Blind flanges are critical flange types in piping systems for closing pipe ends, equipment openings, or reserved connection points. With no center bore, they can completely isolate media and withstand pressures equal to or even higher than the pipe itself. The nickel alloy blind flanges supplied by Hefei Tailan Metal Co., Ltd. are manufactured from high-quality nickel-based alloy forgings through multiple precision processes including forging, solution heat treatment, machining, drilling, and pickling/polishing. Featuring solid structure, high strength, excellent sealing performance, and superior corrosion resistance, they are specifically designed for applications requiring complete isolation such as pipe end closures, and equipment cleaning ports.
Supply Range
Nominal Diameter (DN/NPS): DN15 – DN600 (1/2 inch – 24 inches); Larger diameters negotiable
Pressure Class: Class 150, 300, 600, 900, 1500, 2500 (ASME)
Facing Type: Raised Face (RF), Flat Face (FF), Ring Type Joint (RTJ)
Flange Type: Blind Flange, Thickened Blind
Machining Precision: Sealing surface roughness Ra 3.2μm – 6.3μm (as per standard requirements)
Surface Condition: Machined, Pickled, Polished optional
Marking Method: Steel stamp marking on flange outer edge, conforming to MSS SP-25 or customer requirements
Special Notes:
- Blind flanges have no center bore, thickness is typically slightly larger thansame size welding neck flanges
- High pressure class blind flanges have significantly increased thickness, requiring consideration of material cost and weight
- Blind flanges with lifting lugs or special designs available for easy installation and removal
Strict Non-Destructive Testing
Every nickel alloy blind flange undergoes rigorous NDT inspection:
Penetrant Testing (PT) : Detecting surface-opening defects, conforming to ASTM E165 standard
Ultrasonic Testing (UT) : Detecting internal defects, conforming to ASTM A388 standard, particularly suitable for thick-walled blinds
Hardness Testing: Verifying heat treatment effectiveness and mechanical property uniformity
Multiple Facing Types Available
Various facing types available according to service conditions:
Raised Face (RF) : Most common, suitable for Class 150-2500
Ring Type Joint (RTJ) : For high pressure, high temperature, strict leakage prevention
Flat Face (FF) : For cast iron flanges or low pressure conditions
Dimensions, Standards and Size Range
When a buyer specifies Blind flanges, the first question is almost always which
dimensional standard applies, because it fixes the bolt circle, the flange
diameter and the allowable centre-to-end geometry. For nickel alloy flanges
that split is as follows.
| Size band | Dimensional standard | Typical usage |
|---|---|---|
| NPS 1/2 – NPS 24 (DN15 – DN600) | ASME B16.5 | Process piping, the overwhelming majority of industrial orders |
| NPS 26 – NPS 48 (DN650 – DN1200) | ASME B16.47 Series A and B | Large-bore lines, tank nozzles and offshore risers |
Note that ASME B16.5 and B16.47 are dimensional standards only. They
govern geometry, tolerances and marking; they say nothing about metallurgy. The
material requirement is written separately, and for nickel alloys the usual
reference is ASME SB-462, which covers forged or rolled nickel alloy pipe
flanges, forged fittings and valves intended for corrosive high-temperature
service. SB-462 explicitly lists UNS N10276 (Hastelloy C-276), UNS N06022
(Hastelloy C-22), UNS N06200, UNS N08020 (Alloy 20) and UNS N08031 among the
grades it covers. Where the item is supplied as a forging rather than a rolled
ring, ASME SB-564 (Nickel Alloy Forgings) is the governing material
specification, and it covers UNS N06625 (Alloy 625), UNS N04400 (Monel 400),
UNS N06600 (Inconel 600) and UNS N10276 among others.
Pressure Class and Facing
Nickel alloy flanges are ordered against ASME B16.5 pressure classes
(Class 150 through Class 2500) or against the EN 1092-1 PN ratings. The facing
has to be matched to the service, and this is where most late-stage
non-conformances occur:
- Raised Face (RF) — the default for Class 150–2500
and the correct choice for general process service. - Ring Type Joint (RTJ) — required for high-pressure or
high-temperature service where a leak-tight metal-to-metal seal is
mandatory. - Flat Face (FF) — used where the mating flange is
cast iron or where the bolting is at very low pressure.
Blind flanges supplied by Hefei Tailan Metal is machined from forged or rolled
nickel alloy stock with the hub a solid disc used to blank off a line end or vessel nozzle. If your project requires an
unusual facing, a specific corrosion allowance, or a matching pipe wall
thickness, state it on the enquiry and we will confirm the exact line item
against the applicable standard before quotation.
Matching Pipe and Fitting Supply
Flanges are only one half of a pressure boundary, and dimensional
compatibility with the pipe and fittings they connect to is what determines
whether the joint assembles correctly on site. We supply the matching
Inconel pipe in the same grade family, so a single order can cover
pipe, fittings and flanges on one heat-number basis. For socket-weld and
threaded pressure classes the fitting dimensions follow ASME B16.11 rather than
B16.9, while butt-weld fittings follow B16.9 and pipe wall thicknesses follow
ANSI B36.10M for carbon steel and B36.19M for stainless. If you are matching an
existing line, send us the nominal size, schedule or wall thickness, class and
facing, and we will confirm dimensional compatibility in writing before the
order is placed.
Need the pipe first? Our welding neck flanges and
slip-on flange pages carry the same grade cross-reference tables, and
the our flange portfolio overview lists every flange type we manufacture.
Enquiries are answered with a quotation, not a catalogue reply.
