EN 10253-1 Pipe Fittings: Dimensional Tolerances and End Finish

1. Tolerances on dimension according to EN 10253-1

1) All diameters of EN 10253-1 pipe fittings shall be measured at the welding ends of the fittings. The tolerance is ±1% or ±0.5 mm whichever is the greater.

2) In order to ensure the flow-way area through the fitting is not excessively reduced, the internal diameter(not applicable to dished ends and caps) shall be greater than 80% of the theoretical internal diameter(ID), as calculated by: ID = OD - 2T.

3) Tolerances for ovality are:

at the welding ends: 2%;

on the body for elbows and return bends: 4%.

The ovality(Ov) shall be calculated by:

Ov = 200 * (Dmax - Dmin) / (Dmax + Dmin) in %.

Dmax: maximum measured diameter in one section.

Dmin: minimum measured diameter in one section.

4) Wall thickness tolerances

D	T	Tolerance
mm	mm	minus	plus
≤406.4	≤4 >4	-12.50%	0.35

*D: Outside diameter at the welding end. T: Wall thickness.

*The minus tolerance also applies to the body of the fitting.

5) Tolerances on specific dimensions

D	F-G-H	B	C	K	L
≤114.3	±2	±7	±7	±4	±2
114.3<D≤219.1	±2	±7	±7	±7	±3
219.1<D≤406.4	±3	±7	±10	±7	±5

*D: outside diameter;

*F: distance from the axis of the center line to the face of the branch outlet of equal tee.

*G: distance from the axis of the center line to the face of the branch outlet of reducing tee.

*H: Face to center-line distance for 45°.

*B: Face to top distance for 180° return bends.

*C: Center to center distance for 180° return bends.

*K: height of dished ends or caps.

*L: Face to face length of reducers(both concentric & eccentric).

6) Tolerances on the form of fittings

The tolerance on the form of each type of fitting Q = 1% of the outside diameter(D) or 1 mm, whichever is greater. See the figure illustrated below.

Angularity Tolerances of EN 10253-1 Fittings

2. End finish of EN 10253-1 butt welding pipe fittings

According to DIN EN 10253-1,

for wall thickness T < 3.0 mm, the ends may be plain or slightly chamfered.

for wall thickness T ≥ 3.0 mm, the ends shall be bevelled with an angle of 30 degrees to 35 degrees with a face of 1.6 mm ± 0.8 mm.

The welding ends of EN 10253-1 pipe fittings shall be free from harmful blurs.

Specially, the ends of dished ends with diameter ≥ 159 mm shall be bevelled with an angle of 30 degrees to 35 degrees with a face of 1.6 mm ± 0.8 mm.

EN 10253-1 Pipe Fittings: introduction, chemical composition and mechanical properties.

EN 10253-1 Pipe Fittings: inspection and testing method.

EN 10253-1 Pipe Fittings: marking, coating and packaging.

Views: Author：hbmetals Date:15/07/22