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Testing steam traps using airborne ultrasound inspection

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1 Testing steam traps using airborne ultrasound inspection
Welcome To: Testing Steam Traps Using Airborne Ultrasound Inspection. I am Allan Rienstra, general manager of SDT North America. This Free training presentation will help guide you toward better steam trap inspection utilizing airborne ultrasound technology. Learn… and enjoy! © SDT North America 2003 All Rights Reserved

2 What is Steam? Add heat energy to water (BTU’s) British Thermal Units
Produces gas from water 1 lb water, 700F 1 lb water, 2120F + 142 BTU = + 970 BTU = 1 lb steam, 2120F Steam is an invisible gas produced by adding heat energy to water to raise its temperature to the boiling point. Heat energy is commonly expressed in British Thermal Units. It takes one BTU to change the temperature of one pound of water, by one degree Fahrenheit. This works in reverse too. When one pound of steam condenses back to one pound of water, one BTU of heat energy is lost back to the atmosphere. April 11, 2017 SDT North America

3 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 A steam system is a collection of components that deliver steam from the boiler room to the point of use. The design and installation of the system impact how efficiently steam is transferred from Point A to Point B. The goals are: Minimum steam loss Maximum transfer of heat Timely removal of condensable and non-condensable gases. Poor designs and failed components mean more steam is condensed back to water, wasting expensive heat energy. April 11, 2017 SDT North America

4 What is a Steam Trap? Automatic valve
Open for condensate, air, and CO2 Closed for steam Purpose Maintain efficient heat transfer Eliminate corrosive gases Eliminate water hammer A steam trap is an automatic valve that opens for condensate and non-condensable gases and closes for steam. It is designed to trap and remove water, air, and CO2. These undesirables hinder the efficient transfer of heat through the system, can corrode system components, and cause system damaging water hammer. April 11, 2017 SDT North America

5 Types of Steam Traps Operative modes Four common types Density
Temperature Velocity Four common types Inverted bucket (A) Float and thermostatic (B) Thermostatic (C) Thermodynamic or disk (D) A B C D There are four common types of steam traps, and all work to remove impurities from the steam system. The four types are known as: Inverted Bucket Float and Thermostatic Thermostatic Thermodynamic or Disk Traps work on one of three operative modes. Change in Density Change in Temperature Change in Velocity April 11, 2017 SDT North America

6 Testing Methods Visual Testing Thermal Testing Ultrasonic Testing
Evaluating the condition of traps should be a part of every plant’s regular PM. Traps can be tested using one of three methods, but for the best results, combine all three. Visual Testing Thermal Testing Ultrasonic Testing When testing traps using these methods it is equally important to Know your surroundings and pay attention to safety. Serious burns can result from carelessness or unfamiliarity. Know the system and understand how the traps function. Traps are tested online with live steam inside them. They are going to cycle at different stages, and those stages are reliant on ongoing processes in motion Choose the test methods that will give the best result, and… Document your findings for trending April 11, 2017 SDT North America

7 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 The best, and most commonly used technology for evaluating steam trap condition is an Ultrasonic Data Collector. Some ultrasonic devices also collect infrared temperature readings which conveniently combines all three test methods… Visual Thermal Ultrasonic Ultrasonic data collectors sense high frequency noise created by the turbulence of steam and condensate, and the mechanical movements of the traps inner components. Ambient plant noise is ignored while sounds inside the trap are translated to an audible level. The ultrasonic data is listened to for quality interpretation, measured for quantitative interpretation, and logged for trending. April 11, 2017 SDT North America

8 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 There is a basic setup procedure to follow when testing steam traps with ultrasonic data collectors. In all cases, these 4 basic steps come first: Connect headphones to the detector Connect the contact sensor to the detector Turn the detector on and ensure equipment is functioning Touch the contact sensor to the housing of the trap April 11, 2017 SDT North America

9 Setting Sensitivity of Detector
23.1 CONTACT dBµV A = 50 Low Pressure For Low-Pressure Steam: 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 Note* Setting proper amplitude is done by having enough sound in the headphone to be able to diagnose a failure. CONTACT 49.1 A = 20 dBµV The sensitivity of the detector needs to be set such that an ideal level of sound is heard in the headphones. For low pressure steam, the sensitivity is best set between the range of A=50 to A=80 For high pressure steam, set the detector between A=10 and A=50. Evaluating steam trap condition is a combined science of listening and measuring ultrasound levels. So its important to clearly hear the sounds in the headphones. High Pressure April 11, 2017 SDT North America

10 Ultrasound Testing – Data Collection
Listen to internal ultrasounds Take dBµV readings and store to data collector to trend: dBµV during collection phase dBµV during dumping phase Make an audio recording of trap cycle to compare, share, and train future inspectors Listen to the quality of sound produced in the headset. Hear the trap collect and purge as it cycles out impurities and maintains a clean and efficient steam system. Record and store the dBµV reading during both collection and purging phase. Measure the temperature upstream and downstream of the trap and log it to the detector’s data collector Keep audio recordings of the different traps used in your facility. This is useful for comparing, predicting failures, and for training future inspectors. April 11, 2017 SDT North America

11 Trouble Shooting Logic Tree
Follow this basic logic tree to trouble shoot your traps. At the end of this training you will be given an opportunity to request your very own copy. Tree supplied by Plant Support and Evaluations, inc April 11, 2017 SDT North America

12 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 Inverted Bucket traps work on the principle that condensate is more dense than steam. Steam causes an upside down bucket to float, which keeps the discharge valve closed As the denser condensed gases collect the bucket sinks, opening the discharge valve and purging the steam system A proper functioning trap will continuously cycle through collection and discharge phases. April 11, 2017 SDT North America

13 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) Purge phase (Sudden gushing sound as air and condensate is purged) If clear cycling sounds are not evident: 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 Testing Inverted Bucket Traps Following procedures for basic ultrasound testing discussed earlier, measure and log ultrasound levels upstream and downstream. Also log temperature readings at the same points. Listen for a clear cycling sound characterized by Slow gurgling sounds as condensate collects Rapid gushing sound as air and condensate are purged If the cycling sounds are not evident it is possible the trap is either stuck open, plugged, or stuck shut. Look at the upstream/downstream dBµV values. If its louder downstream, trap is open and condensate is passing If the sound level is low, trap is closed or plugged April 11, 2017 SDT North America

14 Float and Thermostatic
Works on combined principle of density and temperature Density: No condensate, ball sinks and valve is closed Condensate collects and lifts ball, opening discharge valve Temperature A separate thermostat reacts to temperature changes from the presence of non-condensable gases (air, co2, and carbonic acids) As it cools it opens a secondary discharge valve at the top of trap Float and Thermostatic traps combine a floating ball purge action with a separate temperature controlled device that opens when the presence of air and condensate cool the trap to a preset temperature. When no condensate is present the ball sinks and closes the purge valve. As condensate collects the ball lifts and opens the discharge valve. Non-condensable gases such as air, CO2, and carbonic acid cool the temperature. When this change of temperature is significant a thermostatic vent opens and discharges the gases. April 11, 2017 SDT North America

15 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 Test Float and Thermostatic Traps first following the basic procedures discussed earlier for ultrasonic inspection. Since F&T traps work on the principle of density the same cycling sound in inverted bucket style traps, characterized by “gurgling and gushing”, should be evident. If not, follow the procedure to determine if trap is open or closed. Listen for the secondary thermostatic valve to open and close characterized by a sharp click sound. Remember that this valve only opens in the presence of non-condensable gases. If none are present then the valve is not called upon to open. These valves can fail open, shut, or chattering. Also scan in airborne mode around the valve for continuous external leakage. April 11, 2017 SDT North America

16 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 Element contracts, opening, and thus purging trap of condensate Steam heats the element Element expands, closing the trap Thermostatic or Bimetallic traps work solely on the principle of temperature. The presence of steam closes the disk. Condensate cools the disk element causing it to contract and open. The system is purged, the temperature rises, and the disk closes the trap. April 11, 2017 SDT North America

17 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 open – higher levels downstream Mechanical Failure – chattering element Following the same basic procedures for ultrasonic testing, thermostatic type traps are tested by logging upstream and downstream levels both ultrasonically and thermally. This style of trap has a shorter cycling phase. Listen for the sharp click as the valve opens, and then closes. Failed bimetallic traps produce either Constant staccato chattering sound Low ultrasound levels if trap is closed Higher ultrasound levels downstream is trap is open April 11, 2017 SDT North America

18 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 Thermodynamic or disk traps operate on the principle of changing velocity of the medium. The internal disk serves the dual function of sealing itself in the open, or purge phase, and closed, or collection phase. The trap purges condensate when steam reaches the inlet orifice. The faster flow rate of steam causes the disk to kinetically pull away from the vent seat allowing condensate to escape and keep the system pure. When the disk pulls away a control chamber is sealed. This chamber builds in pressure causing the disk to snap back to the closed position. April 11, 2017 SDT North America

19 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 snaps shut – sharp snapping sound as disk is pushed closed Failed mechanism – continual snapping sound as disk flutters Record sound files for comparison, trending, and training Testing disk traps with ultrasound requires following basic testing procedures described earlier. After logging temperature and decibel readings upstream and downstream, listen for these characteristics: Disk forces open with a click, followed by rushing sound as condensate discharges. Disk snaps shut and rushing sound stops. If you hear continual snapping sound the mechanism has failed and the disk is simply fluttering. Record the sounds for comparison, trending, and training. April 11, 2017 SDT North America

20 Cause and Effect of Failed Traps
Efficient transfer of heat energy Trap is stuck open? Waste of $$$ Excess steam in system – create back pressure Back pressure can cause other traps to malfunction Trap is stuck shut? Water Hammer Line Freezing and possible rupture Steam traps are necessary for the overall efficiency of heat energy transfer. When traps fail they waste money, they create back pressure in the steam system, and they cause process failures or quality issues with the end product Traps that are closed can create damaging water hammer, line freezing, and possible rupture. When one part of a system does not function properly other parts of the system are forced to “pick up the slack”. Added strain to the rest of the system will expedite future failures, and an eventual breakdown of the system. Make frequent ultrasound inspection of your steam traps a part of your regularly planned maintenance. April 11, 2017 SDT North America

21 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 Thank you for your time. A copy of this presentation is available upon request from SDT North America. Additional resources for steam systems can be found at and April 11, 2017 SDT North America

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