Assembly instructions for cutting ring / compression fitting

Hydraulic lines are capable of causing serious personal injury and environmental damage, but this danger is very often underestimated in practice. Incorrect assembly or improper use of threaded connectors, pipes, and accessories can compromise the product‘s functional reliability, causing it to fail and possibly pose a threat to people and equipment. In extreme cases, violently spraying oil and ruptured lines can even cause fatal injuries.
We therefore recommend most strongly that these assembly instructions must be strictly followed!

Machinery manufacturers and operators must also fulfill additional obligations.
They are responsible for:


  • ensuring that pipelines and threaded connections are used in compliance with the    respective specifications
  • guaranteeing scheduled monitoring and systematic inspections by authorised personnel with the appropriate qualification and knowledge of hose line equipment
  • detecting and eliminating defects

This active assumption of responsibility is attended in the legal framework. Based on the principles of industrial safety, the equipment and product safety act, the machine and pressure device directive and the ordinance on industrial safety and health, tasks are specified further and set out in procedural regulations for those concerned.

This guide supplements the pertinent standards, guidelines and regulations. It also reflects the current state of the art.  No claims are made regarding completeness.

NOTE: All tools and materials must be checked before each assembly procedure to ensure that they are in good condition.

For complete cutting ring assembly in an assembly stud, always use assembly studs that have a corresponding depth dimension T!

Abb: Tiefenmaß
T mm ±0,05 T mm ±0,05
VOM NW04 HL 7,00 VOM NW03 HS 7,00
VOM NW06 HL 7,00 VOM NW04 HS 7,00
VOM NW08 HL 7,00 VOM NW06 HS 7,50
VOM NW10 HL 7,00 VOM NW08 HS 7,50
VOM NW13 HL 7,00 VOM NW10 HS 8,00
VOM NW16 HL 7,50 VOM NW13 HS 8,50
VOM NW20 HL 7,50 VOM NW16 HS 10,50
VOM NW25 HL 7,50 VOM NW20 HS 12,00
VOM NW32 HL 10,50 VOM NW25 HS 13,50
VOM NW40 HL 11,00 VOM NW32 HS 16,00

LL series tolerances match the tolerances of the L series.

  • Pipes must be cut to size at right angles ±0.5° before all pipe fitting operations. Pipe cutters or angle grinders may not be used for this.
  • Lightly deburr the insides and outsides of pipes.
  • After deburring, clean the pipes.
  • Use support bushes for thin-walled pipes.
  • Markings (position of the nut) make it easier to determine the number of turns for   path-dependent assembly.
  • If necessary, use appropriate spanner extensions.