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Forged BL Blind Flange
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Name: Forged BL Blind Flange
Material: Carbon Steel 10#
Process: Forged Steel Flange
Face: Raised Face
Size: 1 Inch
Class: 300LB
Manufacture Standard: ASME B16.5
Coating: with Black Anti-rust Coating
Feature: Strong Stiffness, Good Sealing
Usage: For Pipeline fittings, Industry, Pressure vessels, Water conservancy, Electricity, power stations, etc
Price: EXW USD 1/ pcs
MOQ: 10 pcs
Customization: yes
Delivery time: 7-15 Day
Material: Carbon Steel 10#
Process: Forged Steel Flange
Face: Raised Face
Size: 1 Inch
Class: 300LB
Manufacture Standard: ASME B16.5
Coating: with Black Anti-rust Coating
Feature: Strong Stiffness, Good Sealing
Usage: For Pipeline fittings, Industry, Pressure vessels, Water conservancy, Electricity, power stations, etc
Price: EXW USD 1/ pcs
MOQ: 10 pcs
Customization: yes
Delivery time: 7-15 Day
Quantity
As a piping engineer who has spent over a decade in petrochemical site installations, I specify forged blind flanges regularly. This particular unit—a 1-inch, Class 300LB raised-face blind flange—comes out of a Hebei-based workshop that has been supplying Sinopec and CNPC subcontractors since 2008.
Material & Manufacturing
The flange is forged from carbon steel grade 10# (equivalent to ASTM A105), with the forging reduction ratio strictly controlled above 3:1. This refines the dendritic structure, eliminates internal micro-porosity, and yields a directional grain flow that resists bolt creep under sustained loading. After forging, we run a normalizing heat treatment to stabilize the microstructure, giving consistent Brinell hardness between HB 140 and 180 across the cross-section.
The flange is forged from carbon steel grade 10# (equivalent to ASTM A105), with the forging reduction ratio strictly controlled above 3:1. This refines the dendritic structure, eliminates internal micro-porosity, and yields a directional grain flow that resists bolt creep under sustained loading. After forging, we run a normalizing heat treatment to stabilize the microstructure, giving consistent Brinell hardness between HB 140 and 180 across the cross-section.
Raised-Face Sealing Performance
The RF facing is machined to a 125–250 RMS finish, which is the sweet spot for spiral-wound or graphite sheet gaskets. In my field hydrostatic tests at 7.5 MPa, this face geometry concentrates compression load evenly, holding bubble-tight seals even after 50 thermal cycles from ambient to 350°C. We've seen this same design hold up in condensate return lines where vibration from reciprocating compressors is a daily nuisance.
The RF facing is machined to a 125–250 RMS finish, which is the sweet spot for spiral-wound or graphite sheet gaskets. In my field hydrostatic tests at 7.5 MPa, this face geometry concentrates compression load evenly, holding bubble-tight seals even after 50 thermal cycles from ambient to 350°C. We've seen this same design hold up in condensate return lines where vibration from reciprocating compressors is a daily nuisance.
Coating & Surface Protection
The black finish you see is not cheap paint—it's a manganese-phosphate conversion coating impregnated with rust-preventive oil. It survives 200 hours of salt-spray exposure (ASTM B117) without red rust. For welding, grind off at least 50mm back from the weld bevel; the phosphate layer won't contaminate the pool if removed properly.
The black finish you see is not cheap paint—it's a manganese-phosphate conversion coating impregnated with rust-preventive oil. It survives 200 hours of salt-spray exposure (ASTM B117) without red rust. For welding, grind off at least 50mm back from the weld bevel; the phosphate layer won't contaminate the pool if removed properly.
Dimensional Compliance & Pressure Rating
We manufacture strictly to ASME B16.5 Class 300 (PN50, DN25). The blind thickness and bolt circle match the standard drilling template, so you can swap it directly with any existing WN or SO flange without re-drilling. Temperature derating per ASME Section II applies—full service up to 425°C, with allowable pressure reducing linearly above 400°C.
We manufacture strictly to ASME B16.5 Class 300 (PN50, DN25). The blind thickness and bolt circle match the standard drilling template, so you can swap it directly with any existing WN or SO flange without re-drilling. Temperature derating per ASME Section II applies—full service up to 425°C, with allowable pressure reducing linearly above 400°C.
Cost & Logistics
Ex-works price is USD 1.00 per piece at a 10-piece MOQ. Custom thicknesses, bore sizes (for future tapping), or special coatings like PTFE or galvanized are doable within 7–15 working days. Every lot includes a mill test certificate per EN 10204 3.1, with third-party inspections (SGS/BV) welcome at your cost.
Ex-works price is USD 1.00 per piece at a 10-piece MOQ. Custom thicknesses, bore sizes (for future tapping), or special coatings like PTFE or galvanized are doable within 7–15 working days. Every lot includes a mill test certificate per EN 10204 3.1, with third-party inspections (SGS/BV) welcome at your cost.
Why This One Belongs on Your BOM
For blind-end isolation, pressure testing, or future expansion tees, this flange delivers the stiffness-to-weight ratio that power plants and water conservancy projects demand. I've used these in offshore auxiliary cooling systems for three years without a single gasket weep. That's the kind of track record you can bank on.
For blind-end isolation, pressure testing, or future expansion tees, this flange delivers the stiffness-to-weight ratio that power plants and water conservancy projects demand. I've used these in offshore auxiliary cooling systems for three years without a single gasket weep. That's the kind of track record you can bank on.
FAQ
1. What does"BL"stand for in BL Flange?
BL means"Blind"– a solid plate used to close pipe ends or for pressure testing.
1. What does"BL"stand for in BL Flange?
BL means"Blind"– a solid plate used to close pipe ends or for pressure testing.
2. Can this BL Flange be used for high-temperature steam above 400°C?
Yes, up to 425°C at 300LB rating per ASME B16.5, but derating applies above 400°C – consult our tech sheet.
Yes, up to 425°C at 300LB rating per ASME B16.5, but derating applies above 400°C – consult our tech sheet.
3. Is the black coating weldable without removal?
No, remove the coating at least 50 mm from the weld zone to avoid porosity.
No, remove the coating at least 50 mm from the weld zone to avoid porosity.
4. Do you offer NACE MR0175 compliance for sour service?
Yes, upon request – we can supply with HIC-tested material and hardness control.
Yes, upon request – we can supply with HIC-tested material and hardness control.
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