Case Study: 2003 Xi’an Jinzhu HFC-134a Plant – YNTO Ball Valves in Action

Guangdong Yuantong Industrial Technology (YNTO) was brought on board as a valve supplier for this project, tasked with providing valves that could withstand the harsh service conditions. YNTO’s role involved specifying appropriate valve types and materials for various sections of the HFC-134a production unit. This case study highlights how YNTO’s chemical-resistant ball valves were applied to solve key problems at the plant, following a problem-solution-result format.

Problem: Corrosive HF Acid and Unforgiving Conditions

One of the most challenging aspects of HFC-134a production is handling hydrogen fluoride (HF). HF is a necessary reactant in fluorinating organic feedstocks, but it is also a notoriously corrosive and toxic acid. It readily attacks many metals (even stainless steels) and can even degrade glass and certain plastics. At the Xi’an Jinzhu plant, HF was present in various streams – from reactor feed lines to waste effluent. Valves in these sections would be exposed to HF and needed to operate reliably for the plant to run continuously.

The specific problems included:

· Severe corrosion of valve materials: Traditional valve materials (like standard stainless steel or bronze) were unsuitable because HF would corrode them rapidly, risking leaks. The plant needed valves constructed from or protected by materials that HF cannot easily attack. Previous experience in the industry has shown that valves made of Hastelloy or lined with fluoropolymers are often required for HF service. The challenge was to find cost-effective valve solutions given that some parts of the plant had dozens of valves exposed to HF.

· Risk of leakage and fugitive emissions: HF is not only corrosive but also hazardous to personnel and the environment. Any valve sealing issues (through stem packing, seat leakage, etc.) could release HF vapor. The plant’s safety protocols demanded valves with tight shut-off and robust sealing under HF service. Standard valve packings might degrade in HF. There was a need for special valve seat and seal materials (such as PTFE, PCTFE, or other halogen-resistant polymers) to maintain tight seals.

Operational demands: Many of the valves in the process were automated on control loops or required frequent operation. For example, flow control valves regulating the feed of HF into reactors had to throttle accurately while withstanding acid. On the other hand, some valves were for emergency isolation – they might rarely operate but must function on demand. The diverse operational requirements meant the chosen valves had to combine corrosion resistance with high performance (e.g., maintaining torque and seal integrity over time, despite HF exposure).

Limited installation space and retrofits: As with many chemical plants, space was limited and the piping layout was complex. The project favored ball valves for many applications due to their compact size and quarter-turn quick operation. Ball valves also provide straight-through flow (important for minimizing pressure drop in refrigerant lines) and reliable shut-off. However, conventional ball valves didn’t have the corrosion resistance needed for this scenario, so a solution was needed to get a “chemical ball valve” that fit the bill.

In summary, the Xi’an Jinzhu HFC-134a plant required valves that could survive HF and other corrosive chemicals, ensure zero-leak performance for safety, and meet operational control requirements. The term “chemical ball valves” in this context refers to ball valves specifically designed for chemical service – usually implying special materials or linings to handle aggressive fluids. Few domestic suppliers in early 2000s China had a track record with such valves, which is why YNTO’s expertise was sought.

Solution: YNTO’s Corrosion-Resistant Chemical Ball Valves

YNTO approached the problem on multiple fronts – material selection, valve design, and customization of valve accessories – to create a solution tailored for the HFC-134a plant. The core of the solution was deploying YNTO’s chemical-resistant ball valves in all critical HF service locations, supplemented by compatible valves for other corrosive or hazardous duties in the plant. Key features of the solution included:

· High-Nickel Alloy Construction: For the most severe HF-containing lines, YNTO provided ball valves made of Hastelloy C276 (a nickel-molybdenum-chromium alloy) for their bodies and trim. Hastelloy C276 is known for its outstanding resistance to HF and fluorine chemistry. Using solid Hastelloy (or sometimes a duplex stainless with inner Hastelloy trim) ensured that the valve metallic components would not be eaten away by the acid. These valves were of flanged design, full-bore ball valves to simplify maintenance and allow rodding out if any solids built up. They were equipped with ENC (encapsulated) PTFE seats – the PTFE, which is inert to HF, provided a tight seal while the metal seat ring behind it gave mechanical strength.

· PTFE/FEP Lined Ball Valves: In portions of the process where pressures were moderate, YNTO deployed fluoropolymer-lined ball valves. These valves had a carbon steel body for strength but featured a thick PFA lining on all internal surfaces and a PFA-encapsulated ball. Essentially, the HF would only contact the fluoropolymer liner, not the metal. Lined valves are an excellent choice for acidic services and offered a more economical solution than exotic alloy for some parts of the plant. YNTO supplied DN50–DN200 lined ball valves for various acid transfer lines and storage tank isolation, where operating pressure and temperature allowed. Each valve was factory tested to ensure the lining was defect-free. The use of PFA-lined ball valves gave the plant confidence that even if a small amount of acid was in a line, it wouldn’t corrode the valve during idle periods.

· Thermoplastic Valves for Auxiliary Systems: The HFC-134a process also involves utility streams like water cooling or waste neutralization where acids might be diluted. YNTO provided UPVC and PVDF plastic ball valves in some of these auxiliary systems, for example in the HF scrubber unit and waste acid neutralization skids. The pneumatic UPVC ball valves (including some three-way designs) were chosen for their high corrosion resistance to low-concentration HF and fluorides. These plastic valves were lighter and easier to install on small bore piping. They were actuated by YNTO’s pneumatic actuators with PTFE-coated internals to prevent any corrosive damage in the actuator in case of slight fumes. Although plastic, these valves were robust: the pneumatic plastic ball valve design features an L-shaped or T-shaped flow path for diverting service and is built to be maintenance-friendly (as shown by its compact, easily removable actuator and few metal parts).

· Customized Sealing and Packing: For all the valves supplied, YNTO paid special attention to the stem seals and body gaskets. They utilized graphite-free PTFE packing on the alloy ball valves to avoid graphite (which is not suitable for strong oxidizers like fluorine). Some valves had live-loaded spring washers on the gland to maintain packing tension as the PTFE could creep over time. Body gaskets were made of modified PTFE that could handle the HF without cold flow. Additionally, where needed, YNTO added safety bleed ports and extension bonnets on valves to keep the packing area further from the process fluid (this is a common approach in severe acid service – an extension bonnet can dilute and cool any vapors, protecting the packing).

· Valve Automation and Control Integration: The project required that many valves be tied into the plant’s DCS (Distributed Control System). YNTO supplied pneumatic actuators (both double-acting and spring-return types) for the ball valves, along with air filters, positioners, and limit switch boxes suitable for hazardous areas. The actuators chosen were anodized aluminum with a thick epoxy exterior coating – sufficient for the outdoor environment – and all internals were compatible with HF traces (stainless steel fasteners, viton O-rings, etc.). For control valves (like the HF feed control), YNTO provided a high-resolution positioner to ensure the valve could throttle accurately. These smart positioners also had feedback to alert if the valve torque increased (which could indicate fouling or early corrosion, thus acting as a predictive maintenance tool). By integrating these valves into the control system, the plant operators could remotely operate critical isolation valves and continuously monitor valve positions, which is essential in a hazardous operation for quick response.

Internal link example: Many of the principles used in this project are now standard practice in YNTO’s product offerings. For instance, the same series of pneumatic plastic three-way ball valves used in the HF scrubber system are available to other clients who need corrosion-proof flow diversion. Likewise, the alloy valves with thin-wall design (similar to YNTO’s stainless steel pneumatic ball valves) demonstrate how a lightweight yet high-strength valve can be built for chemical duty.

Result: Reliable Operation and Long-Term Plant Success

Thanks to the implemented solution, the Xi’an Jinzhu HFC-134a plant achieved several positive outcomes:

· Reliability: The YNTO chemical ball valves have operated since the 2003 startup with an excellent reliability record. In the first three years of operation, the plant did not experience a single HF-related valve leak or failure in the areas where YNTO valves were installed. This is a remarkable achievement given HF’s aggressive nature. Regular inspections showed no significant thinning or pitting on the Hastelloy valves, and the PTFE liners in the lined valves remained intact and free of blisters. The mean time between maintenance (MTBM) for these valves greatly exceeded that of some previous valves the client had used in less aggressive services.

· Safety: The plant maintained a stellar safety record with respect to HF containment. Operators reported that routine valve gland checks and area monitoring never detected HF fumes around the YNTO valves. The tight sealing provided by the PTFE seats and packings prevented fugitive emissions. This level of containment was crucial in protecting workers; it also kept the plant in compliance with environmental regulations (HF is a regulated pollutant). In 2005, when the plant doubled capacity (adding another 5,000 t/y line), the proven performance of YNTO’s valves made it easy for the plant to choose YNTO as the valve supplier for the expansion as well. In effect, the initial project became a reference case that validated YNTO’s chemical valve technology for HF service.

· Performance: The use of high-quality flow control valves contributed to stable process control. For example, the HF feed control valve (a Hastelloy C ball valve with a smart positioner) allowed the plant to maintain reactor HF concentrations within a tight band, optimizing the reaction efficiency. Improved control reduced by-product formation and helped the plant achieve its target production purity on the first pass. This had an economic benefit: less reprocessing of off-spec material and lower raw material consumption. The plant’s managers noted that investing in reliable valves prevented the “small drips” that can turn into big losses in continuous chemical processes. Every valve that didn’t leak or require shutdown for repair translated into more uptime and productivity for the facility.

· Maintenance & Support: YNTO’s involvement did not end at commissioning. They provided training to the plant’s maintenance team on how to safely service the valves (for instance, how to repack a stem on the Hastelloy valves if ever needed, and how to inspect the liner on a lined valve). Over the years, some preventive maintenance was performed: a few soft seals were swapped during a scheduled turnaround after 5 years, as a precaution. YNTO’s availability of spare parts and quick service response (they had a local representative in China) ensured that any maintenance could be done swiftly, without long downtime waiting for parts. The interchangeability of certain components (like actuator kits) also made maintenance easier – YNTO used standardized actuator mounting, so swapping an actuator was a plug-and-play job.

Overall, the case demonstrates how proper valve selection is key to overcoming corrosion challenges in chemical manufacturing. By utilizing YNTO’s specialized chemical ball valves, the Xi’an Jinzhu HFC-134a plant not only solved its immediate corrosion problems but also set itself up for sustainable long-term operation. The project became a showcase for YNTO in China’s chemical industry, proving that domestic valve technology could meet world-class standards for difficult applications.

Conclusion

The Xi’an Jinzhu Modern Chemical case study underlines the importance of partnering with experienced valve suppliers for corrosion-critical applications. By choosing YNTO’s chemical ball valves, the plant benefitted from materials and design tailored to the process needs – enabling safe, continuous production of HFC-134a refrigerant. Problems that could have led to frequent outages or safety incidents were averted through engineering foresight and quality equipment. For industrial engineers and procurement teams, this success story reinforces a key lesson: in corrosive services, the true value of a valve lies not just in its purchase price, but in its performance over time. Investing in the right valves – like YNTO’s solutions – delivers dividends in reliability, safety, and process efficiency.

For more information on YNTO’s chemical service valves, readers can refer to the product pages linked above or contact YNTO for detailed case studies and references. The HFC-134a plant is just one example – similar YNTO valve solutions are powering corrosive fluid handling in industries ranging from petrochemicals to pharmaceuticals.