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DERVOS 18th Anniversary | Eighteen Years of Progress, Moving Forward Together
DERVOS 18th Anniversary | Eighteen Years of Progress, Moving Forward Together
2026-07-03

In 2026, DERVOS VALVE proudly celebrates its 18th anniversary, marking an important milestone in the company's journey. To commemorate this occasion, DERVOS VALVE organized a three-day anniversary celebration, bringing together all employees to reflect on the company's achievements over the past eighteen years, look ahead to future development, and further strengthen team cohesion through meaningful activities and shared experiences.   Reflecting on 18 Years of Growth   From raw material management and precision machining to assembly and product testing, every stage of production reflects DERVOS VALVE's unwavering commitment to quality.   Over the past eighteen years, DERVOS VALVE has continuously improved its manufacturing system while enhancing product quality and customer service capabilities. Today, our industrial valves are widely used across the oil and gas, chemical, power generation, water treatment, LNG, and other industrial sectors, providing reliable valve solutions to customers worldwide.   Building Consensus for Future Development     During the anniversary celebration, DERVOS VALVE also held its mid-year communication meeting.   The meeting reviewed the company's performance over the first half of the year and outlined key objectives for future development. Representatives from different departments exchanged insights on production management, quality improvement, and cross-functional collaboration, sharing practical experience, reviewing achievements, and discussing future goals together.   The meeting further strengthened communication among departments, reinforced team alignment, and injected new momentum into the company's long-term development.     Embracing Nature Together   In addition to the company's anniversary activities, DERVOS VALVE organized a group excursion to experience the beauty of nature.   Surrounded by picturesque landscapes, employees enjoyed the scenic environment and explored the local culture in a relaxed and enjoyable atmosphere. The trip provided an opportunity to unwind while fostering stronger relationships among colleagues.   This memorable experience enriched the anniversary celebration, strengthened team spirit, and inspired everyone with renewed energy for the work ahead.     Eighteen Years of Commitment, Looking Ahead   Eighteen years represent not only growth and achievement, but also the beginning of a new chapter.     Since its establishment, DERVOS VALVE has remained dedicated to the design, manufacturing, and global supply of industrial valves. Through continuous improvements in product development, manufacturing capabilities, and quality management, the company has provided reliable valve products and technical support to customers across a wide range of industries worldwide.   Looking ahead, DERVOS VALVE will continue to focus on product innovation, manufacturing excellence, and long-term...

Best Ball Valves for Refinery Applications
Best Ball Valves for Refinery Applications
2026-06-23

Refineries operate under some of the most demanding process conditions found in the energy industry. High pressure, elevated temperature, sour media, corrosive fluids, and frequent thermal cycling place strict requirements on valve performance. In these environments, ball valves are widely used because they provide reliable shutoff, low pressure loss, and fast operation. However, selecting the best ball valve for refinery applications depends less on the valve type itself and more on matching the design to the process conditions.   Why Ball Valves Are Common in Refinery Service   Refinery units handle hydrocarbons, hydrogen, steam, sulfur compounds, and various aggressive chemicals. If bubble-tight isolation is required, then trunnion mounted ball valves are generally preferred for larger sizes and higher pressure classes because seat loading remains stable under differential pressure. Floating ball valves are more common in small-bore lines where compact dimensions and simple construction are advantageous.   API 6D and ASME B16.34 designs are frequently specified for refinery piping systems. Fire-safe construction in accordance with API 607 or API 6FA is often mandatory because accidental loss of soft seats must not result in external leakage. If the process medium contains hydrogen sulfide, then materials must comply with NACE MR0175 to reduce the risk of sulfide stress cracking.   Material Selection Depends on Process Media   Material compatibility is one of the primary factors affecting service life. Carbon steel valves are suitable for many hydrocarbon services, while stainless steel provides improved corrosion resistance in wet and chemically aggressive environments. Duplex and super duplex stainless steels are selected when chloride-induced corrosion becomes a concern.   If the process contains sulfur compounds or sour gas, then hardness control and material qualification become critical. In high-temperature applications, thermal expansion must be considered because excessive growth can increase operating torque and accelerate seat wear. If severe erosion is expected, then hard-faced balls and seats with tungsten carbide or chromium carbide coatings can significantly improve durability.   Sealing Performance and Failure Prevention   Soft-seated ball valves provide excellent shutoff performance, but seat materials determine their temperature limits. PTFE and reinforced PTFE are common in moderate-temperature services, while PEEK offers improved mechanical strength and higher temperature capability. If temperatures exceed the limits of polymer seats, then metal-seated ball valves become a more suitable solution.   Most valve failures in refineries are related to seat damage, stem leakage, or corrosion. If particulate contamination is present, then cavity fillers or metal seats may reduce wear. Double block and bleed configurations are often used where positive isolation is required for maintenance...

Fully Welded Ball Valve vs. Threaded Ball Valve: Which Offers Better Pressure Resistance?
Fully Welded Ball Valve vs. Threaded Ball Valve: Which Offers Better Pressure Resistance?
2026-06-11

In natural gas transmission, district heating networks, petrochemical facilities, and industrial utility systems, ball valves are widely used for reliable flow isolation. One of the most common questions during valve selection is: Which provides better pressure resistance—a fully welded ball valve or a threaded ball valve?   Understanding the Structural Difference Between Fully Welded and Threaded Ball Valves   From a structural perspective, fully welded ball valves generally offer higher pressure-bearing capability. The valve body is manufactured using a fully welded construction, eliminating threaded body connections and reducing stress concentration points associated with mechanical joints. Under high-pressure conditions, frequent pressure fluctuations, or significant temperature changes, the welded structure can provide greater mechanical integrity and more stable sealing performance. Threaded ball valves, by contrast, rely on threaded connections to assemble the valve body. While this design simplifies installation and maintenance, threaded joints are inherently more susceptible to stress and deformation. As system pressure increases or when vibration and thermal expansion-contraction cycles are present, threaded connections may become vulnerable to loosening, potentially resulting in external leakage. Common field indications include leakage around the stem packing area, seepage from body connections, or accelerated wear of sealing components.   Why Fully Welded Ball Valves Typically Offer Higher Pressure Resistance   The primary advantage of a fully welded ball valve lies in its one-piece welded body construction. Without threaded body joints, the valve can better withstand internal pressure loads and reduce the possibility of leakage caused by connection failure.   In applications involving high operating pressures, pressure surges, or repeated thermal cycles, the welded structure maintains better dimensional stability and structural strength. This is one of the key reasons why fully welded ball valves are widely used in gas transmission pipelines, district heating systems, and other critical infrastructure projects.   How Sealing Performance Affects Pressure Capability   In high-pressure service, valve failure is not determined solely by body strength. The sealing system also plays a critical role. Fully welded ball valves typically utilize an integral body design that minimizes potential external leakage paths and provides more consistent support for the seat sealing surfaces.   In threaded ball valves, small dimensional changes at threaded joints during long-term pressure cycling may affect seat loading, potentially increasing the risk of internal leakage. If significant leakage, abnormal deformation, or pressure test failure is observed, the valve should be removed from service and inspected immediately. For flammable, toxic, or high-temperature media, disassembly and maintenance under pre...

Knife Gate Valve
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2" 150LB Knife Gate Valve CF8 Lug Handwheel

2" 150LB knife gate valve is made according to MFS standard. The valve body is made of ASTM A351 CF8. It has the structural characteristics of bilateral sealing and with flow deflector. Its connection mode is lug. And it has hand wheel operation mode.

  • Payment:

    30% when order confirmed, 70% before shipment
  • Product Origin:

    China
  • Color:

    Customization
  • Shipping Port:

    Shanghai, China
  • Lead Time:

    30~60 days Ex Works after order confirmation
  • Material:

    ASTM A351 CF8
  • Method of Operation:

    Hand Wheel
Inquiry now
Product Detail

Product Description

Type

Knife Gate Valve

Size

2"

Pressure

150LB

Connection

Lug

Operation

Hand Wheel

Body Material

ASTM A351 CF8

Design Norm

MFS

Flange Connection

AS2129 TABLE E

Face to Face

EN558

Test & Inspection Code

MSS SP-81

Applicable Medium

Water, Oil and Gas

Features

1. Simple structure, easy to manufacture and maintain;

2. Simple structure, low fluid resistance, good sealing performance, and fast opening and closing.

Technical Drawing

Dimension Checking

Pressure Testing

Nameplate & Packing

Inspection report

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The 6 inch stainless steel gate valve, designed as per MSS-SP-81, has the lug type connection per Class 150 and electric actuator. Quick Detail Type Knife Gate Valve Size 6'' Design Pressure ANSI 150 Construction Knife Type Gate Valve ConnectionType Lug Type OperationType Electric Actuator Body Material ASTM A351 CF8 TrimMaterial SS304 Design Code MSS SP81 Medium Water, Oil and Gas Origin China Related Knowledge What are knife gate valves used for? Knife gate valves are originally designed for paper industry. The knife gate valve is especially applicable for heavy liquids with solid particulates, like slurry liquid, that are most corrosive, erosive and abrasive. Compared to wedge gate valve, the knife gate valve has a shorter end to end dimension and lighter weight. Plus, the knife valve has a more sharpened disc to cut through slurry and viscous medium. Both wedge gate valve and knife gate valve can only be used for on-off function not for regulating the flow. Dervos Customer Service With Dervos customer service, you will not have any concern before, during and after buying valves. Pre-sales We will reply on time and also provide technical support upon your request. Order We will check the production details with factory and customers. Sales confirmation will also be sent. During production, we will also send weekly report to let you know the order status. Before shipment, delivery note will be sent to let you know the situation. 18 Month warranty Dervos is always responsible for their products. We will provide 18 months warranty to let our customers without concern.

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The stainless steel knife gate valve is designed with DN800 PN6 flange end and gearbox operation. The soft seated knife gate valve has a unidirectional sealing. Quick Detail Type Gate Valve Size DN800 Design Pressure PN6 Construction Unidirectional, Soft Seated ConnectionType Flange End OperationType Gearbox Operated Body Material CF8M DiscMaterial SS316L StemMaterial SS316 SeatMaterial PTFE Design Code MSS SP81 Medium Water, Oil and Gas Origin China  Dimension Checking Pressure Tesing

MSS SP-81 Manual Lug Type Knife Gate Valve Bi-directional
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    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.

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