What is DIN EN 729/1-3?

Answer 1

It's a German metal standard. It's the equivalent to ISO 3834.

Answer 2

EN 729-1:1995 Quality requirements for welding. Fusion welding of metallic materials. Guidelines for selection and use .
EN 729-2:1995 Quality requirements for welding. Fusion welding of metallic materials. Comprehensive quality requirements .
EN 729-3:1995 Quality requirements for welding. Fusion welding of metallic materials. Standard quality requirements .
EN 729-4:1995 Quality requirements for welding. Fusion welding of metallic materials. Elementary quality requirements .

PLEASE REFER:
http://www.iso3834.co.uk/

(ISO 3834 is the international standard which sets out requirements for manufacturers to meet in order to apply good practice in their welding operations.
Welding is a special process in that completed welds cannot be inspected with sufficient confidence to ensure all imperfections that could cause premature failure are absent. Welding is used in the manufacture in a very wide range of equipment and structures and in many of these, premature failure can be catastrophic with significant injury and cost.

ISO 3834 is not a product standard but it is called up in some product standards in order to ensure good practice when welding is performed so that the risks of premature failure are minimised.

In order to satisfy ISO 3834, a manufacturer must adopt a number of measures in order to provide the controls needed. These measures include verifying welder skills, preparing and qualifying welding procedure specifications and employing or having access to people with knowledge and experience for the type of products manufactured.

ISO 3834 is not a quality management system but it can be used with QMS standards such as ISO 9001: 2000 in order for a manufacturer to demonstrate his manufacturing competence.

ISO 3834 is concerned primarily with welding and the associated manufacturing processes such as cutting, post weld heat treatment, inspection and non destructive testing.

ISO 3834 can be used on its own but it is strengthened if it is supported by some of the elements in a quality management system such as document control, provision of resources, internal audit, corrective action and management review.)