Welding specifications

Criteria for the selection of the execution class for welds

 

The choice of the execution class to be used for the welds depends by different factors linked to the importance of the component and its destination.

A first criteria is reported in the table above about the correspondence between the norms EN 1090 and the EN ISO 5817.

A more detailed criteria is reported in the annex B of EN 1090 as specified hereafter.

 

It is based to the consequences that a failure of the analyzed component can produce in term of human lives, people, environment and social aspects.

 

These aspects are summarized by the following execution factors:

Consequence Class CC

 It identifies the consequence that a collapse of the structure could have.

Three classes are defined as in the following table.

 

Table B.0 - Consequence Classes

 

Consequence class

Description

Examples of buildings and civil engineering works

CC3

High consequences for loss of life, or very serious consequences in terms of economic, social or environmental

Stands for sports facilities, public buildings in which the consequences of collapse are high (for example, a concert hall)

CC2

Medium consequences for loss of life, significant consequences in terms of economic, social or environmental

Residential buildings and office buildings, public buildings in which the consequences of collapse are medium (for example an office building)

CC1

Low consequences for loss of life, and modest or negligible impact in economic, social or environmental

Agricultural buildings, where generally no one enters (for example, stores), greenhouses

 

Service Categories SC

 It defines the hazards connected with the use of the structure.

The service category may be determined on the basis of table below.

 

                                           Table B.1 - Suggested criteria for service categories

Categories

Categories Criteria

SC1

-   Structures and components designed for quasi static actions only (Example: Buildings)

-   Structures and components with their connections designed for seismic actions in regions with low seismic activity and in DCL*

-   Structures and components designed for fatigue actions from cranes (class S0)**

SC2

-   Structures and components designed for fatigue actions according to EN 1993. (Examples: Road and railway bridges, cranes (class S1 to S9)**, structures susceptible to vibrations induced by wind, crowd or rotating machinery)

-   Structures and components with their connections designed for seismic actions in regions with medium or high seismic activity and in DCM* and DCH*

* DCL, DCM, DCH: ductility classes according to EN 1998-1

** For classification of fatigue actions from cranes, see EN 1991-3 and EN 13001-1

 

A structure or part of a structure can contain components or structural details that belong to different service categories.

 

As general rule the SC1 is selected for static actions, while SC2 for fatigue actions.

 

Production Categories PC 

The production category may be determined on the basis of table below.

                                         Table B.2 - Suggested criteria for production categories
 

Categories

Categories Criteria

PC1

-    Non welded components manufactured from any steel grade products

-    Welded components manufactured from steel grade products below S355

PC2

-    Welded components manufactured from steel grade products from S355 and above

-    Components essential for structural integrity that are assembled by welding on construction site

-    Components with hot forming manufacturing or receiving thermic treatment during manufacturing

-    Components of CHS lattice girders requiring end profile cuts

 

A structure or part of a structure may contain components or structural details that belong to different

production categories.


How to determinate the execution class for a weld of specific component

 

The definitions the EXC for a structure (or one of its components) shall be done following the these steps:

 

1)     Select the Consequence Class (CCi; i = 1,2,3) from the Table B.0

2)     Select the Service Category (SCi; i = 1,2) from Table B.1

3)     Select the Production Category (PCi; i = 1,2) from Table B.2

4)     Define the Execution Class (PCi; i = 1,2,3,4)  from the Table B.3 below


Table B.3 - Recommended matrix for determination of execution classes
 

Consequence classes

CC1

CC2

CC3

Service categories

SC1

SC2

SC1

SC2

SC1

SC2

Production

categories

PC1

EXC1

EXC2

EXC2

EXC3

EXC3 *

EXC3 *

PC2

EXC2

EXC2

EXC2

EXC3

EXC3 *

EXC4

* EXC4 should be applied to special structures or structures with extreme consequences of a structural failure as required by national provisions.

 

Based from this table it is possible to select the type of welding needed for the selected application so to prescribe to correct EXC classification.