Eliminating Fugitive Emissions Through Magnetic Actuation
Originally published by Valve World Americas
Fugitive emissions are a huge problem resulting in environmental fines, lost product, and even loss of life in extreme cases. What is even more surprising than the impact of fugitive emissions, is that the majority of these leaks can be eliminated by fixing one problem.
Leaking valves are the number one source of fugitive emissions. Within the oil & gas industry, leaks from valve packing chambers account for roughly 60% of fugitive emissions. Valve packing creates a dynamic seal at the stem which is prone to leak. Over 90% of leaks from valves can be attributed to leaks around the valve stem and packing. As regulations tighten, breakthroughs in technology give us improved ability to monitor and locate leaks. In past years there have also been many advancements in low-emission valve manufacturing and packing. These efforts work to mitigate this serious problem. But, rather than treating the symptom, now we can eliminate the problem at its source.
It is now possible to move from low-e to Zero-e, and eliminate the dynamic seals that create a leak path to the atmosphere through magnetic actuation. Magnetically actuated valves have a solid wall that completely encapsulates the valve stem which is operated through a magnetic coupling. When considering safety concerns with lethal services, environmental hazards, or maintenance nightmares with chronic leakers, one immediately begins to realize the benefit of no-e magnetically actuated valves.
Advancements in magnetics and new mechanical discoveries have opened up applications for high pressure and high torque requirements as well as a wide range of temperature applications from cryogenic to higher temperatures. Magnetically driven valves have now been validated through some of the most stringent API tests and applications verifying the true potential of zero emissions through magnetic actuation. In one API 6FA test, a gate valve was fitted with a MagDrive operator completely encapsulating the stem, eliminating the leak path of an exposed stem packing. This fire test is often catastrophic to valves when measuring how much they leak as they are heated and cooled. The valve fitted with the magnetic operator maintained a solid wall, eliminating the flow path to atmosphere, and continued to perform 44,000 actuations after the valve cooled - without leaking. Magnetic actuation has been shown to completely eliminate fugitive emissions in the harshest environments that are hazardous to personnel, harmful to the environment, costly in lost product or fines, or cause perpetual maintenance in difficult locations. Magnetic actuation can be applied to a wide variety of manufactured valves regardless of the brand, size or application.
The validation of magnetic actuation as a viable solution to fugitive emissions got its start by tackling one of the most difficult challenges first. MagDrive Technologies worked on a NASA project to contain cryogenic helium with true-zero fugitive emissions. The valves were created for NASA’s Morpheus planetary landing vehicle. Helium is often used in space vehicles to pressurize fuel tanks, is the smallest element on the periodic table, and is notoriously difficult to contain. To minimize size and costly payload, NASA wanted to store the helium at cryogenic temperatures, -269 degrees to -300 degrees Celsius. Without magnetics, initial attempts to contain helium resulted in six-foot stem packing intended to isolate the packing from the cold. These valve stems were bulky and still resulted in leaks. Using magnetically driven valves, NASA was able to completely contain true zero emissions with cryogenic helium at 3500psi, moving through the valve at supersonic speeds. The helium could not find a leak path at extreme pressures and temperatures in this first of its kind test. Applying the discoveries further, MagDrive valve technology was then applied to contain other materials such as hydrogen (H), methane (CH4), and even lethal chemicals like phosgene (COCL2) or hydrogen sulfide (H2S). This research effort now opens up the possibility for no-e magnetically-driven valves for quarter turn, including ball, butterfly, and plug valves as well as for rising stem/linear valves including gate and globe.
The use of magnets is not a new idea for the oil and gas industry. Magnetically driven pumps have been successfully implemented to eliminate external leaks for decades and set a potential precedent that magnetics could be used for valves. Magnetic pumps isolate the shaft, similar to magnetic valves, isolating the stem from the actuator with a leak-free chamber. However, magnetically driven pumps operate at low torques and high speeds. Valves typically operate at low speeds and higher torques, and up until now, the challenge has been to derive the required torque necessary for commercial industrial valve applications.
Exciting breakthroughs in mechanical technology and advancements in magnetics can now be applied to industrial valves. The torque requirements to operate a valve can be very high to break free, or simply open or close the valve. MagDrive Technologies solved this problem to deliver any necessary torque requirements, from small valves to large pipelines. For example, MagDrive was tested on a 4” Naval globe valve for high temperature/high torque requirements. The US Navy wanted to ensure the magnetic interlock could deliver enough torque to the valve stem in any environment and a stress test was ordered. The team over engineered the torque requirements to intentionally cause a failure in the valve. During the test, the valve was blocked while the magnetic coupling continued to deliver the closing torque, stressing the valve stem. The magnetically actuated valve drive twisted the ½” valve stem proving that more than enough torque could be delivered through magnetics while shattering misconceptions about magnetically actuated valves. (SEE PHOTO TWISTED STEM)
The US Navy stress test demonstrates a key feature and benefit of magnetic actuation. Magnetic interlock can be calculated precisely. Rather than shattering valve stems, torque requirements can be calculated and backed down from the valve or valve stem breaking point. Rather than causing a valve failure, the magnetic array can be set to jump to the next magnet right before a stem failure occurs. This result is an infinite shear pin protecting the valve from scenarios where an operator might attempt to open or close a valve with an oversized valve wrench and otherwise cause a valve failure.
The immense cost of fugitive emissions is the sum of many different contributors. Serious revenue is lost whenever facilities experience down time. End users pay extraordinary amounts for compliance fines and to conform to content decrees. Magnetic actuation can eliminate the offending leaks. Maintenance on a leaking valve costs much more than the valve itself when factoring in procurement, maintenance, and down time. Magnetically actuated valves can minimize or even eliminate regularly scheduled maintenance for failed packings. Since the valve stem is completely encapsulated, the packing cannot leak to atmosphere, and the process fluid is entirely contained. Magnetically actuated valves can also reduce the monitoring expenses as all dynamic seals are eliminated. Because of this, the valve could now be considered a flange-to-flange connection claiming ‘no detectable emissions’.
Magnetically actuated valves can eliminate leaks ranging from the coldest situations to higher temperature applications with only a few exceptions. Certain magnets can maintain a magnetic field from cold cryogenic temperature (sub 350F) up to a standard 650 degrees fahrenheit. There are other magnets that can withstand upwards of 1000 degrees fahrenheit without compromising magnetic coupling. Most lines don't reach these extremes, but for some high temperature applications, the magnetic coupling simply needs to be thermally isolated from the process line, keeping them within the specified temperature range. Going from hot to cold, cryogenic valves often require an elongated stem, isolating the packing from the cold process fluid. The cold can compromise and embrittle the packing, causing leaks. Some magnets actually increase their magnetic field when they are cold, so magnetic actuation is a dream in cold conditions. After all, this is where it started when cryogenic helium was contained for NASA’s planetary lander. With a magnetically actuated valve, the stem and packing can be encapsulated and in some cases, the packing can be entirely removed. The encapsulated stem can be attached with a static seal or hermetically sealed and welded in place if needed.
In comparison to bellows valves, the encapsulation in a magnetically operated valve does not flex and remains a solid wall. It is not prone to crack or wear like a bellows valve and the magnets float on a cushion of air extending the life of the valve with minimal wear. In addition, they can eliminate emissions without seriously increasing the footprint or height of a standard valve which has not been the case with some bellows valves which are often taller than the spaces where they are needed.
As magnetic actuation has moved from successful research and development, through successful testing validation and into commercialization, a new technology is now available. For those looking to eliminate environmental hazards, dangerous emissions, and costly leaks, while increasing health and safety and the bottom line, magnetically actuated valves provide a true No-E solution.