In applications requiring remote operation or frequent switching, an automatic line blind valve is typically equipped with either electric or hydraulic actuation. The fundamental difference between the two does not lie in whether they can be used, but in their load capacity, response characteristics, environmental adaptability, and system complexity. 1. Electric Actuation (Electric Actuated Line Blind Valve) Electric actuation uses a motor combined with a reduction gearbox to generate torque, driving the blind plate to complete the switching operation. Selection logic: ● If power supply on site is stable → electric actuation should be prioritized ● If remote control or automation integration (DCS/PLC) is required → electric actuation is more straightforward ● If switching frequency is relatively high → electric actuation allows better control of operation speed Key features: ● Simple control: can be directly integrated into control systems, enabling remote operation and position feedback ● Compact structure: no additional hydraulic power unit required ● Lower maintenance requirements: routine checks mainly involve the motor and gearbox Limitations: ● If valve size is large or high thrust is required → electric actuation may have insufficient torque ● If the environment is high-temperature, hazardous (explosive), or dusty → higher electrical protection standards are required (e.g., ATEX) ● If power supply is unstable or frequently interrupted → reliability may decrease Conclusion:If the application involves standard automation requirements and moderate load conditions, electric actuation is generally the preferred solution. 2. Hydraulic Actuation (Hydraulic Actuated Line Blind Valve) Hydraulic actuation generates thrust through hydraulic fluid pressure, making it suitable for high-load applications. Selection logic: ● If valve size is large (e.g., DN300 and above) → hydraulic actuation should be prioritized ● If high thrust is required or resistance/sticking needs to be overcome → hydraulic actuation is more stable ● If a hydraulic system is already available on site → integration cost is lower Key features: ● High thrust output: suitable for heavy-duty blind plates or high-pressure pipelines ● Stable operation: provides continuous output with strong resistance to shock loads ● Good controllability: enables precise control through pressure regulation Limitations: ● If no hydraulic power unit is available on site → system complexity increases ● If ambient temperature variation is significant → hydraulic fluid performance may fluctuate ● If maintenance is insufficient → leakage issues are more likely to occur Conclusion:If the application involves high load and high reliabili...
Recently, DERVOS Valve successfully passed the audit by the American Petroleum Institute (API). The company’s API Spec 6D certification for pipeline valves has been renewed, and the API 600 certification has also been issued. Both certificates are valid through 2029. What is an API6D certificate? API 6D is an internationally recognized standard for valves used in oil and gas pipeline transportation systems. It covers the full process requirements for design, manufacturing, and inspection of products such as ball valves, gate valves, and check valves. The certification typically requires renewal audits every three years. What is an API600 certificate? API 600 is an internationally recognized standard for steel gate valves used in oil and gas refinery applications. It defines requirements for design, materials, manufacturing, inspection, and testing. This certification is generally subject to renewal every three years to maintain validity. According to available information, the audit covered multiple aspects, including quality management system operation, production process control, inspection equipment calibration, and personnel qualifications. During the audit, the API inspection team conducted an on-site review of the entire process at DERVOS Valve, from raw material procurement to final product delivery. A representative from the company’s quality department stated that DERVOS Valve has been continuously improving its standardized system management and has established a quality control system covering the full product lifecycle. Key production processes are supported by standardized work instructions, and inspection records are fully traceable to individual orders. The successful renewal of these certifications demonstrates that DERVOS Valve continues to meet API requirements in product manufacturing and quality assurance within the industrial valve sector. It also supports the company’s qualification to supply products for international projects such as oil and gas pipelines and LNG receiving terminals. The company stated that it will continue to focus on standardized production and process management to ensure the effective operation of its quality management system.
Gate valves and blind valves are both used for pipeline isolation, but they operate on fundamentally different principles.In industrial piping systems, if the objective is true physical isolation (positive isolation), then a blind valve (Blind Valve / Line Blind Valve) is generally more reliable than conventional valves. Instead of relying on seat sealing, it isolates the medium through a solid blind plate, which defines both its application scope and engineering value. The key features of a blind valve can be understood from an engineering perspective as follows: 1. Absolute Physical Isolation If zero leakage is required, then conventional valves (such as gate valves or ball valves) introduce risk, as their performance depends on sealing integrity. Blind valves follow a different logic: ▶ If a solid plate is inserted, then the flow is completely blocked▶ If the blind plate is correctly positioned, then sealing failure is no longer a concern This makes blind valves more suitable for: ● Oil & gas pipeline isolation ● Flammable media (petroleum, LNG, chemicals) ● High temperature steam systems Engineering conclusion:If the project requires verifiable isolation, then a blind valve should be prioritized over sealing-dependent industrial valves. 2. Inline Operation Capability Traditional spade and spacer blinds typically require flange disassembly, which increases operational complexity and introduces safety risks. Blind valves (such as sliding blind valves and swing blind valves) are designed with a different approach: ▶ If frequent switching between operation and maintenance is required, then manual intervention must be minimized▶ If shutdown is not permitted, then switching must be performed under pressurized pipeline conditions (subject to specific design) Therefore: ● Sliding Blind Valve: suitable for limited space and higher automation requirements ● Swing Blind Valve: simple structure, suitable for medium to low switching frequency ● Spectacle Blind Valve: suitable for low-frequency operation and cost-sensitive projects Engineering conclusion:If maintenance is frequent or shutdown is not feasible, then a blind valve with inline operation capability should be prioritized. 3. Mechanical Reliability The reliability of a blind valve does not depend on complex sealing systems, but on: ● Mechanical structural stability ● Material strength (such as A105, WCB, F22, LF2) ● Actuation method (manual, gear-operated, or hydraulic) ▶ If the service conditions involve high temperature, high pressure, or corrosive media, then sealing-based valves are more prone to failure▶ If...
Previously, DERVOS supplied a batch of floating ball valves, trunnion-mounted ball valves, and swing check valves for the MOL refinery upgrade project in Hungary. Detailed specifications and technical data for this project are available in the previous case study.
Recently, the DERVOS team visited Hungary to conduct a follow-up inspection at the same project site. The purpose of the visit was to evaluate the actual operating condition of the supplied valves, communicate directly with the client’s on-site engineering team, and collect feedback after several months of operation.
During the visit, it was confirmed that the MOL refinery is currently in a post-incident recovery phase. In October 2025, a fire occurred in the AV3 crude distillation unit, and repair work is ongoing. Full production capacity is expected to resume in Q3 2026.
Despite this, in units that remain operational or are in maintenance intervals, all valves supplied by DERVOS are functioning normally. The client confirmed that no performance issues related to DERVOS valves have been reported.
The DERVOS team accessed the valve installation areas for on-site inspection. Particular attention was given to four trunnion-mounted ball valves equipped with 2-meter extended stems, a customized design to meet specific operating distance requirements.
It was observed that the extended stem design allows operators to control the valves from a safe and accessible distance. The IP68-rated worm gear operators also demonstrated reliable sealing performance under local environmental conditions.
The team also inspected floating ball valves and swing check valves installed in medium-pressure and high-temperature zones. No leakage or abnormal operation was identified.
During technical discussions, the client’s engineering team provided positive feedback. One project manager commented:
“DERVOS clearly understands our operating conditions. The extended stem solution is exactly what we required. So far, the valves have operated reliably, with no unplanned downtime.”
The client also acknowledged DERVOS for its prompt response during the delivery phase and the clarity of the technical documentation provided.
This visit was part of DERVOS’s standard after-sales follow-up. For each project, DERVOS provides an 18-month warranty from the date of shipment. Any quality-related issues are addressed promptly.
During the visit, the team reviewed installation and maintenance records together with the client’s on-site maintenance personnel. No outstanding issues were identified.
The MOL Danube Refinery, located in Százhalombatta south of Budapest, is one of the largest refineries in Central and Eastern Europe, with a processing capacity of 165,000 barrels per day.
MOL Group is also advancing geothermal exploration around the refinery and has established a solar park and a green hydrogen facility. Although DERVOS valves are used in a conventional refinery upgrade project, this visit provided broader insight into the client’s transition toward low-carbon operations.
This site visit in Hungary was more than a routine follow-up. It reflects DERVOS’s commitment to the full product lifecycle—from engineering and delivery to post-commissioning support.
Going forward, DERVOS will continue to provide reliable valve solutions and proactive field support for MOL and other refinery clients across Europe.
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The refinery of MOL, located in Hungary, requires regular ball valve and check valve replacements to maintain optimal performance. As a trusted check and ball valve supplier of MOL, DERVOS continues to provide ball valves for their operations. In this project, DERVOS supplied a batch of high-performance ball valves and check valves for fluid control in oil and gas applications. They required various types and specifications of ball and check to meet the operational and sealing requirements of different pipeline systems.
In 2017, DERVOS contributed to an innovative environmental initiative led by ECOFUEL, an emerging canadian player in clean technology. This groundbreaking project aimed to produce sustainable diesel from solid waste, setting a precedent in green energy solutions. DERVOS is proud to have provided 136 sets of premium valves to support this pioneering effort.
Project Background In 2024, DervosValve was selected as a trusted valve supplier for a refinery project in Hungary. The client required large-sized industrial valves capable of handling complex and high-pressure oil and gas media. With years of engineering experience and proven track records in the energy sector, Dervos was chosen to provide a complete valve solution tailored to the refinery’s operational needs. Scope of Supply ● 10 pcs Gate Valves ● 9 pcs Check Valves All valves were designed and manufactured according to API and ASME standards, ensuring compliance with international refinery safety and performance requirements. Product Design & Technical Highlights The supplied valves feature bolted bonnet design, flexible wedge, and rising stem with yoke support, which enhance sealing reliability and facilitate maintenance. Their large-scale structure was customized to fit the refinery’s pipeline system, allowing smooth fluid control and stable operation under high temperature and pressure. Performance in Refinery Conditions Refinery environments involve frequent temperature fluctuations and medium impurities. Dervos valves demonstrated outstanding sealing performance, corrosion resistance, and mechanical strength, ensuring long-term stability with minimal maintenance requirements. The bolted bonnet design also makes disassembly and inspection more convenient during scheduled shutdowns. Why the Client Chose Dervos The Hungarian client valued Dervos for: ● Proven experience in oil & gas valve solutions ● Strict material traceability and quality control system ● Flexible customization capabilities for large valve dimensions ● On-time delivery and complete documentation support Throughout the project, our technical and logistics teams worked closely with the client’s engineers, ensuring each valve was tested, packaged, and delivered to meet project timelines and refinery installation standards. Customer Feedback & Project Outcome After installation and commissioning, the refinery reported stable operation and precise flow control performance. The valves’ large design and robust construction fully met system pressure and flow requirements. The client expressed satisfaction with both the quality and Dervos’ technical responsiveness, laying a solid foundation for future cooperation. Conclusion This successful refinery project in Hungary once again highlights Dervos’ ability to deliver reliable, large-size valve solutions for the oil and gas industry. We continue to serve our global partners with precision engineering, professional service, and long-term reliability.
1. Challenges Faced by the Client An oil terminal operator in South Africa, handling multiple light petroleum products such as HSD, MA, and JET-A1 within its pipeline system, encountered the following key challenges: ● Volatile and complex media: Aviation fuels such as JET-A1 require extremely high sealing performance; even minor leakage poses significant safety risks. ● Frequent media switching: Reliable physical isolation is required during product changeover. Conventional valves cannot achieve absolute shut-off. ● Insufficient sealing performance: Standard gate valves and ball valves present a risk of internal leakage after prolonged service. ● Strict safety requirements: The client specified a clear requirement for “zero visible leakage.” 2. Our Solution To address these operating conditions, Dervos Valves supplied a Slide Blind Valve, with the following key configurations: Design Type: Slide Blind (Spectacle Blind / Line Blind) ● Switching between a solid plate and a spacer enables complete shut-off or full flow. ● Provides visual and verifiable positive isolation, meeting high safety requirements. Sealing Design: Drip-tight Construction ● Effectively prevents leakage and evaporation of light hydrocarbons. ● Suitable for stringent sealing requirements of aviation fuel service. Pressure Rating and Standards: ● Class 150, in accordance with ASME B16.34 ● Flanged connection: Raised Face (RF) Material: ASTM A105 Forged Steel ● Offers high mechanical strength and pressure resistance. ● Well-suited for petroleum service, balancing cost efficiency and reliability. Operation: Worm Gear (Turbine Drive) ● Suitable for large diameter (10") applications, reducing manual effort. ● Enhances operational stability and safety during switching. 3. Results Achieved In actual operation, the slide blind valve enabled reliable physical isolation between different petroleum products, ensuring a clearly verifiable disconnected state during media switching. This fundamentally eliminates the risk of internal leakage associated with conventional valves. The drip-tight design effectively controlled evaporation and leakage when handling light hydrocarbons such as HSD, MA, and JET-A1, significantly improving on-site safety performance. In addition, the worm gear operation provided smoother and more controlled switching, reducing manual effort and minimizing the risk of operational errors, even in large-diameter applications. Overall, the solution not only met the client’s stringent requirements for high sealing integrity and safety, but also improved the operational stability and maintenance reliability of the pipeline system.
Zimbabwe National Oil Infrastructure Company (NOIC) Tank Farm Project This article is based on a tank farm project of the Zimbabwe National Oil Infrastructure Company (NOIC), focusing on practical challenges in pipeline isolation and maintenance switching, including flammable media, the requirement for pressurized operation, and high reliability under outdoor conditions. The solution involves a 10" 150LB swing type line blind valve, designed in accordance with ASME B16.34, with WCB cast steel body and metal sealing tested to API 598 zero leakage standards. Combined with worm gear operation and an anti-misoperation mechanism, the valve enables positive isolation switching without depressurization or shutdown. The implementation effectively improves operational safety, enhances maintenance efficiency, and reduces downtime losses. This case provides practical reference for engineers involved in pipeline isolation, valve selection, and online maintenance in the oil & gas industry. Project Background ● End User: Zimbabwe National Oil Infrastructure Company (NOIC) ● Installation Location: Petroleum storage terminal, Zimbabwe ● Medium: Petroleum ● Operating Requirement: The pipeline must reliably switch between normal operation and maintenance conditions, with strict requirements for safe isolation and zero leakage shut-off. Challenges Faced by the Client 1) Flammable Medium with High Safety RequirementsThe transported medium is petroleum. Any leakage may result in serious safety incidents. Therefore, high sealing integrity and operational reliability are required. 2) Requirement for Isolation Under PressureConventional valves cannot provide positive isolation without depressurization during maintenance. Depressurization leads to operational interruption, product loss, and additional restart costs. 3) Outdoor Installation with High Reliability DemandThe valve is installed in an outdoor station. It must withstand site environmental conditions and ensure stable operation with controlled risk of misoperation over long-term service. Solution To address the above conditions, Dervos Valve supplied a 10" 150LB swing type line blind valve with the following key design features: 1) Design Standard and MaterialThe valve is designed and manufactured in accordance with ASME B16.34. The body material is WCB cast carbon steel, suitable for petroleum service conditions, with a temperature range of -29°C to 150°C, offering adequate corrosion resistance and mechanical strength. 2) Sealing PerformanceThe sealing pair adopts a precision-machined soft sealing structure, tested in accordance with API 598. It achieves reliable zero leakage under petroleum service conditions, ensuring safe pipeline isolation. 3) Swing Type Blind StructureThe swing blind plate allows switching between flow and blind positions without pipeline disassembly or depressurization. This enables rapid transition and solves the limitation of conventional valves in achieving online positive isolation. Swing Type Blind Technical Drawing 4) Operation and Safety DesignEquipped with a worm gear operator and anti-misoperation device, the valve ensures smooth manual operation with clear position indication, minimizing the risk of incorrect operation in field conditions. Implementation Results After commissioning, the solution delivered the following benefits: 1) Reliable Isolation PerformanceThe valve meets API 598 leakage requirements. No leakage has been observed during operation, ensuring safe pipeline performance. 2) Improved Maintenance EfficiencyThe swing type structure enables online isolation without depressurization. Maintenance time is significantly reduced, minimizing production interruption. 3) Controlled Operational SafetyClear blind position indication and anti-misoperation design reduce risks for field operators, aligning with safety management practices in oil & gas facilities. Conclusion In this project, Dervos Valve provided a swing type line blind valve solution that achieves safe isolation under continuous operation in petroleum service. The solution ensures long-term sealing reliability and meets the project's requirements for safety, reliability, and operational efficiency in national oil infrastructure applications.
In an industrial steam system project in Hungary, a DN400 PN40 sliding blind valve was applied to achieve safe isolation and zero leakage shut-off under high-temperature conditions. What Challenges Are Commonly Encountered in Steam System Maintenance? In industrial steam systems, maintenance activities often face several practical challenges.In this project, the main issues included: ● The process medium was steam, with an operating temperature of approximately 250°C and a design temperature range from -39°C to 350°C, requiring the equipment to withstand both high-temperature and low-temperature conditions. ● The steam system required high sealing performance; conventional valves are prone to sealing failure under high-temperature steam conditions. ● During pipeline maintenance, safe isolation was required; traditional isolation methods could not achieve blind switching without depressurization. ● The valve was exposed to outdoor conditions, with ambient temperatures as low as -39°C, requiring high structural reliability and safe operation. How Can These Challenges Be Addressed in High-Temperature Steam Pipeline Systems? Based on the actual service conditions and technical requirements, Dervos Valve provided a customized DN400 PN40 forged sliding blind valve solution: 1. Material and Standards Designed in accordance with EN 12516, the valve body is made of ASTM A350 LF2 forged steel, offering both low-temperature impact toughness down to -40°C and stable strength at temperatures up to 350°C, suitable for wide temperature fluctuations. 2. Sealing Design The sealing pair adopts Stellite hardfacing with precision-machined metal sealing surfaces, meeting EN 12266-1 Leakage Class A requirements.Reliable zero leakage performance is maintained under 250°C saturated steam and thermal cycling conditions. 3. Structure and Operation The full-bore design reduces flow resistance, while a gear-operated mechanism ensures smooth operation for large-size PN40 valves. The sliding blind structure enables inline isolation switching without depressurization or pipeline disassembly, combined with: ● Mechanical interlock to prevent misoperation ● Visual position indication This significantly improves maintenance safety. Project Performance Since commissioning, the valve has completed more than 20 pressurized isolation operations, with sealing performance consistently meeting Class A requirements and no internal or external leakage observed. The switching time for each isolation operation is controlled within 10 minutes, significantly reducing maintenance time compared to traditional methods involving depressurization and manual blind insertion. Designed in accordance with EN 12516, the valve has an expected service life of 30 years, contributing to a substantially lower total lifecycle maintenance cost.
Project Type: Safety upgrade of an in-service high-pressure pipelineClient: A major oil & gas company in Russia (Siberia region)Application: Isolation and maintenance blind-off for high-temperature steam / hot oil pipelinesPressure Rating: 2600LB (Class 2600)Core Product: F22 Swing-Type Line Blind Valve (note: swing-type retained; see clarification below)Commissioning: Q3 2024Data Collection Period:12 months 1. Challenges Faced by the Client The pipeline system operates at pressures up to 2600LB, with media including high-temperature steam (up to 520°C) and hot oil. The valve is required to provide highly reliable sealing performance under high-pressure conditions. Maintenance isolation and blind-off operations must be carried out safely without shutting down the system. However, conventional line blind valves presented the following issues under large-diameter and high-pressure conditions: Difficult operation:Each blind-off operation required pipeline depressurization. The average operation time was approximately 45 minutes, requiring coordination of three operators. Leakage risk:Under high-pressure thermal cycling, sealing surfaces were prone to deformation. Two minor leakage incidents had previously resulted in unplanned shutdowns. Harsh environment:In Siberia, winter temperatures can drop to -45°C, while pipeline surface temperatures exceed 60°C in summer. Frequent industrial vibration places high demands on valve structural strength and durability. High maintenance cost:The existing valves required inspection and maintenance every three months, with annual maintenance costs exceeding USD 120,000. 2. Proposed Solution A swing-type line blind valve manufactured in F22 material was provided, designed in accordance with ASME B16.34, ensuring high-pressure and high-temperature resistance while accommodating mechanical stress in industrial environments. The valve adopts a swing-type mechanism, allowing the blind plate to rotate smoothly within the valve body during operation. This enables safe switching between isolation and flow positions without requiring pipeline depressurization, reducing operational risks. The valve body material can be selected as F11 or F22. With high-temperature alloy properties, stable sealing performance is maintained under high-temperature steam or hot oil service. An RTJ (Ring-Type Joint) flange connection is applied, facilitating installation in large-diameter pipelines. In addition, a mechanical interlock is incorporated to prevent misoperation and enhance on-site safety. 2.1 Key Technical Advantages Swing-Type Design for Online IsolationThe blind plate rotates smoothly within the valve body, eliminating the need for valve disassembly or pipeline depressurization. Each isolation / flow switching operation can be completed within approximately 10 minutes by a single operator. F22 High-Temperature Alloy for Extreme Service ConditionsF22 material (containing Cr 2.00–2.50% and Mo 0.90–1.10%) maintains high creep rupture strength at temperatures up to 520°C. It also meets low-temperature impact test requirements down to -46°C, making it suitable for the full annual temperature range in Siberia. Enhanced Sealing ReliabilitySpring-loaded sealing surfaces automatically compensate for dimensional changes caused by thermal cycling. After 500 thermal cycles, the leakage rate remains better than ISO 5208 Rate A (zero visible leakage). Anti-Misoperation DesignEquipped with a mechanical interlock and position indicator to prevent incorrect operation under pressurized conditions, improving on-site operational safety. 2.2 Performance Comparison with Conventional Line Blind Valves Compared with conventional line blind valves, the F22 swing-type solution demonstrates the following performance improvements: ● Operation time (per isolation): reduced from 45 minutes (with depressurization required) to 10 minutes (online switching) ● Personnel required: reduced from 3 operators to 1 operator ● Leakage rate (over 12 months of operation): from 2 recorded minor leakage incidents to zero leakage ● Maintenance interval: extended from every 3 months to ≥18 months ● Operating temperature range: expanded from -20°C ~ 400°C to -46°C ~ 520°C ● Annual maintenance cost: reduced from approximately USD 120,000 to below USD 20,000 3. Achieved Results 3.1 Key Operational Indicators Zero-leakage operation:Over 12 months of service, the valve maintained zero visible leakage, with no unplanned pipeline shutdowns. 78% improvement in operational efficiency:The time required for a single isolation operation was reduced from 45 minutes to 10 minutes, resulting in over 200 hours of annual labor time savings. ...
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