Urea valves play a critical role in the fertilizer industry. Urea, a white crystalline compound, is widely used as a nitrogen-rich fertilizer to enhance crop growth and yield. The production and distribution of urea in the chemical fertilizer process requires the use of specialized valves, manufactured with urea grade material. These valves are designed to withstand the corrosive and abrasive properties of urea, ensuring efficient and reliable flow control. Proper maintenance of Urea valves is crucial to prevent equipment failure, ensure safety, and minimize production downtime.
Although Conval urea globe valves share similarities with the standard Conval globe valves that customers have come to trust and rely on, variations in their design and materials lead to minor differences in the servicing needs. This article explores the differences in servicing a Conval urea globe valve as opposed to a Conval steam globe valve and offers guidance on best practices for maintaining these industrial valves to ensure optimal performance.
Conval’s Urea Design Globe Valve: A Game-Changer for High-Pressure Urea Applications
Conval’s Clampseal® Urea and Ammonia product line comprises Angle, Y, and T pattern globe and check valves feature a modular design that allows for easy in-line repair. The valves are available in special alloys and use a low number of replacement parts that are common across valve sizes. These valves are well suited for high-pressure piping applications, such as urea reactors, strippers, and condensers. They are also ideal for use with process fluids like ammonium carbonate, nitric acid, and urea.
In 2016, Conval successfully received their CRN for their in-line repairable, globe valve design to be built in urea grade materials, 25-22-2 and 316L-UG. Conval’s globe valve design has been used for decades in high pressure, high temperature services and only a few modifications were necessary for its use in urea applications. The table below highlights the differences between the Conval steam globe valve and urea globe valves:
|Conval Steam Globe Valve||Conval Urea Globe Valve|
|Stem movement||Rising, Rotating||Rising, non-rotating|
|Body material||A105, 316, F22, F91||Forged, 316L Urea Grade
|Trim Material||Varies||Ferralium Alloy 255|
|Stem finish||Chrome plate||Kolsterised ®|
|Corrosion resistance||Trim dependant||High|
|Packing||Graphite rings||Live loaded gland with die-formed PTFE or Graphite rings|
Kolsterising® is an industry-proven, surface hardening technology for grades of stainless steel, cobalt and nickel-based alloys, providing ultimate hardness (increased by 4 to 5 times) and improved mechanical and wear properties with no loss of corrosion or affect to the size or shape of the base component.
Servicing and Maintaining Urea-Designed Conval Valves
Conval’s Urea globe valve is in-line repairable, which provides significant cost and time savings due to the high expenses of specialty materials and the intricate and time-consuming process of welding. Conval’s design uses a minimal number of parts, all of which can be delivered within relatively short lead times. Repair procedures are not complex and tools are readily available to purchase or rent.
Conval’s design also ensures commonality of parts between sizes and body materials; this means less stocking requirements for the end user, which is particularly helpful for higher cost materials. The following video highlights the typical process involved in repairing a Conval steam globe valve.
There are minor differences in the process to repair a urea valve compared to a steam valve and these relate to its unique features and the mechanical properties of the urea grade materials. The table below summarizes some of these differences.
|Standard Conval Globe Valve||Urea-Design Globe Valve||Comments|
|Removing the clamp bolt||✓||✓|
|Removing the top works||✓||✓|
|Disassembling the top works||✓||✓*||Urea-design valves are equipped with a bearing housing and key to facilitate disassembly of the rising, non-rotating stem|
|Cutting the seat (to remove imperfections)||Using seat cutting/grinding tool||Only seat grinding tool allowed|
|Re-facing body seal||✓||✓|
|Re-packing the bonnet||✓||✓|
|Lapping the seat using the new stem||✓||Not allowed||Lapping the stem/seat can cause galling in urea-grade materials|
|Re-assembling the topworks||✓||✓*||Urea-design valves are equipped with bearing housing and key to facilitate re-assembly of the rising, non-rotating stem|
|Assembling the topworks||Torque per instruction||Torque per instruction|
|Tightening the packing||Torque per instruction||Torque per instruction|
|Removing the clamp bolt||Torque per instruction||Torque per instruction|
|Appling Lubricant||Only on some trims||✓||Type of lubricant depends on end user process|
Note: * indicates that same process is applied with changes
We Service What We Sell
At Armour Valve, we offer comprehensive servicing support for the products we sell. Our Conval urea globe valves, for instance, can be easily maintained on-site using a Conval Tool Kit, which can be purchased or rented as needed. In addition, our service manager, a factory-trained instructor, can provide training to your technicians on best practices to comfortably service your Conval valves on your own. With a range of aftermarket options available for our customers, visit our Armour Valve Service page to learn more about our services or contact us to discuss your specific requirements and or request an Installation, Operation, Maintenance (IOM) manual.