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.
The Class 300 flanged ball valve has cast steel WCB body, stainless steel ball, stem, seat ring along with Devlon seat insert. We also supply more types of trunnion mounted ball valve, accept customized. Design Feature 1.Firesafe design as per API 607 2.With sealant injection for self lubricating 3.With antistatic design 4.With anti-blowout stem 5.With vent and drain port 6.Full bore design 7.Three-piece type and trunnion ball 8.Gear operated for easy operation Quick Detail Type Ball Valve Size 24" Pressure ANSI 300 Construction Trunnion Type Ball, 3-Piece Body, Side Entry, Full Bore Connection Flange Connection Operation Gearbox Operation Body Material ASTM A216 WCB Design Code API 6D Pressure & Temp Code ASME B16.34 Face to Face ASME B16.10 End Connection ASME B16.5 Test & Inspection Code API 598, API 6D Fire Safe API 607 Temperature Range -29℃~+200℃ Medium WOG Origin China Dimension CLASS 300 DN mm 50 65 80 100 150 200 250 300 350 400 450 500 600 700 NPS in 2 2.5 3 4 6 8 10 12 14 16 18 20 24 28 L (RF) mm 216 241 283 305 403 502 568 648 762 838 914 991 1143 1346 in 8.5 9.5 11.13 12 15.88 19.75 22.38 25.5 30 33 36 39 45 53 L1 (BW) mm 216 241 283 305 457 521 559 635 762 838 914 991 1143 1346 in 8.5 9.5 11.13 12 18 20.5 22 25 30 33 36 39 45 53 L2 (RTJ) mm 232 257 298 321 419 518 584 664 778 854 930 1010 1165 1372 in 9.13 10.13 11.75 12.63 16.5 20.38 23 26.13 30.63 33.63 36.63 39.75 45.89 54 H mm 153 165 195 213 272 342 495 580 625 720 790 840 1050 1150 in 6.02 6.5 7.68 8.39 10.7 13.5 19.5 22.85 24.6 28.35 31 33.1 41.34 45.3 Do(W) mm 400 400 600 850 1100 1500 *350 *350 *600 *600 *800 *800 *800 *800 in 15.74 15.74 23.62 33.46 43.3 59 13.8 13.8 23.6 23.6 31.5 31.5 31.5 31.5 RF(Kg) 18 27 47 80 118 200 365 530 740 1030 1320 1540 2600 3900 BW(Kg) 14 2 38 65 105 185 342 503 713 1000 1285 1498 2540 3825 *Worm Gear or Electric Actuator Operated Dervos Quality Checking System In Dervos, we control quality throughout the whole manufacturing process. Casting inspection: Though casting inspection, we can find out the problem of raw material, such as shoddy casting, unqualified wall thickness, chemical composition and so on, which ensure that you will not be cheated. Machining Inspection: On the one hand, we could ensure machining accuracy through this process. On the other hand, we can find out machining mistake as early as possible, to win more time for repairing and remaking Final Inspection: Final inspection activities include document and QC record review, visual examination, dimension check, pressure test, painting and packing check. You don’t need to come and inspect in person and all the documents could be provided as proof.
DN25 PN40 Forged Steel Gate Valve is made according to BS 5352 standard. The valve body is made of ASTM A105N. It has the structural characteristics of reduced bore, solid wedge, BB, and O,S&Y. Its connection mode is EN1092-1 B. And it has hand wheel operation mode.
The top entry full port ball valve with drain, vent and sealant injection is designed as per API 6D. The high pressure ball valve has Class 900 raised face flange and gearbox. Quick Detail Type Ball Valve Size 16" Pressure ANSI 900 Construction 1 Piece Body, Top Entry, Bolted Bonnet Connection Flanged End Operation Mode Gearbox Body Material A216 WCB Design & Manufacture API 6D Pressure & Temp Code ASME B16.34 End to End ASME B16.10 End Connection ASME B16.5 Inspection API 6D, API 598 Temperature Range -29℃~+200℃ Medium Oil, Water, Gas Related Knowledge What is a top entry ball valve and its advantage? A top entry ball valve is the valve which we assemble from the top side. It has a one single piece body. The less thread connection on the valve body means less weight and leakage paths. Plus, we could have access to the ball part without removing it from the pipeline. The top entry ball valves are often used in the pipeline with less maintenance for internal parts. Inspection Reports For each order, Dervos will provide inspection reports to show you the whole inspection process and results. Plus, we will provide material report to let you know that the material we provide is as per standards.
2" 150LB butterfly valve is made according to API609 standard. The valve body is made of CF8. It has the structural characteristics of high performance and double eccentric. Its connection mode is wafer. And it has bare stem with bracket operation mode.
Dervos manufactures a versatile range of Ball Valves in single, two and three piece constructions. The valves are available in full-bore and regular-bore designs, in a variety of end connections and materials to meet your requirements.
4" 150LBS double eccentric butterfly valve is made according to API 609 standard. The valve body is made of ASTM A216 WCB. It has the structural characteristics of double eccentric. Its connection mode is lug. And it has lever with lock operation mode.
The valves are widely used in electric power, petroleum chemical industry, metallurgy, Marine, oil, natural gas, coal gas, pharmaceutical and other industries.
3/4” 5000psi Forged Steel Floating Ball Valve is made according to ASME B16.34 standard. The valve body is made of A182 F316. It has the structural characteristics of Full Port, Floating Ball, Fire-safe & Anti-static, Blow-out Proof Stem. Its connection mode is NPT. And it has LEVER OP. operation mode. Product Parameters Type Forged Steel Floating Ball Valve Size 3/4” Pressure 5000psi Connection NPT Operation LEVER OP. Body Material A182 F316 Design Norm ASME B16.34 End to End MFG Screwed End ANSIB1.20.1 Test & Inspection Code API 598 Temperature -29 ~ 120°C Applicable Medium Water, Oil and Gas Features 1.Forged from F316 stainless steel, offering superior corrosion resistance and strength for 5000 PSI high-pressure applications. 2.Floating ball design with NPT connection and ASME B16.34 compliance ensures reliable sealing and smooth operation. Technical Drawing Forged Steel Floating Ball Valve Dimension Checking Pressure Testing Nameplate & Packing Inspection Report
DN15 PN40 steam trap valve is made according to GB/T22654-2008° standard. The valve body is made of A105. It has the structural characteristics of bimetal type and BK47-Y model. Its connection mode is RF.
The DN65 PN16 angle type globe valve is made of cast steel 1.0619 body and ss304 trim material, with rising stem, handwheel, RF flange. Quick Detail Type Globe Valve Norminal Size DN 65 NorminalPressure PN 16 Construction Angle Pattern, BB ConnectionType Flanged Operation Handwheel Design Code DIN 3356 Face to Face EN 558 Connection EN1092 Test & Inspection EN12266 Body Material GS-C25 (1.0619) ApplicableTemp -29℃~+425℃ Application WOG Related Knowledge Why use an angle type globe valve? Angle globe valve turns the flow direction by 90 degrees without using an elbow or the extra pipe weld, which reduce the number of joints on the pipeline, save the installation time, and reduce the pressure drop & flow resistance. The angle pattern globe valve are used for application with periods of pulsating flow, since they are able to handle slugging effect. Our Main Product Range As an experienced supplier and vendor of industrial valves, Dervos supply cast steel valve, forged steel valve, cast iron valve, stainless steel valve, bronze valve, brass valve and alloy steel valve and so on, suitable for sea water, water, oil, and gas application.
2” CL800 Swing Check Valve is made according to API602 standard. The valve body is made of A105. It has the structural characteristics of BC. Its connection mode is BSP.
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