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GB/T 19418-2003 English PDF (GBT19418-2003)

GB/T 19418-2003 English PDF (GBT19418-2003)

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GB/T 19418-2003: Arc-welded joints in steel -- Guidance on quality levels for imperfections

GB/T 19418-2003
ICS 25.160.50
J 33
GB/T 19418-2003 / ISO 5817.1992
Arc-welded joints in steel –
Guidance on quality levels for imperfections
(ISO 5817.1992, IDT)
Issued by. General Administration of Quality Supervision, Inspection and Quarantine.
Table of Contents
Foreword ... 3
1 Scope ... 4
2 Normative references ... 4
3 Terms and definitions ... 5
4 Symbols... 6
5 Evaluation of welds ... 6
Annex A ... 18
This Standard is identical to international standard ISO 5817.1992 “Arc-welded joints in steel - Guidance on quality levels for imperfections”.
Annex A of this Standard is informative.
This Standard was proposed by China Machinery Industry Federation.
This Standard shall be under the jurisdiction of National Technical Committee on Welding of Standardization Administration of China.
The drafting organization of this Standard. Harbin Welding Institute.
Main drafter of this Standard. Piao Dongguang.
Arc-welded joints in steel - Guidance on quality
levels for imperfections
1 Scope
This Standard provides guidance on levels of imperfections in arc-welded joints in steel. The levels refer to production quality and not to the fitness-for-purpose (see 3.1) of the product manufactured.
This Standard applies to
- the following welding processes and their defined sub-processes in
accordance with GB/T 5185.
11 metal-arc welding without gas protection;
12 submerged-arc welding;
13 gas-shielded metal-arc welding;
14 gas-shielded welding with non-consumable electrode;
15 plasma arc welding;
- manual, mechanized and automatic processes;
- all welding positions;
- butt welds, fillet welds and branch connections;
- materials in the thickness range 3 mm to 63 mm.
Metallurgical aspects, e.g. grain size, hardness, are not covered by this Standard.
2 Normative references
The following standards contain the provisions which, through reference in this Standard, constitute the provisions of this Standard. For dated references, subsequent amendments (excluding corrections) or revisions do not apply to this Standard. However, the parties who enter into agreement based on this Standard are encouraged to investigate whether the latest versions of these documents are applicable. For undated reference documents, the latest
versions apply to this Standard.
GB/T 324 Weld symbolic representation on drawings (eqv ISO 2553)
GB/T 3375 Welding terminology
GB/T 5185 Welding and allied processes - Nomenclature of processes and
reference numbers (eqv ISO 4063)
GB/T 6417 Classification and explanation of imperfections in fusion welded joints (eqv ISO 6520)
3 Terms and definitions
For the purposes of this Standard, the following terms and definitions apply. 3.1 fitness-for-purpose
a product is fit for its intended purpose when it functions satisfactorily in service during its stipulated lifetime.
3.2 weld thickness
3.2.1 fillet weld thickness (nominal throat thickness), a
height of the largest isosceles triangle that can be inscribed in the weld section 3.2.2 butt weld thickness, s
minimum distance from the surface of the part to the bottom of the penetration, which cannot be greater than the thickness of the thinner of the parts
3.3 short imperfection
one or more imperfections of total length not greater than 25 mm in any 100 mm length of the weld or a maximum of 25 % of the weld length for a weld shorter than 100 mm
3.4 long imperfection
one or more imperfections of total length greater than 25 mm in any 100 mm length of the weld or a minimum of 25 % of the weld length for a weld shorter than 100 mm
3.5 projected area
Table 1 (continued)
No. Imperfection designation
GB/T 6417
reference Remarks
Limits for imperfections for quality levels
4 Localized
2013 The total pore area within the cluster should be summed and
calculated as a percentage of the greater of the two areas. an
envelope surrounding all the pores or a circle with a diameter
corresponding to the weld width.
The permitted porous area should be local. The possibility of
masking other imperfections should be taken into consideration.
The following conditions and limits for imperfections shall be
a) Maximum dimension of he summation of the projected or surface
crack area of the imperfection
8% 4%
b) Maximum dimension of a single pore for
- butt welds
- fillet welds
d ≤ 0.5 s
d ≤ 0.5 a
d ≤ 0.4 s
d ≤ 0.4 a
d ≤ 0.3 s
d ≤ 0.3 a
c) Maximum dimension for localized clustered porosity 4 mm 3 mm 2 mm
5 Elongated
Long imperfections for
- butt welds
- fillet welds
h ≤ 0.5 s
h ≤ 0.5 a
In any case, maximum dimension for elongated cavities,
2 mm
Annex A
Additional information and guidelines for use of this Standard
This Standard specifies requirements for three levels of acceptance for imperfections in welded joints of steel for arc welding processes according to the scope. It may be used - where applicable - for other fusion welding processes or weld thicknesses.
Different parts are very often produced for different applications but to similar requirements. The same requirements should, however, apply to identical parts produced in different workshops to ensure that work is carried out using the same criteria. The consistent application of this International Standard is one of the fundamental cornerstones of a quality assurance system for use in the production of welded structures.
Multiple imperfections show a theoretical possibility of superimposed individual imperfections. In such a case the total summation of all permitted deviations should be restricted by the stipulated values for the different quality levels. However, the value of a single imperfection may exceed for a single pore. This Standard may be used in conjunction with a catalogue of realistic
illustrations showing the size of the permissible imperfections for the various acceptance levels by means of photographs showing the face and root side and/or reproductions of radiographs and of photomacrographs showing the cross-section of the weld. Reference Radiographs for Weld Imperfection
Assessment Based on ISO 5817 issued by International Institute of Welding (IIW) is one of the catalogues that may be used with reference cards to assess the various imperfections and may be employed when opinions differ as to the permissible size of imperfections.

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