API 6D ASME B16.34 CE 2” 600LB A105 Carbon Steel Body DEVLON Soft Seated RF Flanged Connection Manual Handle DBB Double Block and Bleed Ball Valve

I. Product Overview & Core Specifications

The TIANYU DBB double block and bleed ball valve is a precision-engineered fluid control solution purpose-built for critical isolation and pressure management in industrial pipeline systems, engineered to deliver uncompromising safety, reliability, and operational efficiency in high-pressure applications. With a nominal size of 2” (DN50), this valve is optimized for medium-flow pipeline systems, offering a compact footprint while maintaining robust performance characteristics suitable for oil and gas, petrochemical, and industrial process infrastructure. Rated for a pressure class of 600LB, it operates reliably at a maximum working pressure of 10.34 MPa, making it ideal for high-pressure applications where system integrity, leak prevention, and safe maintenance are non-negotiable.

The valve body is constructed from A105 carbon steel (A105N normalized), a premium material renowned for its exceptional mechanical strength, impact resistance, and high-temperature stability. Conforming to ASTM A105 standards, A105 exhibits a minimum tensile strength of 485 MPa, a yield strength of 250 MPa, and excellent ductility, enabling it to withstand cyclic pressure fluctuations, thermal shocks, and mechanical stress in high-pressure pipeline systems. This material choice ensures the valve maintains structural integrity even in extreme operating conditions, including low temperatures (down to -29°C) and high-pressure environments, while its weldability and machinability simplify installation and retrofitting into existing pipeline systems.

Complementing the robust A105 body, the valve seat is fabricated from DEVLON, a high-performance thermoplastic polymer renowned for its exceptional wear resistance, chemical compatibility, and sealing capabilities. DEVLON resists degradation from hydrocarbons, mild acids, alkalis, and a wide range of industrial chemicals, making it suitable for contact with crude oil, natural gas, and process fluids. The soft-seated design achieves bubble-tight shutoff compliant with ANSI/FCI Class VI, minimizing leakage to prevent product loss, environmental contamination, and safety hazards, while the seat’s self-lubricating properties reduce friction between the ball and seat, extending service life and ensuring smooth operation over thousands of cycles.

For seamless integration into pipeline systems, the valve features an RF (Raised Face) flanged connection design compliant with ASME B16.5 standards. Flanged connections provide a secure, leak-proof interface, allowing for easy assembly and disassembly during maintenance or system upgrades. The standardized flange dimensions, bolt patterns, and raised face finish ensure interoperability with global piping systems, reducing installation time and costs while ensuring compatibility with existing infrastructure. The RF face design provides a reliable gasket seal, even under high-pressure conditions, further enhancing the valve’s leak-tight performance.

Actuation is delivered by a precision-engineered manual handle, designed to provide intuitive, responsive control over valve positioning. The handle incorporates a positive-locking mechanism to prevent accidental operation, ensuring the valve remains in the desired position even under vibration or external forces. The ergonomic design of the handle reduces operator fatigue during frequent adjustments, while the compact footprint ensures compatibility with space-constrained installations. A visual position indicator is integrated into the handle assembly, providing clear, at-a-glance confirmation of the valve’s open/closed status, reducing the risk of operator error and enhancing operational safety.

At the core of the valve’s functionality is the double block and bleed (DBB) design, which enables simultaneous isolation of fluid flow from both upstream and downstream sources, while providing a dedicated bleed port to vent trapped pressure or fluid between the two isolation points. This eliminates the need for multiple valves to achieve isolation and bleed-down, reducing system complexity, installation costs, and potential leak points. The DBB design is critical for maintenance scenarios, allowing technicians to safely depressurize and drain sections of the pipeline without risk of cross-contamination or fluid release, enhancing workplace safety and compliance with industry regulations.

II. Design Features & Functional Advantages

The TIANYU 2” 600LB DBB ball valve incorporates innovative design elements that elevate its performance, safety, and operational efficiency beyond conventional isolation valves, addressing the unique challenges of high-pressure industrial fluid control applications.

API 6D ASME B16.34 CE 2” 600LB A105 Carbon Steel Body DEVLON Soft Seated RF Flanged Connection Manual Handle DBB Double Block and Bleed Ball Valve

At the core of its design excellence is the DBB functionality, which redefines safety and efficiency in pipeline maintenance. Unlike traditional isolation valves, which require separate valves to block flow and vent trapped pressure, the DBB design integrates two independent ball valves and a central bleed valve into a single compact unit. This configuration allows technicians to block flow from both upstream and downstream directions, then open the bleed valve to safely vent trapped pressure and fluid between the two isolation points. This eliminates the risk of cross-contamination, fluid release, or pressure buildup during maintenance, enhancing workplace safety and reducing downtime. The DBB design also minimizes the number of potential leak points, improving overall system reliability and reducing maintenance costs.

The soft-seated design, utilizing DEVLON seats, delivers exceptional sealing performance and durability in high-pressure applications. DEVLON is a proprietary thermoplastic polymer that combines the wear resistance of metal with the sealing capabilities of elastomers, making it ideal for soft-seated valve applications. The seat’s self-lubricating properties reduce friction between the ball and seat, minimizing wear and extending service life, while its chemical resistance ensures compatibility with a wide range of industrial fluids. The soft-seated design achieves bubble-tight shutoff compliant with ANSI/FCI Class VI, minimizing leakage even at low pressures or with viscous fluids, ensuring optimal performance in critical isolation applications. The seats are also replaceable, allowing for easy maintenance and extending the valve’s service life without full replacement.

The valve body is manufactured using a precision forging process, which enhances material density and mechanical properties, ensuring a uniform grain structure and resistance to deformation under pressure. The forging process eliminates internal defects such as porosity or inclusions, which could compromise structural integrity in high-pressure applications. The body’s streamlined internal geometry minimizes pressure drop and turbulence, optimizing flow efficiency and reducing energy consumption in high-throughput systems. The body’s robust construction, combined with the A105 carbon steel material, enables it to withstand external loads, including mechanical stress and vibration, making it suitable for harsh industrial environments.

The manual handle design offers a balance of simplicity, reliability, and operational efficiency. The handle is precision-machined from high-strength carbon steel, ensuring compatibility with the valve’s high-pressure requirements and providing exceptional strength and rigidity. The positive-locking mechanism on the handle prevents accidental operation, ensuring the valve remains in the desired position, while the visual position indicator provides clear feedback to operators, reducing the risk of human error. The handle’s compact design makes it suitable for installation in space-constrained environments, such as skid-mounted systems and modular process units, while its ergonomic shape reduces operator fatigue during frequent adjustments.

Safety and environmental protection are integrated into every design detail, starting with the fire-safe design compliant with API 607 and API 6FA standards. In the event of a fire, the DEVLON seat material may degrade, but the valve’s metal-to-metal backup seal—formed by the A105 body and stainless steel ball—ensures continued isolation of fluid flow, preventing catastrophic leakage and minimizing fire propagation. This design provides an additional layer of safety, ensuring the valve maintains integrity even under extreme thermal conditions. The valve also incorporates a bleed port with a threaded connection, allowing for the installation of a pressure gauge, relief valve, or drain line, enabling continuous monitoring of trapped pressure between the two isolation points and controlled bleed-down of fluid during maintenance.

The valve’s modular design enables easy maintenance and component replacement, with the seats, ball, and stem accessible without removing the valve from the pipeline. This reduces downtime and maintenance costs, making it an ideal choice for critical pipeline systems where operational continuity is essential. The bleed valve is also modular, allowing for easy replacement without disassembling the main valve, further enhancing the valve’s maintainability and service life.

III. Manufacturing Process & Quality Assurance

The production of the TIANYU 2” 600LB DBB ball valve adheres to the most rigorous manufacturing processes and quality control protocols in the industry, aligning with API 6D, ASME B16.34, and ISO 9001:2015 standards to ensure every valve meets or exceeds design specifications and global industry requirements. From raw material procurement to final factory testing, every step of the manufacturing process is controlled and documented, with a focus on precision, consistency, and reliability—critical for a valve designed for high-pressure, critical isolation applications.

Raw Material Procurement & Inspection

Raw materials for the valve—A105 carbon steel billets and DEVLON polymer—are sourced exclusively from approved, ISO 9001-certified suppliers with a proven track record of producing high-quality materials for the oil and gas and petrochemical industries. All raw materials are accompanied by a mill test certificate (MTC) that verifies chemical composition, mechanical properties, and compliance with ASTM A105 (for A105 carbon steel) and proprietary DEVLON material specifications. Upon receipt, the raw materials undergo rigorous incoming inspection in TIANYU’s state-of-the-art quality control laboratory, including:

Chemical composition analysis via optical emission spectroscopy (OES) to verify compliance with ASTM standards;
Mechanical property testing (tensile strength, yield strength, elongation, hardness) via universal testing machine (UTM) and Brinell hardness tester;
Non-destructive testing (NDT) including ultrasonic testing (UT) and magnetic particle testing (MPT) to detect internal and surface defects;
For DEVLON, additional testing to verify chemical resistance, wear resistance, and thermal stability.

Any raw material that fails to meet the specified requirements is rejected and returned to the supplier, ensuring only high-quality materials are used in production.

Body & Ball Fabrication

The valve body is manufactured using a hot-forging process, where A105 carbon steel billets are heated to high temperatures (1100-1200°C) and shaped under extreme pressure using precision dies. This process enhances material density, eliminates internal defects such as porosity or inclusions, and improves mechanical properties, including tensile strength and impact resistance. After forging, the body undergoes normalization heat treatment (900-920°C) followed by air cooling, to refine its microstructure and relieve internal stresses, ensuring consistent performance across the component. The body is then machined to precise dimensions using CNC lathes and milling machines, with critical surfaces such as the ball cavity, stem bore, and flange faces finished to a roughness of Ra ≤ 3.2 μm to ensure proper sealing and alignment.

The ball is manufactured from A105 carbon steel or stainless steel, using a precision forging process followed by CNC turning and milling to achieve the required spherical shape and dimensional accuracy. The ball is then lapped and polished to a surface finish of Ra ≤ 0.8 μm, ensuring optimal sealing performance with the DEVLON seat assembly. After machining, the ball undergoes heat treatment to enhance its mechanical properties and corrosion resistance, ensuring long-term performance in high-pressure applications.

Seat & Stem Production

The DEVLON seats are fabricated from high-grade DEVLON polymer, which is molded and machined to precise dimensions using CNC lathes and milling machines. The sealing surface is polished to a roughness of Ra ≤ 0.8 μm, ensuring a tight, leak-proof seal with the ball surface. Each seat undergoes dimensional inspection and material testing to verify compliance with chemical resistance and wear resistance specifications. The stem is machined from A105 carbon steel or stainless steel using CNC lathes, with critical surfaces such as the sealing area and thread finished to tight tolerances to ensure compatibility with the packing system and ball connection.

Assembly & Testing

The valve assembly process is conducted in a controlled, clean environment to prevent contamination of internal components, with skilled technicians following detailed, step-by-step assembly work instructions. The assembly process involves:

Installing the DEVLON seat assemblies into the valve body cavity;
Inserting the ball into the body, ensuring proper alignment with the seats;
Installing the stem through the bonnet packing and connecting it to the ball via a square drive or keyed connection;
Mounting the bonnet to the body and torquing the bonnet bolts to the specified value using a calibrated torque wrench;
Installing the stem packing system, including graphite or PTFE packing rings, to ensure a leak-proof seal;
Attaching the manual handle and position indicator, and calibrating the position indicator to align with the ball’s open/closed status;
Installing the bleed valve assembly and connecting it to the central cavity between the two isolation balls;
Lubricating all moving parts with a high-performance, high-temperature grease compatible with the valve’s materials.

During assembly, critical dimensions and clearances are verified using precision measurement tools, including coordinate measuring machines (CMMs), dial indicators, and calipers, to ensure compliance with design specifications.

Factory Testing & Certification

Before leaving the factory, every TIANYU 2” 600LB DBB ball valve undergoes a comprehensive series of performance tests in accordance with API 6D, API 598, and ISO 5208 standards, with all test results documented in a factory test certificate (FTC) provided with each valve. The testing program includes:

Shell Test: A hydrostatic pressure test conducted at 1.5 times the rated 600LB pressure (15.51 MPa) for a minimum of 30 seconds, to verify the body’s structural integrity and no visible leakage or deformation;
Seat Test (Hydrostatic): A hydrostatic pressure test of the seat assemblies at 1.1 times the rated pressure for both upstream and downstream flow directions, to verify compliance with ANSI/FCI Class VI leakage standards;
Seat Test (Pneumatic): A pneumatic pressure test at 0.69 MPa (100 PSI) to verify the soft-seal’s integrity in low-pressure applications;
DBB Function Test: A functional test to verify the double block and bleed functionality, ensuring the two isolation balls can be closed independently and the bleed valve can safely vent trapped pressure;
Operational Test: A functional test of the manual handle to verify smooth opening and closing, accurate position indication, and positive locking;
Fugitive Emission Test: A test of the stem packing system in accordance with ISO 15848-1, to verify emissions are below the specified limit (≤ 100 ppm for Class A);
Fire-Safe Test: A third-party fire test in accordance with API 607 and API 6FA to verify the metal-to-metal backup seal maintains integrity after fire exposure.

Only valves that pass all tests are certified and released for shipment, with the FTC including all test results, material certifications, and compliance standards for full traceability.

Quality Management System

TIANYU maintains a certified quality management system (QMS) compliant with ISO 9001:2015 and API Q1, the oil and gas industry’s premier quality standard for manufacturing facilities. The QMS covers all aspects of the manufacturing process, from raw material procurement to final delivery, with a focus on continuous improvement, customer satisfaction, and compliance with global industry standards. The QMS is supported by a team of experienced quality assurance (QA) engineers who conduct regular internal audits, process reviews, and supplier audits to ensure compliance, and a document control system that maintains all manufacturing, testing, and certification records for a minimum of 7 years—meeting the traceability requirements of the oil and gas industry.

IV. Application Scenarios & Industry Relevance

The TIANYU 2” 600LB DBB ball valve is a versatile, high-performance fluid control solution designed to meet the demands of a wide range of industrial applications where precise isolation, pressure management, and safety are critical.

Oil & Gas Production & Transmission

In oil and gas applications, including upstream production, midstream transmission, and downstream refining, the valve is used to isolate critical equipment such as pumps, compressors, and meters for maintenance and repair. The DBB functionality ensures safe depressurization of pipeline sections, reducing the risk of hydrocarbon release and environmental contamination. The A105 carbon steel body resists corrosion from crude oil and natural gas, making it suitable for onshore and offshore installations, while the fire-safe design enhances safety in high-risk environments. The 2” size is ideal for medium-flow production and transmission lines, while the 600LB pressure rating handles the high pressures common in wellhead and pipeline applications.

Chemical Processing

In chemical processing plants, the valve is used to isolate process lines, reactors, and storage tanks, ensuring safe handling of corrosive or hazardous fluids. The DEVLON seats resist degradation from acids, solvents, and hydrocarbons, maintaining reliable sealing performance even with aggressive chemicals. The DBB design allows for controlled bleed-down of trapped fluid, preventing cross-contamination between process streams and ensuring compliance with environmental regulations. The A105 carbon steel body provides structural strength and durability, making it suitable for high-pressure chemical process applications.

Pharmaceutical & Biotechnology

In pharmaceutical and biotechnology applications, the valve is used to isolate production equipment such as bioreactors, filtration systems, and transfer lines, ensuring sterile operation and preventing product contamination. The DEVLON seats are compatible with clean-in-place (CIP) and steam-in-place (SIP) processes, while the soft-seated design provides bubble-tight shutoff to maintain sterile conditions. The manual handle allows for precise, hygienic operation, reducing the risk of human error in critical production steps. The DBB design enables safe depressurization of process lines during maintenance, minimizing the risk of contamination and ensuring product purity.

Power Generation

In power generation facilities, including thermal power plants and combined cycle power plants, the valve is used to isolate steam lines, feedwater systems, and fuel gas lines. The A105 carbon steel body withstands high temperatures and pressures, while the DEVLON seats provide reliable sealing performance in steam and fuel gas applications. The DBB design allows for safe depressurization of pipeline sections during maintenance, reducing the risk of equipment damage and ensuring operational safety. The 2” size is ideal for medium-flow power generation systems, while the 600LB pressure rating handles the high operating pressures of these systems.

Offshore & Marine Applications

In offshore and marine applications, including FPSOs (Floating Production Storage and Offloading units) and offshore platforms, the valve is used to isolate critical systems such as firewater lines, fuel transfer systems, and hydraulic control lines. The A105 carbon steel body resists corrosion from saltwater and marine atmospheres, while the fire-safe design enhances safety in high-risk environments. The compact 2” size is suitable for installation in space-constrained offshore modules, while the DBB design enables safe depressurization of pipeline sections during maintenance, minimizing downtime and ensuring operational continuity.

The TIANYU 2” 600LB DBB double block and bleed ball valve delivers uncompromising safety and reliability for critical fluid isolation applications, combining A105 carbon steel’s structural strength with DEVLON’s bubble-tight sealing performance. Its DBB design eliminates the need for multiple valves, reducing system complexity and leak points, while the fire-safe construction enhances protection in high-risk environments. Certified to API, ASME, and CE standards, and backed by ISO 9001/API Q1 quality assurance, it excels in oil and gas, chemical processing, and power generation, ensuring efficient maintenance, regulatory compliance, and long-term operational value.