Jul . 30, 2025 03:40 Back to list

High-Quality Blind Flange for Reliable Pipe Sealing Solutions

Blind flanges serve as critical components in pipeline systems across various industries, offering reliable sealing for unused pipe ends and connections. In this authoritative guide, we explore the intricacies of blind flanges—including blind pipe flange, stainless steel blind flange, and threaded blind flange—with special emphasis on the GOST 12836 PN 2.5 / PN4.0 Blind Flange. By presenting real market data, technical parameters, and deep insights, we offer a clear path for those seeking cutting-edge, reliable solutions.

Figure 1: Stainless Steel Blind Flange for Critical Applications

I. Market Trend and Industry Overview

Driven by growth in oil & gas, petrochemicals, and water treatment sectors, the global blind flange market is witnessing robust expansion. According to Grand View Research, the industrial flange market is projected to reach USD 6.5 billion by 2029, with blind pipe flanges comprising almost 21% of this segment due to their indispensable sealing function.

Blind flange demand is rising in Asia-Pacific, attributed to infrastructure investments.
Material upgrades—including stainless steel blind flange—enhance corrosion resistance for chemical, offshore, and marine use.
Threaded blind flanges are preferred where welding or cutting is not feasible, facilitating rapid maintenance.
Regulatory standards (ISO 7005-1, ANSI/ASME B16.5, GOST 12836) guarantee interchangeability and safety.

Global Blind Flange Specification Overview
Type	Pressure Rating	Material	Main Standards	Typical Application
Blind Pipe Flange	PN 2.5~PN 420 (ANSI Class 150~2500)	Carbon Steel, Stainless Steel, Duplex Steel	ASME B16.5, DIN 2527, GOST 12836	Pipeline Sealing & Isolation
Stainless Steel Blind Flange	PN 6~PN 250	304/304L, 316/316L, 321	EN 1092-1, ISO 7005-1	Chemical, Pharma, Offshore
Threaded Blind Flange	PN 16~PN 100	Stainless Steel, Alloy Steel	ANSI B16.5, MSS-SP-44	Maintenance, Skid Packages
GOST 12836 Blind Flange	PN 2.5, PN 4.0, PN 6.3	Steel 20, 09G2S, SS304/316	GOST 12836, ISO, API	Russian/CIS Oil, LPG, Steam

Emerging Industry Trends

Increasing use of high-performance alloys (Duplex, Super Duplex) for blind flange under severe service conditions.
Integration of RT/UT NDT techniques for 100% leakage detection and ISO 9001-certified QA procedures.
Rising custom flange fabrication requirements due to bespoke project needs.

Figure 2: Blind Pipe Flange Manufacturing at HBYS Valves

II. GOST 12836 PN 2.5 / PN4.0 Blind Flange: Manufacturing Process Flow

GOST 12836 PN 2.5 / PN4.0 Blind Flange from HBYS Valves delivers robust performance for high-pressure, high-temperature systems—compliant with Russia/CIS certified standards.

Raw Material Selection
(Steel 20, 09G2S, SS304/316)

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Forging / Casting
Creating basic flange shape

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Heat Treatment
Normalizing/tempering for toughness

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CNC Machining
Precision drilling, facing

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Final Inspection
Dimensional, RT/UT & hydro test

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Packing & Dispatch
ISO/EN Packing Standards

Main Manufacturing Features:
- Process: Forged or cast per GOST 12836; CNC-machined sealing surfaces achieve 12.5μm accuracy.
- Heat Treatment: Ensures grain refinement for lasting ductility.
- Inspection: Hydrostatic test at 1.5x PN rating; RT/UT (Radiographic/Ultrasonic Testing) for weld seams as per ISO 9001.
- Packing: Wooden crate, with desiccant and customized labeling for traceability.

Key Technical Parameters

GOST 12836 Blind Flange - Specification Sheet
Type	Nominal Size (DN)	Pressure (PN)	Material	Sealing Face	Temperature Range	Certifications
Blind Flange	DN10 to DN1500	2.5MPa, 4.0MPa	Steel 20, 09G2S, SS304, SS316	Raised Face (RF), Flat Face (FF)	-40°C to +550°C	GOST 12836, ISO 9001

Process Flow Video Example

Watch Typical Blind Flange Forging Process (YouTube)

Graph 1: Performance comparison of blind flange types by max pressure, temperature & longevity (data compiled from HBYS Valves, ASME, GOST, ISO studies 2023).

III. Technical Advantages & Material Insights

Material Selection:
- Carbon Steel (Steel 20, 09G2S): Cost-effective, ideal for general fluids.
- Stainless Steel (SS304/316/321): Superior corrosion/acid resistance for harsh chemicals and offshore applications.
- High Alloy Flanges: Duplex/Super Duplex, Nickel alloys (on request for H2S, chlorine service).
Sealing Face Options: Raised Face (RF), Flat Face (FF), Ring Type Joint (RTJ) as per ISO 7005-1 for optimal leak-tightness.
Machining Precision: All surfaces CNC machined with ±0.15mm tolerances; Gasket rings to Ra 3.2μm.
Pressure Endurance: Factory tested up to 1.5x rated PN, with documented hydrostatic/air testing.
Long Lifespan: Service life exceeds 25 years in most medium-duty and high-pressure water/steam systems.
Standards Compliance: Fully compliant with GOST, ISO, and API requirements. PMI (Positive Material Identification) on request.

Graph 2: Market share of blind flange raw materials (source: IndustryData, 2023 global shipments).

Industry Certifications & Quality System

HBYS Valves is ISO 9001:2015 certified, with all blind flanges traceable via batch QC documentation.
Adheres to EN 10204 3.1/3.2 inspection certificates for European/Eurasian clients.
Partners include Gazprom, Lukoil, Siemens, Sinopec; product approvals from SGS and TUV Rheinland.

Figure 3: Threaded Blind Flange - Final QA Inspection

IV. Manufacturer Landscape & Customization

Comparing top blind flange manufacturers, clients can optimize costs and delivery via strategic sourcing:

Leading Global Blind Flange Suppliers
Manufacturer	Main Standards	Max Size (DN)	Delivery Lead Time	Certifications
HBYS Valves	GOST, ISO, ASME, DIN	DN1500	15 ~ 25 days	ISO 9001, TUV, SGS
Bonney Forge (Italy/USA)	ASME, EN, API	DN1200	25 ~ 35 days	API, ISO 9001
Haihao Group (China)	GOST, EN, ASME, JIS	DN1200	20 ~ 30 days	ISO, CCIC
Vallourec (France)	ISO, EN, API	DN1400	35 ~ 45 days	ISO, PED

Note: HBYS Valves offers expedited delivery & custom machining including 3D design, NACE coating, and tagging for project requirements.

Custom Design Flow

Submit technical drawing / project requirement (pressure, size, medium).
HBYS issues 3D design & material proposal within 48 hours.
Client confirms, production within 7-21 days depending on complexity.
100% inspection & logistics tracking until onsite delivery.

Graph 3: Blind Flange Delivery Lead Time Trends – HBYS vs. Industry Average (Source: Third-Party Supply Studies).

V. Application Cases & Client Experience

1. Petrochemical Plant, Sakhalin, Russia
Challenge: High sulfur, offshore gas line sealing.
Solution: HBYS supplied GOST 12836 PN4.0 stainless steel blind flange, NACE MR0175 compliant.
Result: Zero leakage, corrosion-free for 4+ years.

2. District Heating Pipeline, North Europe
Challenge: Large diameter (DN1200), 16 bar, cyclic temp flanges.
Solution: Custom forged blind pipe flanges with graphite gaskets.
Result: No failures after >20,000 thermal cycles.

3. Pharmaceutical Process, India
Challenge: CIP (clean-in-place), high purity requirements.
Solution: Threaded blind flange, SS316L, electropolished (FDA standard referenced)
Result: Passed FDA GMP audit, enhanced hygienic sealing.

VI. Professional FAQ (Blind Flange Terminology)

1. What materials are most common for blind flanges?

Most standard blind flanges are manufactured from Carbon steel (A105, Steel 20, 09G2S) and Stainless Steel (SS304/316/321). High-alloy and Duplex/Super Duplex options are chosen for aggressive media, per ISO/ASTM standards.

2. How are blind pipe flanges installed and what standards apply?

The correct installation requires alignment, suitable gasket selection, and torqueing to spec. Installation standards include ASME B16.5 and GOST 12836, with bolt torques as per manufacturer recommendations.

3. What do the pressure ratings (PN 2.5 / PN4.0) signify?

PN 2.5 (25 bar), PN4.0 (40 bar) indicate the nominal working pressure as defined by ISO 7005-1 and GOST 12836, tested at 1.5x for safety margin during hydro test.

4. What corrosion-resistant coatings are available for blind flanges?

Corrosion protection includes hot-dip galvanizing, FBE (fusion bonded epoxy), and NACE MR0175 coatings for sour service, in line with ISO 12944 recommendations.

5. How to select between stainless steel blind flange vs carbon steel?

Stainless steel is chosen for chemical/oil/offshore applications due to superior pitting resistance (PREN>32 for SS316), while carbon steel is economical for water/gas at ambient.

6. What is a 'threaded blind flange' and when is it used?

A threaded blind flange is machined with inner threads (NPT/BSP), allowing non-welded closure; ideal for small-bore line maintenance or hazardous locations.

7. Are all blind flanges pressure tested prior to shipping?

Yes, all reputable suppliers hydrostatically test blind flanges at 1.5x PN for up to 30 minutes, documented on EN 10204 certificates. API, GOST, and ISO protocols are followed.

VII. Delivery Cycle, Warranty, and Customer Support

Delivery Time: Standard DN15–DN600 flanges: 7–20 working days. Large/custom items: up to 28 days. Emergency rush orders available (contact HBYS for schedule).
Warranty: All blind flange products are backed by a 24-month quality guarantee, with lifetime tech support. PMIs & certificates provided on request.
Customer Support: 24/7 hotline, WhatsApp, and online portal tracking from order to delivery. Pre-sale engineering assistance included.
After-Sales Service: Free technical troubleshooting, replacement for any confirmed manufacturing defect, and remote/onsite inspection support for international customers.
Certification Documents: MTC–EN 10204/3.1, NDT, ITP (inspection/testing plan), and logistics reports supplied with every shipment.

VIII. Conclusion & Further Reading

The blind flange—including blind pipe flange, stainless steel blind flange, and threaded blind flange—will remain a backbone for sealing and pressure containment across evolving industry sectors. With certified manufacturing, rigorous QA, and multifaceted application experience, HBYS Valves and global leaders continue to advance blind flange technology for user safety and cost efficiency.

References & Further Reading:
- Grand View Research: Global Flanges Market Report 2023
- ASME B16.5 Standard: ASME.org
- Materials Selection Forum: ENG-TIPS Flange Selection
- Pipeline & Gas Journal: Key Trends in Industrial Flanges
- FDA GMP for Stainless Flanges: FDA Guidance Document (PDF)

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