In a wedge gate valve, the gate sealing surfaces are wedge-shaped, forming a specific angle relative to the gate centerline. The gate is driven downward by the valve stem to achieve closure. As the stem thrust increases, the normal force acting on the wedge-shaped sealing surfaces also increases, creating a forced sealing effect. This design significantly improves sealing performance under low-pressure conditions. During opening, the gate sealing surfaces disengage from the seat immediately, which helps reduce wear on the sealing faces and extends the service life of the valve. Applicable Standards for Wedge Gate Valves Wedge gate valves are commonly manufactured in accordance with the following standards: ● GB/T 12234-2019 – Steel gate valves with bolted bonnet for petroleum and natural gas industries ● GB/T 12232-2005 – General-purpose flanged cast iron gate valves ● API Standard 600 (2015) – Steel gate valves for petroleum and natural gas industries Types of Wedge Gate Valve Gates Wedge gate valves are typically available in three gate configurations:Solid wedge gate, Flexible wedge gate, Double wedge gate. The flexible wedge gate and double wedge gate rely on controlled deformation of the sealing surfaces to achieve improved contact with the valve seat. This design enhances sealing reliability and effectively prevents gate binding or jamming caused by temperature variations, ensuring smooth operation even under fluctuating thermal conditions. Parallel Slide Gate Valve Design and Sealing Principle In a parallel slide gate valve, the sealing surfaces at both the inlet and outlet ends of the gate are parallel to the gate centerline. For single-gate configurations, sealing is primarily achieved by the medium pushing a floating gate or floating seat into position. In double-gate configurations, sealing can be accomplished through springs or an expansion mechanism between the gates. Throughout the opening and closing process, the gate and seat sealing surfaces remain in constant contact, ensuring reliable sealing. Applicable Standards for Parallel Slide Gate Valves Common standards for parallel slide gate valves include: ● GB/T 23300-2009 – Parallel slide gate valves ● JB/T 5298-2016 – Steel parallel slide gate valves for pipelines ● API 6D – Pipeline valves for petroleum and natural gas industries Types and Features of Parallel Slide Gate Valves Parallel slide gate valves are available in single-gate and double-gate configurations. ● Gates may include flow-through holes or be solid. Gates with flow-through holes match the seat inner diameter, facilitating cleaning and drainage of the pipeline. ● Sealing can be configured at the inlet end, outlet end, or at both ends, depending on application requirements. This design ensures flexibility in sealing arrangements while maintaining reliable oper...
Damage to valve sealing surfaces is typically the result of multiple contributing factors, including material selection, operating conditions, operating practices, and maintenance. The following is a categorized summary of the most common causes: 1. Mechanical Damage ● Wear: Solid particles in the medium (such as sand or welding slag) erode the sealing surface, resulting in scratches or grooves. ● Abrasive scuffing: Frictional wear caused by relative movement of the sealing surfaces during valve opening and closing, particularly in metal-to-metal sealing pairs. ● Impact damage: Deformation of the sealing surface caused by high-velocity fluid impingement or rapid valve opening and closing, leading to impact loading. 2. Chemical Corrosion ● Media corrosion: Acidic, alkaline, or oxidizing media directly attack the sealing surface material, such as metal corrosion caused by H₂S or chloride ions. ● Electrochemical corrosion: When sealing pairs made of dissimilar metals are exposed to an electrolyte, galvanic corrosion may occur due to electrochemical cell formation. ● Erosion–corrosion: The combined effect of corrosive media and high-velocity flow accelerates material loss on the sealing surface. 3. Thermal Damage ●Thermal fatigue:Frequent temperature fluctuations cause repeated thermal expansion and contraction of the sealing surface, leading to cracking or deformation. ●High-temperature oxidation:At elevated temperatures, the sealing surface may undergo oxidation, hardening, or burn-off, as commonly observed in steam valve applications. ●Thermal shock:Sudden exposure to high- or low-temperature media can cause cracking of the sealing surface, such as during rapid condensation or cold media ingress. 4. Improper Installation and Operation ●Installation misalignment: Incorrect valve installation or excessive piping stress can result in uneven loading on the sealing surfaces. ●Over-tightening: Excessive preload applied to the valve stem or bolting may crush or deform the sealing surface, particularly in soft-seated valves or soft sealing gaskets. ●Rough operation: Rapid opening and closing or excessive operating force can cause impact damage to the sealing surfaces. 5. Material Defects ●Improper material selection: The sealing surface material lacks sufficient resistance to process media, high temperature, or wear, such as the use of carbon steel in acidic service. ●Manufacturing defects: Defects in the hardfacing or overlay layer, including porosity, slag inclusions, or improper heat treatment, reduce wear resistance and overall sealing performance. 6. Abnormal Operating Conditions ●Cavitation / flashing: Pressure fluctuations in the fluid generate vapor bubbles that collapse and impact the sealing surface, a phenomenon commonly observed in valves installed downstream of pumps. ●Scaling / deposition: Impurities in the medium accumulate on the sealing surface, impairing tight shutoff, suc...
In 2025, Dervos organized its annual team trip, a five-day journey to Chongzuo, Weizhou Island, and Nanning in Guangxi Province. The trip aimed to provide relaxation and strengthen team communication, offering a well-paced and content-rich experience that combined natural landscapes with local cultural immersion. In Chongzuo, the team focused on nature sightseeing. Bamboo rafting tours allowed close observation of the local ecology and offered opportunities to see rare species such as the white-headed leaf monkey. The group also visited Detian Waterfall, experiencing its scale and flow firsthand. The overall itinerary was designed with a relaxed pace, providing ample time for rest and team bonding. Next, the team traveled to Weizhou Island. The volcanic landforms and coastal scenery added a unique visual dimension to the journey. Beyond sightseeing, participants engaged in local agricultural activities, including dragon fruit picking and banana harvesting, gaining insight into local lifestyles. The team also visited several beaches, fully appreciating the island environment. The final stop was Nanning. Team members explored the night market, sampled local specialties, and experienced the city’s daily life, bringing the Guangxi trip to a relaxed conclusion. This annual trip allowed the Dervos team to foster more natural communication and connection outside of work, recharging energy for the months ahead. Dervos remains committed to its guiding principle: I come, I see, I conquer!
Payment:
30% T/T When Order, 70% T/T Before ShipmentProduct Origin:
ChinaColor:
CustomizationShipping Port:
Shanghai ChinaLead Time:
35~60 days Ex Works After Order ConfirmationMaterial:
Stainless Steel Gate Valve, Forged Steel Gate ValveMethod of Operation:
Manual Gate Valve, Handwheel Gate ValveMade of stainless steel, the cryogenic gate valve has extended bonnet, reduced bore, non-rising handwheel, socket weld connection, complying with API 602.
Quick Detail
|
Type |
Gate Valve |
|
Size |
1'' |
|
Design Pressure |
ANSI 1500 |
|
Construction |
Extended Stem, Bolted Bonnet, Solid Wedge |
|
ConnectionType |
Socket Weld (SW) |
|
OperationType |
Handwheel Operation |
|
Body Material |
A182 F316L |
|
TrimMaterial |
SS316L |
|
Design Code |
ASME B16.34 |
|
Face to Face |
ASME B16.10 |
|
End Connection |
ASME B16.11 |
|
Medium |
Water, Oil and Gas |
|
Origin |
China |
Available Modifications for Dervos Valves
-Design Pressure
-Nominal Diameter
-Body Material & Trim Material
-Material & Type for Packing and Gasket
-Valve Operation Type
-Modifications of End Connection
-Available Extended Stem or Bonnet
-Available By-Pass Valve
-Customized Coatings & Packaging
Related Knowledge
Why do we use extended stem for cryogenic valves?
The cryogenic valves are mainly used in low temperature liquid media, like liquefied natural gas and petroleum products.
The reasons why we use extended stem for cryogenic valves are as below:
1.To maintain the temperature of stem packing in a proper level, since the very low temperature will influnce the sealing function of stem pakcing.
2.To prevent the heat outside from entering the valve and cause energy loss to the application
3.The long stem structure facilitates the quick replacement of the valve's main part through the valve cover.
4.To prevent the parts (like handwheel) over stem from freezing
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The gate valve, made according to API 600, is made of CF8, one kind of cast steel. The 4 inch valve is equipped a handwheel, outside yoke, bolted bonnet and extended bonnet. All the accessories are traceable.
Line blind valve is a kind of gate valve that cuts off gas medium manually, electrically or pneumatically or hydraulically. It is generally divided into electric blind valve, hydraulic blind valve, closed plug valve and electric open blind valve.
DN50 PN16 Cast Steel gate valve is made according to BS EN 1984 standard. The valve body is made of ASTM A216 WCB. It has the structural characteristics of bolt cover, exposed pole. Its connection mode is EN1092-1 B. And it has Hand Wheel operation mode.
Made of F316, the floating ball valve is designed under the code of ASME B16.34. The valve consists of two-piece body, floating ball, lever operation, with good reliable sealing performance and small torque.
The 1.5 inch 800LB bellow seal globe valve is designed with outside screw and yoke, handwheel operation, sw end. The reduced port globe valve is has forged steel A105N body. Design Feature 1.Outside screw and yoke 2.Rising stem 3.Bolted bonnet design 4.Bellow seal packing for reliable stem sealing 5.Reduced bore design 6.Handwheel Operated Quick Detail Type Globe Valve Size 1.5'' Design Pressure Class 800 Structure BB, OS&Y, Reduced Port, Bellow Seal Packing Connection Type Socket Weld Operation Handwheel Design Code API 602 End to End ASME B16.10 Connection End ASME B16.11 Pressure & Temperature ASME B16.34 Test & Inspection Standard API 598 Body Material Forged Steel ASTM A105 Trim Material Trim 8 Applicable Temperature -29℃~+425℃ Application W.O.G Origin China Related Knowledge What is a bellw seal valve? For bellow seal globe valves, the lower end bellows is welded on the valve stem to prevent the process fluid from eroding the valve stem. The other end is placed between the valve body and the valve cover to form a static seal. The double seal design ensure that if bellow seal pakcing fails, the stem packing will also function. The bellow seal globe valves are applicable for media like steam, flammable, explosive, heat transfer oil, high purity, and toxic media etc. Special Tests Besides general tests we will do (hydraulic and air test), we could also do tensile strength test, metallographic test, fugitive emission test, and NDE test (UT,RT,PT,MT) upon customers’ specific requests.
2" 150LB Y Strainer is made according to ASME B16.34 standard. The valve body is made of LCB. It has the structural characteristics of Y-Type, Double Mesh Screen, Mesh Size 1/16", Hole Pitch 3/32". Its connection mode is RF.
DN15 PN63 Forged Steel Globe Valve is made according to BS 5352 standard. The valve body is made of A105N+STL. It has the structural characteristics of through way type, bolt bonnet and structural length of 130mm. Its connection mode is EN1092-1 B. And it has hand wheel operation mode.
The 1 inch sleeved type plug valve is made of A216 WCB as per API 599. Thanks to its PTFE seat, the valve has excellent sealing and anti-corrosion performance. The valve is capable in working condition lower than 180 degree.
4x3" 150LB floating ball valve is made according to API 6D standard. The valve body is made of A182 F51. It has the structural characteristics of two piece, floating ball, reduced diameter, anti-fire, anti-static, anti-flying valve stem, bidirectional, with locking device. Its connection mode is RF. And it has lever operation mode.
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.
Bolt bonnet Gate valve follow EN1984 design standard, raised face flanged connection, outside screw and yoke, handwheel operation, GP240GP body/bonnet/wedge material, F6a stem, metal seal/seated. Quick Detail Type Gate Valve Size DN200 DesignPressure PN40 Construction Bolt Bonnet Gate Valve Connection Type Raised Face Flange Connection Operation Handwheel Design Code EN 1984 Face to Face DIN 3202 End Connection EN 1092-1 Test & Inspection EN 12266-1 Body Material GP240GH Temperature Range -29~425℃ Application WOG
Made of carbon steel, the 4 1/16" wellhead gate valve is designed per API 6A with RTJ flange, non rising stem, parallel gate as its features. Design Feature 1.Full port design for small flow resistance 2.Small torque value for easy operation 3.No limitation for flow direction 4.Parellel disc 5.Self-tightening seal packing minimizes maintenance 6.Metal to metal seat for stem and wedge 7.Compact structure with light weight Quick Detail Type Wellhead Gate Valve Size 4.1/16" Nominal Pressure 10000PSI Construction Parallel Gate, Non-Rising Stem Connection Flange Operation Handwheel Operation Body Material ANSI 4130 Trim Matetial SS410 Material Class EE TempretureClass P-U ProductSpecificationLevel PSL3 PerformanceRequirement PR2 Medium Water, Oil and Gas Origin China Product Application Dervos valves can be widely used in varieties of industries, such as petrochemical, pipeline, oil & gas, marine, water treatment, power station industries and etc.
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