How IMI co-created a new valve design to transform urea production

And yet, despite urea’s worldwide importance, many dedicated manufacturing facilities rely on outdated or underperforming flow control technologies. The situation is further complicated by the exceptional demand and huge cost associated with downtime, whether planned or unplanned.

In urea manufacturing facilities, site teams cannot perform valve maintenance while a valve is in service due to the time required to effectively diagnose and upgrade these components. As a result, many are left relying on the assets near failure.

But now some sites are taking a different approach, recognising the transformative potential of new valve designs to secure higher yields, better-quality product and greater site reliability.

Here is where Valve Doctor™ candidate Nadeem Saba’s recent work with a large urea manufacturing facility in Egypt offers a good example.

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We didn’t initiate this project with design ideas, but instead with an in-depth investigation into why urea production was so inefficient.

Working alongside the customer’s engineers, our team conducted a detailed on-site study, a teardown inspection, and a series of ongoing interviews to fully map the failure modes of the plant’s existing stripper letdown valves.

These sessions revealed several recurring issues common to urea production: crystallisation, scratched stems triggering leakages and packing failures caused by erosion and corrosive exposure. If left unchecked, these problems result in significant losses and pose serious safety hazards.

Our analysis also uncovered key design flaws that are unsuitable for the harsh conditions encountered during urea production. Caged trims, for instance, created stagnant zones where carbamate could build up, corroding valve internals and restricting their range of motion.

Putting initial observations to the test, our partner removed these cages during their next scheduled shutdown period and saw an immediate improvement. This breakthrough, along with an absence of replacement parts and few modern alternatives, provided the rationale for a total rethink of the site’s existing assets.

This approach required major changes that could only be realistically delivered during a planned outage. Clearly, this was a decision with considerable expense attached.

Nevertheless, the customer was keen to proceed as earlier work from IMI on the site’s desuperheaters in 2015 had produced impressive results. At the time, the existing probe-type desuperheater was prone to frequent failures due to nozzle cracks. This led to inefficient desuperheating, which in turn caused thermal stress and damage to downstream pipes. Our field knowledge and technical expertise enabled our experts to custom-design the site’s desuperheaters with appropriate logic modifications. The outcome of this project was that the new desuperheaters resolved the damage issue and resulted in considerable OPEX savings for the customer.

Using the same approach, we developed a detailed site analysis, and our engineers set out to create a new valve concept. One designed to withstand the extreme conditions found during urea synthesis.

The first step was to optimise the valve’s flow and plug geometry for smooth energy dissipation. This was achieved by positioning a control edge upstream of the seat to block the entry of potentially damaging particles before the plug engages.

During normal control operation, the smallest flow area within the trim is intentionally located downstream. This reduces the risk of erosion in critical sealing areas by directing high-velocity flow and entrained particles away from sensitive valve surfaces. Consequently, this will enhance long-term reliability and integrity.

Our design also incorporated a low-angle impingement to direct the medium tangentially to the sealing surface. This minimises the direct, perpendicular impact of high-velocity flows or particles on the valve’s critical parts. Taken together, such design refinements significantly reduce erosion risk while maintaining a tight, bi‑directional shutoff.

One of the more significant innovations of this new design is evident in the packing system.

As our investigations demonstrated, traditional valve materials are often ill‑equipped to handle urea’s abrasive, crystallising nature, leading to accelerated wear and leakage into the atmosphere. We responded with a composite packing configuration that uses aramid yarn with fluoropolymer dispersion and a wiper/back‑up ring arrangement.

These materials are well-proven in the urea services sector, and the packing arrangement is unique. The prolonged distance between the top and bottom rings maximises the stabilising lever effect of the valve stem during harsh operational conditions, making it particularly suitable for the urea industry. It is a self-energising, low-friction system that requires no external preload. The main benefit for our customers was that it is virtually maintenance-free and does not require tightening over time.

This variation on our EEEasy-Seal solution meant the plant would effectively eliminate leakage, deliver smooth stem operation, and achieve greater longevity between overhauls. All of these are highly desirable in an industry where plants often run around the clock.

Coatings were another area we targeted for improvement. We recommended high-end disposition to produce strong, defect-free coatings (suitable for duplex and superduplex stainless steel) without heating the base material. These coatings form robust bonds that include non-weldable materials and significantly increase hardness and cavitation resistance. They also provide resistance to flashing and erosion/corrosion and deliver excellent performance in the demanding conditions of the urea industry.

By early 2024, we had finalised a new BEU valve design and begun manufacturing at our Remosa facility in Sardinia.

Confident in the engineering principles underpinning it, our partners and IMI’s engineering experts both agreed to move directly to installation without a prototype phase. This new valve, the first of its kind, was produced in just over nine months and then subjected to a series of factory acceptance tests that were witnessed by our partner,

These tests, conducted under conditions exceeding those during urea production, showed a significantly improved flow rate. They also confirmed material selection, with no wear or corrosion damage observed throughout. At the time of writing, the new valve is expected to be installed by the end of the year.

This project is typical of how IMI responds to complex customer challenges. Our team is always willing to undertake thorough analysis and R&D to deliver a lasting solution. It’s a commitment much needed within an industry that has historically suffered from a lack of innovation. But now, with other facilities looking to install the solution, a new era of efficiency is underway in urea production worldwide.

Learn more about IMI’s BEU Urea+ Control Valve for Urea Fertiliser Plants.