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 When the valve is fully open, the gate is completely withdrawn from the flow path, allowing the fluid to pass through with minimal obstruction.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 ...
The 8 inch top entry ball valve with features of cavity pressure self-relief and emergency sealant injection is designed as per API 6D. It’s capable to handle working pressure up to 900LB.
Payment:
30% when order confirmed, 70% before shipmentProduct Origin:
ChinaColor:
CustomizationShipping Port:
Shanghai, ChinaLead Time:
30~60 days Ex Works after order confirmationMaterial:
ASTM A105.Method of Operation:
Bare StemQuick Details
|
Type |
Ball Valve |
|
Nominal Diameter |
2"~60" (DN50~DN1500). |
|
NominalPressure |
150 lbs~2500 lbs (PN16~PN420). |
|
Construction |
Top Entry,One Piece Type |
|
Connection |
BW,RTJ |
|
Operation |
Gearbox, Electric, Pneumatic, Elector Hydraulic Actuator, Gas Over Oil Actuator. |
|
Body Material |
ASTM A105. |
|
Design Code |
API 6D. |
|
Pressure & Temp |
ASME B16.34 |
|
End toEnd Dimension |
ASME B16.10 |
|
Inspection |
API598 |
|
Temperature Range |
-46℃~+200℃. |
|
Media |
Oil, Water, Gas |
Dervos top entry ball valves are engineered to meet international standards of API 6D, ASME B16.34 and others on request. The range contains both soft , metal or composite seats that can be configured to provide an effective double block and bleed (DB&B) .
Features
·Soft, metal or composite material seated
·Bi-directional tight shut-off
·Double block & bleed
·Fire safe and fire tested
·Low operating torque design
·Wide range of materials and sizes
·Anti-blowout stem design
·Suitable for above ground or below ground installation
·Top-entry design enable maintenance in line
·Forged or cast body optional
·Extended Bonnet
Reports
Along with each order, Dervos will provide inspection reports and material test reports free of charge after shipment. All these certificates will let you have a clear picture of inspection process and results. Plus, these reports can be used for traceability.
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 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.
12" 1500LB top entry ball valve is made according to API 6D standard. The valve body is made of ASTM A216 WCB. It has the structural characteristics of top mounted, fixed ball, full bore, fire-safe design and anti-static, blowout-proof stem, inner diameter: 295mm. Its connection mode is RTJ. And it has turbine operation mode.
8" 150LB cast steel globe valve is made according to BS 1873 standard. The valve body is made of ASTM A216 WCB+STL. It has the structural characteristics of straight through, rising stem, plug valve disc. Its connection mode is RF. And it has hand wheel operation mode.
2”150LB Sight Glass is made according to ASME B16.34 standard. The valve body is made of WCB. Its connection mode is RF.
Made 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
The 6 Inch PSB globe valve has 1500LB design pressure, butt weld end, and gearbox. The full bore globe valve is made of carbon steel WCB body and trim 5 material. Quick Detail Type Globe Valve Size 6'' Design Pressure Class 1500 Construction Pressure Seal Bonnet, Plug Type Disc, Rising Stem Connection Type Butt Weld Operation Type Bevel Gearbox Opearted Design Code BS 1873 End to End ASME B16.10 Connection End ASME B16.25 Pressure & Temperature ASME B16.34 Test & Inspection Standard API 598 Body Material Cast Steel WCB Trim Material Trim NO. 5 Temperature Range -29℃~+425℃ Application WOG Origin China Material & Dimension NPS DN Class 2 2 1/2 3 4 6 8 50 65 80 100 150 200 L(RF) L1(BW) 900LB 368 419 381 457 610 737 1500LB 368 419 470 546 705 832 2500LB 451 508 578 673 917 1022 L2(RTJ) 900LB 371 422 384 460 613 740 1500LB 371 422 473 549 711 841 2500LB 454 514 584 683 927 1038 H(Opne) 900LB 550 605 678 798 930 1230 1500LB 550 605 866 956 1260 1263 2500LB 560 720 755 1230 1791 2086 W 900LB 350 350 400 450 458 610* 1500LB 400 400 450 560 610* 610* 2500LB 400 450 560 310* 610* 760 Weight (RF) 900LB 78 108 102 142 400 960 1500LB 85 110 135 230 660 1590 2500LB 140 168 247 620 1500 3200 Weight (BW) 900LB 66 91 87 128 355 868 1500LB 77 101 122 209 595 1440 2500LB 100 118 180 438 1148 2594 *Manual gear operator is recommended No Part Name Carbon steel to ASTM Alloy steel to ASTM Stainless steel to ASTM WCB WC6 WC9 C5 CF8 CF8M CF3 CF3M 1 Body A216 WCB A217 WC6 A217 WC9 A217 C5 A351 CF8 A351 CF8M A351 CF3 A351 CF3M 2 Seat Ring A105 A182 F11 A182 F22 A182 F5 A182 F304 A182 F316 A182 F304L A182 F316L 3 Disc A105 A182 F11 A182 F22 A182 F5 A182 F304 A182 F316 A182 F304L A182 F316L 4 Stem A182 F6 A182 F304 A182 F304 A182 F316 A182 F304L A182 F316L 5 Disc nut A182 F6 A182 F304 A182 F304 A182 F316 A182 F304L A182 F316L 6 Cap SS Spiral Wound graphite or SS Spiral Wound PTFE 7 Body Seal Flexible Graphite+316 8 Adjustment Gasket F6 F6 F316 9 Stem packing Flexible Graphite+316 10 Gland Nut A194 2H A194 8 11 Gland Eyebolt A193 B7 A193 B8 12 Pin Carbon steel or Stainless Steel 13 Cap Nut Carbon steel or Stainless Steel 14 Gland A182 F6 A182 F304 A182 F316 A182 F304L A182 F316L 15 Gland Flange A216 WCB A351 CF8 16 Yoke A216 WCB A351 CF8 17 Stem Nut A439 D2 or B148-952A 18 Screw Carbon steel 19 Handwheel Ductile Iron or carbon steel 20 Name Plate Stainless steel or Aluminum 21 Washer Carbon steel 22 Nut Carbon steel or Stainless Steel Related Knowledge Why do we use pressure seal bonnet? Pressure sealed bonnet are often used for valves with high design pressure. The higher the internal pressure gets, the greater the sealing force beween body and bonnet become. For bolted bonnet valves, the body and bonnet are joined by studs and nuts with a gasket between the flange faces to facilitate sealing. However,as system pressure increases,the potential for leakage through the body and bonnet increases. But for pressure sealed valve, “bonnet take-up bolts” to pull the bonnet up and seal against the pressure seal gasket. That is why when pressure increase, the performance of pressure seal gasket between body and bonnet becomes better.
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.
Made as per API6D, the two pc floating ball valve, 3/4inch and 150LB, has different ends.Find your floating ball valve or other valves easily in Dervos.
The inverted bucket type steam trap is known as the most reliable steam trap. The DN20 WCB inverted bucket steam traps are used in steam heating systems to stop steam from draining out, so choosing the right trap can help steam heating equipment work more efficiently.
2" 150LB ball valve is made according to ISO17292 standard. The valve body is made of B148 C95400. It has the structural characteristics of full flow, floating ball, anti-fire, anti-static and anti-flying valve stem. Its operation mode is lever and connection mode is RF.
3" 300LB stainless steel globe valve is made according to BS1873 standard. The valve body is made of A351 CF8M. It has the structural characteristics of ammonia shut-off valve. Its connection mode is RF. And it has handwheel operation mode.
DN80 PN25 Cast Steel Gate Valve is made according to DIN3352 standard. The valve body is made of 1.0619+STL. It has the structural characteristics of Bonnet, Straight-through Type. Its connection mode is EN1092-1 B. And it has hand wheel operation mode.
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