Recently, Dervos Valve helped a client in Hungary overcome a common challenge in industrial steam systems: how to safely isolate high-temperature pipelines without leakage or downtime. Operating with saturated steam at around 250°C and exposed to temperatures as low as -39°C, the client’s system demanded a solution that was both robust and reliable. Traditional valves often failed to maintain a tight seal under such conditions, and conventional isolation methods required depressurizing the line, increasing downtime and operational risk. To address these challenges, Dervos supplied a DN400 PN40 sliding line blind valve, engineered specifically for the project’s harsh conditions. The valve’s sliding blind mechanism allows operators to switch between flow and isolation positions without depressurizing the system, enhancing safety and efficiency during maintenance. Built with forged 20GML steel and a metal-to-metal stainless steel sealing structure, the valve delivers reliable performance under both high-temperature steam and extreme outdoor climates. Its full-bore design minimizes flow resistance, while the worm gear manual actuator ensures smooth and controlled operation even at large sizes and high pressure ratings. Safety features such as anti-misoperation devices and protective blind plate structures further reduce the risk of errors during handling. Since installation, the valve has enabled leak-free operation, safer maintenance procedures, and stable performance in extreme temperatures. Designed for a service life exceeding 30 years, it provides a long-term, low-maintenance solution, giving the client confidence in their steam system’s reliability and safety. This project highlights how a carefully engineered sliding line blind valve can solve critical isolation challenges in high-temperature steam applications, combining operational safety, durability, and efficiency in one solution.
In industrial piping systems, gate valves are generally considered low-resistance isolation valves. When the valve is fully open, the gate is completely withdrawn from the flow path, allowing the fluid to pass through with minimal obstruction. However, from a strict engineering perspective, not all gate valves are classified as full port valves. If the seat bore is equal to or very close to the pipeline internal diameter, the flow experiences little or no restriction. In this case, the valve can be considered full port (or near full port). This design is commonly used in oil and gas pipelines, water transmission systems, and other applications where low pressure drop is required. If the seat bore is slightly smaller than the pipe internal diameter, a minor flow restriction will occur inside the valve. In such cases, the valve is more accurately described as reduced bore. This configuration is more common in smaller sizes or cost-optimized valve designs. In engineering practice, a simple selection logic can be applied: ● If the system requires minimum flow resistance or pipeline pigging, the valve bore must match the pipeline diameter. ● If the valve is used for general isolation purposes, most standard gate valves can already meet the required flow capacity. Therefore, a concise conclusion can be drawn: Gate valves are typically close to full port designs, but whether they are truly full bore depends on whether the seat bore equals the pipeline internal diameter. QA Q1: Are gate valves always full bore?Not necessarily. If the seat bore equals the pipe internal diameter, the valve can be considered full bore. If it is slightly smaller, it is classified as reduced bore. Q2: Why do gate valves have relatively low flow resistance?When the valve is fully open, the gate is completely removed from the flow path, allowing the fluid to pass through in a nearly straight line, which results in low pressure drop. Q3: Are gate valves suitable for high-flow pipelines?Yes. If the system requires low pressure drop, gate valves are commonly used. Q4: Is the concept of full port the same for gate valves and ball valves?Not exactly. For ball valves, the bore size is determined by the ball port diameter, while for gate valves, it is mainly determined by the seat bore diameter.
Large diameter ball valves are commonly used in industries such as petroleum and chemical processing, power generation, long-distance pipeline transportation, and large-scale water treatment systems. If installation is not performed correctly, it may lead to sealing leakage, valve jamming, or structural stress damage. Therefore, proper installation practices are essential to ensure long-term stable operation. 1. Pre-installation Inspection If pre-installation inspection is insufficient, operational failures are more likely to occur during service. First, inspect the valve body for transportation damage. If scratches, impact marks, or deformation are found on the valve body or sealing surfaces, installation should be stopped and the supplier should be contacted. Next, verify valve model, pressure rating, and connection standards. If the system design pressure does not match the valve pressure class, operational safety risks may occur. For example, if a low-pressure class valve is mistakenly used in a high-pressure pipeline system, the valve body may experience plastic deformation under water hammer impact. It is also necessary to check the condition of the ball surface and sealing rings. If there are scratches on the ball surface, sealing performance will be reduced. This is especially critical in gas transmission systems where micro-leakage is more likely. 2. Installation Direction Large diameter ball valves usually have a flow direction marking. If the installation direction is incorrect, the following problems may occur: If the fluid flow direction matches the design direction, the operating torque will remain more stable. If the valve is installed in reverse, the stem may experience increased mechanical load, which will accelerate stem wear during long-term operation. For double-seal bidirectional ball valves, although bidirectional flow is allowed, installation according to the marked flow direction is still recommended to ensure more uniform sealing stress distribution. In high-temperature or steam systems, if the installation direction is incorrect, thermal expansion may accelerate sealing ring aging. 3. Pipeline Stress Control Large diameter ball valves are heavy. If installed without proper support, additional bending moments may be transferred to flange connections. If pipeline systems experience axial displacement, pipeline supports should be installed for segmented fixation. If support structures are not provided, the valve body may bear long-term gravitational tensile load, eventually causing flange seal failure. It is generally recommended to install independent supports on both sides of large diameter ball valves. If the pipeline system is subject to thermal expansion and contraction, expansion compensation devices must be installed; otherwise, sealing surfaces may gradually fail. 4. Bolt Tightening Process Flange connections of large diameter ball valves usually ...
This 1/2 Inch plug valve is made of A216 WCB, according to API598.With little required maintenance and trouble-free operation, a high integrity bubble-tight seal is provided both in-line and to atmosphere.
Payment:
30% when order confirmed, 70% before shipmentProduct Origin:
ChinaColor:
CustomizationShipping Port:
Shanghai, ChinaLead Time:
30~60 days Ex Works after order confirmationMaterial:
A216 WCBMethod of Operation:
WrenchQuick Detail
|
Type |
Plug Valve |
|
Nominal Diameter |
1/2 Inch |
|
NominalPressure |
800LB |
|
Construction |
Sleeve Type |
|
Connection |
NPT |
|
Design & Manufacture |
API599 |
|
Ends End Dimension |
ASME B1.20.1 |
|
F to F Dimension |
ASME B16.10 |
|
Pressure Test |
API598 |
|
Body Material |
A216 WCB |
|
Plug Material |
A315 CF8 |
|
Temp. Range |
≤120°C |
|
Media |
Water, Oil, Gas, etc |
Features
-Free of cavities
-Maintenance free – self lubricating
-Easy accessible adjustment of the plug, even with mounted actuator
-Bi-directional in-line bubble-tight seal independent of line pressure
-Multiple external bubble-tight seals independent of line pressure
-Positive flow direction indication
Technical Drawing
Witness Tests
Packing
DVS Purchasing System
Dervos purchasing system plays an important role in order follow up and supplier management.
What does our purchasing team do?
-Confirm production plan with the factory
-Follow up the order according to the production plan very closely
-Take every measure to initiate all related resources to solve the delay crisis
-Seek new suppliers and put them into our supplier pool by evaluating them onquality, equipment, certificates, price level, technical supports etc
-Do annual evaluation on current suppliers and eliminate those unqualified ones.
All these actions will make sure that clients’ order will be delivered on time and we can find most suitable products among qualified suppliers in an efficient way.
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 6 inch sleeved plug valve features in non lubricated design and soft seat. The full port plug valve is made of carbon steel body and PTFE seat as per API 6D, with Class 150 flange connection. Quick Detail Type Plug Valve Size 6'' Design Pressure 150LB Construction Self-Lubricated Type, Sleeved Type, Soft Seat Connection Type RF Flange Operation Gearbox Operation 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 A216 WCB Temperature Range -29℃~+425℃ Application Water, Oil, Gas Material & Dimension No Part Name Carbon steel to ASTM Stainless steel to ASTM WCB LCB CF8 CF8M CF3 CF3M 1 Body A216 WCB A350 LCB A351 CF8 A351 CF8M A351 CF3 A351 CF3M 2 Bonnet A216 WCB A350 LCB A351 CF8 A351 CF8M A351 CF3 A351 CF3M 3 Plug A105 A182 F304 A351 CF8 A351 CF8M A351 CF3 A351 CF3M 4 Stem A182 F6 A182 F6 A182 F304 A182 F316 A182 F304L A182 F316L 5 Seat Ring PTFE 6 Gasket PTFE or Stainless Steel and Graphite 7 Stem Seat PTFE PTFE PTFE PTFE PTFE PTFE 8 Small spring 17-17PH 9 Small ball A182 F304 or A182 F316 10 Gland A182 F6 A182 F6 A182 F304 A182 F316 A182 F304L A182 F316L 11 Gland Flange A216 WCB A350 LCB A351 CF8 A351 CF8M A351 CF3 A351 CF3M 12 Stem packing PTFE or Graphite 13 Bonnet bolt A193 B7 or A320 L7 or A320 B8 or A193 B8M 14 Bonnet nut A194 2H or A194 4 or A194 8 Class 150 DN mm 15 20 25 40 50 65 80 100 150 200 250 300 NPS in 1/2 3/4 1 1 1/2 2 2 1/2 3 4 6 8 10 12 L(RF) mm 108 117 127 165 178 191 203 229 394 457 533 610 in 4.25 4.6 5 6.5 7 7.5 8 9 15.5 18 21 24 L1(BW) mm 140 152 165 190 216 241 283 305 457 521 559 635 in 5.5 6 6.5 7.48 8.5 9.5 11.13 12 18 20.5 22 25 L2(RTJ) mm 119 129.7 139.7 178 191 203 216 241 406 470 546 622 in 4.69 5.11 5.5 6.9 7.5 8 8.5 905 16 18.5 21.5 24.5 H mm 59 63 75 92 153 165 195 213 272 342 495 580 in 2.3 2.5 2.95 3.74 6.02 6.5 7.68 8.39 10.7 13.5 19.5 22.85 D(W) mm 130 130 160 230 400 400 600 850 1100 1500 350* 350* in 5.1 5.1 6.3 9 15.74 15.74 23.62 33.46 43.3 59 13.8 13.8 Weight (Kg) RF 2.3 3 4.5 7 15 20 25 40 97 160 240 390 BW 2.0 2.5 3.8 5.8 12 17 21 36 92.8 154 227 365
The PTFE sleeved plug valve is made of CF3 body and plug as per API 6D. The valve owns the feature of reduced port and good sealing performance. We call this type of valve as non lubricated plug valve or self lubricated plug valve. Quick Detail Type Plug Valve Size 2'' DesignPressure 300LB Construction Sleeved Type, Non Lubricated Type, Soft Seat ConnectionType Flange Operation Lever Operation Design Code API 599, API 6D Face to Face ASME B16.10 End Connection ASME B16.5 Pressure & Temp ASME B16.34 Test & Inspection API 598 Body Material CF3 Temperature Range -29℃~+120℃ Application Water, Oil, Gas Dimension Checking Hydrostatic Testing
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.
Non-Lubricated, Sleeved Plug Valves incorporate state-of-the-artPPL seat design. With little required maintenance and trouble-free operation, the 3 inch 150 LB valve will ensure a high integrity bubble-tight seal.
DN250 PN25 plug valve is made according to API599 standard. The valve body is made of A216 WCB. It has the structural characteristics of soft sealing plug valve. Its connection mode is RF. And it has turbine operation mode.
DN50 PN40 plug valve is made according to API 599 standard. The valve body is made of A216 WCB. It has the structural characteristics of ferrule type, reduced diameter. Its connection mode is RF. And it has lever operation mode.
6” 150LB Forged Steel Floating Ball Valve is made according to API608 standard. The valve body is made of A216-WCB. It has the structural characteristics of Full Port, Floating Ball, Fire-safe & Anti-static, Blow-out Proof Stem. Its connection mode is RF. And it has hand wheel operation mode. Product Parameters Type Forged Steel Floating Ball Valve Size 6” Pressure 150LB Connection RF Operation Hand Wheel Body Material A182 F304 Design Norm API 608 Face to Face ASME B16.10 Flange Ends Dimensions ASME B16.5 Test & Inspection Code API 598 Temperature -29 ~ 120°C Applicable Medium Water, Oil and Gas Features 1.Made from F304 stainless steel, offering excellent corrosion resistance and durability for 150LB pressure systems. 2.Floating ball design with RF flange, compliant with API 608, ensures smooth operation and tight sealing performance. Technical Drawing Cast Steel Floating Ball Valve Technical Drawing Dimension Checking Pressure Testing Painting Nameplate & Packing Inspection Report
16" 150LB Cast Steel gate valve is made according to API600 standard. The valve body is made of A216 WCB. It has the structural characteristics of Bright pole bracket, body cover bolted connection. Its connection mode is RF. And it has Turbine operation mode.
With butt weld end and gearbox, the fully welded ball valve is designed per ASME B16.34. The one piece ball valve has trunnion type ball, antistatic design and full port structure. Quick Detail Type Ball Valve Size 10" Pressure ANSI 300 Construction Trunnion Type, One Piece Body, Full Bore, Fully Welded Connection Butt Weld (BW) Operation Gearbox Body Material Forged Steel A105 Design API 6D Pressure & Temp ASME B16.34 Face to Face ASME B16.10 End Connection ASME B16.25 Inspection API 598 Temperature Range -29℃~+125℃ Media W.O.G Related Knowledge What is a fully welded ball valve? What is the benefit and advantage of a fully welded ball valve? A fully welded ball valve is welded after forging without any bolted connection on the body. Compared with flanged ball valve, it features in maximum strength at minimum weight. The design of the valve gives it advantage: -Overall small size and light weight -Fewer leak paths on the body -High machining precision of ball part -High resistance to external and internal pressure and strength 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.
2”900LB Pressure Seal Bonnet Gate Valve is made according to ASME B16.34 standard. The valve body is made of A182-F91. It has the structural characteristics of PSB, OS&Y,Solid Wedge . Its connection mode is BW sch 80 ASME B16.25. And it has Handwheel operation mode.
4" 900LB check valve is made according to API 594 standard. The valve body is made of A351 CF8M. It has the structural characteristics of double disc and wafer type. Its connection mode is RF.
Dual Plate Wafer Type Check Valve is made according to API 594 standard. The valve body is made of A217 WC6+STL. It has the structural characteristics of Dual Plate Wafer. Its connection mode is Wafer.
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