Commentary: Control Valve Diagnostics

Nov. 11, 2005

David Douglas Chemical and refinery production plants can achieve significant time and cost savings by implementing an effective preventive and predictive management program for control valves in the field.

David Douglas

Chemical and refinery production plants can achieve significant time and cost savings by implementing an effective preventive and predictive management program for control valves in the field. Critical control valve diagnostics can detect and correct problems before they happen, preventing catastrophes and ensuring that field sites function at their optimum efficiency and minimum cost.

Instituting a control valve diagnostic program can be as simple as using the right diagnostic tools and selecting the right vendor to diagnose and repair the valve on site, or, if need be, in the plant.

When a valve is taken out of the field for repair, the accessories causing the problem are not always sent to the repair shop along with the dysfunctional valve. As a result, vendors are often forced to engage in a general repair instead of addressing specific problems, which can be hidden or left in the field. In addition, valve removal, re-installation, and setup present their own set of nightmares. Therefore, diagnostics should always begin on site.

Advantages of Inline Testing
According to some estimates, for every half hour of performance testing, as much as 40 hours of maintenance labor can be reallocated. For this reason, control valve diagnostics are no longer an interesting novelty or luxury item. They are a highly leveraged, integral part of installing, monitoring, and maintaining modern control valves. Inline diagnostics increase plant uptime and lower production costs, especially compared to the traditional method of pulling valves out of the field for inspection.

Recently, an on-site prediagnostic run on 160 control valves for a major oil company revealed that only 15 percent needed to be pulled. The company saved approximately half a million dollars. Test data can come from a variety of sources, depending on a plant’s needs and maintenance decisions.

Standalone systems can provide a wealth of information, but so can integrated, online, self-diagnosing smart control valves. The key to getting the most out of the available technology is interpreting the data in a quick and accurate way. Increased engineering participation in these areas benefits all interested parties, from end-users to valve service providers.

Implementing a sustainable and effective control valve program is as easy as putting in place a few common-sense solutions and sticking to them. Such a program is affordable, tested, and competitive. The results speak for themselves, and the alternatives are not only costly, but could also be dangerous.

When Valves Must Be Pulled
Valves returned from repair should be tested to meet OEM requirements. Additionally, prior to installation, every new valve from the manufacturer should be tested on the bench. That way, deficient valves can be returned without wasting installation or setup time. When healthy valves are placed back inline, the setup and documentation of properly installed parts function much more smoothly.

Maintenance labor is used efficiently if problems and performance expectations are established as soon as the valve arrives. It is the rework and fault-finding that makes the job difficult. And post-repair testing is absolutely necessary to ensure proper valve function and to establish a paper trail for later squabbles. More subtle procedures, such as adjusting packing pre-load and checking actuator leaks are therefore simplified, standardized, and documented. With preparation, valve data can be consolidated into one easily accessible database.

Since information is the name of the game, simple file transfer can quickly move copies of valve records and performance standards to all repair workers participating in turnaround. Such a hygienic method ensures that everyone works from a standard playbook with a minimum of clerical work.

During turnaround, target valves and relevant accessories can be tested at the beginning, ensuring that only "unhealthy" valves are pulled. Valves can also be calibrated to function more accurately with the plant systems, thereby saving money in reaction time.

More product is generated from a higher percentage of unit uptime as a result of properly maintained valves. Properly operating valves not only throttle better, but they are also less prone to hunting-type instability. Their improved control creates better yields and higher efficiencies. By carefully using the diagnostic equipment, the actual dynamic response and control capabilities can be clearly defined, leading to the establishment of appropriate control strategies.

When it comes to repair, the vendor should have access to the plant’s performance standards with clearly defined expectations via networked file transfer or hard copy. This results in focused repair efforts instead of head-scratching and ultimately ineffective shotgun strategies.

Maintenance histories can then be updated and test data can be sent back to the plant for archival. The diagnostic report can be put into a data package for future reference and the valve history can help in the next repair or diagnostic cycle to better understand problems.

The bottom line is savings — savings in time, money, and work. Fewer valves pulled means shorter turnaround and more uptime. Less money and time are wasted on pointless repairs. Maintenance efforts are maximized and focused effectively. Future decisions are based on facts instead of speculation.

Utilizing available technology to institute an effective, common-sense control valve maintenance program is not just the smart decision, it is imperative for a plant to stay competitive and safe. The extent to which a program is implemented is up to management, but its absence is just not feasible in today’s modern system.

About the Author
David W. Douglas is the president of Paradigm Services LP and CPL Control Products of Louisiana, with over 25 years experience in global manufacturing and services for all phases of the oil and gas industry. His experience includes general management, acquisitions and divestitures, workouts and turnarounds, international and domestic alliance partnering, distribution channel management, and technical sales management. Paradigm Services is engaged in aftermarket service, repair, and remanufacturing of valves and actuators installed in refineries, petrochemical plants, power generation facilities, and pipelines and oil and gas production facilities. Prior to Paradigm Services, Mr. Douglas was President and CEO of ENERPRO International, Inc., He held various Management positions within Baker Oil Tools, Baker Hughes Tubular Services, and Reed Tubular. Mr. Douglas can be reached at 281-478-5200 or [email protected].

For More Information:

Sponsored Recommendations

Learn About: Micro Motion™ 4700 Config I/O Coriolis Transmitter

An Advanced Transmitter that Expands Connectivity

Micro Motion 4700 Coriolis Configurable Inputs and Outputs Transmitter

The Micro Motion 4700 Coriolis Transmitter offers a compact C1D1 (Zone 1) housing. Bluetooth and Smart Meter Verification are available.

Keys to Improving Safety in Chemical Processes

Many facilities handledangerous processes and products on a daily basis. Keeping everything undercontrol demands well-trained people workingwith the best equipment.

Micro Motion™ G-Series Coriolis Flow and Density Meter

Micro Motion G-Series: market-leading compact design featuring advanced process diagnostic capability.