Blind Flange
Blind flanges to ASME B16.5 / B16.47 — solid discs that close a flanged opening or vessel nozzle — in carbon, alloy, stainless, duplex and nickel grades.
Technical specification
| Parameter | Specification |
|---|---|
| Product | Forged fittings (socket-weld / threaded) & flanges |
| Dimensional standard | ASME B16.11 (forged fittings) · B16.5 / B16.47 (flanges) |
| Classes | SW 3000/6000/9000 · Thd 2000/3000/6000 · Flange 150–2500 |
| Facings (flanges) | RF · FF · RTJ |
| Size range | 1/8" – 4" (forged fittings) · 1/2" – 60" (flanges) |
| Material specifications | ASTM A105/A105N, A350, A182, B564, B462 |
| Sour service | NACE MR0175 / ISO 15156 where specified |
| Documentation | EN 10204 3.1 / 3.2, PMI, TPI |
How it is made
Forgings are open- or closed-die forged from bar or billet, then heat treated to the grade requirement — carbon A105 as-forged or normalised; low-temp A350 normalised (and tempered) with Charpy testing; Cr-Mo A182 F-grades normalised & tempered; austenitic stainless solution annealed; duplex solution annealed and rapidly cooled. Socket-weld and threaded fittings are machined to ASME B16.11 (NPT threads to ASME B1.20.1); flange faces are machined to the specified finish and facing (RF serrated, RTJ ring groove). Class denotes a pressure-temperature rating basis, not a pressure in psi.
Grades & materials
All grades supplied for this product family, with representative chemistry. Exact grade, class and condition are confirmed per order.
| Material family | Grades | UNS | Standard | Service |
|---|---|---|---|---|
| Carbon steel | A105 / A105N | K03504 | ASME B16.5/B16.11 / ASTM A105 | General service |
| Low-temp carbon | A350 LF2 Cl.1/2, LF3, LF6 | — | ASTM A350 | Low temperature |
| Cr-Mo alloy | A182 F1, F11, F12, F22, F5, F9, F91, F92 | — | ASTM A182 | High-temperature |
| Austenitic stainless | A182 F304/304L/304H, F316/316L/316H, F321, F347, F317L, F44 (6Mo) | — | ASTM A182 | Corrosion / high temp |
| Duplex / super duplex | A182 F51 (2205), F60 (2205), F53 (2507), F55 (2760) | — | ASTM A182 | Chloride / sour |
| Nickel alloys | B564 N06600 (600), N06625 (625), N04400 (Monel), N10276 (C-276), N08825 (825) | — | ASTM B564 | Severe corrosion |
| Alloy 20 | B462 N08020 | N08020 | ASTM B462 | Sulphuric acid |
Chemical composition (representative)
| Grade | C | Mn | Si | Cr | Ni | Mo | Other |
|---|---|---|---|---|---|---|---|
| A105 | 0.35 max | 0.60–1.05 | 0.10–0.35 | 0.30 max | 0.40 max | 0.12 max | Cu 0.40 max |
| A350 LF2 | 0.30 max | 0.60–1.35 | 0.15–0.30 | 0.30 max | 0.40 max | 0.12 max | — |
| A182 F11 Cl.2 | 0.05–0.15 | 0.30–0.60 | 0.50–1.00 | 1.00–1.50 | — | 0.44–0.65 | — |
| A182 F22 Cl.3 | 0.05–0.15 | 0.30–0.60 | 0.50 max | 2.00–2.50 | — | 0.87–1.13 | — |
| A182 F91 | 0.08–0.12 | 0.30–0.60 | 0.20–0.50 | 8.0–9.5 | 0.40 max | 0.85–1.05 | V 0.18–0.25, Nb 0.06–0.10, N 0.03–0.07 |
| A182 F304L | 0.030 max | 2.00 max | 1.00 max | 18.0–20.0 | 8.0–13.0 | — | — |
| A182 F316L | 0.030 max | 2.00 max | 1.00 max | 16.0–18.0 | 10.0–15.0 | 2.0–3.0 | — |
| A182 F51 (2205) | 0.030 max | 2.00 max | 1.00 max | 21.0–23.0 | 4.5–6.5 | 2.5–3.5 | N 0.08–0.20 |
| A182 F53 (2507) | 0.030 max | 1.20 max | 0.80 max | 24.0–26.0 | 6.0–8.0 | 3.0–5.0 | N 0.24–0.32 |
| A182 F44 (6Mo) | 0.020 max | 1.00 max | 0.80 max | 19.5–20.5 | 17.5–18.5 | 6.0–6.5 | N 0.18–0.25, Cu 0.5–1.0 |
| B564 625 | 0.10 max | 0.50 max | 0.50 max | 20.0–23.0 | 58.0 min | 8.0–10.0 | Nb 3.15–4.15 |
| B462 Alloy 20 | 0.07 max | 2.00 max | 1.00 max | 19.0–21.0 | 32.0–38.0 | 2.0–3.0 | Cu 3.0–4.0, Nb 8×C–1.0 |
Standards & specifications
Dimensional
- ASME B16.11 forged socket-weld & threaded fittings
- ASME B16.5 flanges NPS ½–24
- ASME B16.47 A/B flanges NPS 26–60
- ASME B16.20 ring-joint / spiral-wound gaskets
Material & service
- ASTM A105/A350 carbon & low-temp forgings
- ASTM A182 alloy, stainless & duplex forgings
- ASTM B564/B462 nickel & Alloy 20
- NACE MR0175 / ISO 15156 sour service
Mechanical properties (representative grades)
Representative grades — full MTC values on request. Values are ASTM/ASME specification minima or ranges at room temperature.
| Grade | Type | Tensile (MPa) | Yield min (MPa) | Elong min (%) |
|---|---|---|---|---|
| A105 / A105N | Carbon | 485 | 250 | 22 |
| A350 LF2 Cl.1 | Low-temp C (−46 °C) | 485–655 | 250 | 22 |
| A350 LF3 | 3½Ni (−101 °C) | 485–655 | 260 | 22 |
| A350 LF6 Cl.1 | Low-temp C-Mn | 440– | 250 | 22 |
| A182 F1 | C-½Mo | 485 | 275 | 22 |
| A182 F11 Cl.2 | 1¼Cr-½Mo | 515 | 310 | 20 |
| A182 F12 Cl.2 | 1Cr-½Mo | 485 | 275 | 20 |
| A182 F22 Cl.3 | 2¼Cr-1Mo | 515 | 310 | 18 |
| A182 F5 | 5Cr-½Mo | 485 | 275 | 20 |
| A182 F9 | 9Cr-1Mo | 620 | 380 | 20 |
| A182 F91 | 9Cr-1Mo-V | 585 | 415 | 20 |
| A182 F92 | 9Cr-2W | 620 | 440 | 20 |
| A182 F304 / F304H | Austenitic SS | 515 | 205 | 30 |
| A182 F304L | Austenitic SS | 485 | 170 | 30 |
| A182 F316 / F316H | Austenitic SS | 515 | 205 | 30 |
| A182 F316L | Austenitic SS | 485 | 170 | 30 |
| A182 F317L | Austenitic SS | 515 | 205 | 35 |
| A182 F321 | Austenitic SS | 515 | 205 | 30 |
| A182 F347 | Austenitic SS | 515 | 205 | 30 |
| A182 F44 (6Mo) | Super-austenitic | 650 | 300 | 35 |
| A182 F51 (2205) | Duplex | 620 | 450 | 25 |
| A182 F60 (2205) | Duplex | 655 | 485 | 25 |
| A182 F53 (2507) | Super duplex | 795 | 550 | 15 |
| A182 F55 (2760) | Super duplex | 750 | 550 | 25 |
| B564 N06600 (600) | Ni-Cr | 550 | 240 | 30 |
| B564 N06625 (625) | Ni-Cr-Mo | 760 | 345 | 30 |
| B564 N04400 (Monel 400) | Ni-Cu | 480 | 170 | 35 |
| B564 N10276 (C-276) | Ni-Mo-Cr | 690 | 283 | 40 |
| B564 N08825 (825) | Ni-Fe-Cr | 585 | 235 | 30 |
| B462 N08020 (Alloy 20) | Ni-Fe-Cr-Mo | 551 | 241 | 30 |
Testing, inspection & documentation
| Test / document | Detail |
|---|---|
| Chemical / PMI | Product-analysis chemistry; PMI on alloy, stainless & nickel grades |
| Tensile | Tensile, yield and elongation per grade (ASTM A370) |
| Impact (Charpy) | A350 LF2/LF3/LF6 at the grade test temperature; and where specified |
| Hardness | Brinell/Rockwell; NACE MR0175 hardness for sour service (e.g. F22 ≤ 22 HRC) |
| Corrosion | IGC per ASTM A262 (austenitic); ferrite / phase check (duplex) |
| NDE | UT / MPI / DPT as specified; 100 % visual and dimensional |
| Certification | EN 10204 3.1 as standard; 3.2 with third-party endorsement |
Applications & industries served
Available forms, sizes & range
Provide with your enquiry
- NPS and pressure class.
- Facing (RF / FF / RTJ) and finish.
- Material grade and bore/schedule where relevant.
And the commercial detail
- Standard (B16.5 / B16.47) and edition.
- Required tests and certification.
- Quantity and any drawing or BOQ.
Frequently asked questions
What is a blind flange used for?
It bolts onto a flanged opening or nozzle to close it — for isolation, pressure testing, future tie-ins or vessel closures.
Can it be drilled later?
Yes — a blind can be machined to add a bore or tapping to order, but as supplied it is a solid disc.
What classes are available?
Class 150 to 2500 with RF or RTJ facing to ASME B16.5 / B16.47.
Request a quote
Send your requirement to Sagiant Piping Industries and our team responds with grade, material selection, availability and pricing for blind flange. Attach a BOQ, line list or drawing for a faster, more accurate quotation.
- Fast RFQ response with grade & material-selection support
- EN 10204 3.1 / 3.2 certification, PMI & third-party inspection
- BOQ & line-list project supply — India & export
Mechanical & chemical values shown are ASTM/ASME specification figures; certified heat-specific values appear on the MTC. Availability is confirmed with the quotation.
