Fact Statement: The fire is still under investigation, and publicly available information has not yet confirmed the exact cause of the accident. Therefore, this article does not analyze the cause of the accident, nor does it attribute the accident to any specific valve, piping component, or equipment. Instead, it focuses on valve safety issues commonly involved in the commissioning of large-scale chemical facilities.   On August 25, 2026, a serious fire occurred at the Amur Gas Chemical Complex (AGCC) in the Amur Region of Russia’s Far East. As of August 26, the accident had resulted in 7 deaths, 152 injuries, and 9 people missing.   According to an official statement from AGCC, the fire occurred in the auxiliary process section of the plant’s pyrolysis unit, while the main project equipment was not damaged. This accident is deeply distressing and once again reminds us that, in natural gas chemical projects, the safety of auxiliary process sections, particularly the reliability of valves, is by no means an “auxiliary” issue.   1. What Is the Auxiliary Process Section of a Cracking Unit?   An ethylene cracking unit is an extremely complex system with highly demanding process requirements. The cracking furnace is the heart of the unit, where natural gas or naphtha is cracked at temperatures above 800°C into basic chemical feedstocks such as ethylene and propylene.   The Auxiliary Technological Section, although not located at the center of the high-temperature reaction like the cracking furnace, is responsible for providing stable utilities and various auxiliary media for the entire unit, ensuring the continuous and safe operation of the main unit.   The auxiliary process section mainly includes the following seven subsystems:   1. Fuel Gas/Fuel Oil System: This includes fuel gas buffer vessels, knockout drums, fuel oil pumps, strainers, and burners, and is responsible for supplying stable and clean fuel to the cracking furnace. 2. Steam System: The core equipment is the Steam Drum, which generates and distributes the dilution steam, high-pressure steam, and other steam required by the unit. 3. Feedwater and Condensate System: This includes deaerators, boiler feedwater pumps, condensate recovery tanks, and other equipment responsible for supplying and treating qualified water for the steam system. 4. Compression and Refrigeration System: This includes multistage compressors, intercoolers, separators, and refrigeration compressors, which are used to compress and cool cracked gas and provide refrigeration for downstream separation. 5. Drying and Purification System: This mainly consists of molecular sieve dryers used to remove trace moisture from cracked gas and prevent freezing and blockage of downstream equipment at low temperatures. 6. Relief and Flare System: This includes flare knockout drums, flare tips, and other equipment used to safely burn and dispose of combustib...

Operation Type Is a Shutdown Decision   A line blind valve is chosen for positive isolation, but the operation type decides how practical that isolation will be during a shutdown. Manual, gear-operated, and hydraulic designs can all move the blind between open and closed positions, yet they do not create the same workload, speed, or safety margin. For shutdown planning, the right question is not only “Can the valve isolate the line?” It is “Can operators switch, verify, lock, and return the valve to service safely within the shutdown window?”   Manual Operation: Simple, but Limited   Manual operation is usually suitable for smaller line blind valves, lower pressure classes, infrequent switching, and sites where operators have clear access around the valve. It keeps the design simple and avoids dependence on hydraulic power units or control systems. The limitation is physical effort. As size, pressure class, seal load, and plate weight increase, manual operation becomes slower and more exposed to human error. If several operators, lifting tools, or extended handling time are needed, the valve may no longer be a good fit for a tight shutdown schedule.   Manual operation is best treated as a low-complexity option for manageable sizes and low switching frequency.   Gear Operation: Better Control for Medium-Duty Shutdowns   A gear-operated blind valve gives operators more mechanical advantage and better control than direct manual operation. It is useful when the valve is too large or stiff for simple manual switching, but the site does not justify a hydraulic system. Gear operation often fits plant shutdowns where isolation is planned, access is available, and switching speed matters but is not the only priority. It can reduce operator strain and make the changeover more predictable.   The buyer should still review gearbox location, handwheel access, operation turns, torque, locking method, and position indication. A gear operator that cannot be reached safely during shutdown is not a good solution, even if the valve design is correct.   Hydraulic Operation: For Large, High-Pressure, or Time-Critical Lines   Hydraulic operation is usually considered when the pipeline isolation valve is large, high-pressure, frequently switched, or located in a difficult operating area. It can reduce manual handling, shorten changeover time, and improve control during planned isolation. This makes hydraulic line blind valves attractive for refineries, gas systems, terminals, high-temperature service, and shutdowns where every hour of downtime has a cost. Hydraulic operation can also support safer distance between personnel and the moving mechanism, depending on the control arrangement.   The tradeoff is system complexity. Hydraulic cylinders, hoses, power units, seals, and controls need inspection and maintenance. Buyers should ask how the valve is operated if hydraulic power is lost, how the pos...

Both sliding and swing type line blind valves are used for the same core purpose: positive isolation. In the closed position, a solid blind plate  blocks the pipeline bore, giving operators a visible and mechanical isolation method before maintenance, inspection, shutdown work, or media changeover.   The difference is not whether one can isolate and the other cannot. The real question is how the valve moves, how much space the site has, how often the line must be switched, and how difficult the operation will be under pressure, temperature, and site-access limits.   A sliding type line blind valve moves the blind plate laterally. This design is often useful where side clearance is available but swing clearance is limited. A swing type line blind valve rotates the blind plate into or out of the flow path. It is often selected where fast, clear changeover is needed and the installation area allows the plate to swing.   Selection Factor Sliding Type Line Blind Valve Swing Type Line Blind Valve Structure Blind plate slides sideways between open and closed positions Blind plate rotates or swings between open and closed positions Operation Often gear, hydraulic, pneumatic, or electric assisted for easier plate movement Manual, gear, hydraulic, pneumatic, or electric operation depending on size and class Maintenance Sliding tracks, sealing surfaces, and drive parts should be checked regularly Pivot, locking parts, sealing surfaces, and drive parts need inspection Space Requirement Usually better when swing radius is restricted, but needs side travel space Needs enough swing clearance around the pipeline Suitable Service Frequent switching, compact plant layout, limited swing area Clear operation path, quick changeover, maintenance isolation, oil, gas, steam, or chemical lines   For compact plants, pipe racks, or areas with nearby equipment, sliding type designs may be easier to arrange. Their lateral movement can avoid the large arc required by a swing plate. This is one reason sliding line blinds are often considered when installation space is a serious constraint.   Swing type designs are often preferred when the site has enough clearance and operators want a simple visual change between open and blind positions. For large sizes or higher pressure classes, the operation method becomes important. Gear, hydraulic, pneumatic, or electric operation can reduce manual effort and improve safety.   When choosing between the two, start with the site layout. If the valve cannot physically move through its full travel, the design is wrong no matter how good the specification looks. Then check pressure class, medium, temperature, material, sealing type, switching frequency, and required test standard.   For high-temperature steam, hot oil, gas, toxic media, or flammable service, do not select only by valve type. Confirm body material, blind plate material, seal material, operating torque, ...