What is BS 4504?
BS 4504 is the British dimensional standard for circular flanges to metric PN ratings, widely specified across the United Kingdom, the Commonwealth and markets that inherited British engineering practice.
Key Takeaways
- BS 4504 scope: Weld neck, slip on, blind, plate and lap joint flanges in PN-rated sizes, with dimensions that broadly align with the DIN and EN 1092-1 metric series.
- Size range: DN 10 to DN 600 across common service.
- Ratings: PN6, PN10, PN16, PN25 and PN40.
- Material grades: Carbon steel, and 304 / 304L / 316 / 316L stainless to the equivalent British and EN material designations.
- Kalp Alloys manufactures to BS 4504 in Ahmedabad, India, with EN 10204 3.1 and 3.2 certification issued in its own name.
- Third-party inspection by SGS, BV, TUV or Lloyds can be witnessed at our plant before dispatch.
What BS 4504 governs
BS 4504 is the British dimensional standard for circular flanges to metric PN ratings, widely specified across the United Kingdom, the Commonwealth and markets that inherited British engineering practice.
Weld neck, slip on, blind, plate and lap joint flanges in PN-rated sizes, with dimensions that broadly align with the DIN and EN 1092-1 metric series.
Scope, sizes and ratings at a glance
The envelope below is the practical reference: what to state on a purchase order so the item that arrives is the item the line needs.
| Parameter | Detail |
|---|---|
| Size range | DN 10 to DN 600 across common service |
| Ratings | PN6, PN10, PN16, PN25 and PN40 |
| Material grades | Carbon steel, and 304 / 304L / 316 / 316L stainless to the equivalent British and EN material designations |
| Designation system | PN — nominal pressure in bar |
| Common ratings | PN6, PN10, PN16, PN25, PN40 |
| Superseded by | BS EN 1092-1 |
| Typical markets | UK, Gulf, East and Southern Africa, South Asia |
| Interchangeable with ASME B16.5 | No |
| Broadly aligns with | DIN and EN 1092-1 metric series |
The point buyers most often get wrong
BS 4504 has largely been replaced by BS EN 1092-1 in current design work, but it remains the reference on installed plant across the UK, the Gulf, East and Southern Africa and South Asia. For an Indian manufacturer exporting to those markets it is a practical advantage to hold both the ASME and the BS or EN dimensional range, because a single project frequently contains both.
What Kalp Alloys manufactures to BS 4504
Kalp Alloys is a manufacturer, not a stockist. Production runs at our own facility at 5, Jay Vijay Industrial Estate, B/h. Akash Vikas Estate, Keval Kanta Road, Rakhial, Ahmedabad, which means the heat number stamped on the part traces to our own melt record and the mill test certificate is issued in the name of Kalp Alloys.
That matters on standard-led purchasing more than anywhere else, because an approved-vendor submission or a code-governed line has to show who made the part. A certificate passed down a trading chain names a mill the buyer has no relationship with and cannot query.
Grades supplied against BS 4504 cover Carbon steel, and 304 / 304L / 316 / 316L stainless to the equivalent British and EN material designations. Non-standard bores, thicknesses, drilling patterns and facing finishes are produced to customer drawing.
Ordering against BS 4504
State the dimensional standard, the size or NPS range, the rating or schedule, the facing where applicable, the material specification and grade, the quantity, and the certification level required. A quotation is typically returned within 24 hours.
Drawings for non-standard items can be sent by email or on WhatsApp at +91 81608 73937 and are reviewed by the technical team. Stock sizes dispatch in three to seven days; made-to-drawing items carry a firm lead time quoted at order confirmation. There is no minimum order on stock sizes and trial quantities are accepted.
Frequently Asked Questions
BS 4504 is the British dimensional standard for circular flanges to metric PN ratings, widely specified across the United Kingdom, the Commonwealth and markets that inherited British engineering practice.
DN 10 to DN 600 across common service. Ratings covered are PN6, PN10, PN16, PN25 and PN40.
Carbon steel, and 304 / 304L / 316 / 316L stainless to the equivalent British and EN material designations.
They are closely related and in many sizes dimensionally aligned, because EN 1092-1 was harmonised from the national metric standards including BS 4504. Confirm size by size rather than assuming equivalence.
Yes. BS 4504 and EN 1092-1 are the dominant designations in the UK market, and both are manufactured at Ahmedabad with EN 10204 3.1 or 3.2 certification.
Yes. Kalp Alloys manufactures to BS 4504 at its own facility at 5, Jay Vijay Industrial Estate, B/h. Akash Vikas Estate, Keval Kanta Road, Rakhial, Ahmedabad, and issues the EN 10204 3.1 or 3.2 mill test certificate in its own name rather than passing through a third-party mill certificate.
An EN 10204 3.1 mill test certificate as standard, stating the ordered standard, grade and heat number, with chemical and mechanical results and a dimensional inspection report. EN 10204 3.2 with third-party inspection by SGS, BV, TUV or Lloyds is arranged where the project requires it.