ISO 15761 is a standard for small-bore steel valves used in the oil and gas industry, covering sizes from DN 15 to DN 100 and pressure classes from Class 150 to Class 2500. It applies to gate valves, globe valves, and check valves. These valves are not produced in a single step, but through a sequential manufacturing chain. The quality of each stage directly affects the next. Understanding this chain helps identify critical issues more efficiently during valve selection, compliance review, and supplier evaluation. Complete Manufacturing Process Step 1: Material Selection Material determines the applicable service conditions and is the starting point of the entire process. Common materials under ISO 15761 include: ● Carbon steel for general oil and gas service ● Low-temperature carbon steel for cryogenic or low-temperature conditions (e.g., LNG applications) ● Stainless steel for corrosive media If the service contains hydrogen sulfide (H₂S), materials must also comply with NACE MR0175 / ISO 15156 to prevent sulfide stress cracking. This requirement is applied independently of ISO 15761. Incorrect material selection cannot be compensated by subsequent process control. Step 2: Forging This step determines the internal quality of the valve body. Forging involves forming heated metal under pressure, resulting in a dense internal structure with a lower probability of defects. It is typically preferred for high-pressure or high-reliability applications. For Class 800 and above, forged bodies are commonly selected in engineering practice to reduce internal defect risks and improve structural reliability, although final selection depends on project specifications. Step 3: Machining After forming, precision machining is performed to meet dimensional and sealing requirements. Sealing surface machining is a critical control point. The contact surfaces between the seat and disc must undergo multiple machining and lapping processes to achieve specified flatness and surface roughness, directly affecting shut-off performance. The stem surface must also meet low roughness requirements to ensure long-term packing sealing stability. Excessive roughness accelerates packing wear and may lead to external leakage during operation. Step 4: Welding (Hardfacing of Sealing Surfaces) This process is used to enhance sealing surface performance. For wear or corrosion-resistant applications, sealing surfaces are typically overlaid with hard alloys such as Stellite to improve resistance. During welding, heat input and dilution rate must be controlled to prevent excessive mixing of the base material, which would reduce surface hardness. The hardfacing layer is usually required to meet a specified hardness range (e.g., Stellite typically ≥ HRC 35–45). This process must be performed by qualified welders, with welding procedure specifications (WPS), procedure qualification records (PQR...
In applications requiring remote operation or frequent switching, an automatic line blind valve is typically equipped with either electric or hydraulic actuation. The fundamental difference between the two does not lie in whether they can be used, but in their load capacity, response characteristics, environmental adaptability, and system complexity. 1. Electric Actuation (Electric Actuated Line Blind Valve) Electric actuation uses a motor combined with a reduction gearbox to generate torque, driving the blind plate to complete the switching operation. Selection logic: ● If power supply on site is stable → electric actuation should be prioritized ● If remote control or automation integration (DCS/PLC) is required → electric actuation is more straightforward ● If switching frequency is relatively high → electric actuation allows better control of operation speed Key features: ● Simple control: can be directly integrated into control systems, enabling remote operation and position feedback ● Compact structure: no additional hydraulic power unit required ● Lower maintenance requirements: routine checks mainly involve the motor and gearbox Limitations: ● If valve size is large or high thrust is required → electric actuation may have insufficient torque ● If the environment is high-temperature, hazardous (explosive), or dusty → higher electrical protection standards are required (e.g., ATEX) ● If power supply is unstable or frequently interrupted → reliability may decrease Conclusion:If the application involves standard automation requirements and moderate load conditions, electric actuation is generally the preferred solution. 2. Hydraulic Actuation (Hydraulic Actuated Line Blind Valve) Hydraulic actuation generates thrust through hydraulic fluid pressure, making it suitable for high-load applications. Selection logic: ● If valve size is large (e.g., DN300 and above) → hydraulic actuation should be prioritized ● If high thrust is required or resistance/sticking needs to be overcome → hydraulic actuation is more stable ● If a hydraulic system is already available on site → integration cost is lower Key features: ● High thrust output: suitable for heavy-duty blind plates or high-pressure pipelines ● Stable operation: provides continuous output with strong resistance to shock loads ● Good controllability: enables precise control through pressure regulation Limitations: ● If no hydraulic power unit is available on site → system complexity increases ● If ambient temperature variation is significant → hydraulic fluid performance may fluctuate ● If maintenance is insufficient → leakage issues are more likely to occur Conclusion:If the application involves high load and high reliabili...
Recently, DERVOS Valve successfully passed the audit by the American Petroleum Institute (API). The company’s API Spec 6D certification for pipeline valves has been renewed, and the API 600 certification has also been issued. Both certificates are valid through 2029. What is an API6D certificate? API 6D is an internationally recognized standard for valves used in oil and gas pipeline transportation systems. It covers the full process requirements for design, manufacturing, and inspection of products such as ball valves, gate valves, and check valves. The certification typically requires renewal audits every three years. What is an API600 certificate? API 600 is an internationally recognized standard for steel gate valves used in oil and gas refinery applications. It defines requirements for design, materials, manufacturing, inspection, and testing. This certification is generally subject to renewal every three years to maintain validity. According to available information, the audit covered multiple aspects, including quality management system operation, production process control, inspection equipment calibration, and personnel qualifications. During the audit, the API inspection team conducted an on-site review of the entire process at DERVOS Valve, from raw material procurement to final product delivery. A representative from the company’s quality department stated that DERVOS Valve has been continuously improving its standardized system management and has established a quality control system covering the full product lifecycle. Key production processes are supported by standardized work instructions, and inspection records are fully traceable to individual orders. The successful renewal of these certifications demonstrates that DERVOS Valve continues to meet API requirements in product manufacturing and quality assurance within the industrial valve sector. It also supports the company’s qualification to supply products for international projects such as oil and gas pipelines and LNG receiving terminals. The company stated that it will continue to focus on standardized production and process management to ensure the effective operation of its quality management system.
Line blinds are utilized in pipeline systems when there is a need for either complete closure or unimpeded flow transition without a significant drop in pressure. The THD (Through-Hole Design) enables swift and seamless adjustments in position. The THD-slide variant boasts a multi-bolt configuration, making it easier to operate with reduced face-to-face dimensions. The inclusion of extra body bolts renders this style particularly well-suited for high-pressure applications.
Payment:
30% when order confirmed, 70% before shipmentProduct Origin:
ChinaColor:
CustomizationShipping Port:
Shanghai, ChinaLead Time:
30~60 days Ex Works after order confirmationFeatures
1. Swift Transition: Blinding can be performed safely in a matter of minutes, even by operators with minimal experience.
2. Economical Solution: Decreases maintenance hours, resulting in savings on labor costs.
3. Toolless Handling: The process is simplified with a hand-wheel operation, eliminating the need for tools to achieve full shut-off.
Standard Specifications
|
Size |
1'' - 60'' (DN 25 to DN 1500) |
|
Pressure Class |
Class 150 - 2500 (PN 2.5 to PN 400) |
|
Design & Manufacture code |
ASME B16.34 |
|
Flange Standard |
ASME B16.5 |
|
Material |
Carbon Steel, Stainless Steel, Hastelloy, and Titanium |
|
Actuation |
Manual, Pneumatic Hydraulic and Electric |
Technical Drawing
Adaptable Design
In addition to its conventional design, the THD-Slide is available in variations tailored for High-Temperature, Fire Safety, and Non-Drip applications. For installations constrained by limited space, a compact version can be provided as well.
Easy Seal Inspection
In this design, the seals are housed within the spectacle plate. This characteristic offers the advantage of convenient access for inspection and seal replacement. Assessing the condition of these seals can be performed external to the operational process, prior to any position changes, thereby ensuring the integrity of the seal's quality.
Cost Effectiveness
The THD-Slide features a straightforward and robust design engineered to deliver complete shutdown, extended operational lifespan, and cost-effective service with minimal maintenance requirements. The distinctive mechanism for opening and closing the THD-Slide enables a single individual to rapidly and safely blind pipelines without the need for any tools or equipment.
THD-Slide Cutout
Part Description
|
Part Description |
Material |
|
Handwheel |
QT400-18 |
|
Stem |
A182 F6A |
|
Stem Nut |
Alloy Copper |
|
Body |
A350 LF2 |
|
Seal Carrier |
A350 LF2 |
|
Seals in plate |
Viton |
|
Spectade Plate |
A350 LF2+ENP |
|
Position Stop |
A193 B7 |
|
Driving module |
A350 LF2 |
|
Body stud/Nuts |
A193 B7/A194 2H |
|
Other materials and seal rings are available upon request |
|
Options
●Hand Wheel Extensions
●Locking Device
●Limit Switches
●Drain/Vent ports
●Spectacle Plate Covers to Protect Seals
●Compact Design (integral tapped end flange)
●Rain/Dust Shield
●Torque Limiter
Operation of Standard
Mechanism Principle
In normal conditions, the blind valve's diversion hole is in contact with the pipeline, and the blind valve is in the open position. When maintenance is required, and the pipeline must be cut off, then loosen the stem of blind valve to move the flat end onto the pipeline, and make the blind valve turn to closed position from open position; tighten the stem and let the blind valve to perform sealing function and cut off the pipeline.
When the maintenance work is completed, loosen the stem and move the blind plate to the diversion hole and connected to the pipeline. The blind valve was turned to closed position from open one. Lock the stem, and seal it, the pipeline is now open, and the blind plate valve returns to the open position.
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Line blind valve (eyeglass valve) is a kind of gate valve that cuts off gas medium manually, electrically or pneumatically or hydraulically. It is generally divided into electric blind valve, hydraulic blind valve, closed plug valve and electric open blind valve.
10" 150LB line blind valve is made according to ASME B16.34 standard. The valve body is made of A105. It has the structural characteristics of anti-drip. Its connection mode is RF. And it has turbine operation mode.
This DN400 PN40 forged slide blind valve provides positive isolation for steam pipelines and high-temperature industrial systems—physically blocking flow with a solid blind plate to ensure zero leakage during maintenance. Unlike conventional valves that rely on seats that can wear or degrade, this blind valve creates an absolute physical barrier, protecting personnel and preventing costly shutdowns. The sliding blind mechanism enables operators to switch between flow and isolation positions without depressurizing the line, significantly reducing downtime. Constructed from a one-piece forged A182 LF2 steel body, it delivers exceptional low-temperature toughness (down to -46°C) and reliable performance under PN40 pressure and high-temperature steam service up to 350°C. Designed to EN12516-1/2 and 100% pressure tested to EN12266-1/2, this valve features RF flanges per GOST 33259-Type B and a gear operator for smooth, high-torque actuation on large-diameter lines. It is a trusted choice for refineries, power plants, and industrial pipeline isolation where safety and reliability are paramount. Product Parameters Type Slide Blind Valve Size DN400 Pressure PN40 Connection RF Operation GEAR Body Material A182 LF2 Design Norm EN12516-1/2 Face to face Supplier Standards Flange dimension GOST 33259-Type B Test & Inspection Code EN12266-1/2 Temperature -46 ~ 350°C Applicable Medium Water, Oil and Gas Features • True Physical Barrier – Zero Leakage Isolation– Solid blind plate creates a true physical barrier. The one-piece forged LF2 body eliminates weld seams, ensuring structural integrity under PN40 pressure and thermal cycling. • Inline Operation Without Depressurization – Sliding mechanism enables switching without system blowdown. LF2 steel ensures reliable operation down to -46°C, ideal for cold climates and cryogenic steam conditions. • Gear-Operated for Large Diameters – High-torque gearbox ensures smooth and controlled operation for DN400 valves, even under demanding conditions. • Low-Temperature Toughness – ASTM A182 LF2 forged steel ensures reliable operation down to -46°C, ideal for cold climates and cryogenic steam conditions. Sliding Type Line Blind Valve Technical Drawing Dimension Checking Pressure Testing Painting Nameplate & Packing Inspection Report
This 10-inch Class 150 Sliding Line Blind Valve provides absolute positive isolation for steam turbine pipelines and high-temperature industrial systems. Unlike conventional gate or ball valves that rely on seats subject to wear, the sliding blind mechanism creates a solid physical barrier—delivering zero leakage during maintenance and ensuring personnel safety. The gear-operated sliding plate allows operators to switch between flow and isolation positions without depressurizing the line, significantly reducing downtime. The drip-proof design prevents fugitive emissions, making it ideal for steam, oil, gas, and other critical services. Constructed from ASTM A105 forged carbon steel with RF flanges per ASME B16.5, the valve is designed to ASME B16.34 and tested to API 598. It offers reliable performance in applications up to 425°C (sealing dependent), combining durability, safety, and ease of operation. Product Parameters Type Sliding Blind Valve Size 10” Pressure 150LB Connection RF Operation Turbine Body Material A105 Design Norm ASME B16.34 Face to face Manufacturer Standard Flange dimension ASME B16.5 Test & Inspection Code API 598 Temperature -29 ~ 150°C (Higher temperature up to 425°C available with metal seat) Applicable Medium Water, Oil and Gas Features • Forged A105 Carbon Steel Body – Provides strength and durability for reliable performance in industrial pipeline service. • Drip-Proof Design – Prevents fugitive emissions and protects internal components, making it ideal for environmentally sensitive applications and steam turbine systems. • Absolute Physical Isolation – Solid blind plate provides true physical separation of the pipeline, ensuring safe maintenance without relying on sealing surfaces. • Online Switching – No Depressurization Required – Sliding mechanism allows switching between open and blind positions without pipeline blowdown, reducing downtime and media loss. • Gear-Operated for Large Diameters – High-torque turbine drive enables smooth and controlled operation for large valves, even under demanding conditions. Slide Type Line Blind Valve Technical Drawing Dimension Checking Pressure Testing Painting Nameplate & Packing Inspection Report
Introduction This 10" Class 300 Sliding Line Blind Valve provides absolute positive isolation for medium‑ to high‑pressure pipelines, combining the reliability of a solid physical barrier with the simplicity of manual screw‑operated actuation. Unlike conventional valves that rely on seats prone to wear, the sliding blind mechanism creates a true physical barrier, ensuring zero leakage during maintenance without the need for system depressurization. This significantly reduces downtime and enhances personnel safety. The manual screw‑operated design offers precise, controlled movement of the blind plate, with inherent self‑locking capability to maintain position under pressure—ideal for applications where electric or pneumatic power may not be available or preferred. Constructed to ASME B16.34 with RF flanges per ASME B16.5, this valve is available in forged carbon steel (A105), stainless steel, or alloy materials to suit your service conditions. Each unit is 100% pressure tested to API 598. This 10" Class 300 configuration is a popular choice for steam, oil, gas, and chemical pipelines. Other sizes from 1" to 60" and pressure classes up to Class 2500 are available as part of our full line blind valve series. THD-Slide Cutout Features 1.Manual Screw‑Operated with Self‑Locking Precision screw drive allows smooth, controlled positioning of the blind plate. The self‑locking mechanism maintains position under pressure without additional braking devices. 2.Absolute Physical Isolation Solid blind plate creates a true barrier, ensuring zero leakage during maintenance—unlike seat‑dependent valves that can wear or degrade over time. 3.Inline Operation Without Depressurization Sliding mechanism enables switching between flow and blind positions without system blowdown, reducing downtime and product loss. 4.10″ Class 300 – The Optimal Balance Offers higher pressure capability than Class 150 while remaining more economical than Class 600, making it a versatile choice for a wide range of industrial applications. 5.Forged Carbon Steel Construction A105 forged body provides high strength, impact resistance, and reliable performance under thermal cycling. 6.Tested to API 598 100% hydrostatic and pneumatic testing ensures leak‑tight performance before shipment. Standard Specifications Parameter Specification Type Sliding Line Blind Valve Size 10″ (DN250) Pressure Rating Class 300 (PN50) Connection RF Flange, ASME B16.5 Operation Manual Screw-Operated (Self-locking) Body Material A105 Forged Carbon Steel (other alloys available) Seal / Seat Material Metal-to-Metal (Stainless Steel + Graphite) Design Standard ASME B16.34 Face-to-Face Dimension Per ASME B16.10 or manufacturer standard Test & Inspection API 598 (100% hydrostatic & pneumatic) Temperature Range -29°C to +425°C (depending on sealing) Applicable Media Steam, Oil, Gas, Water, Hydrocarbons Application Pipeline isolation, refineries, petrochemical plants, power generation Technical Drawing Flexible Design Options Tailored Configurations for Demanding Applications Beyond the base model, this line blind valve can be customized for high-temperature service, fire-safe requirements, and zero-emission (drip-proof) operation. For installations where space is at a premium, a compact variant is available, offering the same robust isolation performance in a reduced footprint. Simplified Seal Maintenance– No Disassembly Required Seals are integrated into the spectacle plate, allowing operators to inspect or replace them without dismantling the valve. Condition checks can be performed while the valve remains in service, before any position change, ensuring seal integrity is verified before operation. Low Total Cost of Ownership The valve’s streamlined, heavy‑duty construction delivers reliable positive shut‑off with minimal upkeep. Its unique actuation mechanism allows a single operator to quickly and safely isolate the pipeline—no tools required—reducing labor time and simplifying maintenance procedures. Options ●Hand Wheel Extensions ●Locking Device ●Limit Switches ●Drain/Vent ports ●Spectacle Plate Covers to Protect Seals ●Compact Design (integral tapped end flange) ●Rain/Dust Shield ●Torque Limiter
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