Study of requirements for safe air lines

Status:

completed 02/2021

Aims:

In recent years, the Expert Committee Woodworking and Metalworking (Fachbereich Holz und Metall, FBHM) has repeatedly received reports of burst compressed air lines (hoses and plastic pipes) and injuries, e.g. blast injuries. The topic was considered by the expert committee to be a topical prevention issue. The aim was to prevent such incidents occurring in future as far as possible by providing information for companies. The pipes/hoses are used on pneumatically controlled machinery, for the supply of power in the form of compressed air to mobile and stationary machines (tools), and in the supply lines of power drives (cylinders).

The FBHM intended to publish a Fachbereich Aktuell article on the subject of pneumatic pipes/hoses. The aim was to provide users, operators and designers of pneumatic systems and machines with guidance on selecting and using pneumatic pipes/hoses. An analysis and study by the IFA of the requirements to be met by safe pneumatic pipes/hoses was to serve as the basis for the information sheet.

Activities/Methods:

During analysis and study of safety requirements for pneumatic pipes/hoses, the German Ordinance on industrial safety and health (BetrSichV) was considered with regard to relevant tests. Functional and – in particular – safety requirements and criteria from standards governing hose material, hose assemblies and connection arrangements were also examined. Manufacturers of hose assemblies and connection elements were consulted regarding their experience with hose assemblies and problems arising in the field. This revealed differences in fields of application, interpretations of terms, and requirements. By means of surveys conducted at the expert meeting on machine and equipment safety held at the Institute for Occupational Safety and Health of the German Social Accident Insurance (IFA) and personal contacts with experts, information was gathered on the incidence of accidents caused by burst compressed air lines within the scope of the German Social Accident Insurance Institutions. The principal conducted a search in accessible accident reports to identify injuries and adverse health effects caused by burst or detached hoses, pipes and compressed air lines. Test recommendations for hydraulic hose assemblies which are derived from the requirements of the German Ordinance on Industrial Safety and Health (BetrSichV), and have already been summarized in an issue of the Fachbereich Aktuell series of publications were also examined with regard to their suitability for transfer and adaptation to pneumatics.

Results:

A typical accident scenario caused by the failure of pneumatic lines resulting in serious injuries or health impairments such as blast injuries was not identified. This was the case both for the dialogue with the accident insurance institutions at the expert discussion on machine and equipment safety, and for the searches and contacts with experts conducted by the principal.

Technical requirements concerning pipes/hoses and their connection elements are already set out in standards, but have not yet been widely applied by manufacturers of pneumatic pipes/hoses and connection elements. The BetrSichV obliges employers to provide their employees with safe work equipment. This therefore also applies in the context of pneumatic pipes/hoses.

The results of the project activities were summarized in a draft edition of the Fachbereich Aktuell series of publications. References to normative requirements and to the statutory basis for tests required for certain applications and situations were compiled and can be found in the draft. This resulted in detailed test requirements, for example for a visual and functional test to be performed prior to commissioning of a machine or device that is supplied with compressed air. Criteria for recurring or non-recurring tests of compressed air lines were set out and the scope of testing was described. Guidance on the selection and installation of pipes/hoses was presented in detail. For the draft, factors influencing the test intervals for pipes/hoses and the intervals for replacement were also presented. Application of the recommendations by companies, designers and OSH professionals and during maintenance is expected to make a positive contribution to occupational safety and health.

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