critical
information about steam or water in the power cycle. For any power plant running on steam, it is
absolutely crucial to ensure about the purity of boiler feed water and steam during electricity
generation; especially to steam equipment like steam turbine, super heater, boiler valves,
condenser, steam boiler. A well designed steam and water analysis system can help prevent
damage of steam boiler, steam turbine, and other critical parameters in the steam. These
parameters contains pH, silica, sodium, Conductivity, Dissolved Oxygen, Phosphate and
Chlorides etc. To keep the power plant operating and functioning with minimum corrosion, the
power plant have fully integrated steam and water analysis system (SWAS).
To protect these equipment SWAS works in to stages:-
1. Sample Extracting
2. Sample Transport
3. Sample Conditioning
4. Sample Analysis
1. Sample Extracting: In the sampling system, sample extraction probe is the first important
component. The correct choice of sample extraction probe should never be over looked
as analysis of extracted sample is going to represent the exact process condition. As the
probe is directly attached to the process pipe work, it may have to withstand severe
conditions. For most applications, this sample probe is made up of stringent codes, which
is application to high-pressure and high-temperature pipework. It is used to measure
sample flow rate and sample extraction probe.
2. Sample Transport: The sample meets least resistance is important while transporting the
sample. To process the flow of sample joints and bends in the pipeline need to be
minimal.
3. Sample Conditioning System: It is also known as sampling system and Wet Panel in
some countries. In this stage, The sample coolers is used to cool the sample at the

2. required temperature, then depressurized in pressure regulators and then transfer to
various analyser while the flow characteristics is kept constant through black pressure
regulatory. While working with these systems, there are a lots of safety equipment
provided in wet panels for operators safety.
There are few important components of sampling systems (WET RACK)
1. Sample Cooler: In the sampling system, sample coolers are CIOL-IN-SHELL type
CONTRA-FLOW heat exchangers that plays an important role in bringing down the
temperature of hot steam. The preferable sample cooler design should be double
helix. The coil should be in shell type to provide contra-flowheat exchange. Coil
Materials are available such as Stainless steel AISI 316, Monal 400 & Inconel 625
and so on. It must meet ASME PTC 19.11 standard requirements.
2. High Pressure Regulator:
Piston Type High Pressure Regulations: These type of high pressure regulators are
used in primary conditioning where sample pressure are higher than 100 Kg/cm2.
3. Back Pressure Regulator(BRP): These type of regulatorsisusedtoavoidlow flow
conditionstoanalysersinthe eventsgrabsample valve operations.Inthe absence of
such a device,whenthe grabsample valve isopenedthe samplewouldflow tograb
sample line. The combinationof apressure regulatorandbackpressure regulatorin
Steamand wateranalysissystem providesverystablepressureandflow conditions,
therebyensuringreliable,accurate,andefficientanalysis.

3. 4. SightGlass:This componentisusedtoview the sample flow insidethe sample line. The
presence of coolingwaterisindicatingthrougha rotatingwheelsandthe side glassis
made up of highgrade stainlesssteel.
5. Sample Filter:Toensure particle-free sample,sample filterisused.Usingthisany
particle of size upto 40 micronscan be filteredout. Forgedstainlesssteel bodyand
hexagonal capare the twopart in sample filterwhichhelpeasycleaningof filter
element.

4. 6. Pressure Relief Valve: Thiscomponentsisfittedwithsamplecoolerandprotectssampler
coolerincase the coil fails.
7. Hi-TempIsolationValve: Thisvalve isusedformosthighpressure andtemperature
applicationsasitiseasyto operate.Itis designedwithplug/seatgeometryandstuffing
box that allowthese valvestooperate forextendedperiodof time.
4. Sample AnalysisSystem: A sample analysissystemisalsoknownasAnalyserPanel,DryPanel
or Dry Rack in some countries. Itisusuallyafree-standingenclosedpanel containing
transmitterelectronics.The systemmountedonpanels. Inthissystemstage,sample is
analysedonthe basisof pH, conductivity,chloride,dissolvedoxygen,hydrazine,phosphate,
silica,andsodiumetc.
What HappenIf You Don’t Have SWAS?
1. Steamand Water Analysissystemismandatoryinthermal powerplantasitkeepsconstant
watch onproblemassociatedwithcorrosion,dosingoptimization,planteffluents,andboiler
blowdown.
2. In thermal powerplant50% of forcedpowerplantshutdownscanbe attributedto
impurities.Steamandwateranalysissystemisimportanttoanalyse the impuritiesinthe
turbine.
3. SWASare properlymaintainedinpowerplantthatrunat 95+PLF / PAF.

5. 4. People whohave goodknowledge, expertise andexperience preferon-line monitoringof all
the necessaryparametersinvolvedinplantcycle chemistry.
URL: https://marcepinc.com/blog/steam-and-water-analysis-system-(swas)-%E2%80%93-corrosion-
control-in-boiler-&-turbine