Articles
Scott Cargill Shares His Experience With Auto-ignition During a UT Inspection
Scott Cargill, Past President of ASNT shared the below auto-ignition story with us. It is well worth the read.
Auto-Ignition? What’s that? Wait a minute, I’m almost positive it has something to do with the MSDS – Materials Safety Data Sheet (old school) or with the harmonized global system of today just SDS – Safety Data Sheet. If only I had read the data sheet for “Never Seez”. If you’ve never had the displeasure of getting Never Seez on you, and then on absolutely everything you touched and all over your clothes well… You just haven’t lived.
So my story starts one summer afternoon in the central valley of California where the summer days get to 100 degrees F, more so than not, I was tasked with taking ultrasonic readings on several piping circuits in the “Crude Unit,” specifically one of the heaters in the unit and its auxiliary piping coming off of it. Typically I would have used “Methocell” a water based cellulous couplant, but the piping coming off the active heater was far and above the 100-150 degrees that a water based couplant can maintain its structure, in fact at the temperatures of the piping (I was guessing around 500 degrees F) the only thing methocell was going to do was to lose all of its viscosity at best, and at worst loose its viscosity AND dry up into a dry film before I could get the readings. Because of those thoughts, I pulled out a can of “Never Seez” a thin grease used to prevent nuts and bolts from seizing, galling or in some conditions refuse to thread correctly. In other-words I had repurposed a nuts and bolts lubricant to stand in for a couplant on high temperature environments. It beat using axel grease in that it comes in a quart sized can with an applicator brush, versus the cylinder of grease you had to dig out of the tube.
Here, armed with a suitable substitute high temperature couplant, my harness, boots, hardhat GLOVES! And safety glasses, because Safety is ALWAYS number one and the very important on every jobsite right? (please note at no time before or during had I ever read the data sheet for Never Seez), So up I go, climbing up the ladder, up on top of the 24” 5 chrome half molybdenum insulated piping, Ultrasonics instrument (Krautkramer USK 7) strapped around my neck, my pot of “grease”. I sat down on the piping, arranged my scope and probe, sat my grease down, and promptly applied a large dollop inside the inspection port. Here’s where it gets fun: I turned to set down the pot of grease, and to pick up my scope and probe so I could take the reading, only to find when I turned back that there was a FIRE right in front of me, the inspection port acting as a chimney. HOLY Marshmallow roast UT man!
Now at this point you may be thinking, Hmm, Heater, Petroleum refinery, (lots of things there do like to blow up easily) Fire, this just doesn’t sound like a good combination to have right? Well, as I quickly went Pewww Pewww Pewww puff puff puff blowing out the fire in front of me, I calmly took my readings as no one had noticed my little kersnuffle, re-plugged the hole with the inspection port plug hoping that without an abundance of fresh air that it wouldn’t reignite after I left. Now of course this is when and where I thought it may be important to read the MSDS for Never Seez, and, boy, did I get the palm slap to the head when I read that the flash point for Never Seez was only 475 degrees F. You can all safely assume and rightly so, that the piping that I had just applied the grease to was well over 500 degrees, so Well Duh, Seems they knew what they (The Manufacturer) were saying cause it sure as heck did ignite all by itself.
I learned a lesson that day. Sometimes it really does pay to follow the rules and to actually use the right tool for the right job. A properly formulated high temperature couplant designed to be used at those temperatures doesn’t leave you with a holy marshmallow moment at height, on a hot pipe in a noisy refinery sitting on and in a highly flammable and volatile section of the plant.
Share your auto-ignition story with us and other NDT professionals. Email it to: marian@echoultrasonics.com
2020 High Temperature Couplant Chart
SuperSoniX™ – A new UT Couplant with a Historic Name
In May of 1940, Floyd Firestone, a Professor in the department of Physics at the University of Michigan, filed US patent 2280226 in which he described an instrument for the detection of flaws and measuring thickness in metal objects. Dr. Firestone used the term “Supersonic Vibration Waves” to describe what we now refer to as pulse-echo Ultrasound Testing (UT).
The term “Supersonic Inspection” was used in reference to UT officially until the first manned aircraft flight by USAF Captain Chuck Yeager exceeded the sound barrier of 768 mph in October of 1947. Captain Yeager’s flight in the Bell X-1 “Rocket plane” became known as supersonic flight. Gradually the term Ultrasonic Testing replace d Supersonic Testing in NDT.
Echo UltraSonics® new water-based gel couplant, SuperSoniX, is named in honor of Dr. Firestone and his work which gave rise to our world of UT.
SuperSoniX is our third-generation acrylic polymer water based couplant that improves on the electrolyte stability and reduces the tendency for the polymer to collapse when exposed to corrosion or marine salts. In practice this means less reapplication of couplant during a test procedure, especially on objects that are exposed to the environment.
SuperSoniX offers several benefits, including; a broader operating range, a slower evaporation rate, a longer drying time, improved stability against corrosion salts and is environmental and operator friendly.
Couplant Selection
While many couplants will couple sound and perform adequately for the same inspection, often one will deliver performance that will make a significant improvement on inspection reproducibility and defect detection (the #1 goal of UT). The right couplant can minimize couplant re-application during an inspection, reduce total time for the inspection and lower cost. Let us recommend the most appropriate couplant for your application and temperature range.
More Information
Contact Marian (360) 671-9121 or marian@echoultrasonics.com) for more information and free samples. We have over 50 years of history developing and manufacturing most of the couplants in use yesterday and today and can help in selecting the best couplant for your specific application.
Silver Bullet Couplants – for inspections that are almost impossible without the right couplant.
Many UT applications require a specialty UT couplant. For difficult inspections that require high acoustic impedance, shear wave, reduced surface noise, extreme temperature range or extended service life for sensors, we have the right couplant.
High Impedance Couplant: A high impedance couplant typically has an acoustic impedance above 3.5 M Rayls. Water based couplants typically have acoustic impedances between 1.5 and 1.8 M Rayls depending on the Glycerin content (0% glycerin at 1.5 M Rayls, 12% glycerin at 1.8 M Rayls, 100% glycerin at 2.4 M Rayls).
The advantage of a high impedance couplant is that more of the acoustic energy is transmitted between the transducer (or delay line) and test object and less is reflected and scattered at the surface of the test object. This is particularly important when:
- The test object surface is very rough (porous cast iron, scale, rough grinding).
- The contact area for the delay line or transducer is small (pencil point probes measuring pit depths).
- Materials such as concrete which are high impedance, scatter acoustic energy and often have a rough surface.
There are currently two options for water-soluble, high impedance couplants:
- Z+ MV, a medium viscosity Glycerin based couplant (which has an operating range of 0 to 200°F; however, its viscosity increases quickly with temperature below 45°F.
- Z+ fluid– does not contain Glycerin and maintains a fluid viscosity down to sub-zero temperatures.
Normal Incidence Shear Wave Couplant:
Not to be confused with angle beam generated shear waves (which rely on refraction of a longitudinal beam), normal incidence shear wave transducers propagate the shear wave with the transducer perpendicular to the test object and do not rely on refraction. A normal incidence shear wave couplant requires a very high viscosity, high elastic modulus to perform acceptably. Currently there is one commercially available water-soluble couplant that meets this requirement: Echo Shear Wave Couplant
Flow Meter and Sensor Couplant:
For permanent or long-term use, a flow meter couplant should resist creep, have good resistance to weather and chemicals as well as a broad temperature range. Water-based couplants are suitable only for short-term flow metering applications. Echo 8 ZH is not water-based and is an excellent couplant for flow metering sensors.
Cryogenic UT Inspection:
CryoSoniX is the only ultrasonic couplant for use in cryogenic applications such as refrigerated ethylene. With an operating range of -200˚ to 60˚F (-129˚ to 16˚C), CryoSoniX enables repeatable and reliable inspections.
Phased Array Wedge Couplant:
Forever Wedge is an ideal couplant for use between phased array or angle beam transducers and the wedge. Forever Wedge couplant won’t leach out, is impervious to water and couplants and when applied correctly, often lasts the life of the wedge or until it is replaced. Forever Wedge eliminates phased array element drop out due to wedge couplant failure.
Looking for the right fluid for your AUT Inspections?
Echo’s automated ultrasonic testing fluids offer solutions for those who’ve encountered problems with other fluids. Often, fluids are too thick to pump, run off too fast, smoke too much, auto-ignite, freeze or vaporize so quickly that there’s no time to conduct the inspection.
With AUT fluids in multiple viscosities (thicknesses) spanning a broad range of temperatures, Echo has solutions to each of these problems. Several Echo AUT fluids are water-soluble, too, so they don’t leave a film on water when used at sea.
Echo AUT fluids have viscosities ranging from 125 to 5000 cps and covering temperatures from -70° F to 1250° F (-57° C to 675° C).
The five AUT fluids listed below are arranged by increasing Operating Range:
Echo 4HT is a water-soluble fluid with an operating range of -70° F to 450° F (-56° C to 230° C). It has low toxicity and good surface wetting. Echo 4HT is slow drying and is compatible with a broad range of materials, including most metals, plastics and composites.
VersaSonic fluid is a plant-based, biodegradable fluid with low toxicity and an operating range of -10° F to 700° F (-23° C to 371° C). Above 400° F (200° C), VersaSonic works best when sprayed or pumped (discharged) at the point of use.
Echo 8HT features minimal residue in a broad range of AUT and MUT ultrasonic flaw- and thickness-gaging applications, from -50° F to 800° F (-45° C to 425° C). The Echo 8HT line is compatible with all metals and most plastics. Echo 8 HT is available in three viscosities: grades 1, 4 and 10.
SpectrumGlide, a high-performance fluid for high-temperature testing, has a viscosity formulated to reduce runoff and provide longer dwell time at temperatures from -50° F to 730° F (-45° C to 387° C). SpectrumGlide was developed by Eclipse Scientific and is distributed under license by Echo.
EchoTherm Extreme fluid is the highest-temperature fluid couplant available. EchoTherm Extreme is a high-viscosity fluid that produces less smoke and minimal residue. It has the broadest operating range, from -40° F to 1250° F, and its auto-ignition point is above 1300° F (704° C).
No matter the testing environment or application, it’s likely that Echo Ultrasonics has — or can develop — just the right couplant. Give the Echo experts a call to find the right couplant for your needs or to request a sample.
ASNT Annual Conference a big success
Thanks to everyone who visited with us at ASNT in Nashville.
Couplant sample requests are being entered and we will be in touch soon. We had many discussions regarding the use and success of EchoPure for Phased Array inspections. EchoPure is the solution for phased array element drop out and the resulting difficulty in reproducing flaw indication. The water-free formulation and strong coupling film of EchoPure provides a continuous film between the part and the transducer and resists “air gap puddling” which is common with couplants containing water.
For more information, visit our EchoPure webpage or download the datasheet from Resources.
