BS Flanges | British Standard Pipe Flanges for Industrial Piping Systems
BS flanges are engineered for piping infrastructure adhering to British Standards (predominantly BS 10 tables), providing reliable mechanical connections for valves, pumps, and pipes in industrial fluid systems. Built for legacy and specialized applications across the UK and international markets, these flanges are produced via precision forging or plate cutting, ensuring exact bolt-hole alignment, stable pressure containment, and dependable gasket seating. Every production batch undergoes strict dimensional verification and material analysis to meet rigorous industrial demands without unnecessary marketing embellishment.
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![BS Plate Flange]()
BS Plate FlangeExecution Standard: BS4504
Size Range: DN10 – DN4000
Pressure Rating: PN2.5 – PN250
Material Options: Carbon Steel (Q235, S235JR, S355JR), Stainless Steel (304, 316L), and... -
![BS Weld Neck Flange]()
BS Weld Neck FlangeExecution Standard: BS 4504
Type / Model: Forged Weld Neck Flange
Connection Type: Butt welding with bolted flange joint
Available Materials: Q235, S235JR, S355JR, S355J0,...
Plate Flanges (Flat Face and Raised Face): Cut directly from carbon or stainless steel plate, utilized in low-to-medium pressure utility lines, water treatment, and general industrial plumbing where cost-efficiency and straightforward welding are prioritized.
Boss or Screw-on Flanges: Featuring threaded bores matching British Standard pipe threads, enabling mechanical assembly without welding, ideal for hazardous environments where hot work is prohibited.
Materials and Standards
|
Technical Parameter |
Standard Specification / Options |
|
Carbon Steel Grades – Structural & Utility |
BS 970 or EN 10025: S235JR, S355JR |
|
Carbon Steel Grades – Forged |
ASTM A105 or A105N for high-integrity forged carbon steel applications |
|
Stainless Steel Grades – Austenitic |
AISI 304, 304L, 316, 316L |
|
Stainless Steel Applications |
Corrosive fluid handling, chemical processing, and marine environments |
|
Applicable Standards |
BS 10: Tables A, B, D, E, F, H, and J |
|
Transitional Dimensions |
BS 4504 or EN 1092-1, where applicable |
|
Material Certification |
EN 10204 3.1 inspection and test reports |
Technical Specifications
|
Parameter |
Specification Details |
|
Size Range |
DN15 to DN1200 (1/2 inch to 48 inch) |
|
Pressure Ratings |
Table D, Table E, Table F, Table H (BS 10 specifications) |
|
Flange Facings |
Flat Face (FF), Raised Face (RF), Ring Type Joint (RTJ) |
|
Manufacturing Process |
Closed-die forging, free forging, and CNC flame-cut plate fabrication |
|
Surface Treatment |
Anti-rust oil coating, yellow or black industrial primer, hot-dip galvanizing, or pickled passivation for stainless steel |
|
Testing and Inspection |
Dimensional coordinate measuring, PMI (Positive Material Identification), ultrasonic testing (UT) upon request |
Applications
Water and Wastewater Treatment: Municipal fluid distribution, pumping stations, and filtration skid assemblies.
Shipbuilding and Marine Engineering: Shipboard ballast lines, auxiliary cooling water systems, and deck piping.
Chemical and Process Industries: Low-pressure chemical transport, acid transfer lines, and industrial utility headers.
HVAC and Steam Infrastructure: Commercial heating loops, low-pressure steam distribution, and chiller plant piping.
Manufacturing and QC
Raw Material Control: Raw steel billets and plates are sourced from verified mills with verified chemical composition heat numbers. Incoming material undergoes spectrometer analysis to confirm carbon, chromium, nickel, and manganese percentages.
Forging and Forming: Billets are heated in temperature-controlled induction furnaces and shaped using hydraulic forging presses ranging from 1,000 to 3,000 tons, refining the internal grain structure and eliminating internal porosity.
Precision Machining: CNC vertical lathes and multi-axis machining centers execute facing, boring, and bolt-hole drilling operations, maintaining surface finish roughness parameters (Ra 3.2 um to 6.3 um) required for effective gasket sealing.
Quality Verification: Dimensional inspections utilize digital calipers, height gauges, and coordinate measuring machines (CMM) to verify bolt circle diameters, hub thicknesses, and outer diameters against BS 10 tolerances. Every batch is supplied with traceable mill test certificates.
Customization and OEM
Custom Dimensions and Drawings:
Production accommodates non-standard hub lengths, specialized pitch circle diameters (PCD), or custom bore tolerances based on client engineering drawings.
Special Material Sourcing:
Procurement and fabrication of alloy steels, duplex stainless steels, or specific carbon steel grades tailored to corrosive or high-temperature operating environments.
Surface Finishing Options:
Hot-dip galvanizing coating thickness adjusted to ASTM A153 or BS EN ISO 1461 standards, or specialized epoxy coatings for subterranean installation.
OEM Marking and Packaging:
Custom laser etching on the rim including nominal size, pressure rating, material grade, heat number, and client-specified part numbers.
Packaging and Delivery
Corrosion Protection:
Flange faces are protected with heavy-duty plastic bolt-hole covers and coated with water-displacement anti-rust inhibitors, wrapped in moisture-resistant polyethylene film.
Export-Grade Wooden Pallets:
Flanges are secured onto heavy-duty fumigated wooden pallets or enclosed plywood crates using steel strapping to prevent transit shifting and edge impact damage.
Documentation Inclusion:
Each shipment contains commercial packing lists, original EN 10204 3.1 Material Test Reports (MTR), and fumigation certificates enclosed in waterproof pouches.
Logistics Support:
Containerized sea freight (FCL or LCL) and air freight options coordinated from major industrial ports with standard export clearance documentation.
FAQ
Q: Do your BS flanges strictly conform to BS 10 tables, or are they metric equivalents?
A: Our BS flanges are manufactured to traditional British Standard BS 10 dimensions (Tables D, E, F, and H), ensuring correct bolt spacing, outer diameters, and thickness profiles for legacy UK piping layouts without metric conversion discrepancies.
Q: What is the standard surface finish on the gasket seating face?
A: Standard production applies a concentric serrated finish with a surface roughness of Ra 3.2 to 6.3 um, which provides optimal bite for compressed asbestos-free or elastomer gaskets to prevent media leakage.
Q: Can you supply hot-dip galvanized finishes for outdoor or underground installations?
A: Yes. Hot-dip galvanizing (HDG) is available for all carbon steel BS flanges, executed in compliance with BS EN ISO 1461 to ensure uniform zinc coating thickness and corrosion resistance in soil or marine atmospheres.
Q: What documentation is provided with each shipment?
A: Every delivery includes mill test certificates (MTRs) conforming to EN 10204 3.1, detailing chemical composition, mechanical tensile test results, hardness values, and heat numbers traceable to the raw material melt.
Q: Are your carbon steel BS flanges weldable without preheating?
A: Standard carbon steel grades (such as S235JR or ASTM A105 with controlled carbon equivalents) exhibit excellent weldability. Standard arc welding procedures can be applied without specialized preheating for standard wall thicknesses.
Q: What is the typical lead time for standard versus custom-drilled flange orders?
A: In-stock standard sizes (Tables D and E in common DN sizes) typically ship within 7 to 10 business days. Custom-machined configurations, specialized alloy grades, or large bulk project orders generally require 25 to 35 days depending on forging schedules.
Q: How do you protect flange faces from impact and corrosion during ocean freight?
A: All flange faces are fitted with heavy-duty plastic bolt-hole protectors, sprayed with marine-grade rust preventative oil, and packed vertically or horizontally with inter-layer cushioning inside fumigated wooden crates.
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