Need the actual Type B wall thicknesses?
Send us the fitting type, size, wall series and grade. Our team replies with the EN 10253-2 / -4 Type B thicknesses at the intrados or body, free of charge. We aim to reply within one business day.
1. What Is EN 10253?
EN 10253 is the European standard series governing wrought steel fittings for butt welding. Published by the European Committee for Standardisation (CEN) and adopted as a national standard by all EU and EEA member states, it is the European equivalent of ASME B16.9 but with important structural differences in both dimensional requirements and quality documentation.
The standard is divided into four parts, each addressing a different material category or inspection regime:
| Part | Scope | Arshya Supply |
|---|---|---|
| EN 10253-1 | Non-alloy steels without specific inspection requirements | On request |
| EN 10253-2 | Non-alloy and ferritic alloy steels with specific inspection requirements (e.g. P235GH, P265GH, 16Mo3, 13CrMo4-5, 10CrMo9-10). Defines Type A and Type B. | Standard supply |
| EN 10253-3 | Austenitic and austenitic-ferritic (duplex) stainless steels without specific inspection requirements | On request |
| EN 10253-4 | Austenitic and austenitic-ferritic (duplex) stainless steels with specific inspection requirements (e.g. 1.4404, 1.4571, 1.4462). Defines Type A and Type B. | Standard supply |
Arshya Pipe Fittings manufactures to EN 10253-2 (non-alloy and alloy steel) and EN 10253-4 (austenitic and duplex stainless steel) as standard production. Both parts carry specific inspection requirements, so the fittings are supplied with EN 10204 inspection documents (3.1 as standard, 3.2 on request). We supply both Type A and Type B. Type B is our specialism.
2. Type A vs Type B — What the Standard Says
The most important concept in EN 10253 procurement is the difference between Type A and Type B. Both types are defined in EN 10253-2 and EN 10253-4. The difference is about pressure capacity compared with the connecting pipe. It is not about how the bore is finished.
Type A — Reduced Pressure Factor
- Strength: A Type A fitting is weaker than straight pipe of the same material and wall thickness. The standard gives it a reduced pressure factor.
- Design: The piping designer must allow for the reduced factor. This means a lower allowable pressure or a thicker wall for the fitting.
- Inspection documents: Supplied with EN 10204 inspection documents under EN 10253-2 / -4, the same as Type B.
- Typical use: Systems where the design calculation shows the reduced pressure factor is acceptable.
Type B — Full Service Pressure
- Strength: A Type B fitting is for use at full service pressure. It has the same strength as the connecting pipe of the same material and wall thickness.
- Wall thickness: Type B fittings often need extra wall thickness, for example at the inside of an elbow bend, to reach full service pressure.
- Inspection documents: Supplied with EN 10204 inspection documents under EN 10253-2 / -4, the same as Type A.
- Typical use: Systems where the designer wants the fittings to carry the same pressure as the pipe without an extra allowance.
3. Pressure Rating Comparison
Under EN 13480-3 (European Metallic Industrial Piping standard), the designer calculates the required wall for each component. A Type B fitting can carry the same pressure as the connecting pipe of the same material and wall thickness. For a Type A fitting, the reduced pressure factor must be applied. The result is either a lower allowable pressure for the same wall, or a thicker wall for the same pressure.
| Parameter | Type A | Type B |
|---|---|---|
| Defined in | EN 10253-2 / EN 10253-4 | EN 10253-2 / EN 10253-4 |
| Pressure capacity vs connecting pipe | Reduced pressure factor | Full service pressure |
| Allowance needed in the design | Yes | No extra allowance for the fitting |
| Wall thickness | Set by the design | Often extra wall where needed |
| EN 10204 inspection documents | Yes (3.1 standard, 3.2 on request) | Yes (3.1 standard, 3.2 on request) |
| Ends machined to pipe bore | On request | On request |
Always perform design calculations to EN 13480-3 using the actual material allowable stress at design temperature and the minimum wall thickness of the fitting supplied.
4. PED 2014/68/EU Category and Fitting Type
The Pressure Equipment Directive 2014/68/EU (PED) categorises pressure equipment into four risk categories — I (lowest) through IV (highest) — using Annex II tables that cross-reference fluid group against the product of maximum allowable pressure (PS in bar) and nominal size (DN).
PED Fluid Groups
Group 1 (higher risk)
Flammable, explosive, or toxic fluids. Includes hydrocarbons, acids, ammonia, chlorine. Triggers lower PS×DN thresholds for Cat III–IV uplift.
Group 2 (lower risk)
All other fluids — steam, compressed air, water above 110°C, inert gases. Higher PS×DN thresholds before Cat III–IV applies.
For buttweld pipe fittings, the PED category determines the required conformity assessment route:
| PED Category | Typical Conformity Route | Fitting Type (designer's choice) | Notes |
|---|---|---|---|
| Category I | Module A (internal production control) | Type A or Type B | Lowest risk — self-declaration by manufacturer |
| Category II | Module A2, D1 or E1 | Type A or Type B | Notified Body involvement in surveillance only |
| Category III | Module B+D, B+F, B+E, B+C2 or H | Type A or Type B | Notified Body EU-type examination (B) or full QA approval (H); traceable docs essential |
| Category IV | Module B+D, B+F, G or H1 | Type A or Type B | Notified Body EU-type examination (B), unit verification (G) or full QA with design examination (H1); full traceability, NDE |
Practical implication for procurement
EN 10253 does not link Type A or Type B to a PED category. The pressure-equipment designer chooses the type as part of the design. Type A can be used where the design allows for its reduced pressure factor. Type B is used where the fitting must carry full service pressure at the wall thickness of the connecting pipe. Using Type A does not by itself invalidate the PED Declaration of Conformity (DoC). What matters is that the fitting supplied matches the type and wall thickness used in the design. State the type clearly on the order.
5. Weld Bevel and End Preparation
Weld end preparation works the same way for Type A and Type B. End preparation for EN 10253-2 / -4 fittings conforms to EN ISO 9692-1 (Welding and allied processes — Joint preparation — Part 1: Manual metal-arc welding, gas-shielded metal-arc welding, gas welding, TIG welding and beam welding of steels).
Standard bevel geometry (EN ISO 9692-1 Type 1.3)
- Bevel angle: 37.5° ± 2.5° (total included angle ~75°)
- Root face (land): 1.6 mm ± 0.8 mm
- Surface finish: Ra ≤ 12.5 µm on the bevel face
- Perpendicularity: Squareness tolerance of 0.5 mm across the face
Optional end machining to pipe bore
- On request we machine the ends to match the bore of your EN 10216 / EN 10217 pipe
- Available for both Type A and Type B fittings
- A matched bore reduces the internal step at the weld root
- Useful for orbital TIG welding and for pharmaceutical, food-grade and ultra-pure process lines
For high-alloy stainless steels (duplex, super-duplex, 6Mo), bore alignment at the weld root matters for orbital GTAW. If your weld procedure needs a matched bore, ask for end machining on the order. This applies to Type A and Type B alike.
6. Ordering Requirements for Type A and Type B Fittings
A correctly written EN 10253-2 or EN 10253-4 purchase order needs six data points. A missing one creates ambiguity. At best this leads to an RFI to the manufacturer. At worst it leads to a shipment that cannot be accepted against the design specification. The most common error is not stating the type.
Standard designation — explicitly state the type
Write the part and the type, for example “EN 10253-2 Type B” or “EN 10253-4 Type A”. Do not write just “EN 10253”. The type must match the one used in the pressure design.
Pipe standard for end machining (if required)
If you need the ends machined to match the bore of your pipe, state the pipe standard. Common choices: EN 10216-5 (seamless stainless, most common for process), EN 10217-7 (welded stainless), EN 10216-2 (seamless non-alloy and alloy steel). End machining is a service on request. It is not part of the Type A / Type B definition.
Outside diameter series
EN 10253 uses DN sizes that map to OD series from EN ISO 1127. Most European process piping uses OD Series 1 (matching the OD of the connecting pipe). State this explicitly: “OD Series 1” or “EN ISO 1127 Series 1”.
Wall thickness
State the wall thickness as either the pipe schedule (e.g. SCH 40, SCH 80) or the actual wall in mm (e.g. T = 6.3 mm) as defined in the reference pipe standard. A Type B fitting may have extra wall where needed to reach full service pressure. If you order end machining, the pipe wall also sets the machined bore diameter.
Material grade with EN Werkstoffnummer
Do not rely on grade names alone (e.g. “316L”) — state the full EN designation: 1.4404 (316L), 1.4301 (304), 1.4462 (duplex 2205), 1.4410 (super-duplex 2507). For alloy steel to EN 10253-2: e.g. 13CrMo4-5 (1.7335).
Certificate type — EN 10204 3.1 or 3.2
EN 10253-2 and EN 10253-4 fittings, Type A or Type B, are supplied with EN 10204 inspection documents. We supply EN 10204 3.1 (validated by the manufacturer's own authorised inspection representative, independent of production) as standard. EN 10204 3.2 (validated additionally by a third-party inspector appointed by the purchaser or by an independent inspectorate) is available on request, for example for nuclear or offshore projects.
Example correct PO line item
EN 10253-4 Type B, 90° LR Elbow, DN100 (4"), OD Series 1, T=6.3mm (SCH 40 equiv.), Material 1.4404 (316L), EN 10204 3.1 certificate required, ends machined to bore of EN 10216-5 pipe T=6.3mm (optional), PED 2014/68/EU DoC required.
7. Arshya's EN 10253 Type A and Type B Capability
Arshya Pipe Fittings Pvt Ltd supplies both EN 10253 Type A and Type B fittings. Type B is our specialism. We focus on European process piping, power generation and petrochemical customers who require PED compliance and full traceability on every order. On request we machine the ends to match the bore of your EN 10216 / EN 10217 pipe.
Size range
- DN15 (½") to DN1200 (48")
- Wall thickness: SCH 10 through SCH XXS
- Fittings: 90° LR / SR elbows, 45° elbows, 180° return bends, equal and reducing tees, concentric and eccentric reducers, pipe caps, stub ends
Material grades
- Austenitic: 1.4301 (304), 1.4307 (304L), 1.4306, 1.4401 (316), 1.4404 (316L), 1.4432, 1.4571 (316Ti), 1.4541 (321), 1.4550 (347)
- Duplex / Super-duplex: 1.4462 (2205), 1.4410 (2507), 1.4501 (Zeron 100)
- 6Mo / High-alloy: 1.4547 (254 SMO), 1.4529 (Incoloy 926)
- Nickel alloys: Alloy 625, Alloy 825, Alloy C276
3.1
EN 10204 3.1 certificate on every heat — standard, not optional
DoC
PED 2014/68/EU Declaration of Conformity available on request
TPI
Third-party inspection by TUV, Lloyd's Register, Bureau Veritas on request
Additional certifications available