Zhejiang Chengjiu Pipeline Co., Ltd. is one of the most reliable manufacturers and suppliers of ss blind flange in China, also supports customized service. Please feel free to buy high quality ss blind flange from our factory. Good service and reasonable price are available.

A SS Blind Flange is a solid, bore-free disc used to seal the end of a pipe, nozzle, or pressure vessel opening, providing a reliable, leak-tight closure that withstands full system pressure.
At Chengjiu, we produce SS blind flanges to ASME B16.5 (NPS 1/2" to 24"), ASME B16.47 (NPS 26" to 60"), and EN 1092-1 Type 05 (DN 15 to DN 1500) standards. Available materials include ASTM A182 F304, F304L, F316, F316L, F51 (Duplex 2205), and F53 (Super Duplex 2507), with face types of Raised Face (RF), Flat Face (FF), Ring Type Joint (RTJ), and Tongue & Groove (TG).

Design & Structure of an SS Blind Flange

Unlike other flange types, an SS blind flange has no central bore. It is a solid circular plate with evenly spaced bolt holes around the perimeter, engineered to bolt directly onto a mating flange, valve, or vessel nozzle. The sealing surface is machined to match the mating flange face type, ensuring leak-tight performance when compressed against a gasket.

Key structural features include:

Solid disc body with no bore - full material cross-section for maximum pressure containment.
Bolt holes uniformly distributed on the bolt circle diameter (BCD) for even load distribution.
Machined sealing face (RF, FF, RTJ, TG) to match the mating flange precisely.
Forged construction standard for pressure-rated service; plate material also permitted for certain classes under ASME B16.5.

Standards & Pressure Ratings

Standard	Size Range	Pressure Class	Face Types
ASME B16.5	NPS 1/2" – 24" (DN 15–600)	Class 150, 300, 600, 900, 1500, 2500	RF, FF, RTJ, TG, MFM
ASME B16.47 Series A	NPS 26" – 60" (DN 650–1500)	Class 150, 300, 600, 900, 1500	RF, FF, RTJ
ASME B16.47 Series B	NPS 26" – 60" (DN 650–1500)	Class 150, 300, 600, 900, 1500	RF, FF, RTJ
EN 1092-1 Type 05	DN 15 – DN 2000	PN 2.5, 6, 10, 16, 25, 40, 63, 100, 160, 250, 400	FF (Form A), RF (Form B)
JIS B2220	DN 15 – DN 600	5K, 10K, 16K, 20K, 30K	FF, RF

Material Grades

Grade	UNS No.	Key Property	Typical Use
F304 / F304L	S30400 / S30403	General corrosion resistance	Water, food & beverage, general piping
F316 / F316L	S31600 / S31603	Superior chloride & acid resistance	Chemical, marine, pharmaceutical
F321	S32100	Titanium-stabilized, high-temp	Heat exchangers, steam systems
F51 (Duplex 2205)	S31803 / S32205	High strength + pitting resistance	Oil & gas, seawater systems
F53 (S.Duplex 2507)	S32750	Exceptional chloride resistance	Offshore, desalination, subsea
904L	N08904	High molybdenum, sulfuric acid	Sulfuric acid, phosphoric acid plants

For full chemical composition and mechanical properties → check our Material Data Sheet

Sealing Face Types

Face Type 面型	Code 代号	Description 说明	Best Suited For 适用工况
Raised Face	RF	Small circular raised area around bore; most common
Flat Face	FF	Full-face seating; entire flange face is flat
Ring Type Joint	RTJ	Machined groove holds metallic ring gasket

Key Functions & Applications

Primary Functions

Pipe End Sealing - Permanently or temporarily close an unused pipe end, nozzle, or vessel connection without removing the flange.
Pressure Testing - Isolate a piping section during hydrostatic or pneumatic pressure tests; the solid disc withstands full test pressure.
System Isolation - Block off process lines during maintenance, turnaround, or future expansion phases.
Flow Diversion Planning - Preserve the option to connect new piping in the future by maintaining a bolted flange termination.

Industries Served

Oil & Gas - Wellheads, manifolds, subsea pipelines, and downstream process units; RTJ or high-pressure RF grades preferred.Chemical

Chemical & Petrochemical - Aggressive acid, caustic, and solvent services requiring F316L or duplex grades.

Water Treatment & Desalination - Seawater and high-chloride brine environments; Super Duplex 2507 ideal

Power Generation - Steam isolation in high-temperature, high-pressure boiler and turbine systems.

Pharmaceutical & Food - Sanitary piping closure; ultra-clean surface finish and crevice-free design.

Marine & Offshore - Saltwater ballast and cooling circuits; pitting and crevice corrosion resistance critical.

SS Blind Flange vs. Other Isolation Methods

Method	Reusable	Pressure Rating	Installation Speed	Best For
SS Blind Flange	Yes	Full class rating	Moderate (bolted)	Permanent/long-term isolation
Spectacle Blind	Yes	Full class rating	Moderate	Frequent switching open/closed
Pipe Cap	No (welded)	Full rating	Slow (welding needed)	Permanent sealing
Gate Valve	Yes	Full class rating	Fast (operate handle)	Frequent isolation/flow control
Plug / Thread Cap	Limited	Low-medium only	Fast	Small bore threaded lines

Why Choose Chengjiu for SS Blind Flanges?

Full in-house forging, heat treatment, machining, and surface finishing - no subcontracting of critical processes.
EN 10204 3.1/3.2 MTRs; hydrostatic testing, PMI, PT/MT/UT NDT all available.
Covers ASME B16.5, ASME B16.47, EN 1092-1, JIS B2220, DIN 2527, GOST standards in one facility.
Custom sizes, special alloys (Duplex, Super Duplex, 904L), and non-standard face machining accepted.

FAQ

Q: What is the difference between a blind flange and a spectacle blind?

A: A blind flange is a standalone solid disc bolted to a mating flange to permanently or semi-permanently close off a line. A spectacle blind is a figure-8 shaped device with a solid disc on one side and an open ring on the other, allowing the operator to switch between isolation and open flow by rotating the assembly - without disconnecting any bolts. Blind flanges are preferred when switching is infrequent; spectacle blinds suit lines requiring regular alternation between open and closed states.

Q: Can an SS blind flange be used for high-pressure service above Class 300?

A: Yes. Blind flanges are available in all pressure classes under ASME B16.5, from Class 150 up to Class 2500. At higher classes, the flange thickness and bolt count increase significantly. For very high-pressure or sour-gas service (H2S-containing media), RTJ face type in conjunction with a Duplex or Super Duplex material grade is recommended per ISO 15156 / NACE MR0175.

Q: What gasket should be used with a raised face SS blind flange?

A: For Class 150-300 service, spiral wound gaskets (SWG) with 316L stainless steel winding and a PTFE or graphite filler are standard. For Class 600 and above, a SWG with inner and outer centering rings (ASME B16.20) is recommended. For RTJ face flanges, choose the ring material one hardness grade softer than the flange to prevent face damage. Always match the gasket material to the process fluid, temperature, and applicable standard.

Q: How do I determine the correct blind flange class for my system?

A: Blind flange class selection is based on the maximum operating pressure and temperature of the system. Use the pressure-temperature (P-T) rating tables in ASME B16.5 for your specific material group. For example, an F316L flange at 100°C in Class 300 can withstand approximately 48 bar; the same flange at 400°C is rated only around 32 bar. Always include a safety margin and consult your piping engineer for final selection.

Q: Do you offer material test reports (MTR) and third-party inspection for SS blind flanges?

A: Yes. All Chengjiu SS blind flanges are supplied with EN 10204 3.1 or 3.2 material test reports as standard. Third-party inspections by SGS, Bureau Veritas (BV), TUV, DNV, or a customer-nominated inspector can be arranged on request. NDT options include PMI, magnetic particle testing (MT), dye-penetrant testing (PT), and ultrasonic testing (UT). Hydrostatic testing is performed as standard per the applicable code.

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