Reference tables are transcribed from EN 1092-1:2018; table numbers, printed page numbers and cell values keep the standard's original wording.
Clause 5.10 of EN 1092-1:2018 defines what has to appear on a steel flange, lapped end or collar. The full marking is a fixed sequence that identifies the manufacturer, the standard, the type, the size, the rating, the material and — where certification is required — the heat. Type 21 integral flanges are excluded from this general marking requirement.
The clause also covers the case where the part is too small to carry everything: a shortened minimum marking is then allowed. Marking must be visible and durable, and the standard treats the EN 1092-1 mark plus the manufacturer's name or trademark as the manufacturer's declaration of compliance.
StandardEN 1092-1:2018
Clause§5.10 (p. 19)
Required marksa to i
ExampleXXX/EN 1092-1/11/DN 150/PN 40/P265GH/A2345
Exempt type21 (integral flange)
Marks required on flanges, lapped ends and collars
§5.10.1 — general marking requirements (p. 19)
Item
What must be marked
Example / note
a
Flange/collar manufacturer's name or trade mark
XXX
b
Number of the European Standard
EN 1092-1
c
Flange/collar type number
11, 05, 34 …
d
DN, nominal size
DN 150
e
PN designation
PN 40; a lower PN may be marked where the dimensions are identical
f
Wall thickness S, only if it is not according to this standard
S = 9 mm
g
Name, number or grade of the material
P245GH, 1.0352 …
h
Heat number of the melt and/or a suitable identification code for traceability, where test certification is required
A2345
i
Additional marking (M) for flanges according to Annex I
34M
The marks are applied in this order and separated by slashes. Type 21 flanges are excluded from the general marking requirement.
Designation examples
The standard gives one worked example of the full marking: XXX/EN 1092-1/11/DN 150/PN 40/P265GH/A2345. Reading it left to right: XXX is the manufacturer, EN 1092-1 is the standard, 11 is the weld-neck flange type, DN 150 is the nominal size, PN 40 the rating, P265GH the material and A2345 the heat or identification code.
The second example, XXX/EN 1092-1/34M/…, adds the letter M to the type number for a flange made to the fixed-inner-diameter rules of informative Annex I.
Minimum marking for small parts
Where a part is too small to carry the full marking, §5.10.1 allows this shortened set:
Flange/collar manufacturer's name or trade mark.
The letters EN.
PN designation, for example PN 40.
Name, number or grade of the material.
Heat number of the melt and/or a suitable identification code for traceability.
Stamping and declaration of compliance
Marking must be visible and durable.
Hard stamping is positioned on the outer rim of the part and must not be liable to start cracks in the flange material.
The marking EN 1092-1 together with the manufacturer's name or trademark, on or in relation to the product, is the manufacturer's declaration that the product meets the standard.
That declaration is a claim by or on behalf of the manufacturer, not a third-party certificate; a separate inspection certificate to EN 10204 can still be required by the purchaser (§5.13).
FAQ
What must be marked on an EN 1092-1 flange?
The manufacturer's name or trade mark, EN 1092-1, the type number, DN, PN, the wall thickness if it is non-standard, the material name/number/grade, the heat number or identification code where test certification is required, and any Annex I additional mark. The marks are separated by slashes in the order a to i.
What does XXX/EN 1092-1/11/DN 150/PN 40/P265GH/A2345 mean?
XXX is the manufacturer, EN 1092-1 the standard, 11 a weld-neck flange, DN 150 the nominal size, PN 40 the nominal pressure, P265GH the material grade and A2345 the heat number or traceability code.
What is the minimum marking if the flange is too small?
The manufacturer's name or trade mark, the letters EN, the PN designation, the material name/number/grade and the heat number or identification code. The type, DN and wall thickness may be omitted in that case.
Does the marking certify compliance?
Yes, in the standard's terms: the EN 1092-1 mark together with the manufacturer's name or trademark on or in relation to the product represents the manufacturer's declaration of compliance with EN 1092-1. It is not a substitute for a material certificate or a third-party inspection certificate.
Sources
EN 1092-1:2018, §5.10.1 — General marking requirements (p. 19)
EN 1092-1:2018, §5.10.2 — Stamping (p. 19)
EN 1092-1:2018, §5.10.3 — Declaration of compliance (p. 19)