Steam blowing is one of the most aggressive and important cleaning operations performed on certain high-energy steam systems before a new power plant or major steam-piping modification is placed into service.
The purpose is simple: remove construction debris from the steam piping before that debris can reach expensive equipment such as a steam turbine.
The method is anything but simple.
Unlike ordinary water flushing or low-pressure air blowing, a steam blow uses high-energy steam moving through specially prepared piping. The operation can create extreme noise, high temperatures, major thermal expansion, vibration, powerful discharge forces, and dangerous high-velocity debris.
For that reason, steam blowing is a carefully engineered commissioning activity. The actual steam conditions, pressure buildup, temporary piping design, blow sequence, target criteria, exclusion zones, valve operations, thermal cycles, and acceptance requirements must come from the approved commissioning procedure.
Steam-blow cleaning is recognized as a critical power-plant commissioning activity because particles left in steam piping can damage steam-turbine components when the unit begins operating. DOE guidance specifically identifies steam-blow cleaning of steam piping as an important part of power-plant commissioning. (The Department of Energy’s Energy.gov)
This guide explains the overall process so pipefitters, welders, apprentices, supervisors, commissioning personnel, and other industrial workers understand what is actually happening during a steam blow.
What Is Steam Blowing?
Steam blowing is a pre-commissioning cleaning process in which steam is passed through steam piping at controlled conditions designed to remove loose contamination from the inside of the system.
During construction, high-pressure steam piping can collect welding slag, mill scale, rust, metal particles, grinding debris, dirt, sand, and other foreign material.
If those particles remain when steam is eventually sent toward the turbine, the steam itself can accelerate them.
At that point they stop being ordinary construction debris.
They become high-speed projectiles moving through precision machinery.
The turbine contains carefully manufactured valves, blades, nozzles, seals, and other components. Debris entering those areas can cause erosion, impact damage, reduced efficiency, vibration, or expensive repairs.
Steam blowing is therefore performed before the normal steam path is placed into full operation.
Why Ordinary Flushing May Not Be Enough
Water flushing is very effective for many industrial piping systems.
Air blowing can also remove loose contamination from systems where introducing water is undesirable.
High-pressure steam piping presents a different problem.
The system will ultimately operate with steam moving at substantial velocity and temperature. Cleaning the system under conditions that create sufficient cleaning force can remove material that lower-energy cleaning methods may leave behind.
ASME commissioning guidance notes that air blows do not provide the same thermal cycling of steam-circuit piping and are not considered a direct substitute for steam blowing in applicable systems. (ASME Digital Collection)
Thermal cycling is important because heating and cooling the steam piping causes the metal to expand and contract.
That movement can help loosen mill scale, oxides, and other material attached to the internal surfaces.
Steam blowing therefore combines two powerful cleaning mechanisms:
High-velocity steam flow and repeated thermal expansion and contraction of the piping.
Step 1: Review the Approved Steam-Blow Procedure
Every steam blow begins with engineering.
Before steam enters the piping, the commissioning team needs a detailed approved procedure defining exactly how the operation will be performed.
The procedure may identify the steam source, piping boundaries, temporary steam-blow piping, permanent components that must be removed, temporary valves, discharge location, silencers, target assemblies, required steam conditions, blow durations, cooling periods, thermal cycles, exclusion zones, communication requirements, and acceptance criteria.
The actual process varies significantly between plants.
A combined-cycle plant with an HRSG may use a different arrangement from a conventional boiler plant.
Different steam systems within the same plant may also require separate blows.
The field crew should never determine steam-blow conditions using a general rule of thumb.
The approved commissioning plan controls the operation.
Step 2: Identify Which Steam Systems Require Cleaning
A power plant can contain several steam circuits.
Depending on the design, these may include main steam, hot reheat, cold reheat, auxiliary steam, extraction steam, or other related systems.
Not every line is necessarily cleaned in exactly the same way.
The commissioning procedure divides the plant into specific blowing circuits.
Each circuit needs a defined steam path from the steam source to the temporary discharge.
The crew should understand which system is being blown during each stage and which systems remain isolated.
Step 3: Walk the Entire Steam-Blow Boundary
Before temporary piping is installed and steam is introduced, perform a physical line walk.
Follow the piping from the steam source to the discharge.
Verify valves.
Check blinds.
Identify temporary spools.
Look at drains.
Verify supports.
Check branch connections.
Confirm which equipment has been removed or isolated.
High-energy steam should never be allowed to travel into an unexpected branch because someone assumed a valve was closed.
The drawings define the plan.
The field walk confirms reality.
Step 4: Remove Sensitive Equipment From the Blow Path
The entire purpose of the steam blow is to keep construction debris away from the turbine and other sensitive equipment.
That means the actual operating flow path may be temporarily changed.
Depending on the plant design, turbine stop valves, control valves, strainers, flow-measuring devices, specialty components, or other sensitive equipment may be bypassed or protected.
Temporary spool pieces may replace permanent components.
Steam may be redirected away from the turbine entirely and into temporary steam-blow piping.
This temporary configuration allows the steam to clean the piping without intentionally sending the debris through the equipment the project is trying to protect.
Step 5: Install Temporary Steam-Blow Piping
Temporary piping is a major part of many steam-blow operations.
This piping creates the temporary route from the system being cleaned to the safe discharge location.
Calling it “temporary” does not mean it is simple.
Steam-blow piping may experience high temperature, pressure, flow, vibration, thermal expansion, and large reaction forces.
The temporary system therefore requires engineered supports, guides, anchors, expansion provisions, drains, and other controls.
A poorly designed temporary steam line can move dramatically once steam begins flowing.
Temporary steam-blow piping must be treated as a serious high-energy piping system.
Step 6: Verify Supports, Anchors, and Guides
Steam piping moves when it gets hot.
A lot.
A long run of steel piping can change length significantly between ambient temperature and normal steam-blow temperature.
Permanent steam piping is designed with supports, guides, anchors, spring hangers, expansion loops, offsets, or other methods that allow controlled thermal movement.
Temporary steam-blow piping requires the same basic engineering awareness.
Before beginning, verify the approved support configuration.
A support that looks perfectly adequate while the pipe is cold may experience completely different forces once the system heats and expands.
Step 7: Verify Drains and Low Points
Steam systems create condensate as they warm.
When cold piping first sees steam, some of that steam immediately condenses against the metal surfaces.
Liquid water can therefore collect in low points.
That condensate must be controlled.
Steam piping commonly uses drains and steam traps during normal operation to remove condensate from steam systems. DOE guidance describes steam traps as devices used to remove condensate from operating steam piping. (The Department of Energy’s Energy.gov)
During commissioning, the approved steam-blow procedure establishes how drains and temporary drain arrangements will be handled.
Poor condensate control can contribute to water hammer and other serious problems.
Step 8: Understand the Water-Hammer Hazard
Steam and water inside the same piping system require respect.
If condensate collects in a low point and high-velocity steam begins pushing it through the pipe, the water can form a moving slug.
When that slug hits an elbow, valve, reducer, or closed section, the momentum can create a violent hydraulic impact.
This is commonly referred to as water hammer.
In high-energy steam piping, the forces can be severe.
That is why warm-up, drainage, valve operation, and condensate management are carefully controlled before aggressive steam-flow conditions are established.
Step 9: Establish the Steam-Blow Discharge Area
The discharge point may be the most obvious indication that a steam blow is underway.
High-velocity steam leaves the temporary piping and enters a designated safe discharge area.
The discharge can create tremendous noise.
Hot steam can travel significant distances.
Rust, scale, and metal particles can leave with it.
Nobody should be standing in the discharge path.
The surrounding area must be evaluated for workers, vehicles, equipment, buildings, overhead utilities, roads, and other potential exposures.
The discharge location is engineered—not chosen because it happens to be an open piece of ground.
Step 10: Install Silencers or Mufflers When Required
Steam blowing can be extraordinarily loud.
The discharge of high-energy steam can create noise levels that affect a large area of the plant.
Projects may therefore use temporary silencers or mufflers.
These devices reduce discharge noise while still allowing the required steam flow.
Even with a silencer, hearing protection and exclusion controls may still be necessary.
The site safety plan determines the actual requirements.
Never assume that because the discharge has a silencer, normal hearing protection is automatically sufficient.
Step 11: Install the Target Assembly
Many steam-blow procedures use target plates to evaluate how much debris is still leaving the piping.
A target assembly positions a prepared metal surface in the steam discharge under controlled conditions.
Particles traveling with the steam strike the target.
After the blow, the target is removed and inspected.
Early targets may show many impact marks.
As the piping becomes cleaner, the number and size of new marks generally decrease.
The exact target material, surface preparation, exposure time, placement, and acceptance criteria must come from the approved procedure.
DOE best-practice guidance describes target-plate inspection as part of evaluating steam-blow cleanliness in power-plant commissioning. (The Department of Energy’s Energy.gov)
Step 12: Establish the Exclusion Zone
Steam blowing requires a controlled area.
Potential hazards include:
- High-temperature steam
- Extremely high noise
- Flying debris
- Hot temporary piping
- Unexpected steam leakage
- Thermal movement
- Temporary piping failure
- Discharge forces
The exclusion zone should follow the approved safety and commissioning plan.
Unauthorized workers should remain outside.
This can require coordination across a large portion of the project because steam-blow noise and discharge can affect areas far beyond the immediate piping system.
Step 13: Conduct the Pre-Blow Safety Meeting
Before introducing steam, the entire team should understand the sequence.
Who controls the steam source?
Who operates the main valves?
Who monitors pressure?
Who watches temperature?
Who monitors drains?
Who controls the target assembly?
Who determines whether the blow is complete?
Who has authority to stop the operation?
Communication should be established in advance.
Steam blowing is loud enough that ordinary conversation may become impossible.
Radios or other communication methods are often necessary.
There should be one coordinated operation.
Step 14: Begin Warming the Steam Piping
Cold steam piping should not simply receive maximum steam flow instantly.
The system is warmed according to the approved procedure.
As steam enters, the metal begins heating.
Condensate forms.
Drains remove water.
Supports begin moving.
Spring hangers may change position.
Expansion loops and offsets begin absorbing growth.
The piping is transforming from a cold construction system into a hot operating-style system.
This is one of the reasons steam blowing provides a valuable commissioning check beyond simple internal cleaning.
Step 15: Monitor Thermal Expansion
As temperature rises, the piping expands.
The commissioning team monitors critical locations.
Supports should move as expected.
Guides should guide.
Anchors should remain where designed.
Spring hangers should respond properly.
Temporary piping should expand along its engineered path.
Any unexpected binding, lifting, interference, or support movement needs evaluation.
A pipe that cannot expand as designed can develop substantial loads.
Step 16: Watch for Interference
Construction projects are crowded.
Scaffold tubes, temporary steel, cable trays, platforms, structural members, equipment, insulation supports, or other items can accidentally obstruct pipe movement.
Something that has several inches of clearance while cold may become an interference point after the pipe expands.
The warm-up stage gives the project an opportunity to identify these problems before normal plant operation.
Step 17: Drain Condensate Continuously as Required
Condensate management remains important throughout warm-up.
Drains are operated according to the commissioning procedure.
As the system approaches the required steam conditions, the amount and behavior of condensate change.
The objective is to establish the steam conditions needed for cleaning without allowing uncontrolled liquid accumulation.
The procedure determines when drains remain open, when they are throttled, and when they are closed.
Step 18: Establish the Required Steam Conditions
Once the system is sufficiently warmed, steam conditions are increased toward those required for the blow.
The exact pressure, temperature, flow rate, and operating method depend on the plant design and commissioning plan.
These are engineered values.
The objective is to produce sufficient cleaning force through the steam piping.
Steam-blow engineering often evaluates a cleaning-force ratio or similar relationship comparing the cleaning conditions with expected operating conditions. ASME technical literature discusses using the necessary cleaning-force ratio to avoid both ineffective cleaning and unnecessary overcleaning. (ASME Digital Collection)
The field crew follows the established procedure rather than trying to estimate cleaning force on the jobsite.
Step 19: Understand Cleaning Force
Steam blowing works because high-velocity steam creates drag and shear forces on loose internal contamination.
Imagine a piece of mill scale barely attached to the inside wall of the pipe.
At low steam velocity, it may remain in place.
As steam flow increases, aerodynamic forces increase.
Thermal expansion and contraction may already have weakened its attachment.
Eventually the particle breaks loose.
Now it enters the steam flow.
From that point forward, the steam accelerates it toward the discharge.
That is why the turbine cannot be left in the direct cleaning path.
Step 20: Perform the First Steam Blow
Once the required conditions are achieved and the area is confirmed clear, the steam blow is performed according to the commissioning sequence.
High-energy steam moves through the prepared piping.
Loose material is carried downstream.
The temporary discharge releases the steam into the controlled area.
The event can be extremely loud even with noise controls.
For workers who have never experienced a major steam blow, the scale can be surprising.
This is not ordinary plant steam venting.
It is a planned cleaning operation using significant steam energy.
Step 21: Keep Personnel Away From the Discharge
Nobody should approach the discharge during a blow.
Hot steam can cause severe burns.
Debris can leave the pipe at high velocity.
Visibility around the discharge may also be poor.
The discharge area remains controlled until the blow has ended and the responsible personnel determine that it is safe to enter.
Never assume the area is safe simply because the noise stopped.
Hot components and residual pressure may remain.
Step 22: Reduce Steam Flow According to the Procedure
Once the blow cycle is complete, steam flow is reduced or isolated according to the approved sequence.
The piping does not instantly become cold.
The system still contains heat.
Some sections may retain pressure.
Temporary piping remains extremely hot.
Everyone should continue treating the system as an energized steam system until the appropriate conditions are verified.
Step 23: Inspect the Target Plate
When the system is in the required safe condition, the target can be inspected.
Impact marks provide evidence of the debris still traveling through the steam path.
Early targets may show substantial contamination.
Small impacts can indicate scale or rust particles.
Larger marks may indicate larger foreign material.
The project procedure defines what target condition is acceptable.
Do not invent the acceptance standard based on appearance.
Step 24: Understand Why One Blow Is Usually Not Enough
A steam blow is commonly performed through multiple cycles.
The first blow removes some material.
Then the piping cools.
Cooling causes the steel to contract.
That thermal contraction can loosen additional scale and oxides.
The system is then heated again.
The piping expands again.
Another blow is performed.
Each heat-and-cool cycle can help free additional material.
This thermal cycling is one of the reasons steam blowing can be so effective for steam systems. ASME guidance specifically distinguishes steam blowing from air blowing because air blowing does not provide the same thermal cycling of the steam circuit. (ASME Digital Collection)
Step 25: Allow the Piping to Cool
After the required blow sequence, the system may be allowed to cool according to the commissioning plan.
Cooling is not simply downtime.
It is part of the cleaning process.
As the steel contracts, internal scale can crack and loosen.
The next heating cycle may then dislodge material that survived the previous blow.
The exact cooling period and temperature requirements depend on the procedure.
Step 26: Reheat the System
The steam system is warmed again.
Drain condensate.
Monitor supports.
Watch expansion.
Verify temporary piping.
Bring the system back toward the required cleaning condition.
Experienced crews do not become careless because they have already completed several cycles.
Every heat-up deserves the same attention.
Thermal systems change every time the temperature changes.
Step 27: Perform Another Blow
The next steam blow carries newly loosened material toward the discharge.
Another target may be exposed.
The process is then evaluated again.
Over repeated cycles, the amount of debris should generally decrease.
The target condition becomes progressively cleaner.
Eventually the required acceptance criteria can be met.
Step 28: Blow Separate Steam Circuits
A large power plant may require multiple steam paths to be cleaned.
The valve lineup and temporary piping configuration may change so steam is directed through another section.
For example, one stage may clean part of the main steam system while another cleans reheat piping.
The exact sequence depends entirely on plant design.
Each circuit must receive the cleaning required by the commissioning plan.
Step 29: Reconfigure Temporary Piping When Required
Steam-blow projects can require significant temporary piping changes between stages.
Blinds may be moved.
Temporary spools may be changed.
Target assemblies may move.
Discharge routing may be altered.
Valve lineups may change.
Every configuration change needs careful control.
The previous blow’s arrangement should never be assumed correct for the next stage.
Step 30: Repeat Thermal Cycling
Heating.
Expansion.
Blowing.
Cooling.
Contraction.
Reheating.
Blowing again.
This sequence may repeat several times depending on the system and cleanliness results.
The process can take considerable time and consume substantial steam.
But the cost and schedule impact must be compared with the potential consequence of sending construction debris through a new turbine.
Cleaning before startup is far cheaper than repairing turbine damage afterward.
Step 31: Monitor Supports Through Multiple Cycles
Repeated thermal cycling also gives the commissioning team an opportunity to observe support behavior.
Spring hangers move.
Sliding supports travel.
Guides constrain movement.
Anchors take load.
If something is binding, repeated heating cycles may make the problem easier to identify.
This information can be valuable before the system enters normal operation.
Step 32: Watch Temporary Piping Closely
Temporary piping is often exposed to challenging conditions.
It experiences repeated heating and cooling.
Supports experience movement.
Connections see thermal cycles.
Silencers and discharge components see repeated flow.
Temporary does not mean maintenance-free.
Inspect the arrangement between cycles according to the commissioning plan.
Step 33: Continue Target Evaluation
Target inspection continues throughout the cleaning process.
The commissioning team compares the observed impacts with the project’s acceptance criteria.
The exact criteria may consider the number, size, location, or type of marks on the target.
The goal is not necessarily a target that has literally never experienced a microscopic mark.
The goal is to satisfy the engineered cleanliness standard required to protect the downstream equipment.
Step 34: Avoid Overcleaning
More steam blowing is not automatically better.
Once the system has achieved the required cleanliness, unnecessary additional blowing consumes fuel, water, time, and equipment life.
ASME technical work has specifically examined the issue of steam-blow overcleaning and the use of minimum necessary cleaning force to achieve acceptable results efficiently. (ASME Digital Collection)
Commissioning should be evidence-based.
Clean until the acceptance criteria are met.
Then move forward.
Step 35: Obtain Final Steam-Blow Acceptance
Eventually the target results satisfy the approved criteria.
The designated commissioning, engineering, owner, turbine-vendor, or other required representatives review the results.
The steam-blow stage is officially accepted.
This is a significant milestone.
The steam path has now demonstrated the required internal cleanliness before connection to sensitive turbine equipment.
Step 36: Allow the System to Cool Safely
Once the final blow is complete, the piping must cool before extensive reinstatement begins.
Large steam lines can remain dangerously hot for a long time.
Do not judge temperature by appearance.
Steel at several hundred degrees can look exactly like cold steel.
The approved cool-down and work-release procedures determine when personnel can safely begin dismantling temporary equipment.
Step 37: Verify Zero Pressure
Before opening the steam boundary, verify pressure has been removed.
Never assume the system is depressurized because the boiler or HRSG is no longer actively supplying steam.
Pressure can remain trapped between valves.
Condensate can remain hot.
The piping can still contain thermal energy.
Zero pressure and the required safe temperature conditions need to be verified according to the site’s energy-control procedures.
Step 38: Remove Temporary Steam-Blow Piping
Once the system has been safely released, temporary piping can be removed.
This may involve large-diameter spools, temporary valves, silencers, supports, target assemblies, discharge piping, drains, and other equipment.
Removal can itself become a significant construction operation.
Large temporary spools may require cranes, rigging plans, scaffold changes, and coordinated crews.
Step 39: Inspect Permanent Steam Piping
The permanent system may receive additional inspection after steam blowing.
The project may examine supports, hangers, temporary tie-in locations, flange connections, or other components affected by the temporary configuration.
Any abnormalities identified during thermal cycling should be resolved before normal operation.
Step 40: Reinstall Permanent Components
The system now needs to be returned to its actual operating configuration.
Temporary spool pieces are removed.
Permanent valves or components are installed.
Turbine connections may be restored.
Instruments are returned.
Permanent piping sections are completed.
Temporary blinds are removed or repositioned.
This is one of the most important phases because the turbine is now getting closer to connection with the cleaned steam system.
Step 41: Maintain Cleanliness During Reinstatement
After spending days or weeks cleaning the steam piping, contamination control becomes extremely important.
Open steam piping should not simply be left exposed.
Tools, bolts, grinding debris, rags, welding rods, or other foreign material must not be allowed back into the clean system.
Foreign-material exclusion practices may become stricter at this stage.
Imagine completing the entire steam-blow program and then leaving a wrench inside the pipe during final reinstatement.
Cleaning is only valuable if cleanliness is preserved.
Step 42: Complete the Final Walkdown
Once reinstatement is finished, walk the steam system again.
Compare the field configuration against the P&IDs, isometrics, temporary piping plans, blind lists, valve lists, and commissioning documentation.
Verify that temporary steam-blow piping is gone.
Check permanent valve installation.
Check drains.
Check supports.
Check instrumentation.
Verify temporary blinds and bypasses have been addressed.
Look for anything that does not match the operating configuration.
Steam Blowing vs. Air Blowing
Both processes use flowing gas to remove debris, but they are not equivalent.
Air blowing uses compressed air and can be appropriate for certain cleaning applications.
Steam blowing uses hot steam and provides thermal cycling of the steam piping in addition to high cleaning force.
That thermal expansion and contraction helps loosen internal scale and oxides.
ASME commissioning guidance specifically notes that air blowing does not thermally cycle the steam circuit and therefore is not a recommended substitute for steam blowing where steam blowing is required. (ASME Digital Collection)
Steam Blowing vs. Water Flushing
Water flushing relies on flowing liquid to carry contamination out of the piping.
Steam blowing uses high-energy steam.
Water flushing is appropriate for many industrial systems, but high-pressure steam systems may require more aggressive cleaning conditions before turbine operation.
The choice belongs to the system design and commissioning requirements.
One method does not universally replace the other.
Why Turbine Protection Is the Main Goal
A steam turbine is one of the most expensive and precisely manufactured pieces of equipment in a power plant.
Inside are components designed to interact with high-velocity steam under carefully controlled conditions.
They are not designed to function as construction-debris separators.
A piece of scale that seems insignificant while lying inside a 20-inch steam line can become completely different once steam accelerates it toward the turbine.
Steam blowing removes that material before the normal operating steam path is established.
That is the reason the operation can justify so much temporary piping, time, fuel, noise control, engineering, and manpower.
Common Steam-Blow Mistakes
Steam blowing leaves little room for improvisation.
Problems can arise when the temporary piping is poorly supported, condensate is not properly controlled, workers enter the discharge zone, valve sequences are misunderstood, thermal expansion is restricted, targets are handled incorrectly, temporary configurations are not documented, or the system is opened before pressure and temperature are verified safe.
Another common mistake is focusing entirely on cleanliness and forgetting that the piping itself is experiencing repeated high-temperature cycles.
Steam blowing is simultaneously a cleaning operation and a serious thermal event.
Both need attention.
The Steam-Blow Process in Simple Terms
The overall sequence can be thought of as:
Review → Walk → Protect turbine equipment → Install temporary piping → Verify supports → Establish discharge → Install target → Barricade → Warm the system → Drain condensate → Monitor expansion → Establish cleaning conditions → Blow → Cool → Inspect target → Reheat → Blow again → Repeat until accepted → Cool → Verify zero pressure → Remove temporary piping → Reinstate permanent system → Final walkdown.
That sequence explains the big picture.
The actual steam pressure, temperature, flow, target criteria, blow duration, cooldown requirements, and operating sequence must come from the engineered commissioning procedure.
What Makes a Good Steam-Blow Crew?
A strong steam-blow crew understands that the loud discharge is only one small part of the operation.
They understand the piping configuration.
They know what has been temporarily removed.
They pay attention to drains.
They watch supports.
They understand thermal expansion.
They stay outside exclusion zones.
They communicate valve movements.
They treat temporary piping like real high-energy piping.
They inspect the system between cycles.
They preserve cleanliness after acceptance.
And they never forget the reason for the entire process:
Protect the turbine.
Final Takeaway
Steam blowing is one of the most dramatic commissioning operations found in power generation, but the goal is surprisingly simple.
Get the construction debris out before the turbine sees it.
The challenge is that high-pressure steam piping cannot always be cleaned effectively by simply running water or low-energy air through it.
Steam blowing uses the system’s future operating medium—steam—to create powerful cleaning action.
The piping heats and expands.
Scale loosens.
High-velocity steam carries debris toward the temporary discharge.
The system cools and contracts.
More scale can break loose.
Then it is heated and blown again.
Targets provide evidence of what is still coming out.
The process continues until the required cleanliness is demonstrated.
Then the temporary system is removed, the permanent steam path is reinstated, and the plant moves one step closer to turbine startup.
From a pipefitter’s perspective, steam blowing is an excellent example of why industrial piping is more than simply connecting one spool to another.
Supports matter.
Drains matter.
Valve positions matter.
Thermal movement matters.
Cleanliness matters.
Temporary piping matters.
And a piece of debris that looks harmless during construction can become destructive once the system comes alive.
Steam blowing removes that problem before the turbine ever has to find it.
