© sdt north america 2003 all rights reserved steam traps testing steam traps using airborne...

© SDT North America 2003 © SDT North America 2003 All Rights ReservedAll Rights Reserved

Steam TrapsSteam Traps

Testing steam traps using airborne Testing steam traps using airborne ultrasound inspectionultrasound inspection

April 18, 2023April 18, 2023 SDT North AmericaSDT North America


What is Steam?What is Steam?

Add heat energy to water (BTU’s)Add heat energy to water (BTU’s)

British Thermal UnitsBritish Thermal Units

Produces gas from waterProduces gas from water

1 lb water, 700F

1 lb water, 2120F

+ 142 BTU =

+ 970 BTU =

1 lb steam, 2120F



What is a Steam System?What is a Steam System?

Deliver steam from boiler to point of useDeliver steam from boiler to point of use

Collection of pipes, valves, and steam Collection of pipes, valves, and steam trapstraps

Steam traps keep steam pureSteam traps keep steam pure

Steam traps protect the system from Steam traps protect the system from damagedamage



What is a Steam Trap?What is a Steam Trap?

Automatic valveAutomatic valve

Open for condensate, air, and COOpen for condensate, air, and CO2 2

Closed for steamClosed for steam

PurposePurpose Maintain efficient heat transferMaintain efficient heat transfer Eliminate corrosive gasesEliminate corrosive gases Eliminate water hammerEliminate water hammer



Types of Steam TrapsTypes of Steam Traps

Operative modesOperative modes DensityDensity TemperatureTemperature VelocityVelocity

Four common typesFour common types Inverted bucket (A)Inverted bucket (A) Float and thermostatic (B)Float and thermostatic (B) Thermostatic (C)Thermostatic (C) Thermodynamic or disk (D)Thermodynamic or disk (D)

A B

C D



Testing MethodsTesting MethodsVisual TestingVisual Testing Thermal TestingThermal Testing

Ultrasonic TestingUltrasonic Testing



Ultrasonic Data CollectorsUltrasonic Data Collectors

Sense high frequency (HF) Sense high frequency (HF) soundssounds

Convert HF to representative Convert HF to representative audible sounds audible sounds

Eliminate audible “parasite” Eliminate audible “parasite” noisenoise

Measure and collect data for Measure and collect data for trend analysistrend analysis

Typical Ultrasonic Data Collection System



Ultrasound Testing - BasicsUltrasound Testing - Basics

Connect headphones to detectorConnect headphones to detector

Connect contact sensor to detectorConnect contact sensor to detector

Touch sensor to housing of trapTouch sensor to housing of trap

Adjust sensitivity for measuring and Adjust sensitivity for measuring and listening according to instrument’s listening according to instrument’s instructionsinstructions



Setting Sensitivity of DetectorSetting Sensitivity of Detector

For Low-Pressure Steam:For Low-Pressure Steam: Set Amplitude Level to Set Amplitude Level to

Middle to High Range Middle to High Range between A=50 or A=80between A=50 or A=80

For High-Pressure For High-Pressure Steam:Steam:

Set Amplitude Level from Set Amplitude Level from A=10 to A=50A=10 to A=50

Note* Setting proper amplitude is Note* Setting proper amplitude is done by having enough sound in done by having enough sound in the headphone to be able to the headphone to be able to diagnose a failure.diagnose a failure.

23.1CONTACT 05 17 2003

dBµVA = 50

Low Pressure

CONTACT 05 17 2003

49.1 A = 20

dBµV

High Pressure



Ultrasound Testing – Data CollectionUltrasound Testing – Data Collection

Listen to internal ultrasoundsListen to internal ultrasounds

Take dBTake dBµV readings and µV readings and store to data collector to store to data collector to trend:trend:

dBdBµV during collection phaseµV during collection phase dBdBµV during dumping phaseµV during dumping phase

Make an audio recording of Make an audio recording of trap cycle to compare, share, trap cycle to compare, share, and train future inspectorsand train future inspectors



Trouble Shooting Logic TreeTrouble Shooting Logic TreeIs Steam Trap Operating?

Valves open? Temperature

Hot Cold

Trap Failed Closed or PluggedSelect Sensitivity for Detector

On/Off Type Continuous Type

Float and ThermostaticInv/Bucket,

Thermodynamic, or Thermostatic

Test as per prescribed below Test as prescribed below

Log ResultsLog Results

Tree supplied by Plant Support and Evaluations, inc www.plantsupport.com



Inverted BucketInverted Bucket

Inverted Bucket traps work on Inverted Bucket traps work on the principle of densitythe principle of density

Steam keeps the purge valve Steam keeps the purge valve closedclosed

Condensate opens the purge Condensate opens the purge valvevalve

Collection and purge phases Collection and purge phases are continuousare continuous



Ultrasonic Testing Ultrasonic Testing Inverted Bucket TrapsInverted Bucket Traps

Follow procedures for Basic Ultrasound TestingFollow procedures for Basic Ultrasound TestingLog US dBLog US dBµV readings on upstream and downstream µV readings on upstream and downstream sides of trapsides of trapLog Temp readings on upstream and downstream sides Log Temp readings on upstream and downstream sides of trapof trapDistinct and clear cycling sound indicates proper:Distinct and clear cycling sound indicates proper:

Collection phase (gurgling sounds as condensate collects)Collection phase (gurgling sounds as condensate collects) Purge phase (Sudden gushing sound as air and condensate Purge phase (Sudden gushing sound as air and condensate

is purged)is purged)

If clear cycling sounds are not evident:If clear cycling sounds are not evident: Trap is stuck closed or openTrap is stuck closed or open

Louder downstream, trap is open and condensate is Louder downstream, trap is open and condensate is passingpassingLow sound level, trap is closedLow sound level, trap is closedListen for faulty mechanical sounds to identify traps in Listen for faulty mechanical sounds to identify traps in early stages of failureearly stages of failureRecord sounds for future comparisons and operator Record sounds for future comparisons and operator trainingtraining



Float and ThermostaticFloat and Thermostatic

Works on combined principle of Works on combined principle of density and temperaturedensity and temperatureDensityDensity::

No condensate, ball sinks and valve No condensate, ball sinks and valve is closedis closed

Condensate collects and lifts ball, Condensate collects and lifts ball, opening discharge valveopening discharge valve

TemperatureTemperature A separate thermostat reacts to A separate thermostat reacts to

temperature changes from the temperature changes from the presence of non-condensable gases presence of non-condensable gases (air, co(air, co22, and carbonic acids), and carbonic acids)

As it cools it opens a secondary As it cools it opens a secondary discharge valve at the top of trapdischarge valve at the top of trap



Ultrasonic Testing Ultrasonic Testing Float and Thermostatic TrapsFloat and Thermostatic Traps

Follow procedures for Basic Ultrasound Follow procedures for Basic Ultrasound TestingTestingLog US dBLog US dBµV readings on upstream and µV readings on upstream and downstream sides of trapdownstream sides of trapLog Temp readings on upstream and Log Temp readings on upstream and downstream sides of trapdownstream sides of trapInspection of ball float follows same procedure Inspection of ball float follows same procedure for inverted bucket – identify cycle of collection for inverted bucket – identify cycle of collection and purge phasesand purge phasesDamaged secondary vent valve characterized Damaged secondary vent valve characterized by chattering, or constant ventingby chattering, or constant ventingScan outside of trap in airborne modeScan outside of trap in airborne mode



Thermostatic or BimetallicThermostatic or Bimetallic

Works on principle of expansion Works on principle of expansion and contraction brought on by and contraction brought on by temperature changes of hot temperature changes of hot steam, and cooler condensate steam, and cooler condensate and airand airTemperature sensitive elementTemperature sensitive element::

Condensate cools elementCondensate cools element Element contracts, opening, and Element contracts, opening, and

thus purging trap of condensatethus purging trap of condensate Steam heats the elementSteam heats the element Element expands, closing the trapElement expands, closing the trap



Ultrasonic TestingUltrasonic TestingThermostatic/Bimetallic TrapsThermostatic/Bimetallic Traps

Follow procedures for Basic Follow procedures for Basic Ultrasound TestingUltrasound Testing

Log US dBLog US dBµV readings on upstream µV readings on upstream and downstream sides of trapand downstream sides of trap

Log Temp readings on upstream and Log Temp readings on upstream and downstream sides of trapdownstream sides of trap

Failure signsFailure signs Trap is closed – low ultrasound levelsTrap is closed – low ultrasound levels Trap is open – higher levels downstreamTrap is open – higher levels downstream Mechanical Failure – chattering elementMechanical Failure – chattering element



Thermodynamic or DiskThermodynamic or Disk

Operates on the principle of Operates on the principle of velocityvelocity

Condensate and air enter the trapCondensate and air enter the trap

Flow velocity increases as steam Flow velocity increases as steam reaches inletreaches inlet

Disk is force toward the inlet seat Disk is force toward the inlet seat and bleeds off condensateand bleeds off condensate

Increase in pressure snaps the Increase in pressure snaps the disk closeddisk closed

Cycle starts againCycle starts again



Ultrasonic TestingUltrasonic TestingThermodynamic or Disk TrapsThermodynamic or Disk Traps

Follow procedures for Basic Ultrasound TestingFollow procedures for Basic Ultrasound TestingLog US dBLog US dBµV readings on upstream and downstream µV readings on upstream and downstream sides of trapsides of trapLog Temp readings on upstream and downstream sides Log Temp readings on upstream and downstream sides of trapof trapCharacteristics to listen for:Characteristics to listen for:

Disk is forced open – rushing sound as condensate dischargesDisk is forced open – rushing sound as condensate discharges Disk snaps shut – sharp snapping sound as disk is pushed Disk snaps shut – sharp snapping sound as disk is pushed

closedclosed Failed mechanism – continual snapping sound as disk fluttersFailed mechanism – continual snapping sound as disk flutters

Record sound files for comparison, trending, and trainingRecord sound files for comparison, trending, and training



Cause and Effect of Failed TrapsCause and Effect of Failed Traps

Efficient transfer of heat energyEfficient transfer of heat energyTrap is stuck open?Trap is stuck open? Waste of $$$Waste of $$$ Excess steam in system – create back pressureExcess steam in system – create back pressure Back pressure can cause other traps to malfunctionBack pressure can cause other traps to malfunction

Trap is stuck shut?Trap is stuck shut? Water HammerWater Hammer Line Freezing and possible ruptureLine Freezing and possible rupture



EndEnd

Thank you, we appreciate your attention and interest!Thank you, we appreciate your attention and interest!Click below to download a copy of our “Basics of Ultrasonic Steam Click below to download a copy of our “Basics of Ultrasonic Steam Trap Testing”Trap Testing”Request additional information about ultrasonic testingRequest additional information about ultrasonic testing

Contact:Contact:SDT North AmericaSDT North America1-800-667-53251-800-667-5325www.sdtnorthamerica.comwww.sdtnorthamerica.comfreecd@[email protected]

Some Steam Trap graphics provided by: Plant Support and Evaluations, Inc Some Steam Trap graphics provided by: Plant Support and Evaluations, Inc www.plantsupport.com www.plantsupport.com

© sdt north america 2003 all rights reserved steam traps testing steam traps using airborne...

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