Typical Misunderstandings and Countermeasures of Multi turn Electric Gate Valves

1、 Cognitive bias in the installation and debugging process

1. The chain reaction caused by improper spatial layout

Many users only focus on the size of the valve body, but ignore the reserved working space around it. In practical operation, it has been found that when the distance between adjacent pipelines is less than 1.5 times the diameter of the valve body, maintenance and disassembly will become extremely difficult. More seriously, failure to set the height of the operating platform according to regulations (within 0.8 meters below the centerline of the handwheel) can lead to fatigue and errors in personnel during long-term bending operations.

2. Hidden hazards of directional errors

About 60% of users have misconceptions about flow direction, believing that two-way sealed valves can be installed freely. In fact, even for equipment with nominal bi-directional pressure, there is an optimal fit angle for its internal wedge-shaped gate. Reverse installation will cause uneven pressure distribution on the sealing surface and increase the local wear rate by more than three times.

3. Mechanical blind spots with fixed foundations

The practice of simply fixing brackets with anchor bolts is common, but it ignores the influence of dynamic loads. When the pipeline undergoes thermal expansion and contraction to generate thrust, rigidly connected valves are highly susceptible to additional shear stress. The correct approach is to use elastic supports with buffer pads and install compensating joints in long-distance pipelines.

2、 Practical fallacies in the operational control phase

1. The cognitive trap of opening and closing speed

It is generally believed that a slow switch is safer, but in reality it is not. Experiments have shown that valves with a full stroke opening time of less than 15 seconds have a 40% reduction in impact energy compared to uniform operation. The key is to understand the principle of "fast opening, slow closing" - fast opening reduces turbulence erosion, slow closing avoids water hammer effect.

2. Dangerous habits of staying in the middle position

Many operators are accustomed to stopping the valve in a semi open state to regulate flow, which can be fatal to multi turn valves. At a microscopic level, the medium continues to erode the partially closed sealing surface, forming a groove like erosion.

3. Accumulated damage caused by exceeding the limit operation

The phenomenon of forcibly rotating mechanical limit devices is not uncommon. A certain refinery once recorded that the operator exceeded the upper and lower limits seven times in a row to catch up with the schedule, resulting in the deterioration of the lubricating oil in the worm gear box and the occurrence of pitting and peeling on the gear meshing surface. Modern intelligent valve controllers have electronic fence functions, which can effectively prevent such illegal operations.

3、 Defects in the construction of maintenance system

1. Extensive mode of lubrication management

Most people are aware of the importance of regular refueling, but they do not know that different lubricants need to be selected for different working conditions. Using ordinary lithium based grease in a high-temperature steam environment can lead to carbonization and failure of the lubricating grease; Not adding antioxidant additives in sulfur-containing media will accelerate bearing corrosion.

2. Surface maintenance of stuffing box

A common misconception is to blindly tighten the gland bolts with a wrench, without realizing that excessive compression will accelerate the wear of the packing. Professional practice should follow the principle of "gradual adjustment", with each rotation not exceeding half a turn, and using an infrared thermometer to monitor the temperature rise of the friction area.

3. Consequences of Neglecting Storage Conditions

Valves that are temporarily out of service and stored outdoors will experience internal corrosion within six months. Proper storage should be placed vertically in a dry and ventilated environment, with regular manual turning to maintain flexibility.

4、 Decision errors during the selection and adaptation phase

1. Formal tendency of parameter matching

Simply selecting based on nominal diameter and pressure rating has become the norm, while ignoring the specificity of actual process parameters. For example, when transporting slurry containing solid particles, a valve stem treated with wear-resistant coating must be selected; For low-temperature liquefied natural gas, an extended valve cover structure is required.

2. Empiricism of driving methods

Inertial thinking believes that electric actuators are superior to manual ones, but in areas with frequent power outages, electric valves lacking emergency manual switching mechanisms can become safety hazards. The new composite drive device integrates seamless manual and automatic switching function and has been successfully applied in the underground drainage system of coal mines.

3. Isolation thinking in attachment configuration

It is common to purchase valves separately without considering supporting components such as filters and pressure reducing valves.

5、 Shortcomings in emergency response capabilities are becoming apparent

1. Rough handling of jamming phenomenon

The practice of violently striking when encountering a stuck gate is extremely dangerous.

2. One sided investigation of electrical faults

Only check the power circuit and ignore the root cause of signal interference.

3. Surface articles on leak management

Promptly replacing the packing upon discovering an external leak, without delving into the root cause.