Blind Flange – ASME B16.5 NPS 1/2-24 Class 150-2500

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Blind Flange

Product Description

A solid flange used to close the end of a piping system, pressure vessel, or valve. Provides easy access for inspection and future system expansion.

Every flange is supplied with a mill test certificate (EN 10204 3.1), material traceability, and optional third-party inspection (BV / SGS / TUV). Available in Raised Face, Flat Face, and Ring Type Joint configurations per ASME B16.5.

Applications

Blind flanges serve as removable pressure-holding covers at pipeline termini, vessel nozzle openings, and valve end closures. They are essential for hydrostatic testing of newly constructed piping spools, temporary isolation during plant shutdowns, and permanent end caps on pressure vessels and heat exchanger channels. Classes up to 2500 withstand full design pressure with a safety factor per ASME B16.5.

Typical installations include pump discharge blanking during maintenance, pipeline pig launcher/receiver closures, tank outlet isolation, and manway covers on distillation columns. In oil and gas fields, blind flanges isolate wellhead test lines at pressures reaching 102 bar (Class 600) and temperatures up to 425°C with A105 carbon steel.

They are also used in steam utility headers, condensate recovery loops, and chemical storage tank manifold ends. Stainless F304/F316 blind flanges handle corrosive media in pharmaceutical and food processing, while low-temperature A350 LF2 grades serve LNG and cryogenic service down to -46°C.

Quality Assurance & Certification

Every blind flange is forged and fully machine-finished under an ISO 9001-certified workflow. We supply EN 10204 3.1 mill test certificates with each shipment, documenting material heat analysis, tensile and yield strength, Charpy impact values where specified, and dimensional conformance to ASME B16.5 thickness and bolt hole tolerances.

NDT options include ultrasonic testing for internal laminations, magnetic particle inspection on carbon steel, and liquid penetrant examination on stainless flanges. Third-party inspection by BV, SGS, or TUV can witness hydrostatic test protocols and dimensional verification before release.

Blind flanges receive anti-rust coating for carbon steel units, face protection covers, and are packed in seaworthy wooden cases. Each piece is clearly marked with size, class, material grade, heat number, and manufacturer identity per ASME B16.5 marking requirements.

ASME Standard Data

Dimensional, pressure–temperature and material data transcribed from the ASME B16.5-2025 standard (NPS 1/2–24, Metric/Inch). Ratings shown for carbon steel Group 1.1 (ASTM A105) and stainless Groups 2.1–2.3 (A182 F304/F316 family).

1. Pressure–Temperature Ratings — Group 1.1 Materials (A105) — SI Units (bar)

Source: ASME B16.5-2025, Table 2-1.1 (SI Units). Notes: (1) Prolonged use above 427°C permissible but not recommended; (2) only killed steel above 455°C; (3) not over 260°C; (4) not over 371°C; (5) not over 343°C; (6) see para. 2.5.3 for minimum temperatures.

2. Pressure–Temperature Ratings — Group 1.1 Materials (A105) — U.S. Customary Units (psig)

Source: ASME B16.5-2025, Table 2-1.1C (U.S. Customary Units). SI and US tables are independently rounded per ASME practice.

3. Material Group Correspondence (ASME B16.5, Table 1.1-1)

Source: ASME B16.5-2025, Table 1.1-1 (Material Groups). “…” denotes not applicable in the standard.

4. Minimum Use Temperatures (ASME B16.5, Appendix G, Table G-1)

Source: ASME B16.5-2025, Nonmandatory Appendix G, Table G-1 (Example Minimum Use Temperatures). Impact testing requirements per applicable code.

5. Blind Flange Dimensions — Class 150, SI Units (mm, ASME B16.5 Table 9)

Source: ASME B16.5-2025, Table 9 (Class 150, SI). Class 300/400/600/900/1500/2500 dimensions also per Table 9. Full column set (incl. hub X and A_h) per standard.

Note: ASME B16.5 lists Blind flange outside diameter (O) and thickness (tf) to the same values as the corresponding Class 150 flange in Table 8; blind flanges share O and tf with the welding-neck / slip-on flange of the same NPS.

Frequently Asked Questions