By Kevin Jackson, Director Business Development Americas & Steve Freitas, Director New Product Development – IMI Critical Engineering
The gas transmission market has traditionally used a rotary ball valve for controlling pressure and flow rate. These valves have limited ability to control velocity, noise, and energy absorption. The industry has been forced to add additional noise attenuation by burying or covering the valves.
On the other hand, liquefaction facilities have traditionally used a linear globe style control valve with torturous path fluid control trims to control pressure because of its ability to control velocity, noise, and pressure energy absorption. However, rangeability has always posed a problem in achieving the low flow rate at high Δp (pressure drop) required at start-up/ line-fill with the ability to supply high flow rates and low Δp.
Work arounds have had to be used to accommodate the globe valves ability to have higher than normal rangeability. Two typical examples of the work around are set out below: Applied Technologies.
In 2003, patents (US 2003/0192602 A1) were filed and granted that combined a ball valve together with torturous path fluid control DRAG™ trims that could be engineered to control the velocity, noise, and pressure energy absorption as per ISA S75-01 and the required rangeability for the full flow condition.
Manufacturing techniques at that time, 2004, consisted of EDM (Electrical Discharge Machining), vacuum brazing, and welding to be able to manufacture the engineered design. This process was very labor intensive and led to long lead times and high costs.
In further testing of a 24” LNG FEEDGAS valve, that was 1 of 4 supplied to a Caribbean LNG facility, with multiple inlet FEEDGAS lines, the rangeability and ability to control or balance the FEEDGAS inlet was required in order to keep the LNG trains optimized.
Capacity testing was carried out to prove that the concept of the rotary torturous path ball valve was sound and accurate.
The valve Cv was tested using the IMI CCI 8” R&D Test Loop. This test loop has the following elements: an accumulator; an isolation valve; a pressure regulating valve; and an orifice plate. The 24” valve is installed at the end of this loop. An 8” x 24” expander with integral flow-straightener is installed upstream of the 24” valve; a 24” x 120” long diffuser is installed after the 24” valve, as shown in Figure 3.
The control valve for this project has been Cv tested in accordance with IMI CCI Test Procedure TP521. The test is conducted by blowing down air through the test valve, and recording the following data:
• DP – orifice delta pressure (psid)
• P0 – orifice inlet pressure (psig)
• P1 – specimen inlet pressure (psig)
• T1 – orifice inlet temperature (OF)
As a design concept and small batch production valve, the tortuous path ball control valve was a success in meeting the criteria that was given at the outset:
• High rangeability >500 : 1
• Control velocity, noise, and kinetic energy at high Δp
• 2003 – Control Components Inc., 22591 Avenida Empresa, Rancho Santa Margarita, CA 92688, USA.
• 30” ASME 600CL ball fitted with DRAG™ trim
• Approx. 80 man hours required to manufacture ball assembly
• Approx. delivery time 40 weeks
• 1 of 12 valves supplied to 3 sites in North Africa
• 8 of the valves are still in operation today
IMI Critical Engineering/CCI has been working with 3D/additive manufacturing since 2010, investigating and testing it for the use in the manufacturing of standard production parts, such as DRAG™ trim.
The technology and recognition of the process has grown enormously as it has advanced in the past three years. With the advancements in additive manufacturing machines, it has had a large impact on the design and manufacturer of complex components for a wide number of industries including aerospace, defense, medical, and automotive industries.
For IMI Critical Engineering/CCI, additive manufacturing is commonly used for producing DRAG™ trim components. Additive manufacturing simplifies the manufacturing process, reduces raw material usage, and speeds up delivery times. Additive manufacturing also improves the accuracy and consistency of valve trim components.
In 2019, IMI Critical Engineering opened the project for the tortuous path ball control valve for high rangeability applications using the acquired isolation ball valve IMI Truflo Italy and the additive manufactured DRAG™ element to produce an economically and supply viable product to the marketplace.
The gas industry is seeing an increasing trend in the demand for fugitive emission control mandated by global standards such as ISO 15848 and API622. Fugitive Emissions through any static or dynamic joints or seals within the valve are the key areas of potential leakage. Quarter-turn valves by design have better sealing capabilities through their life, so as the LNG industry looks towards carbon reduction, valve selection will be crucial.
With more than 160,000 DRAG™ trims installed in severe service control applications world-wide and 14,000 isolation valves installed in applications where safety, integrity and performance are critical, the newly named dBX Shield™ rotary control valve has a strong pedigree.
Additive manufacturing is still a developing technology and machines have limitations in the production of component size. To get around this, a methodology was developed to produce the DRAG™ trim in “pizza” like shapes that allow the use of 3D additive manufacturing, and does not limit the size of valve to the machine’s capability.
With this design approach, there is no limitation on size or pressure class. Base material for the trim is Inconel 718, as this delivers optimal performance for both the printing and design requirements.
This design also allows trims to be engineered specifically to meet customer process flow requirements. The ball valve retains all of its capabilities in terms of sealing, fire safe certification, and quarter turn actuation with full modulating functionality.
The design delivers the highest rangeability in its class at 1000:1 full noise, velocity, and kinetic energy that fully meets ISO/IEC control valve sizing.
The use of this valve in LNG FEEDGAS, and gas pipelines, significantly reduces infrastructure capital cost through less valves, less noise attenuation, and lighter weights associated with the valve compared to a traditional globe control valve. This is demonstrated in examples 2 and 3 above.
Using the IMI dBX Shield™ as the FEEDGAS inlet valve for an LNG facility requiring approx. 12,000 Sm3/hr to 1,200,000Sm3/hr of gas would simplify and reduce:
• Capital investment by approx. USD $1.2million in savings on control valves and piping.
• Simplified start-up and reduced I/O count.
• Increased controllability and reliability for multi pipe inlet piping.