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 When the valve is fully open, the gate is completely withdrawn from the flow path, allowing the fluid to pass through with minimal obstruction.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 ...
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.
1" 300LB Forged Steel Bellows Globe Valve is made according to API602 standard. The valve body is made of A350-LF2+316. It has the structural characteristics of Welded Bonnet, Rising Stem (OS&Y), Bellows Type. Its connection mode is RF. And it has Handle Wheel operation mode. Product Parameters Type Forged Steel Bellows Globe Valve Size 1” Pressure 300LB Connection RF Operation Hand wheel Body Material A350-LF2+316 Design Norm API602, ASME/B16. 34 Face to Face ASME/B16.10 Flange dimension conform ASME B16.5 Test & Inspection Code API598 Temperature -46 ~ 345°C Applicable Medium Water, Oil and Gas Features 1. LF2 forged steel body offers excellent low-temperature toughness and structural reliability for 300LB service. 2.Bellows-sealed globe valve design compliant with API 602 eliminates stem leakage and ensures safe, precise flow control. Technical Drawing Dimension Checking Pressure Testing Nameplate & Packing
The DN100 safety valve, made of WCB and according to GB/T12241-2005, usually work as the over-pressure protection device that work under a steam, air, water or other non-corrosive medium.
DN200 PN10 triple eccentric butterfly valve is made according to EN593 standard. The valve body is made of ASTM A216 WCB. It has the structural characteristics of triple eccentricity, two-way one-to-one ratio. Its connection mode is wafer. And it has turbine operation mode.
3/4” 150LB Forged Steel Floating Ball Valve is made according to API608 standard. The valve body is made of A182 F304. It has the structural characteristics of Full Bore, Floating Ball, Fire-safe and Anti-static, Blow-out Proof Stem. Its connection mode is NPT. And it has hand wheel operation mode. Product Parameters Type Forged Steel Floating Ball Valve Size 3/4” Pressure 150LB Connection NPT Operation H.W. Body Material A182 F304 Design Norm API 608 Face to Face MFG Screwed End ASME B1.20.1 Test & Inspection Code API 598 Temperature -29 ~ 120°C Applicable Medium Water, Oil and Gas Features 1.High-temperature F304 stainless steel body ensures superior corrosion resistance and durable performance. 2.API 608 certified design guarantees reliable shut-off and long-term service in demanding industrial application. Technical Drawing Dimension Checking Pressure Testing Nameplate & Packing Inspection Report
DN80 PN10 Air Release valve is made according to CJ/T217-2005 standard. The valve body is made of QT450. Its connection mode is EN1092-1.
10" 150LB swing check valve is made according to API 6D standard. The valve body is made of ASTM A216 WCB. It has the structural characteristics of swing type, built-in type, fully open. Its connection mode is RF.
1-1/2" 300LB Forged Steel Gate Valve is made according to API 602 standard. The valve body is made of ASTM A182 F316. It has the structural characteristics of BB,OS&Y. Its connection mode is RF. And it has hand wheel operation mode.
Chinese Valve manufacturer Dervos supplies Check Valve that featured with through conduit, plug type disc and replaceable seat. Expect these 14 inch 150LB check valve, other types valves of different materials, sizes are also available.
6" 150LB strainer is made according to ASME B16.34 standard. The valve body is made of ASTM A352 LCB. It has the structural characteristics of Y-shaped and bolt cover. Its connection mode is RF.
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