New technology addresses control valve stem seal maintenance, regulatory issues

Packing serves as the primary valve stem sealing system in today’s control valves. This seal typically incorporates a mixture of packing rings that are compressed against the valve stem to eliminate or reduce process fluid leaks.

10/21/2004



Patented seal technology from Woodward provides a solution to common stem seal problems by creating a pressurized, viscous barrier between a set of high-pressure seals to prevent process fluids from leaking to the atmosphere.

Packing serves as the primary valve stem sealing system in today’s control valves. This seal typically incorporates a mixture of packing rings that are compressed against the valve stem to eliminate or reduce process fluid leaks. Packing material is typically made of Teflon or graphite-based materials and is selected on the basis of application conditions. Rings are compressed with a packing follower that can be manually adjusted or "live-loaded" with springs that apply continuous sealing force. The packing seal system functions by creating a tight seal between the material and valve stem.
High friction loads lead to seal wear and contamination and make these types of packing seals subject to frequent maintenance. As the valve strokes during normal operation, the valve stem abrades the packing material. Over time, the seal wears, and the packing needs to be repaired or replaced.
Seal contamination is another significant source of packing system maintenance. In an open bonnet valve design, the valve stem area is exposed to the surrounding environment. Foreign material (dust, dirt, corrosives), common in a plant environment, clings to the valve stem and is pulled through the seal system, causing seal damage.
If the seals are not properly maintained, fluid can leak past the packing box into the atmosphere. Leakage can be an environmental or safety concern—or both—depending on fluid type. The Clean Air Act limits fugitive valve emissions (fluid leaks) for hydrocarbon-based fluids, measured at the point of origin. Plants that do not meet fugitive emissions standards may be subject to stiff penalties. Regulatory requirements, combined with poor sealing performance, can greatly increase the cost of valve monitoring and maintenance.
A patented E3 Seal technology recently introduced by Woodward provides one solution to common stem seal problems. This new design creates a pressurized, viscous barrier between a set of high-pressure seals, preventing process fluids from leaking to the atmosphere. This system also lubricates the valve stem and protects it from environmental debris and corrosion, significantly extending the required maintenance interval over that of traditional packing systems.

The advanced E3 Seal technology, part of the company’s new GVP-100 control valve system, eliminates fugitive emissions and helps users comply with Clean Air Act standards and state emissions mandates without need for frequent routine stem seal maintenance.

Click here for more information on E3 Seal technology and to download a complete technical application note from the Woodward Web site .

Click here to read more from Control Engineering on the GVP-100 control valve.

—Edited by Jeanine Katzel, senior editor, Control Engineering, jkatzel@reedbusiness.com





No comments
The Engineers' Choice Awards highlight some of the best new control, instrumentation and automation products as chosen by...
The System Integrator Giants program lists the top 100 system integrators among companies listed in CFE Media's Global System Integrator Database.
The Engineering Leaders Under 40 program identifies and gives recognition to young engineers who...
This eGuide illustrates solutions, applications and benefits of machine vision systems.
Learn how to increase device reliability in harsh environments and decrease unplanned system downtime.
This eGuide contains a series of articles and videos that considers theoretical and practical; immediate needs and a look into the future.
Robotic safety, collaboration, standards; DCS migration tips; IT/OT convergence; 2017 Control Engineering Salary and Career Survey
Integrated mobility; Artificial intelligence; Predictive motion control; Sensors and control system inputs; Asset Management; Cybersecurity
Big Data and IIoT value; Monitoring Big Data; Robotics safety standards and programming; Learning about PID
Featured articles highlight technologies that enable the Industrial Internet of Things, IIoT-related products and strategies to get data more easily to the user.
This article collection contains several articles on how automation and controls are helping human-machine interface (HMI) hardware and software advance.
This digital report will explore several aspects of how IIoT will transform manufacturing in the coming years.

Find and connect with the most suitable service provider for your unique application. Start searching the Global System Integrator Database Now!

Mobility as the means to offshore innovation; Preventing another Deepwater Horizon; ROVs as subsea robots; SCADA and the radio spectrum
Future of oil and gas projects; Reservoir models; The importance of SCADA to oil and gas
Big Data and bigger solutions; Tablet technologies; SCADA developments
Automation Engineer; Wood Group
System Integrator; Cross Integrated Systems Group
Jose S. Vasquez, Jr.
Fire & Life Safety Engineer; Technip USA Inc.
This course focuses on climate analysis, appropriateness of cooling system selection, and combining cooling systems.
This course will help identify and reveal electrical hazards and identify the solutions to implementing and maintaining a safe work environment.
This course explains how maintaining power and communication systems through emergency power-generation systems is critical.
click me