Looking for the skinny on bs4504 flanges? You’ve come to the right place! This comprehensive guide will give you the deets on everything bs4504 – from specs and standards to customization options. Grab a cuppa and let’s dive in.


An Introduction to bs4504 Flanges

A bs4504 flange is a type of flange that conforms to British Standard bs4504. This spec defines requirements for steel pipe flanges in sizes up to 24 inches/600mm nominal bore.

bs4504 flanges are made from forged carbon or alloy steel and designed for use in process piping and equipment in industries like:

  • Oil and gas
  • Chemical and petrochemical
  • Power generation
  • General industrial applications

The bs4504 specification outlines dimensions, tolerances, materials, pressure ratings, face finishes, and markings for these flanges. It also references testing methods to ensure quality.

Key Features of bs4504 Flanges

There are a few key features that distinguish bs4504 flanges:

  • Materials – Typically made from carbon steel or alloy steel. Stainless steel also possible.
  • Pressure ratings – Available in PN6 to PN40 classes.
  • Face types – Usually flat face (FF) or raised face (RF). Some ring joint (RJ) options.
  • Facings – Spec requires machine finished facings with serrated or spiral groove pattern.
  • Bolting – Stud, nut, and gasket bolt sets must conform to bs4504 as well.

These flanges come in slip-on or welding neck end connections to suit different piping assembly needs.

Deciphering the Markings

bs4504 flanges are required to have specific markings stamped or cast into them. Here’s what the markings mean:

  • Material grade – e.g. Grade B, Grade C25, etc.
  • Pressure rating – PN class (PN6, PN16, etc.)
  • Size – Nominal bore in mm
  • Manufacturer’s name or mark
  • Standard designation – bs4504

Knowing how to interpret these markings is crucial for proper flange identification and selection.

Why Choose bs4504 Flanges?

bs4504 flanges offer several benefits that make them a popular choice across various industries:

  • Wide range of sizes – From 15mm to 600mm nominal bore.
  • Higher pressure ratings – Up to PN40 available.
  • Robust design – Can handle high temps and tough operating conditions.
  • Standardized dimensions – Easier to find replacements.
  • British pedigree – Trusted industrial heritage.

For many engineers and plant operators in the UK and Europe, the bs4504 standard provides a reliable, familiar flange option.

When to Use Alternative Standards

While useful in many situations, bs4504 flanges aren’t the only game in town. Here are a few instances when you may want to consider alternative flange standards:

  • For low pressure applications, a PN10 flange from EN or DIN may suffice.
  • For very high pressure or exotic alloys, ANSI flanges are a good choice.
  • For sizes above 24”, EN or ASME flanges offer larger range.
  • For specialized corrosion resistance, stainless steel flanges conforming to ASTM/ASME specifications may be preferable.

There’s no one-size-fits-all flange for every scenario. Picking the right standard depends on the specifics of your piping project.

Customization Options for bs4504 Flanges

Another advantage of bs4504 flanges is the ability to customize certain aspects, including:

  • Materials – Grade B carbon steel is standard, but stainless, alloy steels, nickel alloys available for specialized corrosion and temperature resistance.
  • Facings – Machine smooth finish standard, but serrated or full face (no spiral grooves) options allowable.
  • Pressure classes – Some manufacturers will produce interim PN classes like PN25 or PN35.
  • Size ranges – Possible to get flanges outside normal 15-600mm size range.
  • Special drilling – Custom bolt circles and flange holes for non-standard mating flanges.

Work closely with your supplier to tailor bs4504 flanges to your exact requirements.

Finding a bs4504 Flange Supplier

Looking for reliable bs4504 flanges? Jmet Corp. stocks a wide range of carbon and stainless steel bs4504 flanges off-the-shelf and made-to-order. With over 30 years of experience supplying bs4504 and other flange types to industries across the UK and beyond, we can help you find the perfect flanges for your application.

[Contact us today] to discuss your project and get a fast quote. We provide quality products, technical expertise, and stellar customer service. Whether you need standard or custom bs4504 flanges, in small batches or bulk orders, we’ve got you covered!

FAQs About bs4504 Flanges

Q: What materials are bs4504 flanges made from?

A: Most commonly carbon steel Grades A/B or alloy steel Grades C/D. Stainless steel also possible for specialized corrosion resistance.

Q: What types of bs4504 flanges are available?

A: Slip-on (SO) and welding neck (WN) are the two main types. Some socket weld (SW) and lap joint (LJ) also produced.

Q: What face types can you get with bs4504 flanges?

A: Flat face (FF) and raised face (RF) are typical. Some manufacturers offer ring type joint (RTJ) faces.

Q: What size range does the bs4504 standard cover?

A: Nominal bore sizes from 15mm to 600mm (1/2” to 24”). Custom sizes outside this range also possible.

Q: How do you identify the pressure class of a bs4504 flange?

A: Pressure class or PN rating will be stamped on flange (e.g. PN16, PN25). Ratings range from PN6 to PN40.

Q: Can you get special drillings or customization with bs4504 flanges?

A: Yes, manufacturers can often provide special bolt circles, flange holes, materials, etc. to suit non-standard applications.


Phew, we covered a lot of ground on the broad world of bs4504 flanges! Here are the key takeaways:

  • bs4504 is a British standard that defines carbon and alloy steel pipe flanges from 15-600mm bore size.
  • These flanges offer good high pressure/temperature ratings and a standardized design.
  • Markings identify size, pressure class, material, and standard.
  • bs4504 flanges are a versatile piping component but not the only option – alternative standards may suit some applications better.
  • Customization is possible by tailoring materials, facings, pressure classes, and dimensions.
  • For top-quality standard or custom bs4504 flanges, be sure to contact the experts at Jmet Corp.

Whether you’re an engineer designing a new process plant or a maintenance tech needing replacement flanges, this guide provides valuable insights on bs4504 flange selection and use. Feel free to get in touch with questions or when you’re ready to order. Our team is standing by to deliver the ideal bs4504 flanges for your piping project.