ISO 13920 Welding — General tolerances for welded constructions

ISO 13920 Welding — General tolerances for welded constructions —Dimensions for lengths and angles, shape and position

Soudage — Tolérances générales relatives aux constructions soudées — Dimensions des longueurs et angles, formes et positions

Table 1 — Tolerances for linear dimensions

Tolerance class	Range of nominal sizes I mm
	2  <l≤ 30	30 <l≤ 120	120 <l≤ 400	400 <l≤ 1000	1000 <l≤ 2000	2000 <l≤ 4000	4000 <l≤ 8000	8000 <l≤ 12000	12000 <l≤ 16000	16000 <l≤ 20000	l > 20000
	Tolerances t mm
A	±1	±1	±1	±2	±3	±4	±5	±6	±7	±8	±9
B		±2	±2	±3	±4	±6	±8	±10	±12	±14	±16
C		±3	±4	±6	±8	±11	±14	±18	±21	±24	±27
D		±4	±7	±9	±12	±16	±21	±27	±32	±36	±40

Table 2 — Tolerances for angular dimensions

Tolerance class	Range of nominal sizes l (mm) (length of shorter leg)
	l ≤ 400	400 < l ≤ 1 000	l > 1 000
Tolerances Δα (degrees and minutes)
A	±20′	±15′	±10′
B	±45′	±30′	±20′
C	±1°	±45′	±30′
D	±1° 30′	±1° 15′	±1°
Calculated and rounded tolerances, t, in mm/m *
A	±6	±4.5	±3
B	±13	±9	±6
C	±18	±13	±9
D	±26	±22	±18

* The value indicated in mm/m corresponds to the tangent value of the general tolerance. It is to be multiplied by the length.

Table 3 — Straightness, flatness and parallelism tolerances

Tolerance class	Range of nominal sizes I mm (relates to longer side of the surface)
	30 < l ≤ 120	120 < l ≤ 400	400 < l ≤ 1000	1000 < l ≤ 2000	2000 < l ≤ 4000	4000 < l ≤ 8000	8000 < l ≤ 12000	12000 < l ≤ 16000	16000 < l ≤ 20000	I > 20000
	Tolerances t mm
E	0.5	1	1.5	2	3	4	5	6	7	8
F	1	1.5	3	4.5	6	8	10	12	14	16
G	1.5	3	5.5	9	11	16	20	22	25	25
H	2.5	5	9	14	18	26	32	36	40	40

TESTING OF STRAIGHTNESS, FLATNESS, AND PARALLELISM

Straightness:

Flatness:

Parallelism:

Joining

Thermal Welding