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!
The 4 inch cryogenic ball valve, designed as per API609, has many parts equipped RPTFE --It has the lowest coefficient of friction and the best corrosion resistance of any known plastic material, so that the valve can handle quite extreme situations.
Payment:
30% T/T When Order, 70% T/T Before ShipmentProduct Origin:
ChinaColor:
CustomizationShipping Port:
Shanghai, ChinaLead Time:
30~60 days Ex Works after order confirmationMaterial:
F316Method of Operation:
LeverQuick Details
|
Type |
Ball Valve |
|
Nominal Diameter |
4" |
|
NominalPressure |
300LB |
|
Construction |
Bolted Weld, Extended Stem or Bonnet, Full Port |
|
Connection |
RF |
|
Operation |
Lever Operated |
|
Body Material |
F316 |
|
Design Code |
API 607 |
|
Pressure & Temp |
ASME B16.34 |
|
End toEnd Dimension |
ASME B16.10 |
|
Connection Size of Flanges |
ASME B16.5 |
|
Inspection |
API598 |
|
Temperature Range |
-196℃~+120℃ |
|
Media |
Oil, Water, Gas |
Design Feature
Extended stem and bonnet to position the stem packing above the cryogenic fluid and provide a column of warmer vapor that insulates the stem seal from the effects of low temperatures.
High-density seats and seals throughout the valve enable the valve to be rated down to -196°C service.
Vent hole is in the upstream face of the ball. This prevents the cold liquids from becoming trapped in the valve.
Stem primary seal and bearing are located near the packing end of the extended stem thus keeping these parts from the low temperatures and providing a blow-out proof stem design.
Valves are specially cleaned to remove all grease and oils that may react with the service media
Each valve after cleaning is packaged and sealed in a heavy poly bag to keep the valve clean until installation.
Technical Drawing
Our Service
Dervos customer service is one of our biggest competitive advantages. In Dervos, we provide-
1. Quotation within 24 hours or no later than 3 days
This will let you meet the quotation submission deadline and enhance your working efficiency
2. Weekly status report of your order
In this way, you will have a clear picture of your order. You do not need to waste time on pushing us for status update
3. An 18-month warranty period
A warranty certificate will issued after shipment and you will not have any concern after buying valves.
4. Solutions to complaints within 3 days
Quick and responsible actions to complaints will protect your reputation and reduce the financial loss as much as possible.
If you are interested in our products and want to know more details,please leave a message here,we will reply you as soon as we can.
The Class 1500 4'' cryogenic ball valve is designed with extended stem for low temperature application. The valve is made of LF2 with fully welded body, butt weld end and gearbox operation. Design Feature-Fully welded & forged body-Extended stem or bonnet-Full port design and piggable-Anti blow-out stem-Antistatic function- Automatic cavity relief-Bi-directional seat and DBB design-With stem and seat grease fittings Quick Detail Type Ball Valve Size 4" Pressure ANSI 1500 Construction One-Piece Body, Fully Weld, Extended Stem or Bonnet, Full Port Connection Butt Weld Operation Gearbox Operated Body Material Low Temperature Steel A350 LF2 Design Code API 6D Pressure & Temp ASME B16.34 End to End Dimension ASME B16.10 End Connection ASME B16.25 Inspection API 598 Temperature Range -46℃~+200℃ Media Oil, Water, Gas Related KnowledgeWhat is the difference between full bore and reduced bore ball valve?The internal diameter of a full bore ball valve is the same as the inner diameter of the pipe. The full bore ball valve has little resistance and pressure drop to the flow. Plus, the full bore ball valve is piggable.However, the internal diameter of a reduced port (standard port) ball valve is smaller than the inner pipe size. Flow restriction caused by the reduced port will cause a pressure drop. And sometimes a pig to clean the pipe will get stuck in the reduced port ball valve.
DN900 150LB Triple Offset Metal Seated Butterfly Valve is made according to API609 standard. The valve body is made of C95500. It has the structural characteristics of Triple offset, bidirectional equal pressure zero leakage. Its connection mode is FF double flange. And it has Turbine operation mode.
The API 6D through conduit gate valve is designed with double expanding wedges, metal to metal seat and diversion hole for pigging. The valve has good performance on sealing, less flow resistance and is suitable for application with some solids or particles. Quick Detail Type Gate Valve Size 18'' Design Pressure ANSI 600 Construction Double Expanding Wedges, Fully Metal Seat, With Diversion Hole ConnectionType RTJ Flange OperationType Gearbox Operated Body Material WCB WedgeMaterial A105+STL+ENP StemMaterial 17-4PH SeatMaterial A105+STL+ENP Design Code API 6D Face to Face Dimension ASME B16.10 End Connection ASME B16.5 Pressure & Temp ASME B16.34 Medium Water, Oil and Gas Origin China
1" 150LB swing check valve is made according to API 602 standard. The valve body is made of A105. It has the structural characteristics of bolt cover, swing type and full bore. Its connection mode is RF (Welded Flange).
The 8 inch lubricated plug valve features in inverted and pressure balanced type structure. The flanged metal seated plug valve is suited for natural gas application. Quick Detail Type Plug Valve Size 8'' Design Pressure 300LB Construction Lubricated Type, Inverted Type, Pressure Balanced Type, Metal Seated Connection Type Flanged Connection Operation Gear Operated Design Code API 599 Face to Face ASME B16.10 End Connection ASME B16.5 Pressure & Temp ASME B16.34 Test & Inspection API 598 Body Material WCC Temperature Range -29℃~+425℃ Application Water, Oil, Gas Dimension Class Size 1 1/2 2 2 1/2 3 4 6 8 10 12 300 B 191 216 241 283 305 403 419 457 502 C 156 165 191 210 254 318 381 445 521 D 20.6 22.2 25.4 28.3 31.8 36.5 41.3 47.6 50.8 E 169 178 219 235 362 F 106 118 143 165 187 248 300 392 O 73 92.1 105 127 157 216 270 324 381 Weight(RF) 16 21 38 60 101 192 281 508 Related Knowledge What is a plug valve? Plug valve is a quater-turn valve whose plug rotates around the centerline of valve body to realize on-off function. The plug valve is used for cutting off, distributing and changing the flow directoin. Currently, plug valves are mainly applicable for small size, normal temperature, and low pressure conditions. The advantages of plug valve are shown below: -Quick opening and closing the valve -Small fluid resistance -Reliable leak-tight service -Available inline maintenance
24” 150LB Dual Plate Wafer Type Check Valve is made according to API 594 standard. The valve body is made of A216 WCB+SS316. It has the structural characteristics of Dual-plate wafer type, wafer body design. Its connection mode is Double flange, ASME B16.5.
DN25 PN40 Flange Lift Check Valve is made according to EN 12266 standard. The valve body is made of A182-F304L. It has the structural characteristics of Lift Type, Spring-loaded. Its connection mode is EN1092-1 B.
14" 150LB butterfly valve is made according to API609 standard. The valve body is made of WCB+EPOXY COATING. It has the structural characteristics of center line. Its connection mode is wafer. And it has gear operation mode.
4" 150LB wafer check valve is made according to API 594 standard. The valve body is made of A351 CF8M+STL. It has the structural characteristics of double disc. Its connection mode is wafer.
1/2” 400LB Floating Ball Valve is made according to ASME B16.34 standard. The valve body is made of B62 C83600. It has the structural characteristics of Two-Piece. Its connection mode is Lever OP..
4” 125LB Y Type Strainer is made according to ASME B16.34 standard. The valve body is made of Ductile Iron A395. It has the structural characteristics of Y-Type, Body-Bonnet Bolted Connection. Its connection mode is FF.
The 2 piece type floating ball valve has full port, fire safe design, anti blowout stem, ANSI 150 flange and lever operation. The carbon steel ball valve is designed with A216 WCB body, F316 stem and ball, PTFE soft seat. Quick Detail Type Ball Valve Size 4" Pressure 150 LB Construction Floating Type Ball, Two Piece Body, Full Bore Connection Raised Face Flange End Operation Wrench Operation Body Material Cast Steel WCB Trim Material SS316 &PTFE Design Standard API 6D Pressure & Temp Code ASME B16.34 Face to Face ASME B16.10 End Connection ASME B16.5 Inspection Code API 6D Temperature Range -29℃~+125℃ Media Water, oil and gas Material & Dimension No Part Name Carbon steel to ASTM Stainless Steel to ASTM WCB LCB CF8 CF8M CF3 CF3M 1 Body A216 WCB A352 LCB A351 CF8 A351 CF8M A351 CF3 A351 CF3M 2 Bonnet nut A194 2H A194 4 A194 8 3 Bonnet bolt A193 B7 A320 L7 A193 B8 4 Cap A216 WCB A352 LCB A351 CF8 A351 CF8M A351 CF3 A351 CF3M 5 Gasket SS Spiral Wound/graphite or SS Spiral Wound/PTFE 6 Ball A105/Ep.Cr or F6 A182 F6 A351 CF8 A351 CF8M A351 CF3 A351 CF3M 7 Seat Ring RPTFE or POM 8 Small spring Stainless Steel 9 Small ball A182 F304 A182 F316L 10 Stem A182 F6 A182 F6 A182 F304 A182 F316 A182 F304L A182 F316L 11 Stem Seat PTFE 12 Stem Packing PTFE or Graphite 13 Gland A182 F6 A182 F304 A182 F316 A182 F304L A182 F316L 14 Gland Bolt A193 B7 A193 B8 15 Galnd Flange A216 WCB A351 CF8 16 Positioning Plate Steel 17 Wrentch A216 WCB The material is according to ASTM standard CLASS 150 DN mm 15 20 25 40 50 65 80 100 150 200 250 NPS in 0.5 0.75 1 1.5 2 2.5 3 4 6 8 10 L (RF) mm 108 117 127 165 178 191 203 229 394 457 533 in 4.25 4.6 5 6.5 7 7.5 8 9 15.5 18 21 L1 (BW) mm 140 152 165 190 216 241 283 305 457 521 559 in 5.5 6 6.5 7.48 8.5 9.5 11.13 12 18 20.5 22 L2 (RTJ) mm 119 129.7 139.7 178 191 203 216 241 406 470 546 in 4.69 5.11 5.5 6.9 7.5 8 8.5 9.5 16 18.5 21.5 H mm 66 74 87 105 132 152 182 215 250 285 495 in 2.6 2.9 3.48 4.2 5.28 6.08 7.28 8.6 10 11.4 19.5 Do(W) mm 130 130 160 230 400 400 600 850 1100 1500 *350 in 5.1 5.11 6.3 9 15.74 15.74 23.62 33.46 43.3 59 13.8 RF(Kg) 2.3 3 4.5 7 15 20 25 40 97 160 240 BW(Kg) 2.0 2.5 3.8 5.8 12 17 21 36 92.8 154 227 *Worm Gear or Electric actuator operated Special Tests & Inspections In addition to regular hydraulic testing and air testing, Dervos could also do specials test as per clients’ requests, such as PT test, RT test, UT test, cryogenic test, low leakage test, fire proof test, and hardness test and so on.
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