only if, when properly installed and maintained and used for their intended purpose, they do not endanger the health and safety of persons and, where appropriate, domestic animals or property.Directive 97/23/EC
1. Member States shall take all appropriate measures to ensure that the pressure equipment and the assemblies referred to in Article 1 may be placed on the market and put into service only if, when properly installed and maintained and used for their intended purpose, they do not endanger the health and safety of persons and, where appropriate, domestic animals or property.
2. The provisions of this Directive shall not affect Member States entitlement to lay down, with due regard to the provisions of the Treaty, such requirements as they, may deem necessary to ensure that persons and, in particular, workers are protected during use of the pressure equipment or assemblies in question provided that this does not mean modifications to such equipment or assemblies in a way not specified in this Directive.
3. At trade fairs, exhibitions, demonstrations, etc., Member States shall not prevent the showing of pressure equipment or assemblies as defined in Article 1 not in conformity with the provisions of this Directive, provided that a visible sign clearly indicates their non-conformity and their non-availability for sale until brought into conformity by the manufacturer or by his authorized representative established within the Community. During demonstrations, appropriate safety measures shall be taken in accordance with any requirements laid down by the competent authority of the Member State concerned in order to ensure the safety of persons.