DGUV Information 209-071 - Safe maintenance of hydraulic systems (DGUV Informati...

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Annex 1
Annex 1
Safe maintenance of hydraulic systems (DGUV Information 209-071)

Anhangteil

Titel: Safe maintenance of hydraulic systems (DGUV Information 209-071)
Normgeber: Bund
Amtliche Abkürzung: DGUV Information 209-071
Gliederungs-Nr.: [keine Angabe]
Normtyp: Satzung

Annex 1

A
Troubleshooting

In hydraulic systems, a multitude of different errors can occur. The first step is to describe the error more precisely. (Trouble-shooting tree by using "General operating instructions 0/1" according to Bosch, version 1.0)

When the nature of the fault has been determined, the individual components are subject to a closer examination.

B
Notices on maintenance

(on the basis of the "General operating instructions 0/1" according to BOSCH, version 1.0, pages 63 ff.)

The safety notices listed in the following have to be observed at all times and carefully.

  • Conduct all maintenance works in due time, properly, and completely.

  • All employees have to be informed before starting any maintenance works.

  • The maintenance area has to be secured in a wide-ranging manner before starting any works.

  • Corresponding signs have to inform about maintenance works.

  • Signposts have to be attached to the control cabinet, the circuit breaker, actuators, and access in particular.

  • If the hydraulic assembly has to be switched off, it has to be secured against unintended re-closing by the following measures:

  • All drives have to be switched off and the hydraulic system has to be disconnected from the mains using the circuit breaker.

  • The pressure of the hydraulic assembly or component has to be reduced.

  • Possibly existing accumulators have to be depressurized.

  • The circuit breaker has to be secured against unscheduled re-closing.

Prior to every manual intervention on the hydraulic component:

All required details on depressurization and on the hydraulic components that are not depressurized automatically can be found in the corresponding operating instructions.

  • Cylinders have to be moved to the safe stop position.

  • All loads have to be lowered.

  • All pumps have to be turned off.

  • All vertical cylinders have to be supported mechanically against lowering. Maintenance works on lifted units must not be conducted without securing the units externally.

  • Existing accumulators have to be depressurized properly.

  • The pressure supply has to be switched off and the hydraulic assembly has to be secured against unscheduled re-closing.

  • It has to be ensured that only authorized personnel stays in the work area.

  • The required personal protection equipment has to be used.

  • The sections of the system and pressure lines to be opened have to cool down before starting any maintenance works.

  • Pressurized segments have to be opened slowly.

  • Due to check valves in the pressure lines above the pumps, the hydraulic system may still be under pressure after disconnecting it from the proper pressure supply. Some segments, e. g. servo cylinders, still remain pressurized due to the locked position of the proportional valves (the hydraulic scheme contains all valves in basic position).

  • Only new and tested components and spare parts identical in construction and lubricants in OEM quality are admissible for replacement/use. Installing used and untested components is strictly forbidden due to safety reasons.

  • During maintenance works which possibly require the removal of certain safeguarding equipment, machine movements must only be carried out with the utmost care. The safeguarding equipment has to be re-installed and tested for functionality before every commissioning procedure.

  • Welding, burning, or grinding works on the hydraulic aggregate or its superstructures must only be conducted upon approval of the local safety official and using appropriate protective covers against contaminations.

  • When conducting installation works above body height of the operator, dedicated climbing aids and work platforms have to be used. System parts must not be used as climbing aid.

  • Tools and devices required for the maintenance works have to be removed from the machine/system.

  • Leakages have to be remedied immediately at all times.

  • The personnel have to be informed about restarting the machine/system beforehand at all times.

C
Scope of visual inspection

(before initial and re-commissioning)

The following scope of testing is recommended:complied with?
-Does the hydraulic control system, including all connections of the individual parts, correspond to the hydraulic scheme and the system description? 
-Do the data given on the nameplate and in the operating instructions correspond to the data of the energies provided? 
-Are there main control units for all energies supplied? 
-Are there devices for reducing the energy (depressurization units)? 
-Have all measurement, venting, and bleeding points, as well as all parts been marked in accordance with the hydraulic circuit diagram? 
-Have the hydraulic valves used as "device for rescuing persons" been marked in accordance with the operating instructions? 
-Are monitoring devices for all safety-relevant system parameters (e. g. pressure, flow, temperature, oil level) installed and visible? 
-Have all actuators been marked practicably and can they be operated quickly, safely, and clearly (especially for manually controlled systems)? 
-Have the setting values on all adjustable hydraulic parts (e. g. pressure relief valves, throttle valves, pressure switches) been marked in accordance with the hydraulic circuit diagram? 
-Do all warning signs (especially for hydraulic accumulators and energy saved otherwise) exist? 
-Have all pipelines been selected and installed in accordance with the hydraulic circuit diagram and parts list and installed according to section 4.2? 
-Have all hose assemblies been selected, marked and installed in accordance with the hydraulic circuit diagram and parts list and installed according to section 4.3.4? 
-Have hose assemblies not been used in line areas with higher requirements (e. g. keeping a load elevated)? 
-Are hose assemblies, if required, equipped with an efficient protection against lashing and/or leakages of hydraulic fluids? 
-Have all safety devices been installed and do they comply with the system description? 
-Are planned emergency stop devices available? 
-Have the hydraulic accumulators used been subjected to an equipment and installation test (and further pressure equipment if required). 

D
Scope of testing of functional test

The following scope of testing is recommended:complied with?
-Have the setting values of all settable hydraulic parts been set in accordance with the labeling and have the settings been saved? 
-Does the hydraulic control system comply with the intended function and does this function correspond to the system description? 
-Do all safety circuits work in accordance with the system description? 
-Do all emergency stop devices work and do they work in accordance with the system description? 
-Is re-closing only possible after safety conditions are fulfilled? 
-Does the operation of the emergency stop devices not result in additional hazards and does their deactivation not result in automatic start? 
-Are there no hazards due to interaction with linked systems (locks)? 
-Do the control devices for starting and shutting down work in accordance with the system description? 
-Are all monitoring devices of the safety-relevant system parameters functional? 
-Are the devices for reducing still existing energy efficient and can they be used without any risks after disconnection from the energy supply? 
-Do switching the energy supply on and off, energy reductions, as well as failure and return of the energy not lead to hazards? 
-Does using the system as intended not result in extraordinarily high pressure surges or pressure boosts? 
-For testing any part of the hydraulic system with the maximum operating pressure that can be achieved under all intended applications:
  • Have no measurable leakages occurred?

  • Did all hydraulic parts withstand the pressure?

 
-Does the system temperature not exceed the thresholds specified in the system description? 
-Does all user information relevant for operating the hydraulic system in a safe manner exist (e. g. hydraulic circuit diagram, parts list, system description, drawings, operating/maintenance instructions, documents on hydraulic accumulators, safety data sheets on the hydraulic fluids used, etc.)? 

E
Scope of testing of safe provision and use

The following scope of testing is recommended:complied with?
-Do the operating and ambient conditions of the machine still comply with the intended use?
For this, the following has to be observed for example:
  • product type, cycle times, number of units

  • pressures, flows, and temperatures in the hydraulic system

  • hydraulic fluid(s) used

  • velocities/stopping times of the dangerous movements

  • moved/elevated masses

  • type of feeding and removal

  • installation location

  • external influences (e. g. vibrations, moisture, contaminations, mechanical influences, ambient temperature, etc.)

  • position of the transport paths and type of means of transportation

  • space and access for operation and maintenance

  • arrangement and attachment of accessories

  • interaction with other machines

 
-Is the user information of the manufacturer still complete and existing? 
-Are all safeguarding devices mentioned in the user information still existing and installed? 
-Do all safety devices work in accordance with the system description, e. g.
  • safety distances (especially after changing the application conditions),

  • secondary protective measures (especially after changing the application and ambient conditions)?

 
-Are the provided emergency stop devices existing and efficient and does the effect correspond to the system description? 
-Is restarting only possible after restoring the safe condition? 
-Does the operation of the emergency stop devices not result in additional hazards and does their deactivation not result in automatic start? 
-Are there no hazards due to interaction with linked systems (locks)? 
-Do the control devices for starting and shutting down work in accordance with the system description? 
-Have the setting values of all settable hydraulic parts (e. g. pressure relief valves, throttle valves, pressure switches) been set in accordance with the specifications and have the settings been saved? 
-Are all monitoring devices of the safety-relevant system parameters functional (e. g. pressure, flow, temperature, oil level)? 
-Are all signposts and warning signs, as well as labels on parts, lines, measurement points, connection openings, depressurization devices, or the like still existing and can these be read? 
-Do all depressurization and shut-off devices, including their devices against unauthorized re-closing, work as intended? 
-Do the hose assemblies used show none of the deficiencies mentioned in section 4.3.5? In case of detected deficiencies section 4.3.6 has to be followed 
-Are the protective measures against lashing and/or leakages of hydraulic fluids on the relevant hose assemblies still existing or are they installed? 
-Have the periods for recurring tests on the pressure devices used (hydraulic accumulators) been adhered to? If required, these have to be conducted or arranged by the operator. 
-Have the maintenance intervals been adhered to and has the lifetime of wearing parts been considered as recommended by the manufacturer? 
-Have the recommended replacement intervals for the hydraulic fluid, as well as the measures for maintaining the purity class been observed? 
-In case of modifications to the machine and in the hydraulic system (control system and equipment), as well as after more complex maintenance works, especially if pipes had to be re-routed, the test extent has to be expanded reasonably as for new systems in accordance with section 7.2, e. g.:
  • design and function of the hydraulic control system

  • pressure surge, pressure boosts

  • pressure test

  • maximum system temperature and noise level

  • energy supply (switching on and off, reduction, failure and return)

  • selection and installation of additional and newly installed pipelines and hose assemblies

 
-Have all changes been identified and have these been incorporated into the documentation of the machine? 

F
Involvement of staff members

From the German accident prevention regulation "Basic principles of prevention" (BGV A1)

General support obligations and behavior

§ 15 (1) In accordance with their possibilities, as well as according to the instructions and orders of the entrepreneur the insured are obliged to provide for their safety and health at work, as well as for the safety and health of those affected by their actions or omissions. The insured have to support the measures for preventing occupational accidents, occupational diseases, and work-related health risks, as well as for an efficient first aid. Insured have to follow the corresponding instructions of the entrepreneur. The insured must not follow orders that are obviously directed against safety and health.

(2) Insured must not induce a condition by consuming alcohol, drugs, or other intoxicating agents due to which they could endanger themselves and others.

(3) Section (2) is also applicable to taking medicaments.

Special support obligations

§ 16 (1) The insured have to report any identified direct substantial hazards for safety and health, as well as any defects regarding the safeguarding measures and protection systems immediately to the entrepreneur or the responsible supervisor. Without prejudice to this obligation the insured should also report identified hazards for safety and health and deficiencies regarding safeguarding measures and protection system to the specialist for occupational safety, the company doctor, or the safety official.

(2) If an insured notices that regarding the prevention of occupational accidents, occupational diseases, or work-related health hazards

  • work equipment or other devices show deficiencies,

  • substances are not packaged, marked, or composed properly or

  • a work procedure is deficient,

he has to remedy the deficiencies immediately as far as this is part of his job and if he is authorized to do so. Otherwise, he has to report the deficiency to the superior immediately.

Using facilities, work equipment and substances

§ 17 Insured have to use facilities, work equipment, and substances, as well as safeguarding measures as intended and within the framework of the jobs assigned to them.

Access and remaining prohibitions

§ 18 Insured must only remain at dangerous spots within the framework of the jobs assigned to them.