BS 4504 Flanges Suppliers
PN6 to PN40 Flange Dimensions
BS 4504 Standard Flanges: Dimensions | Specifications | Material Grade | Standards | About BS 4504 Standard | All Product Types
BS 4504 flanges are designed as per British Standards to accommodate a wide range of pressure ratings from PN6 to PN40 and nominal diameters up to DN1000. These flanges are ideal for pipelines, valves, and pressure vessels used in diverse industries including chemical processing, marine applications, water treatment, and power generation.
The standard includes multiple flange types such as Welding Neck (WN), Slip-On (SO), Blind (BL), Threaded (TH), and Loose Flanges, each engineered with accurate face finishes, bolt patterns, and gasket seating surfaces. BS 4504 flanges are dimensionally compatible with EN 1092-1 and ensure smooth interchangeability across European pipeline systems.
Designed with tight dimensional tolerances, these flanges are manufactured to support easy installation and reliable sealing even under fluctuating pressure and temperature. Available in carbon steel, stainless steel, and alloy grades, BS 4504 flanges are tested and supplied with EN 10204 Type 3.1 or 3.2 certification, along with custom packaging and export-ready documentation upon request.
The BS 4504 specification also allows integration with PN-rated gasket systems and is compliant with most international piping codes. These flanges are often selected for critical applications due to their excellent sealing performance, corrosion resistance, and mechanical durability, especially in offshore, refinery, and utility plant installations. Optional surface finishes like zinc-coated, epoxy painted, or anti-rust varnish further enhance service life.
BS 4504 Flanges – Complete Technical Overview of PN6 to PN40 Pressure Ratings, Dimensions, Tolerances, and Face Types.
For complete technical details, including dimensions, pressure rating classes, weight charts, sizes, tolerances, and material specifications of our BS 4504 Standard Flanges, please download the full Catalog PDF below.
Exporter and Manufacturer of BS 4504 Standard Flanges including SO, BL, WN, TH Types with EN 10204 Certification in Stainless & Carbon Steel.
Technical Specifications of BS 4504
| Specification | Details |
|---|---|
| Standard | BS 4504 – British Standard Specification for Circular Flanges for Pipes, Valves and Fittings |
| Flange Types | Weld Neck (WN), Slip-On (SO), Blind (BL), Threaded (TH), Loose Plate Flange |
| Size Range | ½″ NB to 40″ NB (DN15 to DN1000) |
| Pressure Ratings | PN6, PN10, PN16, PN25, PN40 |
| Face Types | Raised Face (RF), Flat Face (FF), Tongue & Groove |
| Drilling Specifications | Standardized bolt hole dimensions as per BS 4504 drilling templates |
| Dimensional Tolerances | As per BS 4504 specification (EN ISO 2759 for reference) |
| Surface Finish | Stock Finish, Smooth Finish, Spiral Serrated (3.2 to 6.3 μm Ra) |
| Inspection & Testing | Hydro Test, Visual & Dimensional Check, Ultrasonic or MPI (as per order) |
| Certification | EN 10204 Type 3.1 / 3.2, ISO 9001:2015, PED 2014/68/EU, AD 2000 W0 |
| Applications | Power Plants, Water Supply, Marine, Oil & Gas, Petrochemical, Paper & Pulp, HVAC |
| Origin | Made in India (by Nutech Overseas) |
| Export Network | USA, Europe, and Middle East |
Complete Material Grade Chart - BS 4504 Flanges
| Material Category | BS 4504 Flange Grades |
|---|---|
| Stainless Steel BS 4504 Flange | ASTM A182 F304 / F304L / F304H, F316 / F316L / F316Ti, F310, F309S, F317 / F317L, F321 / F321H, F347 / F347H, F904L, ASTM A351 CF3 / CF3M / CF8 / CF8M / CF8C, DIN 1.4301, 1.4306, 1.4307, 1.4311, 1.4401, 1.4404, 1.4408, 1.4409, 1.4541, 1.4571, 1.4550, 1.4435, 1.4539 |
| Duplex Steel BS 4504 Flange | ASTM A182 F51 / F52 / F53 / F54 / F55 / F57 / F59 / F60 / F61, UNS S31803 / S32205 |
| Super Duplex Steel BS 4504 Flange | ASTM A182 F53 / F55 / F57 / F59 / F60 / F61, UNS S32750 / S32760 |
| Carbon Steel BS 4504 Flange | ASTM A105 / A105N, ASTM A350 LF2, ASTM A694 F52 / F56 / F60 / F65 / F70 / F80, ASTM A216 WCB, DIN 1.0460 / 1.0402 / 1.0619, Die Steel, Mild Steel |
| Alloy Steel BS 4504 Flange | ASTM A182 F5 / F9 / F11 / F12 / F22 / F91, AISI 4130 / 4140 |
| Nickel Alloy BS 4504 Flange | Nickel 200 / 201, ASTM B564 |
| Monel BS 4504 Flange | Monel 400 (UNS N04400), Monel K500 (UNS N05500), ASTM B564 |
| Inconel BS 4504 Flange | Inconel 600 / 601 / 625 / 690 / 718 / 783 / X750, ASTM B564 |
| Incoloy BS 4504 Flange | Incoloy 800 / 800H / 800HT (UNS N08800), Incoloy 825 (UNS N08825), Incoloy 925, ASTM B564 |
| Hastelloy BS 4504 Flange | Hastelloy C276 (UNS N10276), C22 (UNS N06022), C4, C2000, B2, B3, X, ASTM B564 |
| Alloy 20 BS 4504 Flange | Alloy 20 / 20Cb-3, Carpenter® 20, ASTM B462 |
| 254 SMO BS 4504 Flange | SMO 254 / 6Mo, UNS S31254, DIN 1.4547, ASTM A182 |
| Copper Nickel BS 4504 Flange | Copper Nickel 90/10 (C70600), 70/30 (C71500), UNS C71640, ASTM B61 / B62 / B151 / B152 |
| Copper BS 4504 Flange | TP1, TP2, T1, T2, C10100–C12300, C14200–C17200, C21000–C71520, including C10930, C11000, C11400, C12000, C12200, C26000, C28000, C33000, C44300, C70600, etc. |
| Brass BS 4504 Flange | Grades 3602, 2604, H59, H62, etc. |
| Aluminium BS 4504 Flange | Aluminium Grades 5052, 6061, 6063, 2017, 7075, etc. |
| Titanium BS 4504 Flange | ASTM B381 Gr.1 / Gr.2 / Gr.4 / Gr.5 / Gr.7, UNS R50250 / R50400 / R50550 / R50700 / R52400 / R53400 / R56320 / R56400 |
| Other Special Grades | Al6XN, Tin Bronze, Aluminium Bronze, Lead Bronze, Nimonic 75 / 80A / 90 |
International Flange Standards We Manufacture & Supply
This is a frequently searched topic due to the overlap between European standards. While BS 4504 and EN 1092-1 flanges share similar characteristics, they are not always interchangeable due to the following key differences:
- Design Origin:
- BS 4504 is a British standard (now mostly withdrawn)
- EN 1092-1 is the harmonized European replacement standard
- Dimensional Tolerances:
- Slight variations in bolt-hole pitch, thickness, and outside diameter may cause alignment issues during installation.
- Drilling Patterns:
- EN 1092-1 uses standardized Type designations (Type 01, 05, 11, etc.), whereas BS 4504 doesn’t follow the same classification.
- Material Requirements:
- EN 1092-1 often includes stricter material traceability and mechanical property norms compared to older BS 4504 flanges.
Flanges from both standards should not be mixed unless proper dimensional checks and engineering validation are done. Always match standards across the entire piping system to avoid leakage, misalignment, or pressure failure.
BS 4504 flanges are manufactured in a wide range of materials to suit varying pressure, temperature, and corrosion conditions. The choice of material directly affects the flange’s durability, cost-efficiency, and suitability for the intended application.
Common Materials Include:
- Carbon Steel (e.g., C22.8, ASTM A105):
Ideal for general-purpose applications with moderate pressure and temperature.
- Stainless Steel (e.g., 304, 316):
Provides excellent corrosion resistance, especially in food processing, chemical plants, and marine environments.
- Alloy Steel (e.g., ASTM A182 F11, F22):
Suitable for high-temperature, high-pressure applications in refineries and power plants.
- Duplex / Super Duplex (e.g., UNS S31803, S32750):
Combines high strength with outstanding resistance to chloride stress corrosion.
- Copper-Nickel (e.g., CuNi 70/30):
Common in offshore and seawater systems.
Impact of Material Selection:
- Affects gasket compatibility
- Determines corrosion and temperature resistance
- Influences mechanical strength and lifecycle cost
- Impacts compliance with regional industry standards and project specifications
Selecting the correct material not only ensures long-term reliability but also compliance with safety and operational standards.
Yes, BS 4504 flanges are still widely used in legacy systems and industries that follow British engineering specifications. Although officially withdrawn and largely replaced by EN 1092-1, many stockists and manufacturers continue to supply BS 4504 flanges due to:
- Compatibility with existing piping systems
- Client project specifications in older plants
- Global familiarity with PN-rated flange systems
However, for new installations, engineers often recommend transitioning to EN 1092-1 for better standardization and compliance across European projects.
This is a common query when comparing metric and imperial flange standards. Here's how they differ:
| Parameter | BS 4504 (PN Rating) | ASME B16.5 (Class Rating) |
|---|---|---|
| Pressure Designation | PN6, PN10, PN16, PN25, PN40 | Class 150, 300, 600, 900, 1500 |
| Measurement System | Metric | Imperial (inches) |
| Bolt Hole Patterns | Vary by PN and flange type | Standardized across pressure classes |
| Application Region | Europe, UK, Asia | USA, Gulf Countries, International Projects |
| Interchangeability | Not directly interchangeable with ASME flanges | Requires engineering review before use with PN systems |
They are not directly interchangeable, so engineers must review pressure and dimension charts before cross-usage.
Yes. While BS 4504 defines the dimensional and pressure parameters, customization is possible for enhanced performance in demanding environments such as:
- Offshore rigs / marine structures
- Desalination and chemical plants
- Refineries in high-temperature zones
Custom Options Include:
- Surface coatings like FBE, PTFE, or galvanization
- NORSOK or NACE MR0175 compliance for sour service
- Enhanced gasket face finishes (serrated, smooth, etc.)
- Material upgrades to Duplex / Inconel / Monel
Such enhancements must retain dimensional compliance with BS 4504 while improving lifecycle durability.
Despite being replaced by EN 1092-1 in many regions, BS 4504 flanges are still in regular use across several countries where legacy systems or British engineering practices remain:
Common Export Destinations Include:
- United Kingdom & Ireland
- Gulf Countries (UAE, Saudi Arabia, Oman)
- South Africa and Nigeria
- Malaysia, Singapore, and Indonesia
- Bangladesh and Sri Lanka
- European nations transitioning to EN 1092-1
Nutech continues to manufacture and export BS 4504 flanges with full dimensional and material traceability to meet these regional demands.
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