GB/T 19418-2003Arc-welded joints in steel -- Guidance on quality levels for imperfections (English PDF)

Foreword

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.

4 Localized

(clustered)

porosity

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

fulfilled.

a) Maximum dimension of he summation of the projected or surface

crack area of the imperfection

16%

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

cavities,

wormholes

Long imperfections for

- butt welds

- fillet welds

h <= 0.5 s

h <= 0.5 a

In any case, maximum dimension for elongated cavities,

wormholes

2 mm

Not

permitted

Not

permitted

Annex A

(Informative)

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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