Flanged Gate Valve

Testing with media such as water, oil, and steam confirms extremely low flow resistance and zero-leakage sealing performance with rigid gates; the Flanged Gate Valves support various actuation methods, including manual, worm gear, pneumatic, and electric drives. As a professional valve supplier, Bolaisi strictly adheres to quality control standards throughout the casting, machining, and pressure-testing processes, meeting the requirements for complete shut-off in large-diameter pipelines across sectors such as municipal water supply, district heating, petrochemicals, power generation, metallurgy, and gas distribution.

Detailed Introduction

Bolaisi specializes in the R&D and manufacturing of industrial fluid shut-off valves, with a stainless steel valve production base located in Wenzhou, Zhejiang. As a reliable supplier for fluid piping systems, the company has established a comprehensive, closed-loop quality control system. This encompasses everything from flaw detection on raw steel materials, valve body casting and heat treatment, precision gate grinding, and packing assembly to dual-stage testing (hydrostatic and pneumatic) of the finished product. Before leaving the factory, every gate valve undergoes simulated testing for high/low-temperature performance and pressure durability. With years of deep expertise in gate valve manufacturing, the brand focuses on products characterized by low flow resistance, zero leakage, and long service life; all data regarding pressure ratings, sealing capabilities, and high-temperature performance are derived from long-term, real-world pipeline testing, ensuring honest and accurate specifications. Product Drawing

Product Specifications

1. Brand/Model: Bolaisi Z41H/W-10P/16P/25P/40P/64P

2. Body Material: WCB cast steel / 304 or 316 stainless steel (high-temperature and corrosion-resistant)

3. Nominal Diameter: DN15–DN1200

4. Sealing Type: PTFE soft seal or metal-to-metal hard seal

5. Pressure Rating: PN10/PN16/PN25/PN40/PN64

6. Flow Direction: Bidirectional flow; wedge gate provides bidirectional sealing

7. Connection Type: GB standard flange or ANSI standard flange

8. Valve Structure: Wedge-type double-disc straight-through gate valve

9. Applicable Media: Clean water, oil, natural gas, high-temperature steam, mildly corrosive fluids

10. Operating Temperature: Soft seal ≤150°C; metal hard seal ≤425°C

11. Actuation Method: Standard manual operation; optional worm gear, pneumatic, or electric actuators available

12. Opening/Closing Principle: Stem lifts the gate for full opening; lowers the gate for complete pipeline shut-off; no throttling loss

Application Scenarios

Industrial Sector: Petroleum, chemical processing, power generation, metallurgy, and natural gas transmission; used for flow control (on/off) of steam, oil, acids/alkalis, fuel gas, etc.

Municipal & Civil: Urban water supply, sewage treatment, and HVAC systems; used to shut off water or steam flow.

Special Operating Conditions: High-temperature/high-pressure pipelines, media containing particulates, highly corrosive media, long-distance transmission pipelines, etc. 

Selection Guide Nominal Diameter

Standard sizes: DN15–DN600; custom sizes available for DN700–DN1200.

Nominal Pressure

Most common: PN10, PN16, PN25, PN40; High-pressure applications: PN64. Do not use low-pressure valves for high-pressure applications.

Flange Standard

General steam, water treatment, standard projects → RF (Raised Face)

High pressure, gasket blowout prevention → FM (Female/Male Face)

Toxic or hazardous chemical media → TG (Tongue and Groove Face)

High temperature/pressure, superheated steam, heat transfer oil → RJ (Ring Joint Face)

Valve Body Material

WCB (Code C) e.g., Z41H-25C

Temperature range: -29°C to 425°C

Media: Saturated steam, heat transfer oil, circulating water, diesel, lubricating oil, non-corrosive oils

CF8 304 Stainless Steel (Code P) e.g., Z41W-16P

Temperature: -20°C to 425°C

Media: Weakly acidic wastewater, food-grade media, tap water, mildly corrosive chemical fluids

CF3M 316L Stainless Steel (Code RL) e.g., Z41W-16RL

Temperature: -20°C to 425°C

Media: Chloride-containing media, seawater, weak acid/alkali chemical raw materials; superior corrosion resistance compared to 304

Sealing Type

Z41H (Cr13 Metal-to-Metal Hard Seal)

Sealing surface: Cr13 stainless steel overlay; temperature resistance ≤425°C

Suitable for: Steam, oils, and clean media free of large particles

Best cost-performance ratio; preferred choice for standard thermal engineering projects. Z41Y (Stellite alloy hard-facing)

Superior wear resistance, high-temperature resistance, and erosion resistance; withstands temperatures up to 550°C.

Recommended applications: Superheated steam, heat transfer oil, media containing dust or carbon particles, and pipelines requiring frequent opening/closing.

The Z41Y is the preferred choice for powder and granular media, as the sealing surface is highly resistant to wear.

Z41W (Integral sealing surface machined directly from the valve body)

The valve body material itself serves as the sealing surface (commonly used for 304/316 stainless steel valves).

Suitable only for clean, corrosive media free of hard particles; not recommended for media containing silt or dust, as these can easily scratch the sealing surface.

Actuation Methods

DN40–DN200: Manual handwheel (standard configuration).

DN250 and larger: Bevel gear drive recommended to reduce operating torque and make opening/closing easier.

For remote automated control: Electric or pneumatic actuators can be installed.

Pre-sales Service | Professional Consultation & Risk-Free Selection

Free professional selection service: We accurately match valve models based on the customer's pipeline media, temperature, pressure, operating conditions, flange standards, and application scenarios, eliminating project risks caused by incorrect model, material, or seal structure selection.

Precise quoting and solution planning: We calculate costs on a one-on-one basis according to customer parameters, quantities, and customization requirements, providing detailed quotes and optimal solutions—offering transparent, reasonable pricing without arbitrary markups or cutting corners on materials.

Provision of technical data and qualification documents: We provide free pre-sales access to product drawings, dimensional specifications, material details, pressure/temperature ratings, factory qualifications, and workshop capabilities, facilitating project initiation, approval submissions, and tender registration.

Free sample inspection, factory visits, and video inspections: We support sample reviews, online video tours of production lines, and real-time workshop footage, allowing customers to inspect the entire production, pressure testing, and quality control process on-site.

In-Sales Service | End-to-End Tracking, Strict Quality & Schedule Control

Order Detail Verification: Double-checking of model, material, pressure rating, standards, connection type, packaging requirements, and shipment dates to eliminate errors, omissions, or parameter discrepancies.

Production Tracking & Updates:Real-time photo and video updates throughout the process—covering scheduling, machining, valve assembly, seal adjustment, and final pressure testing—keep clients informed of production progress at all times.

Comprehensive Quality Control & Individual Pressure Testing: Every valve undergoes 1.5x shell hydrostatic testing and low-pressure air sealing tests before leaving the factory; only zero-leakage, flawless units are warehoused, ensuring strict adherence to acceptance standards.

Standardized Export Packaging:Use of anti-rust treatments, impact-resistant packaging, and solid wood pallets or export-grade wooden crates to prevent rust, damage, or deformation during ocean freight and logistics.

Complete Documentation Package:Simultaneous provision of contracts, invoices, packing lists, quality inspection reports, pressure test reports, material certificates, and customs clearance documents. All data is cross-verified for consistency, facilitating client reconciliation, accounting, customs clearance, tax rebates, and project acceptance.

On-Time Delivery:Established production scheduling ensures stable delivery for both large-volume and custom orders; schedules are strictly maintained without arbitrary delays.

After-Sales Service | Rapid Response, Worry-Free Warranty

Long-Term Warranty Coverage:Genuine factory-produced valves come with a formal warranty; free repair, replacement, and technical support are provided within the warranty period for issues not caused by human error or operational misuse.

24-Hour Rapid Response:Immediate consultation, response, and resolution for installation queries, operational malfunctions, or application compatibility issues—no delays or buck-passing.

Installation Guidance & Technical Support: Free advice on installation methods, usage precautions, and maintenance procedures to ensure correct operation (e.g., strict prohibition of throttling for gate valves, explanations of high-temperature suitability for hard-sealed valves, etc.).

Proper Handling of After-Sales Issues: Immediate verification, replacement, or rectification in the event of shipping damage, product defects, or compatibility issues, ensuring the smooth acceptance of client projects and export orders. Comprehensive After-Sales Support for Export Trade: We assist overseas clients with customs clearance inquiries, document submission, and destination port coordination to ensure the smooth fulfillment of international orders.

Why Choose Bolaisi GB-Standard Gate Valves?

Are you looking for a GB-standard shut-off gate valve that features a large bore, low flow resistance, high-temperature resistance, and automation compatibility? Choose the Bolaisi Z41 series gate valve. Built using mature stainless steel casting processes and validated through extensive pipeline testing under various operating conditions, these valves undergo rigorous quality control at every stage. As a professional industrial valve supplier, we offer a one-stop solution with a full range of specifications and pressure ratings—covering pipe sizes from DN15 to DN1200—making main pipeline shut-off safer and maintenance worry-free. By choosing Bolaisi GB-standard gate valves, you gain four core advantages: ultra-low flow resistance, bi-directional zero leakage, high-temperature resistance, and easy automation integration.

FAQ (Frequently Asked Questions)

Q1: Can gate valves be used to regulate flow or operate in a partially open position for extended periods?

A: Gate valves are designed for full-open/full-close shut-off service; using them for throttling (partial opening) is not recommended. Prolonged partial opening exposes the gate's sealing surface to high-speed fluid erosion, leading to rapid seal wear and internal leakage. For flow regulation, globe valves or control valves are recommended.

Q2: What type of seal should be selected for high-temperature (400°C) steam pipelines?

A: For steam temperatures exceeding 150°C, metal-to-metal hard-sealed gate valves must be used. For ambient-temperature water, gas, or oil, PTFE soft seals are suitable and more cost-effective.

Q3: Can WCB cast steel valve bodies be used for seawater or media with high chloride ion content?

A: WCB carbon steel is suitable only for clean water, steam, and oil. For corrosive environments with high chloride ion levels—such as seawater or pickling processes—stainless steel (304 or 316) valve bodies are required.

Q4: If slight leakage occurs at the valve stem, must the valve be removed from the pipeline for repair?

A: There is no need to remove the valve body. Repairs can be completed simply by loosening the upper gland and replacing the internal flexible packing; the process is straightforward and minimizes downtime. 

Q5: Can an electric actuator be retrofitted to a manual gate valve?

A: Yes. Since the valve bodies feature standardized extended stems, an automation upgrade can be achieved by simply matching the valve with an electric or pneumatic actuator of the appropriate torque—no need to replace the valve body itself.

Q6: Can PN16 and PN25 flanges be mated together?

A: Mixing them is not recommended. Flanges of different pressure ratings differ in thickness, bolt specifications, and pressure-bearing standards; mixing them poses safety risks such as high-pressure leakage or flange deformation. Selection must align with the pipeline's design pressure.

Q7: How can the difficulty of operating large-bore gate valves (DN600 and above) be addressed?

A: Large-bore gate valves come standard with a worm gear mechanism to reduce the torque required for manual operation; for automation projects, electric or pneumatic actuators are fitted to enable remote, one-touch opening and closing.

Q8: How often should gate valves be maintained? Do wear parts need periodic replacement?