EN 10253-2 Type A vs Type B: What Procurement Engineers Must Know
When specifying European buttweld pipe fittings, one question consistently causes confusion on tender documents: Type A or Type B?
The Standard
EN 10253-2 (non-alloy and ferritic alloy steels) and EN 10253-4 (austenitic and duplex stainless steels) cover buttweld pipe fittings with specific inspection requirements. Both parts define two fitting types, Type A and Type B. The difference is their pressure capacity compared with the connecting pipe.
Type A vs Type B
Type A fittings have a reduced pressure factor. They are weaker than straight pipe of the same material and wall thickness. The piping design must allow for this, with a lower allowable pressure or a thicker fitting wall.
Type B fittings are for use at full service pressure. They have the same strength as the connecting pipe of the same material and wall thickness. Type B fittings often need extra wall thickness to achieve this. Matching the fitting bore to the pipe is not part of the definition. On request we machine the ends to match the bore of your EN 10216 / EN 10217 pipe, for either type.
Which to Specify
The choice is made by the pressure-equipment designer. Type B is convenient on European projects designed to EN 13480, because the fitting can carry the same pressure as the pipe without an extra allowance. Type A is acceptable where the design allows for its reduced pressure factor. EN 10253 does not tie either type to a PED category, and using Type A does not by itself invalidate a PED Declaration of Conformity.
Type A and Type B can be used in the same system, provided each fitting matches the type assumed in the design calculation. Mark the type clearly on the line list.
Certificates
EN 10253-2 and EN 10253-4 fittings, Type A and Type B, are supplied with EN 10204 inspection documents (3.1 as standard, 3.2 on request). High-pressure or PED Category III applications typically require 3.2 (third-party countersignature). Always state "EN 10204 3.1" or "EN 10204 3.2 TPI" explicitly on the purchase order — generic "mill certificate" language is ambiguous and may result in a 2.2 test report being supplied.
Common Procurement Errors
Many suppliers from India and the Middle East quote "EN 10253" without specifying Type A or B. Always confirm: ask for the fitting dimensional datasheet and confirm the type and wall thickness against your design. Arshya Pipe Fittings supplies both Type A and Type B; Type B is our specialism.