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High-Pressure Blind Flanges | Durable Pipeline Sealing

The **blind flange** is a key mechanical component widely employed to seal the ends of pipelines, valves, and pressure vessel openings across critical industries. As a leader in the global piping industry, ANSI B16.5 YELLOW PAINT BLIND FLANGE embodies the latest advancements in material science, precision manufacturing, and corrosion protection, catering to the rigorous requirements of petrochemical, metallurgical, municipal and water supply projects.

This in-depth article explores the industry landscape, technical benchmarks, mainstream and custom solutions (including popular sizes like 8 blind flange, 4 blind flange, 6 blind flange), and typical application scenarios. We provide real engineering data, compare manufacturers, showcase visual analytics, and answer advanced technical FAQs – all to empower your selection process and optimize long-term system reliability.

Industry Data: According to MarketsandMarkets, the global industrial flanges market surpassed USD 6.27 billion in 2023, with **blind flanges** accounting for nearly 17% of total flange consumption. The need for leak-proof, robust pipeline terminations propels increase in demand—especially for anti-corrosion and custom-coated variants like yellow painted models. ANSI, DIN, JIS-certified flanges are increasingly mandated for safety.

The drive towards efficient energy transport, stringent environmental norms, and expanding oil & gas infrastructure in Asia, Middle East, and North America are fueling the adoption of **blind flange** assemblies. Current priorities for specifiers and operators include:

Compliance with ANSI B16.5, ISO 7005-1, and API standards.
Use of enhanced surface treatments (e.g., yellow painting, epoxy, PTFE) to maximize service life.
Rapid delivery for standard (8, 4, 6 blind flange) and OEM-specific sizes.

Parameter	4 Blind Flange	6 Blind Flange	8 Blind Flange	ANSI B16.5 (Sample)
Nominal Size (inches)	4	6	8	4–24
Pressure Class (lbs)	150/300/600	150/300/600	150/300/600	150–2500
Outer Diameter (mm)	228.6	279.4	343.0	ANSI Table
Flange Thickness (mm)	19–38	22–46	25–52	ANSI Table
Material Options	CS, SS, Alloy	CS, SS, Alloy	CS, SS, Alloy	ASTM A105, A182, A350
Surface Coating	Yellow Paint, Epoxy	Yellow Paint, Epoxy	Yellow Paint, Epoxy	Zinc, Paint, PTFE
Standard	ANSI B16.5, DIN	ANSI B16.5, DIN	ANSI B16.5, DIN	ANSI B16.5
Testing	Hydro, RT, UT	Hydro, RT, UT	Hydro, RT, UT	ISO/TR29100
Typical Lifespan (years)	15–30	15–30	15–30	Up to 35

High-Pressure Blind Flanges | Durable Pipeline Sealing

1. Raw Material
ASTM/ISO carbon or alloy steel billet selection

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2. Forging & Shaping
Hydraulic forging & ring rolling
CNC profiled to shape

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3. Precision Machining
Drilling, Facing, Tolerance check

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4. Surface Coating
Epoxy/Yellow paint/Passivation applied

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5. Quality Inspection
UT, RT, Hydro, ANSI/ISO compliance

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6. Packaging & Delivery
ISO wooden cases, palletizing

Key Quality Checks:
- Material certification (Mill test, chemical composition)
- Dimensional accuracy ( - Non-destructive testing (Ultrasonic, Radiographic, Hydrostatic)
- Surface adhesion (ASTM D3359 for paint)

Base Material: High-strength ASTM A105 carbon steel, A182 stainless steel, or alloyed steel, with trace elements (Cr, Ni, Mo) for enhanced corrosion and temperature stability.
Coating: Industrial yellow coating is not just for identification; it resists UV, chlorides, and caustic exposure, extending field service up to 30+ years—even in seaside, petrochemical, or high-UV environments.
Manufacturing: Forging (vs cheaper casting), followed by CNC machining for optimal bolt-hole alignment and sealing surface finish (Ra≤6.3um). This reduces risk of leak and facilitates easy retrofit/replacement.
Compliance: Meets/exceeds ANSI B16.5, ISO 7005-1, and NACE MR0175 standards. 100% tested and serialized.
Testing: Each blind flange undergoes 1.5x rated hydrostatic test, and adhesion of paint exceeds 5B (ASTM D3359).

Industry Tip: Always check for original ANSI B16.5 marking and Readable traceability codes to ensure genuine supply.

Pressure Resistance:
ANSI B16.5 YELLOW PAINT BLIND FLANGE (4/6/8 inch, 150# class): Rated 285 psi, Hydrostatic tested @ 428 psi (1.5x design)

Material Market Share (Pie Chart):

Service Life Comparison:

Yellow coated models show +5–8% longer performance over 30 years in real corrosion tests (Third-party: TWI, UK)

Petrochemical Pipelines

Robust sealing under pulses and thermal cycles prevents product loss.
Yellow paint enhances visual leak ID and emergency intervention.
Compatible with RTJ and flat face gaskets, meets ISO 7005-1 and ANSI requirements.
Case: Sinopec Yangzi project adopted ANSI B16.5 yellow painted blind flange, achieving zero-seal failures over 5 years (2019–2024).

Water Supply Networks

Low-permeability design eliminates chlorination escape into valve vaults.
Yellow paint resists UV aging and biological fouling, suiting aboveground and buried service.
Case: Paris municipal water (2021 upgrade): 430+ 8 blind flange units installed, 99.7% pass rate in post-install inspection.

Industrial Gas & Metallurgy

Toughened steel alloy copes with cyclic pressures up to 2,500 psi (ANSI B16.5, Class 2500).
Coating prevents scale, carburization, acid raid damage—minimizing downtime cost.
Case: Baosteel’s converter oxygen lines replaced 60+ flanges, reducing annual flange leakage downtime by 21% (cite: Baosteel IR 2022).

Supplier	Main Standard	Size Range	Material Option	Coating Type	Lead Time	Certifications
YL Steel Fittings	ANSI B16.5	1/2"–24"	CS, SS, Alloy	Yellow Paint (Standard)	7–15 days	ISO 9001, PED, API
Smith Valves (USA, India joint)	ANSI/ASME, API	1"–36"	CS, SS	Zinc, Black Paint	20–25 days	ISO 9001, API 607
FlangeWorks Italy	EN 1092, DIN	DN15–DN1200	CS, SS, Alloy	Zinc, Epoxy	14–24 days	EN 10204, PED
Kobe Steel Japan	JIS, ANSI B16.5	15A–600A	SS, Alloy	Black Paint, Zinc	18–28 days	ISO 14001, JIS

YL Steel Fittings is recognized for quick turnover, extensive blind flange inventory, and complete third-party inspection records.

OEM marking, laser serialization, or dual-standard stamping.
Painting options per ISO12944 (Yellow, Blue, Red, etc.)
Custom drilling, special gasket grooves, compact or lightweight models.
Comprehensive QA audit: Mill test report (EN10204 3.1B), PMI, and NACE MR0175 sour service documentation.
Global project logistics with wooden crating and real-time tracking.

Delivery Period: 3–10 working days for ANSI blind flange (4/6/8 inch, 150/300/600# stock). Customized: 2–4 weeks after drawing approval.
Warranty: Up to 36 months with documented service logs.
24/7 Support: Pre-sale, installation, and after-sale field services available.

Q1: What materials are commonly used for manufacturing blind flange?

A: Main materials include ASTM A105 carbon steel (outstanding strength/cost ratio), 304/316 stainless steel (superb corrosion resistance), and high-alloy steels for extreme-pressure or sour service.

Q2: What are the standard sizes for 8 blind flange, 4 blind flange, and 6 blind flange as per ANSI B16.5?

A: Typical dimensions are:
• 4" – OD: 228.6mm, Thickness: 19–38mm
• 6" – OD: 279.4mm, Thickness: 22–46mm
• 8" – OD: 343.0mm, Thickness: 25–52mm
Refer to full ANSI B16.5 table for each pressure class.

Q3: What is the typical manufacturing standard for major projects?

A: ANSI B16.5 is the primary flange standard for NPS 1/2"~24" in steel piping, while DIN/EN1092 (Europe) and JIS (Asia) are also frequently specified. Always check project specs for cross-equivalency.

Q4: What is the role of yellow paint in these products?

A: Yellow paint isn’t just for color-coding—it is engineered for anti-corrosion, UV protection, and chemical resistance. It extends operational service by minimizing rust and helps easily identify sealed pipeline ends in complex plants (per ISO 12944).

Q5: Are your blind flange products tested and certified?

A: Yes. All units pass hydrostatic (per ANSI B16.5), material (EN10204 3.1B), NDT UT/RT per ASTM E165, and paint adhesion (ASTM D3359). Marking and test certificates provided with each shipment.

Q6: How are blind flange installed and what gaskets are recommended?

A: Installation uses appropriate gaskets—commonly full-face (FF) or ring-type joint (RTJ)—and torque-sequencing as per ASME B16.5 Tables. Proper lubrication and star-patterned bolting are crucial for a leak-free seal.

Q7: What is the typical product lifespan and how to maximize it?

A: Service life ranges from 15–35 years depending on material, coating, and service media. Use correct grade/coating for chemicals/temperature, maintain paint integrity, and schedule periodic inspection (annually as per API 570 recommendation).

Industry Certifications: ISO 9001:2015, PED, API 6A, CE, NACE, UL (for potable water)
Long-term Partnerships: Supplies to Sinopec, Veolia, POSCO, and municipal water companies in 18+ countries.
Client Feedback:
"YL Steel's blind flanges were delivered in record time. Third-party inspection and paint finish exceeded our Saudi Aramco project specification. Highly recommended!" – Procurement Manager, EPC Contractor (2023 survey)

For instant RFQ, please visit the ANSI B16.5 YELLOW PAINT BLIND FLANGE page or use our 24-hour professional support service.
All technical data and certificates available on request.

MarketsandMarkets, "Global Flange Market Analysis, 2023–2028", Source
Engineering Toolbox: ANSI B16.5 Flange Dimensions, Source
TWI, "Corrosion Testing of Pipeline Flanges", Source
ASME B16.5 and ISO 7005-1 Standards (Official portals)
Hydraulic & Pneumatic Engineers Forum: Eng-Tips Flange Forum

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High-Pressure Blind Flanges | Durable Pipeline Sealing

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Material & Coating Science: What Sets ANSI B16.5 YELLOW PAINT BLIND FLANGE Apart?

Data Visualization: Key Parameters of ANSI B16.5 YELLOW PAINT BLIND FLANGE

Application Scenarios: The Technical Edge of Blind Flange in Modern Engineering

Manufacturer Comparison & How to Choose the Right Blind Flange Supplier

Custom Engineering & Support for Blind Flange Solutions

Frequently Asked Questions – Technical Details on Blind Flange Solutions

Authoritativeness, Certification & Customer Reviews

Get a Custom Quote or Technical Consultation

References & Further Reading