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!
Product Origin:
ChinaColor:
CustomizationShipping Port:
Shanghai ChinaLead Time:
30~55 days Ex Works After Order ConfirmationMaterial:
Cast Steel Globe ValveMethod of Operation:
HandwheelDervos bellow seal globe valve is designed as per EN13709 with face to face dimesnsion per EN558. The special designed bellow seal make sure zero leakage from stem.
Quick Detail
|
Type |
Globe Valve |
|
Norminal Size |
DN 65 |
|
NorminalPressure |
PN 40 |
|
Construction |
Bolted Bonnet, Rising Stem, Bellow Sealed |
|
ConnectionType |
RF Flange |
|
Operation |
Handwheel |
|
Design Code |
EN13709 |
|
Face to Face |
EN 558 |
|
Connection |
EN1092 |
|
Test & Inspection |
EN12266 |
|
Body Material |
Carbon Steel 1.0619 |
|
Bellow Material |
SS304, SS316, SS316L and etc |
|
ApplicableTemp |
-29℃~+420℃ |
|
Application |
Water, Oil, Gas |
Structure Feature
1. Standard design of double-wall bellow seal
2. Heat-dissipating bonnet design;
3. With lubricant storage device;
4, With design of circlip to fix stem nut;
5. Reasonable product structure, reliable sealing performance and good appearance;
6. The sealing surface is welded with Co-based hard alloy, which has good wear resistance, corrosion resistance, anti-friction performance and long service life;
7. Stem has nitriding treatment with good corrosion resistance and anti-friction performance;
8. With position indicator for stem movement;
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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.
The bellows seal globe valve adopts the bellows seal design, which completely eliminates the shortcomings of the normal valve stem packing seal aging and easy to leak, not only improves the energy efficiency, increases the safety of the production equipment, reduces the maintenance cost and frequent maintenance. It also provides a clean and safe working environment.Its simple structure and the low price makes it almost no "competitors". Quick Detail Type Globe Valve Norminal Size 1.5 Inch NorminalPressure 150LB Construction Bolted Bonnet, Outside Screw & Yoke, Rising Stem, Bellow Seal ConnectionType RF Flange Operation Handwheel Design Code ASME B16.34, API 602 Face to Face ASME B16.10 Flange End ASME B16.5 Test & Inspection API 598 Body Material ASTM A105 ApplicableTemp -29℃~+425℃ Application Water, Oil, Gas Structure Feature 1. Double seal design (corrugated pipe + packing). If the bellows fails, the stem packing will also be avoided; 2. External leakage, and in line with international sealing standards; 3. No fluid loss, reduce energy loss, and improve plant equipment safety; 4. Long service life, reduce the number of maintenance, reduce operating costs; 5. Rugged bellows seal design, ensuring zero leakage of the valve stem, providing maintenance-free conditions. Technical Drawing Dimension 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.
DN200 PN16 Bellow Seal Globe valve is made according to BS EN 13709 standard. The valve body is made of EN 10213 1.4408. It has the structural characteristics of body cover bolt, rising pole bracket, angle type, corrugated pipe seal and structural length of 255mm. Its connection mode is RF. And it has hand wheel operation mode.
The DN32 JIS 5K globe valve is suitable for marine application. The bronze globe valve is handwheel operated with FF flange. Quick Detail Type Marine Globe Valve Size DN 32 Design Pressure 5K Connection Type FF Flange Design Code JIS F7301 Face to Face JIS B2002 Body Material Bronze Trim Material Bronze Application Water, Oil, Gas Purchasing System Late delivery time become a common issue in 2018. However, Dervos keep more than 90% on-time delivery, so how do we achieve that? It owns our purchasing department. How do we react to a delay crisis? -Visit the factory everyday and supervise on site -Initiate related resources, such as machining workshops and skilled workers to help on expediting production What benefits could we do for you by keeping on-time delivery? -Avoid penalty from end user -Accumulate reputation -Gain client’s trust FAQ 1. Do you have your own foundry or forge shop? No, but we have an approved list of foundries over the past decade of casting inspections, which can make sure that our castings are of good quality and all the raw materials are traceable. 2. Can you do NDE Capability radiography, MT, UT, LP? Of course, we can do all these tests upon our clients, but there will be additional charge to these tests. 3. What kind of test will you do for each order? After valve assembly, we will do hydraulic test for shell & sealing and air test. Plus, we will do dimension checking (face to face dimension, flange dimension) as per assembly drawing and standards.
6" 150LB Y type strainer is made according to ASME B16.34 standard. The valve body is made of ASTM B148 C95800. It has the structural characteristics of bonnet with 1/2 "FNPT plug. Its connection mode is RF.
With outside screw and yoke, handwheel operation, NPT, the forged steel globe valve is made of A105 and designed as per BS5352.
The double- disc check valve, made of CF8 stainless steel, has excellent resistance to corrosion. Designed in accordance with DIN 3202, the check valve is about to connect to pipes with WAFER. Quick Detail Type Check Valve Nominal Diameter DN100 NominalPressure PN25 Construction Double disc/ Dual Plate Connection Wafer Type Design & Manufacture DIN 3202 End to End DIN 3202 Flange End Dimension DIN 2401 Test & Inspection API 598 Temperature Range -29℃~+425℃ Body Material A351 CF8 Wedge Material A351 CF8 Media W.O.G. Dervos Packaging Good packing means good first impression. Just imagine how do you feel differently when seeing two boxes below? And you will know the reason why in Dervos we value packaging so much. In Dervos, we make sure- 1. Every valve isclean and dry. What do we do? -Clean the valve before packing -Add anti-rust oil -Add flange cover 2. No damageto valves in delivery. How do we achieve this? -Fix the valve with iron wire -Separate the valve with soft material -Layer the valve with plywood 3. Strong box and clear shipping mark
DN200 PN10 Cast Steel Gate Valve is made according to EN1984 standard. The valve body is made of A216 WCB+STL. It has the structural characteristics of Bonnet , Flexible Wedge. Its connection mode is EN1092-1 / B. And it has hand wheel operation mode.
DN400 PN16 gate valve is made according to EN1984 standard. The valve body is made of 1.0619 + STL. It has the structural characteristics of rising stem and structural length of 600mm.
1/2" 800LB globe valve is made according to API 602 standard. The valve body is made of ASTM A182 F316/F316L+STL. It has the structural characteristics of bolt cover, disc swivel plug, body seat and OS&Y. Its connection mode is SW. And it has hand wheel operation mode.
The 6 inch Wafer check valve is made in strict accordance to API 594. The body material LCC make sure the lug type valve is capable to handle harsh environment, and the INCONEL-X 750 spring promise the valve a long service life.
DN250 PN10 check valve body is made of A216 WCB+STL. It has the structural characteristics of heavy hammer on both sides and flange type. Its connection mode is RF.
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