IMI Metamorphic Trim - Ultra-high delta P, ultra-unique low-flow performance

Then imagine controlling the flow using discrete pressure-reducing stages to effectively avoid severe service issues such as vibration, noise, or cavitation. This was the challenge IMI’s engineers faced with our patented Metamorphic Trim (MMT).

We partnered with a North Sea operator to deliver monoethylene glycol (MEG) injection valves designed to run in pump-recycle mode alongside injection pumps. Production is not possible without the MEG injection pumps, which inject MEG into the process pipes to prevent hydrate formation as the fluid travels to the surface. New wells are deeper and, as a result, have higher pressure, often falling into the ultra-high-pressure category.

Ultra-high-pressure environments increase the risk of hydrate formation, thereby increasing the criticality of the MEG injection pumps and the pump recycle valves. The efficiency of production also depends on the ability of the injecting pumps to dose correctly. Having a MEG injection valve with high rangeability that can withstand the full pressure drop gives the operator the tools to achieve maximum efficiency. At the same time, this minimises the risk of waste from overdosing and mitigates the risk of damage from underdosing.

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The solution would be a control valve that not only provided stable minimum control of 0.5 m3/hr but also controlled up to 10 m3/hr under the same conditions, from an inlet pressure of 623 barg (9036 psig) to an outlet pressure of 0 barg. Our MMT design performed even better, achieving a minimum controllable flow rate of 0.08 m3/hr at full delta P, while maintaining the ability to control up to 10 m3/hr at max delta P. This represents a 125:1 rangeability of the flow rate under the most extreme conditions. In terms of valve rangeability, the max-rated Cv compared to the min-controllable Cv is even more impressive. The qualified valve had a proven, tested Cv rating of 1.1 and a tested min controllable Cv of 0.0039, with 282:1 rangeability. Such performance is unmatched in the industry and unique to the MMT.

Our journey to establishing MMT as a one-of-a-kind solution for ultra-high MEG injection applications was by no means straightforward. MMT is a new patented design that combines the advantages of labyrinth-style trim with discrete pressure-reducing stages and cascade trim. This makes it self-cleaning and suitable for low-flow conditions. Originally designed to meet the tough low-flow requirements of spray water OTC (Once Through Cooler) valves, MMT was first installed in 2021 and is now used in a variety of applications for a range of customers worldwide.

Early on, MMT pivoted from spray water applications to become a solution for challenging oil and gas and petrochemical applications, where problem valves existed with no available solution in the industry. These applications were not limited to high delta-P, low-flow applications, but also extended to high rangeability and dirty-service, slurry applications.

Prior to partnering with our North Sea customer on this ultra-high delta P solution, MMT had been successfully applied in high-pressure (ASME 2500) applications; extending its application range to ultra-high pressure yielded key learnings. After challenges during the factory acceptance test (FAT) of the initial valve design for the MEG injection skid, we returned to the drawing board with the customer to find a solution that met their requirements. It was important that the solution was achievable within the technological constraints introduced by ultra-high-pressure-drop service. Our combined engineering teams designed a first-of-its-kind endurance testing procedure. A test loop was designed and built, which included:

The testing was conducted by a team of our senior engineers, including MMT inventor/patent holder, Marco Mastrovito, Head of Research and Development for Europe Control Valves, Principal Engineer, Valve Doctor® at IMI. The test results were impressive, and the tested valves performed perfectly. Virtually no noise could be heard from the valve under any operating condition.

The team even pulled a vacuum at the valve outlet and tested from 623 barg (9036 psig) P1 pressure to vacuum, without any indication of cavitation noise. After no noise was detected with the microphone, the team used a screwdriver on the valve outlet to see if vibration/noise could be detected. Even then, no cavitation-related noise or vibration was detected.

A 25mm trim valve was tested with a sacrificial trim for one week, including:

The valve passed the test, and the trim parts looked practically new, with no signs of cavitation or galling damage. We repeated a reduced endurance test for 4 additional trims, over an additional two-week period of testing. All trims looked new at the end of testing and will be used by the customer as a spare reserve trim.

MMT has specific features that account for its outstanding performance. Like IMI’s DRAG® technology, MMT includes pressure-reducing stages. The trims tested under 623 bar delta P have 19 pressure-reducing stages, which resemble 38 right-angle turns in a labyrinth trim. Velocity limits for each pressure-reducing stage are reviewed during the design phase, and IMI imposes a limit on the internal trim velocity in the passages.

One hypothesis our research and development team had during the design phase was that the gap between the plug and the SCE is also “multi-stage,” and that the pressure decreases gradually in the valve deadband for extremely low flow conditions. This hypothesis was also proved. To protect the seat at the trim inlet, the Metamorphic trims have a minimum 3mm deadband before the flow passage opening begins. During the gap-flow tests, three points within this deadband were measured. The MMT controlled the flow within the deadband and withstood the full 623 bar (9036 psi) delta P without direct flow through the passage inlets.

Below is a visualisation of the trim ‘unwrapped’. At small openings, some of the fluid is diverted into the passages, while the rest travels through the tight gap between the plug and the SCE. This long, very narrow gap, in combination with the resistances caused by the flow circumventing the passage holes, provides an effective “tortuous” path for the flow, with gradual pressure reduction from the inlet to the outlet. As the test results show, even with these low flow openings, no severe service issues were observed.

The name metamorphic describes a transformation and, in some sense, an evolution. We use it to describe our unique approach to combining two valve technologies; however, it can also be considered an evolutionary step in the valve industry, achieving performance levels not seen before. MMT has been designed with our customers in mind. By addressing the challenges of high delta-P and low-flow applications, we help oil and gas operators optimise efficiency and minimise risk.

Our commitment to collaboration has enabled us to tailor this innovative valve to meet the specific needs of our customers, ensuring maximum performance even in ultra-high-pressure environments and other challenging valve applications where no solutions are available. Examples of these additional applications can be found in our case studies, where MMT was key in delivering OPEX and CAPEX gains. As we look ahead, IMI remains dedicated to our customers, supporting you with cutting-edge solutions that drive success and reliability in your oil and gas operations.

To discover more about our IMI MMT solution, please visit EroSolve Metamorphic Trim.