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© SDT North America 2003 All Rights Reserved Steam Traps Testing steam traps using airborne ultrasound inspection.

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Presentation on theme: "© SDT North America 2003 All Rights Reserved Steam Traps Testing steam traps using airborne ultrasound inspection."— Presentation transcript:

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2 © SDT North America 2003 All Rights Reserved Steam Traps Testing steam traps using airborne ultrasound inspection

3 © SDT North America 2003 All Rights Reserved April 18, 2015April 18, 2015April 18, 2015SDT North America What is Steam? Add heat energy to water (BTU’s) British Thermal Units Produces gas from water 1 lb water, 70 0 F 1 lb water, F BTU =+ 970 BTU = 1 lb steam, F

4 © SDT North America 2003 All Rights Reserved April 18, 2015April 18, 2015April 18, 2015SDT North America What is a Steam System? Deliver steam from boiler to point of use Collection of pipes, valves, and steam traps Steam traps keep steam pure Steam traps protect the system from damage

5 © SDT North America 2003 All Rights Reserved April 18, 2015April 18, 2015April 18, 2015SDT North America What is a Steam Trap? Automatic valve Open for condensate, air, and CO 2 Closed for steam Purpose Maintain efficient heat transfer Maintain efficient heat transfer Eliminate corrosive gases Eliminate corrosive gases Eliminate water hammer Eliminate water hammer

6 © SDT North America 2003 All Rights Reserved April 18, 2015April 18, 2015April 18, 2015SDT North America Types of Steam Traps Operative modes Density Density Temperature Temperature Velocity Velocity Four 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) AB C D

7 © SDT North America 2003 All Rights Reserved April 18, 2015April 18, 2015April 18, 2015SDT North America Testing Methods Visual Testing Thermal Testing Ultrasonic Testing

8 © SDT North America 2003 All Rights Reserved April 18, 2015April 18, 2015April 18, 2015SDT North America Ultrasonic Data Collectors Sense high frequency (HF) sounds Convert HF to representative audible sounds Eliminate audible “parasite” noise Measure and collect data for trend analysis Typical Ultrasonic Data Collection System

9 © SDT North America 2003 All Rights Reserved April 18, 2015April 18, 2015April 18, 2015SDT North America Ultrasound Testing - Basics Connect headphones to detector Connect contact sensor to detector Touch sensor to housing of trap Adjust sensitivity for measuring and listening according to instrument’s instructions

10 © SDT North America 2003 All Rights Reserved April 18, 2015April 18, 2015April 18, 2015SDT North America Setting Sensitivity of Detector For Low-Pressure Steam: Set Amplitude Level to Middle to High Range between A=50 or A=80 Set Amplitude Level to Middle to High Range between A=50 or A=80 For High-Pressure Steam: Set Amplitude Level from A=10 to A=50 Set Amplitude Level from A=10 to A=50 Note* Setting proper amplitude is done by having enough sound in the headphone to be able to diagnose a failure CONTACT dBµV A = 50 Low Pressure CONTACT A = 20 dBµV High Pressure

11 © SDT North America 2003 All Rights Reserved April 18, 2015April 18, 2015April 18, 2015SDT North America Ultrasound Testing – Data Collection Listen to internal ultrasounds Take dBµV readings and store to data collector to trend: dBµV during collection phase dBµV during collection phase dBµV during dumping phase dBµV during dumping phase Make an audio recording of trap cycle to compare, share, and train future inspectors

12 © SDT North America 2003 All Rights Reserved April 18, 2015April 18, 2015April 18, 2015SDT North America Trouble Shooting Logic Tree Tree supplied by Plant Support and Evaluations, inc

13 © SDT North America 2003 All Rights Reserved April 18, 2015April 18, 2015April 18, 2015SDT North America Inverted Bucket Inverted Bucket traps work on the principle of density Steam keeps the purge valve closed Condensate opens the purge valve Collection and purge phases are continuous

14 © SDT North America 2003 All Rights Reserved April 18, 2015April 18, 2015April 18, 2015SDT North America Ultrasonic Testing Inverted Bucket Traps Follow procedures for Basic Ultrasound Testing Log US dBµV readings on upstream and downstream sides of trap Log Temp readings on upstream and downstream sides of trap 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 is purged) Purge phase (Sudden gushing sound as air and condensate is purged) If clear cycling sounds are not evident: Trap is stuck closed or open Trap is stuck closed or open Louder downstream, trap is open and condensate is passing Low sound level, trap is closed Listen for faulty mechanical sounds to identify traps in early stages of failure Record sounds for future comparisons and operator training

15 © SDT North America 2003 All Rights Reserved April 18, 2015April 18, 2015April 18, 2015SDT North America Float and Thermostatic Works on combined principle of density and temperature Density: No condensate, ball sinks and valve is closed No condensate, ball sinks and valve is closed Condensate collects and lifts ball, opening discharge valve Condensate collects and lifts ball, opening discharge valveTemperature A separate thermostat reacts to temperature changes from the presence of non-condensable gases (air, co 2, and carbonic acids) A separate thermostat reacts to temperature changes from the presence of non-condensable gases (air, co 2, and carbonic acids) As it cools it opens a secondary discharge valve at the top of trap As it cools it opens a secondary discharge valve at the top of trap

16 © SDT North America 2003 All Rights Reserved April 18, 2015April 18, 2015April 18, 2015SDT North America Ultrasonic Testing Float and Thermostatic Traps Follow procedures for Basic Ultrasound Testing Log US dBµV readings on upstream and downstream sides of trap Log Temp readings on upstream and downstream sides of trap Inspection of ball float follows same procedure for inverted bucket – identify cycle of collection and purge phases Damaged secondary vent valve characterized by chattering, or constant venting Scan outside of trap in airborne mode

17 © SDT North America 2003 All Rights Reserved April 18, 2015April 18, 2015April 18, 2015SDT North America Thermostatic or Bimetallic Works on principle of expansion and contraction brought on by temperature changes of hot steam, and cooler condensate and air Temperature sensitive element: Condensate cools element Condensate cools element Element contracts, opening, and thus purging trap of condensate Element contracts, opening, and thus purging trap of condensate Steam heats the element Steam heats the element Element expands, closing the trap Element expands, closing the trap

18 © SDT North America 2003 All Rights Reserved April 18, 2015April 18, 2015April 18, 2015SDT North America Ultrasonic Testing Thermostatic/Bimetallic Traps Follow procedures for Basic Ultrasound Testing Log US dBµV readings on upstream and downstream sides of trap Log Temp readings on upstream and downstream sides of trap Failure signs Trap is closed – low ultrasound levels Trap is closed – low ultrasound levels Trap is open – higher levels downstream Trap is open – higher levels downstream Mechanical Failure – chattering element Mechanical Failure – chattering element

19 © SDT North America 2003 All Rights Reserved April 18, 2015April 18, 2015April 18, 2015SDT North America Thermodynamic or Disk Operates on the principle of velocity Condensate and air enter the trap Flow velocity increases as steam reaches inlet Disk is force toward the inlet seat and bleeds off condensate Increase in pressure snaps the disk closed Cycle starts again

20 © SDT North America 2003 All Rights Reserved April 18, 2015April 18, 2015April 18, 2015SDT North America Ultrasonic Testing Thermodynamic or Disk Traps Follow procedures for Basic Ultrasound Testing Log US dBµV readings on upstream and downstream sides of trap Log Temp readings on upstream and downstream sides of trap Characteristics to listen for: Disk is forced open – rushing sound as condensate discharges Disk is forced open – rushing sound as condensate discharges Disk snaps shut – sharp snapping sound as disk is pushed closed Disk snaps shut – sharp snapping sound as disk is pushed closed Failed mechanism – continual snapping sound as disk flutters Failed mechanism – continual snapping sound as disk flutters Record sound files for comparison, trending, and training

21 © SDT North America 2003 All Rights Reserved April 18, 2015April 18, 2015April 18, 2015SDT North America Cause and Effect of Failed Traps Efficient transfer of heat energy Trap is stuck open? Waste of $$$ Waste of $$$ Excess steam in system – create back pressure Excess steam in system – create back pressure Back pressure can cause other traps to malfunction Back pressure can cause other traps to malfunction Trap is stuck shut? Water Hammer Water Hammer Line Freezing and possible rupture Line Freezing and possible rupture

22 © SDT North America 2003 All Rights Reserved April 18, 2015April 18, 2015April 18, 2015SDT North America End Thank you, we appreciate your attention and interest! Click below to download a copy of our “Basics of Ultrasonic Steam Trap Testing” Request additional information about ultrasonic testing Contact: SDT North America Some Steam Trap graphics provided by: Plant Support and Evaluations, Inc


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