One Stop Solution: From Single Valve to DBB And Blind Flange Isolation

Behind the complexities of valve operations, ensuring proper isolation of equipment and systems is crucial for maintaining reliability, regulatory compliance, and optimizing efficiency. It is important for operators to understand essential guidelines for isolating valves in an industrial plant. This article speaks to the key factors involved in operational continuity. Exploring modern advancements in valve technology and isolation strategies provides insights into how industry standards are evolving to meet operational guidelines pertaining to sustainability, safety, and innovation.

By Gobind Khiani, P.Eng., Fellow, Mechanical Engineering – Piping/Pipelines

Isolating an industrial plant involves multiple critical considerations to ensure safety, efficiency, and compliance with regulations. Here are a few top-level considerations:

1. Safety

• Employee Safety: Ensure that the isolation process minimizes risks to workers through proper training, protective equipment, and clear procedures.
• Environmental Safety: Prevent environmental contamination through controlled handling and disposal of hazardous materials.
• Public Safety: Minimize risks to nearby communities by implementing robust emergency response plans.

2. Regulatory Compliance

• Local and International Regulations: Comply with relevant safety and environmental regulations to avoid legal penalties.
• Industry Standards: Adhere to industry best practices and standards for plant isolation and shutdown procedures.

3. Operational Continuity

• Minimize Downtime: Plan the isolation to minimize operational downtime and maintain productivity.
• Maintenance and Repairs: Use the isolation period to conduct necessary maintenance and repairs efficiently.

4. Technical Considerations

• Isolation Procedures: Develop detailed procedures for isolating systems, including lockout/tagout protocols.
• Equipment Isolation: Ensure all equipment is properly isolated, deenergized, and tested for zero energy state.
• Instrumentation: Use reliable monitoring and control systems to verify isolation status.

5. Hazard Identification and Risk Assessment

• Identify Hazards: Conduct thorough hazard identification for all processes and materials involved.
• Risk Mitigation: Implement risk mitigation measures based on the assessment, including engineering controls and administrative procedures.

6. Communication

• Internal Communication: Ensure clear communication among all departments and personnel involved in the isolation process.
• External Communication: Communicate with regulatory bodies, emergency services, and the public as necessary.

7. Training and Competency

• Employee Training: Provide comprehensive training for all employees on isolation procedures and emergency response.
• Competency Assessment: Regularly assess the competency of employees to handle isolation tasks.

8. Emergency Preparedness

• Emergency Plans: Develop and regularly update emergency response plans.
• Drills and Simulations: Conduct regular drills and simulations to ensure readiness for potential incidents.

9. Documentation and Records

• Record Keeping: Maintain accurate records of isolation procedures, risk assessments, and safety checks.
• Documentation: Ensure all procedures and protocols are well-documented and accessible.

10. Environmental Impact

• Waste Management: Implement effective waste management practices to handle hazardous and nonhazardous waste.
• Pollution Control: Use pollution control technologies to minimize environmental impact during the isolation process.

By addressing these top-level considerations, an industrial plant can ensure a safe, compliant, and efficient isolation process.

In industrial settings, isolation levels typically refer to the degree to which equipment, systems, or processes are separated and protected to ensure safety and operational integrity. Different industries might have specific terminologies and standards, but the general levels of isolation include:

1. Primary Isolation

• Definition: The initial and most immediate form of isolation, typically involving the first barrier or control measure to prevent the flow of hazardous energy or materials.
• Examples:
  • Valves: Closing a valve to stop the flow of fluids or gases.
  • Circuit Breakers: Turning off a circuit breaker to cut electrical power.
• Usage: Common in routine maintenance or minor repairs where quick isolation is necessary.

2. Secondary Isolation

• Definition: Additional isolation measures that provide a second layer of protection, often used in conjunction with primary isolation to enhance safety.
• Examples:
  • Blanking or Blinding: Physically inserting a blank or blind into a pipeline to ensure no flow.
  • Double Block and Bleed: Using two isolation valves with a bleed valve in between to ensure complete isolation.
• Usage: Used for more critical maintenance tasks, or when working with hazardous materials where redundancy is important.

3. Tertiary Isolation

• Definition: Further isolation measures that provide an additional safety layer, often including redundant systems and safety devices.
• Examples:
  • Isolation of backup systems: Ensuring that even secondary systems are also isolated.
  • Enhanced containment: Using additional physical barriers or containment areas.
• Usage: Employed in high-risk operations or environments where utmost safety is required, such as chemical plants or nuclear facilities.

4. Physical Isolation

• Definition: Complete physical separation of equipment or systems, often involving disassembly or removal of components.
• Examples:
  • Removal of piping sections.
  • Disconnection of equipment.
• Usage: Utilized during major overhauls, significant repairs, or when equipment needs to be completely taken out of service.

5. Administrative Isolation

• Definition: Procedural and organizational measures to ensure isolation, often involving documentation, permits, and communication protocols.
• Examples:
  • Permit-to-Work Systems: Requiring formal permits for isolation tasks.
  • Lockout/Tagout (LOTO): Ensuring that equipment cannot be re-energized or operated until the work is complete.
• Usage: Essential for managing human factors, ensuring procedural compliance, and maintaining safety culture.

6. Electronic/Remote Isolation

• Definition: Use of electronic systems to isolate equipment remotely, often involving automated controls and monitoring systems.
• Examples:
  • SCADA Systems: Supervisory Control and Data Acquisition systems that allow remote isolation.
  • Remote Actuated Valves: Valves that can be controlled from a distance via electronic systems.
• Usage: Increasingly common in modern industrial plants for convenience and enhanced control, particularly in large or hazardous environments.

7. Emergency Isolation

• Definition: Rapid isolation measures designed to be activated in case of an emergency to quickly contain hazards.
• Examples:
  • Emergency Shutdown Systems (ESD): Systems designed to automatically or manually shut down processes in an emergency.
  • Fire Suppression Systems: Systems that isolate and contain fires or other hazards.
• Usage: Critical in situations where immediate action is required to prevent escalation of an incident.

Each level of isolation serves a specific purpose and is often used in combination to provide a comprehensive safety and control strategy in industrial operations. The appropriate level of isolation depends on the specific risks, operational requirements, and regulatory standards of the industry.

DBB Vs DIB

Originally, double block and bleed was conceived of as pressure responsive valves with a bleed valve in between. Our modern conception was transformed by the introduction of the trunnion ball valve.

When dealing with a typical trunnion mounted ball valve design, you can apply two features on seating arrangements:

Self-relieving seat: A valve seat designed to relieve pressure in the valve cavity. Depending on valve type, the pressure may be relieved to the pressure source, or the low-pressure side. Note: In a ball valve this is called a Single Piston Effect (SPE) seat.

Non-relieving seat: A valve seat designed to hold pressure in the valve cavity. In this instance an alternative means of pressure relief is required.

Note: In a ball valve this is called a Double Piston Effect (DPE) seat.

Double Block and Bleed (DBB): A single Valve with two seating surfaces that, in the closed position, provides seal against pressure from both ends of the valve, with a means of venting/bleeding the cavity between the seating surfaces.

Note: This valve does not provide positive double isolation if only one side is under pressure.

Does DBB Provide Isolation: Not Always! A valve with two SPE seats is considered a block and bleed valve, but if pressure rises in the body cavity the fluid will relieve through the seat with the least resistance, which is the low-pressure side.

Double Isolation and Bleed (DIB): A single Valve with two seating surfaces, each in the closed position, provides a seal against pressure from a single source, with a means of venting/bleeding the cavity between the seating surfaces.

Note: This feature can be provided in one direction or in both directions

DIB1: A DIB valve that has two non-relieving (DPE) seats. An external body relief is required in liquid service which is subject to thermal expansion. This valve provides DIB in either one or two directions, depending on the external relief configuration.

DIB2: A DIB valve with one non-relieving (DPE) and one self-relieving (SPE) seat. This valve only provides DIB in one direction (the side with the non-relieving seat is DIB protected)

The Alberta OHS (occupation health and safety) regulation calls for section 215.5 “Isolation requirements for piping or a pipeline” as below:

215.5(1) To isolate piping or a pipeline containing a substance under pressure, an employer must ensure the use of

• a system of blanking or blinding, or
• a double block and bleed isolation system providing
  • 2 blocking seals on either side of the isolation point, and
  • an operable bleed-off between the 2 seals.

215.5(2) An employer must ensure that piping or a pipeline that is blanked or blinded is clearly marked to indicate that a blank or blind is installed.

215.5(3) An employer must ensure that, if valves or similar blocking seals with a bleed-off valve between them are used to isolate piping or a pipeline, the bleed-off valve is secured in the “OPEN” position, and the valves or similar blocking seals in the flow lines are functional and secured in the “CLOSED” position.

215.5(4) An employer must ensure that the device used to secure the valves or seals referred to in subsection (3) is

• a positive mechanical means of keeping the valves or seals in the required position, and
• strong enough and designed to withstand unintended opening.

215.5(5) Despite subsection (1), if it is not reasonably practicable to provide blanking, blinding or double block and bleed isolation, an employer must develop and implement procedures for an alternate means of isolation certified by a professional engineer as safe and appropriate for the protection of workers.

With the current emphasis on sustainability, social responsibility, and governance (often referred to as ESG—Environmental, Social, and Governance), there is a growing demand for products and solutions that align with these principles. Designing valves with the latest technology can indeed play a significant role in achieving these goals. Here’s how:

1. Environmentally Friendly Design:

• Material Selection: Using sustainable and recyclable materials for valve construction can reduce environmental impact. Incorporating materials that require less energy for production and that are more durable can extend the lifespan of the valves, reducing waste.
• Energy Efficiency: Valves can be designed to minimize energy loss, ensuring that systems operate more efficiently. For example, using smart valve technology to optimize flow rates can reduce energy consumption in industrial processes.
• Leak Prevention: Advanced sealing technologies and designs that minimize leakage can not only enhance safety but also prevent the release of harmful substances into the environment, protecting ecosystems and reducing pollution.

2. Social Acceptability:

• Safety Features: Designing valves with safety features that protect workers and communities is crucial. This includes fail-safe mechanisms, easy-to-use interfaces, and clear labeling.
• Accessibility: This involves ensuring that valves are designed with accessibility in mind so they can be operated and maintained by individuals with varying levels of physical ability.
• Impact on Communities: Valves used in water treatment, for example, can contribute to the availability of clean water in communities, directly impacting public health and quality of life.

3. 3. Governance and Compliance:

• Regulatory Compliance: Valves must be designed to comply with international standards and regulations, such as those set by organizations like ISO or specific governmental agencies. This ensures that the valves meet safety, environmental, and quality requirements.
• Data Collection and Monitoring: Integrating sensors and IoT (Internet of Things) technology into valve designs can enable real-time monitoring and data collection, ensuring compliance with regulatory requirements and facilitating maintenance. This also helps in maintaining transparency and accountability.
• Cybersecurity: With the rise of smart valves and connected devices, ensuring robust cybersecurity measures is essential to protect data integrity and prevent unauthorized access.

4. Technological Integration:

• Smart Valves: Implementing IoT technology into valves can enable remote monitoring and control, predictive maintenance, and real-time data analytics. This not only improves efficiency but also helps in quick response to potential issues, minimizing downtime and environmental risks.
• Automation and AI: Using AI and automation in valve operation can optimize processes, reduce human error, and enhance safety and efficiency. Automated systems can react faster to changes in conditions, improving overall system reliability.

This innovation features a mechanically energized sealing mechanism that functions effectively, regardless of the differential pressure across the valve. It ensures friction-free rotation of the ball against the seats. By integrating two rising stem ball valves into a single valve body, this design achieves a more compact structure, enabling faster and more efficient operation while minimizing potential leak paths. This solution aligns seamlessly with OSHA’s definitions for “isolation” and “blanking or blinding.” It outperforms traditional blinding flanges in sealing capabilities and allows for physical isolation simply by operating the valve. This approach eliminates the need for extensive manual labor, reduces downtime, and minimizes the risk of material spills, making it a highly cost-effective solution.

They have been awarded ASME design of the “Woelfel Best Mechanical Engineering Innovation Award”.

Conclusion

By incorporating these elements into valve design, companies can create products that not only meet the current demands for safety and integrity in pipeline systems, and further incorporate sustainability, social responsibility, and governance, but also set the stage for future savings. Such a holistic approach not only adds value to the product but also aligns with the growing expectations of consumers, regulators, and investors for responsible and sustainable business practices.