What Type B means
EN 10253-2 (non-alloy and ferritic alloy steels) and EN 10253-4 (austenitic and austenitic-ferritic stainless steels) both define two kinds of buttweld fitting. A Type A fitting keeps the wall of the connecting pipe, but it is given a reduced pressure factor. The piping designer has to allow for that, with a lower allowable pressure or a heavier wall.
A Type B fitting is designed to carry the full design pressure of the connecting pipe. Stress in a bend or a branch is higher than in straight pipe, so the standard asks for extra wall at the critical zones: the intrados (inner radius) of an elbow or return, the body of a tee and the body of a reducer. The weld ends still match the pipe wall, so the fitting welds to the line without a step.
For the full comparison, inspection documents and PED aspects, see our EN 10253 Type A vs Type B guide.
Why buyers need the actual Type B thicknesses
- ✓Inspection: the inspector or TPI checks the wall at the intrados or body against a number. “Type B” on its own gives them nothing to measure against.
- ✓Purchase order: stating the required minimum thickness at the critical zone next to “Type B” removes doubt between buyer, supplier and inspector. Our Type B purchase order template shows where it goes.
- ✓Weight and cost: a thicker body means a heavier fitting. Knowing the Type B wall early keeps weights, freight and budget estimates realistic.
How the check works
- Fill in the form with the fitting type, DN or NPS, wall series or wall thickness, EN 10253 part and material grade. Add one line per item in the message box if you have several.
- Our sales team works out the Type B thicknesses for the intrados or body of each fitting from the standard.
- We reply by email with the thicknesses. We aim to reply within one business day, and we can quote at the same time if you add quantities.
We do not reproduce the tables of EN 10253 on this website. The standard is published by CEN and its national members; please buy a copy from your national standards body if you need the full text.
Frequently asked questions
Why does a Type B fitting need a thicker wall than the pipe?
Type B fittings must carry the same design pressure as the connecting pipe. Stress at a bend or branch is higher than in straight pipe, so the standard requires extra wall at the critical zones. Type A fittings keep the pipe wall but carry a reduced pressure factor instead.
What do I need to send?
Fitting type, DN or NPS, wall series or wall thickness (for example S3, 5.6 mm or SCH 40), EN 10253 part (-2 or -4) and material grade. A quantity is optional.
How quickly will I get an answer?
We aim to reply within one business day. The check is free and does not commit you to an order. You can also contact us directly.