One Solenoid Valve Failure Away from Disaster
You could be only one solenoid valve failure away from disaster, but it only takes seconds to decrease the odds of this happening.
The Transocean Deepwater disaster in 2010 was a major incident resulting in 11 lives lost and an estimated 4.9 million barrels of oil discharged into the Gulf of Mexico. Tests performed by Transocean Ltd. And Cameron International after the incident revealed that the coil of a solenoid valve failed to energize, suggesting an electrical coil fault. The investigation team found no evidence to suggest that this fault was a result of the incident. Rather they concluded that the electrical fault likely existed prior to the accident. Had the solenoid valve been working properly, it could have yielded at least a partial closure of the blind shear rams, resulting in a far less serious incident. It’s obvious, the early detection of low-levels of unwanted magnetic fields, i.e. residual magnetism in the plunger, which will result in a position change. The position of the plunger Controls the flow of the process fluid. Magnetization of the plunger increases as the solenoid valve continues to operate. At some point, the flow from the solenoid valve Will fail to meet the required specified rates. Read More Academia.edu . . .
Bob Bartol (Inventor) talks about the core being exposed to the magnetic field,
The core is exposed to the magnetic field created by the electrical coil. Prolonged exposure to this field can result in permanent magnetization of the plunger, resulting in improper behavior of the core, and improper metering of the process fluid. A residual magnetism test on new electrically operated solenoid valves can be critical. We recommend a residual magnetism test should be conducted before installation of any new electrically operated solenoid valves in all manufacturing applications. The minimum sensitivity must be 3 gauss or lower. The Mag-Probe meets this requirement. Please note the following critical industries that would benefit by this test:
Manufacturing, Nuclear, Conventional Power Plants, Aircraft, Ships, Trains, and Oil and Gas Production
Bob Bartol (Inventor) Talks with Mark Lindsey (Manufacturing Supervisor) about Residual Magnetism
Here is a phone conversation between Bob Bartol (Inventor of the Mag-Probe) and Mark Lindsey a customer that was using a glue machine in a manufacturing process. The conversation covered a residual magnetism problem Mark was experiencing with a newly installed electrically operated solenoid valve.
Mark Lindsey (Supervisor)
Using a Mag probe, I detected a small magnetic field around a solenoid valve’s core with the power off.
Bob Bartol (Mag-Probe Inventor)
Are you sure the power was completely off?
Mark Lindsey (Supervisor)
Yes, the wires were disconnected from the power source and the test was made on a bench. I then made a residual magnetism test on a new solenoid valve core after applying power several times, no residual magnetism was detected when I conducted the test using the Mag-Probe. I replaced the old solenoid valve with the new one that I did the Residual Magnetism Test on and the problem was solved.
IMPORTANT NOTE: The core in the solenoid valve remained partially magnetized when the power was switched off. This caused intermittent operation. It became obvious that the material used in the core remained partially magnetized. This is a manufacturing defect and could result in catastrophic problems in aircraft. Fortunately, in this case, it was in a manufacturing plant. All solenoid valves used on aircraft should be tested for residual magnetism prior to installation. It only takes a few seconds, but these seconds can be critical in the aircraft industry. Turnaround time in the commercial aircraft business is critical. Expediting troubleshooting time is paramount. The cost to the airlines can be substantial when they have to offload passengers and replace the aircraft in order to remain on schedule. Especially when the cost of substituting an aircraft can be as high as $5 million dollars.
While not a requirement, I would recommend conducting a Residual Magnetism Test in all critical applications.
Keep in mind, solenoid valves are manufactured in factories around the world. The question is, How Precise are Manufacturer’s Quality Control Inspections for Residual Magnetism on Newly Assembled Solenoid Valves?
According to Bob Bartol at Bartol research the following is an example of this actual failure.
Electrically operated solenoid valves coils can be tested while in operation by detecting their magnetic Fields with the voltage applied. A Bartol Mag-Probe Model HS can be used to perform this test. You must have voltage, current and continuity present in the coil in order to detect a magnetic Field. If voltage is applied to the coil and no magnetic field is detected, the coil is open.
This is an especially valuable procedure, because you go right to the solenoid valve without having to make multimeter measurements or locate terminal strips, or schematics. Consider another advantage. Solenoid valve’s mounted in manifolds. How do you reach the wiring connected to each solenoid valve? We recommend the following procedure when installing all new solenoid valves.
BENCH TEST ALL NEW SOLENOID VALVES! WHY?
The manufacturers do not Quality Control every solenoid valve. It only takes a few seconds once a Power Supply is ready on a bench and you have a Bartol Mag-Probe Model HS available. Cycle the valve on and off 10 or 15 times and check for residual magnetism after Power is removed. Check the coils magnetic field on and off.
Now You’ve Checked the Quality Control 100%.
Whether the valve Is manufactured in the United States or Offshore it doesn’t matter.
HOW MANY TESTS ARE CONDUCTED FOR RESIDUAL MAGNETISM DURING MANUFACTURING? LET’S JUST ASSUME NO MANUFACTURERS DO A RESIDUAL MAGNETISM TEST. BASED ON THE INCIDENT ABOVE THE RISK IS TO GREAT NOT TO CONDUCT THIS TEST!
The data showed that over 50% of solenoid valve failures resulted from four sources; worn or degraded parts, contamination by foreign materials, short circuit in the solenoid valve coil, and open circuits in the solenoid valve coil. There has been a relatively small amount of literature covering solenoid valve failures, especially these failures originating from coil faults. (coil shorts and coil opens) have not yet been successfully addressed despite the efforts of the Oak Ridge National Laboratory in 1990. Read More at Academia.edu . . .
Bartol Research concentrates on electrical faults and residual magnetism. Fortunately, the Bartol Mag-Probe Model HS has been successful in testing the solenoid valve coils. Best of all, when testing with the Mag-Probe, system voltage and current are used. This will result in fewer false “good” tests with a resistance tester. A great number of valves are found in nuclear power plants, oil and gas operations and Space systems where a single malfunction can have serious consequences.
It is surprising that significant problems such as coil faults in solenoid valves still remain and no available solutions have been developed. Given the disaster that took place where an estimated 4.9 million barrels of oil discharged into the Gulf of Mexico, we decided to develop a procedure using the Bartol Mag-Probe to detect residual magnetism at a low level before installation of any new valve. The procedure we developed will assess the condition of the solenoid valve’s electrical coil by observing the magnetic field in a bench test before the valve is installed. This test is conducted by connecting power to the coil, energizing the coil 10 to 15 times, then de-energize the coil, and test the plunger for residual magnetism. This makes the Bartol Mag-Probe Model HS the obvious choice for detecting residual magnetism. If residual magnetism is detected at any level the valve should be rejected and here’s why,
Sometimes residual magnetic force will cause valves with a wet armature to stick open when the coil is de-energized because there is insufficient internal power to move the coil.
The great thing about the Mag-Probe was its design. It was designed to operate effectively in all environments. Here the Bullet Points about the Bartol Mag-Probe.
“Mag-Probe Bullet List”
No calibration required
Works effectively from -80 to +160°F
Requires no direct electrical connection
Suitable for high risk explosive environments
Waterproof, not affected by corrosion or salt spray
Ability to check solenoid valves and relays while equipment is operating
Isolates problems as electrical or mechanical in seconds, without a schematic
Detects transient pulses and momentary loss of power as low as 10 milliseconds
Detects residual magnetism – Great for checking relays before installing on aircraft
Long life power source and low current LED lasts for at least 5000, 5-second operations
Variable Sensitivity – detect 1 gauss using ring magnet – 3 gauss without using ring magnet
Reduce Sensitivity by sliding on the white protective shield – Reduce detection of overlapping magnetic fields
Magnetic sensing instrument used to troubleshoot AC and DC powered solenoids, solenoid valves, relays and heat controllers