SS 304L Spectacle BlindASTM A182 · ASME B16.48 · Manufacturer, stockist & exporter, India
AISI 304L · UNS S30403 · SB
An SS 304L spectacle blind is a figure-8 plate with one solid end and one open ring, fitted between two flanges, made from SS 304L to ASTM A182 F304L. A spectacle blind lets operators positively isolate a line: rotate the solid end into the line to block flow, or the ring end to allow it. Larger sizes use separate spacers and paddle blanks.
- ASTM A182
- ASME B16.48
- EN 10204 3.1 / 3.2
- Export packing
Reviewed by the Kanak Steel & Engineering Co. technical team · Updated October 2026
What is an SS 304L Spectacle Blind?
- What it is
- A figure-8 plate with one solid end and one open ring, fitted between two flanges
- Material
- ASTM A182 F304L
- Dimensions
- ASME B16.48
- Grade
- SS 304L · UNS S30403
- Best at
- Welded tanks, piping and vessels in general corrosive service
SS 304L Spectacle Blind Specification
| Product | SS 304L Spectacle Blind |
|---|---|
| Material standard | ASTM A182 F304L |
| Dimensional standard | ASME B16.48 |
| Sizes | ½" – 24" (ASME B16.5) · 26" – 60" (ASME B16.47) |
| Pressure class | Class 150, 300, 400, 600, 900, 1500, 2500 · PN 6 – PN 100 |
| Facing | RF · FF · RTJ · tongue & groove |
| Bore | To match pipe schedule (state on order) |
| Testing | PMI · dimensional · NDT and IGC on request |
| Documents | EN 10204 3.1 · 3.2 with third-party inspection |
When to Choose a Spectacle Blind
A spectacle blind lets operators positively isolate a line: rotate the solid end into the line to block flow, or the ring end to allow it. Larger sizes use separate spacers and paddle blanks.
- Thickness set by class and size
- Paddle blank and spacer versions for large bores
- Handle or lifting lug to order
More on choosing: Spectacle blind guide.
SS 304L Spectacle Blind: Why 304L for spectacle blinds
A spectacle blind lets operators positively isolate a line: rotate the solid end into the line to block flow, or the ring end to allow it. Larger sizes use separate spacers and paddle blanks. In SS 304L, the choice usually comes down to the medium and temperature — the rows here are the points buyers check for this exact combination.
| Why this grade | Stainless flanges are chosen where carbon steel would rust or contaminate the process. SS 304L is picked for welded tanks, piping and vessels in general corrosive service. |
|---|---|
| Typical service | Process piping — Welded lines in chemical and pharma plants. |
| B16.5 material group | 2.3 |
| Bolting | ASTM A193 B8 studs with A194 8 nuts |
| Welding to carbon steel | ER309L (or E309L electrode) is the usual filler when joining it to carbon steel |
| Matching filler | ER308L (AWS A5.9) |
SS 304L Spectacle Blind Chemical Composition
| Element | Weight % |
|---|---|
| Chromium | 17.5 – 19.5 |
| Nickel | 8.0 – 12.0 |
| Carbon | 0.030 max |
| Manganese | 2.00 max |
| Silicon | 0.75 max |
| Nitrogen | 0.10 max |
| Phosphorus | 0.045 max |
| Sulphur | 0.030 max |
SS 304L Spectacle Blind Mechanical Properties
| Annealed plate & sheet | Value |
|---|---|
| Tensile strength | 485 MPa · 70 ksi |
| Yield strength 0.2% | 170 MPa · 25 ksi |
| Elongation | 40% |
| Hardness | 201 HB max |
Full chemistry, properties and equivalents are on the SS 304L grade page.
Other SS 304L flanges
SS 304L Spectacle Blinds for export
FOB / CIF · Nhava Sheva (JNPT), MumbaiSS 304L Spectacle Blind — questions buyers ask
When should I use a spacer and paddle blank instead of a spectacle blind?
In large sizes a spectacle blind becomes too heavy and awkward, so ASME B16.48 provides separate paddle blanks and spacers.
What pressure rating does a SS 304L spectacle blind have?
It depends on class and temperature. SS 304L forgings are in ASME B16.5 material group 2.3; read your class column in that group's table at the design temperature.
Can SS 304L spectacle blinds be welded to carbon steel?
Yes — ER309L (or E309L electrode) is the usual filler when joining it to carbon steel.
Which standard covers SS 304L spectacle blinds?
The material is ASTM A182 F304L; dimensions follow ASME B16.48. Always state both on your purchase order, with the edition if your project specifies one.
What decides the price of a SS 304L spectacle blind?
The alloy price, the size and pressure class, quantity, and the testing and documents required. Send your list and we quote the same working day.
What documents do you supply?
EN 10204 3.1 mill certificates as standard, 3.2 with third-party inspection on request, plus dimensional and PMI reports.
Sources: the ASTM / ASME specifications named on this page and producer datasheets · Last updated October 2026