Buckeye Marcellus Valve Repair Center

Located in Cannonsburg, PA, in the heart of the Pennsylvania Marcellus shale region, the Buckeye Marcellus Valve repair center provides a complete range of services for the maintenance and repair of Control, Isolation, Safety Relief valves and most other types of valves. With the necessary stamps and certification, Buckeye Marcellus Valve repair center is a one-stop shop for valve repair and maintenance. Buckeye provides these services on-site and in their shop.

One of the most critical final control elements in a process is the control valve. As part of a closed loop system comprising of sensor and a controller, the control valve provides the process regulation required to maintain a certain aspect of the process. Some examples include, regulation of flow, pressure, temperature and level. It is desirable to minimize process variability at every step of the process so as to optimize the performance of the plant. Such optimal control leads to improved efficiency, increased throughput, reduced energy consumption, reduce waste and minimal process upsets. The control valve is one of the most critical parts in reducing process variability.

Over time, control valves performance degrades due to various reasons, resulting in increased process variability, process upsets and potentially downtime. Some of the contributing factors include:

The amount of time it takes, after the controller sends a signal to the valve and the valve actually moves, is called as Deadtime or Lag. In a closed-loop control system, any deadtime or lag results in cycling which increases process variability. Plant operators will often de-tune the loop to deal with lags, which makes the overall process less efficient and increases overall control error. Therefore it is critical to minimize or eliminate lag altogether. Lag could be a result of:

When a valve behaves differently depending on whether it is opening or closing, this phenomenon is called Hysterisis. It means that for a given input to the valve, the valve travels a different distance in an upstroke versus a downstroke. The result of Hysterisis is that the control loop exhibits a non-linear response which makes it harder for the controller to maintain tight control on the process. This leads to cycling, variability and potential de-tuning of the loop reducing process efficiency.

Hysterisis is typically a result of loose linkages, bad positioner or friction in the system. If a positioner does not exist, adding a positioner to the system can help.

Stiction (Sticking/Friction) is a condition where a valve sticks in a certain position during travel for a period of time before breaking loose and moving again. This results in unpredictable valve response, overshoot, cycling and increased variability.

Stiction is typically a result of issues with buildup inside of the valve, sticky internals, actuator sizing and tight shutoff.

In order to enhance control valve life, an operator must perform ongoing and routine maintenance on a fixed schedule depending one valve type, size, location and service. It is necessary to establish a baseline performance for each valve and monitoring the valve performance at each routine maintenance.

Predictive maintenance is the process where an operator monitors control loop performance to see how process variability and loop response changes over time. Tracking and analyzing loop performance can give some indication on valve performance issues when they start instead of when they become a problem.

Some of the common reasons for needing valve repair, in addition to Deadband, Hysterisis and Stiction are internal or external leakage. If the internal valve leakage is greater than the Maximum Allowable Leakage specified by the vendor, it can be an indication of wear and tear of internal components or a problem with the actuator, linkages or positioner. External leakage is a bigger problem as it creates fugitive emissions and environmental problems. This is usually due to a problem with packing and the packing seal.