Discover how engineering excellence, and offshore flow control innovation have driven Severn’s OCT TOV Butterfly Valve to deliver unmatched reliability in seawater service valve applications and harsh offshore environments.

Severn’s research & development team has designed a Butterfly Valve for Seawater Applications that solves the problem of galvanic corrosion in offshore systems and meets strict firesafe valve standards. Utilising over 65 years of engineering excellence in industrial valve design, the team of technical valve specialists achieved this by using Severn’s patented Oblique Cone Technology (OCT). The OCT‑SW Butterfly Valve takes this proven control and isolation valve technology to the next level by eliminating the need for graphite in the seal while maintaining full firesafe performance required for critical offshore safety systems.

What is galvanic corrosion and its costly effects?

The impact of galvanic corrosion in seawater valve systems on critical offshore assets due to marine process conditions is an enduring problem for offshore oil & gas installations, FPSOs, and sealine infrastructure. At best, it increases maintenance workload and repair activity during planned shutdowns. At worst, it can result in rapid or unexpected valve failure, leading to unplanned production downtime or emergency shutdowns.

Either way, galvanic corrosion presents a significant lifecycle cost risk that negatively impacts plant efficiency, operational reliability, and total cost of ownership. However, Severn has utilised its engineering heritage, in‑house R&D capability, and valve repair intelligence to develop a seawater butterfly valve solution that tackles galvanic corrosion head‑on.

Why does galvanic corrosion occur?

The cause of galvanic corrosion (also referred to as dissimilar metal corrosion or bimetallic corrosion) is an electrochemical reaction between two different conductive materials in close proximity within an electrolyte, such as seawater processing systems. One material – typically the least noble – is preferentially corroded.

In offshore valve design, the classic rule of “do not mix metals” is difficult to achieve due to extreme environmental conditions, fire safety requirements, and stringent materials specifications.

Modern offshore safety systems, such as firewater systems, must withstand continuous exposure to corrosive seawater, while delivering reliable isolation and control valve performance during normal operation and emergency conditions. Seawater service valves therefore play a critical safety role, making the elimination of galvanic corrosion while maintaining firesafe valve certification a long‑standing industry challenge.

The graphite challenge in seawater valve applications

In recent years, graphite sealing technology has become widespread in industrial valve manufacture due to its excellent thermal resistance, chemical stability, and flexibility. However, graphite is also the only non‑metallic electrical conductor and is more noble than many metals commonly used in offshore valve construction, including stainless steel, bronze, and titanium.

As a result, when graphite is exposed to seawater in contact with these metals, it can accelerate galvanic corrosion, particularly within seawater butterfly valves, control valves, and firewater isolation valves.

Traditionally, Severn’s Triple Offset Butterfly Valves utilised graphite in parts of their construction, which in seawater service applications could contribute to galvanic corrosion. Over time, this may compromise sealing integrity, valve reliability, and plant safety, potentially leading to costly unplanned outages.

Engineering a long‑term seawater valve solution

By working closely with offshore operators, EPC contractors, and end users, Severn identified this challenge and applied its extensive engineering heritage and technical valve design expertise to develop a long‑term solution.

The Severn engineering team designed a valve that either eliminates graphite entirely or isolates it completely from the line media, significantly reducing the risk of galvanic corrosion during normal operation. This ensures the highest levels of operational safety, asset protection, and system reliability, supporting the industry’s requirement for safe operations and minimal downtime.

OCT‑SW Triple Offset Butterfly Valve for Seawater & Firewater Systems

Severn’s OCT‑SW Triple Offset Butterfly Valve is a high‑performance seawater valve solution developed specifically for offshore sealine applications, firewater systems, and marine utility services.

These valves play a pivotal role in offshore safety systems, particularly where rapid isolation, reliable shut‑off, and firesafe operation are mandatory. Leveraging over 65 years of oil & gas valve engineering experience, the OCT‑SW valve has been designed to help operators meet their core objectives of safety, reliability, and reduced downtime.

Hybrid metallic‑polymer sealing technology

Severn has developed a hybrid polymer‑metallic sealing arrangement that removes the need for graphite laminates. By combining a primary metallic seal with a secondary polymer seal, Severn has:

• Eliminated graphite exposure to seawater
  Increased isolation valve sealing performance
  Maintained full firesafe valve certification

Furthermore, by ensuring that any remaining graphite gaskets and packings are fully isolated from the process media, the design prevents graphite and seawater from ever coming into contact. This eliminates galvanic corrosion risk, protecting production uptime, asset integrity, and operating efficiency.

Certified firesafe and ATEX‑compliant valve design

In addition to mitigating corrosion, Severn’s Butterfly Valves for Seawater Applications meet key firesafe testing standards, including:

• API 6FA
• API 607
• ISO 10497

This confirms the OCT‑SW valve as a certified fire‑safe valve, suitable for critical emergency scenarios.

The design also complies with ISO/IEC 80079‑36:2018 (ATEX) requirements, ensuring that static charge build‑up is eliminated and preventing any risk of spark generation. This makes the valve suitable for a broader range of hazardous area applications, extending beyond seawater service and reinforcing its versatility.

Materials, retrofitting & offshore suitability

The Severn OCT‑SW Butterfly Valve can be manufactured in a range of corrosion‑resistant materials, including:

• Aluminium Bronze
• Super Duplex Stainless Steel
• Titanium

Anti‑blowout protection is provided as standard. Available in standard and non‑standard face‑to‑face dimensions, with lugged and double‑flanged body styles, the valve can be easily retrofitted into existing offshore pipeline systems. This makes it an ideal upgrade solution for operators experiencing galvanic corrosion issues in seawater valve systems.

Severn’s engineering heritage and technical expertise have led to the OCT TOV Butterfly Valve being future-proof for changes in the process conditions to provide increased versatility for the end user seeking reliable high‑performance triple offset butterfly valves, industrial isolation valves, and severe‑service valve solutions.

From the outset, Severn made flexibility a key driving force in the design of the Oblique Cone Technology (OCT) Triple Offset (TOV) Butterfly Valve. Due to Severns extensive diverse engineering heritage and excellence, our expert team of engineers understand that processes and application product demands change over time, whether it is the process conditions or the overall requirements of the valve for the end user. Due to this understanding, the Oblique Cone Technology Triple Offset Butterfly Valve has been designed to incorporate multiple seal options, all fully interchangeable with each other, providing maximum application diversity and usability to ensure safe operations and minimum downtime making it ideal for oil & gas isolation, refinery valve applications, petrochemical process valves, and critical shutdown and control operations.

The Laminate seal is the “traditional” Triple Offset Valve seal and consists of multiple metal and graphite layers providing isolation sealing for high‑temperature, high‑pressure, and severe‑service applications.

The OCT HS seal is a hybrid polymer metallic seal, this seal benefits from a primary metal seal and secondary polymer seal, this provides a reliable and repeatable bubble tight seal time after time. This can also be paired with PTFE packings when graphite being in contact with the line media is a concern. The polymer seal is fully compliant with EN ISO 80079-36 (ATEX) making it an excellent choice for ATEX‑rated butterfly valves, hydrocarbon service valves, and zero‑leakage industrial valves.

The OCT SW Valve takes the hybrid sealing to the next level with its versatile high performance. Severn utilises the OCT-HS seal and has designed a valve that ensure there is no graphite in contact with the line media to remove the risk of costly galvanic effects such as internal corrosion leading to valve failure. Whilst doing so the OCT-SW also maintains firesafe certification making it suitable for Firesafe Triple Offset Valves, API 607 certified valves, and critical isolation applications in hazardous environments.

Should the sealing requirement not become as critical, and process conditions become more arduous, the Laminate and Hybrid seals can be changed for the OCT-SS solid seal. As the name suggests it is a solid metallic seal, that can be made from hard-wearing alloys to add longevity to the sealing life of the valve in arduous conditions and can offer a control valve seat leakage ideal for erosion‑resistant valve applications, abrasive service, and high‑cycle industrial operations.

Based on Severns comprehensive history of severe service control, our team of engineering experts work closely with operators and end uses to identify the correct seal and material selection to provide the maximum reliability and productivity further ensuring minimum downtime supporting industries such as LNG, chemical processing, power generation, and midstream pipeline operations.

All the OCT seals are interchangeable and can be upgraded without the need for main valve components being replaced, further emphasising the OCT TOV Butterfly Valves versatility. The fully in field serviceable valve can be upgraded on-site without the need for specialist tools or knowledge, this further ensures that costly unplanned downtime and site waste is kept to a minimum, along with potential loss in production for the end user. All the seal options can be changed on site within a small space of time to ensure site maintenance costs are reduced by upgrading the existing valve rather than discarding and replacing with a commodity product each time making it a cost-efficient solution for industrial valve maintenance, asset lifecycle extension, and retrofit valve upgrades.

Each OCT valve is specially designed to be versatile and ensure it has multiple purposes for multiple conditions whilst still delivering maximum performance. With the introduction of the interchangeable seal, these can be easily swapped out to match the end users’ requirements, should they change ensuring adaptability for future process changes, sustainability improvements, and long-term operational efficiency.

Severn are breaking tradition with the innovative OCT Butterfly Valve and lifecycle enhancement service.

In the fast-paced industrial landscape, the emphasis on sustainability and cost-effectiveness has never been greater. Severn’s Oblique Cone Technology (OCT) Triple Offset (TOV) Butterfly Valve is at the forefront of a new era in valve technology, where the focus shifts from immediate replacements to intelligent lifecycle enhancement and repair strategies which makes repair not replace valves. This paradigm shift not only promotes sustainable valve maintenance but also ensures safe operations, reduced downtime, helping you achieve your core remits.

Lifecycle Enhancement: Prolonging Valve Longevity

The traditional approach to valve maintenance often involves a “replace-first” mentality. However, Severn’s OCT TOV Butterfly Valve challenges this norm by offering a comprehensive lifecycle enhancement program by repair not replace valves. Through cutting-edge innovative engineering and materials, Severn’s OCT TOV Butterfly Valve is designed to withstand harsh operating conditions, ensuring a longer lifespan with its patented Oblique Cone Technology Triple Offset capabilities for both isolation and control applications.

By prioritizing lifecycle enhancement, industries can optimise their assets, reduce overall operational costs, and minimise the environmental footprint associated with the manufacturing and disposal of new valves.

Repair Intelligence: Smart Solutions for Complex Issues by Severn’s Repair not Replace Valve

Severn’s OCT TOV Butterfly Valve affirms the concept of Severn’s repair intelligence as the valves are designed with modular components, facilitating easy disassembly and reassembly during repairs. This not only reduces maintenance costs but also minimises the need for complete valve replacements, contributing to a more sustainable and cost-effective approach to industrial operations.

Sustainable Valve Maintenance: A Green Approach

Severn’s commitment to sustainability goes beyond the valve’s design. The OCT TOV Butterfly Valve promotes a circular economy by encouraging refurbishment and reconditioning of components. With our expert team of service engineers based globally, we can retrofit, service and repair any of our Butterfly valves on site if performance has dropped or specification or operating conditions have changed, this ensures production downtime is kept to a minimum.

Furthermore, sustainable valve maintenance aligns with global initiatives to reduce carbon emissions. By extending the life of industrial equipment, companies can decrease their carbon footprint associated with manufacturing and disposal, contributing to a greener and more environmentally responsible future.

Safe Operations and Reduced Downtime: The Ultimate Value Proposition

The OCT TOV Butterfly Valve prioritise safety through rigorous testing and compliance with industry standards such as API 598. By implementing repair intelligence and lifecycle enhancement strategies, Severn can ensure the continued reliability and safety of their valves and valve systems.

Moreover, the ability to address issues proactively minimise unexpected costly downtime. This not only enhances operational efficiency but also safeguards against potential safety hazards, ensuring a secure working environment for personnel.

Environmental Impact: A Positive Footprint for Future Generations

By choosing repair over replacement and embracing Severn’s lifecycle enhancement, industries using Severn’s OCT TOV Butterfly Valve actively contribute to reducing the environmental impact of their operations. Through sustainable valve maintenance practices, companies can align with global environmental goals, demonstrating corporate responsibility and leadership in their respective sectors.

Severn’s OCT TOV Butterfly Valve signifies a paradigm shift in the industrial valve landscape. By championing lifecycle enhancement, repair intelligence, and sustainable valve maintenance, this product offers not just cutting-edge technology but a comprehensive solution for industries seeking a balance between operational efficiency, environmental responsibility, and cost-effectiveness. In a world where every decision impacts the planet, choosing to repair, not replace, is a step towards a more sustainable and resilient future.

Remote inspection technology gains momentum.

Adoption of Severn Oculi, our connected system for the remote inspection of valves, is going from strength to strength. As well as assessing valve condition in the field, the digital system can be used to facilitate remote witness testing. 

Severn Glocon Abu Dhabi recently conducted a full pressure, seat leakage and functional test on a 2- 9/16 API 10,000 globe control valve for ADNOC, with the process witnessed virtually by the client team. Various work scopes have been witness-tested in this way in recent weeks to demonstrate the technology to our clients.    

The SVS team has also been holding internal video conferences to introduce the technology and its benefits to the wider Group. If you would like to participate in a future demonstration, please contact support@svsi.ae.  

With the global pandemic response still restricting movements and international travel, remote inspection technology gains momentum as Severn Oculi is proving to be a valuable tool. It’s set to deliver a good return on investment, improving cost efficiency for Severn and our customers alike.

Severn manufactures and supports high quality valves for the energy industries. Its control, choke and small bore subsea valves are pre-eminent in the global market, underpinning the reliability and high performance of business-critical client infrastructure.

Severn’s global reach, technical prowess, and collaborative approach – all founded upon a heritage of British engineering excellence – help to assure production continuity for clients and reduce the prospect of costly downtime. 

Its understanding of the life-cycle of assets positions Severn to offer end-to-end engineering solutions, enabling clients to meet their core imperatives: safe operations and minimum downtime.