NDL valve interlocks Process Interlocking

The NDL valve interlock fits any type of 90 degree valve, such as ball valves, butterfly valves and plug valves. Keys are only released in fully open or fully closed position. A new stainless steel, sliding lever replaces the original valve lever. No periodic maintenance is required.

Valve interlock for ninety degree valves

The NDL fits any type of 90 degree valve, such as ball valves, butterfly valves and plug valves

NDL valve interlock features

  • Permanently mounted on the valve
  • No grease or other lubrication required
  • Ingress protection of key slots by self sealing weather strips
  • Single key in lock, in open or locked closed position
  • Double key lock, in open or locked closed position
  • Minimum of components to make internal mechanism less vulnerable
  • Second safety; integrated second safety to prevent unlocking with an unauthorized object other than the designated linear key

Valve interlock for pig launching and receiving


  • No alterations to host valve required
  • Custom made bracket and adaptor for mounting to the valve
  • Original nut is used if possible
  • Can be mounted in a live plant

The NDL can be mounted on each size of valve, however to a maximum stem diameter of 40 mm. Above that size, a customized interlock is provided. For valves with a lever above 730 mm a gearbox is recommended.

Total linear concept

Netherlocks has eliminated nearly all rotating movements from the lock designs. Keys are inserted linearly and the internal locking mechanism consists only of linear moving components. This reduces internal wear and tear and makes the mechanism less vulnerable for dirt and and. Lubrication with grease is not required.

  • No wear and tear
  • No grease
  • Less vulnerable to sand and dirt

Valve interlocks for ninety degree valves


  • Linear keys
  • Uniquely coded
  • Key codes are registered, for easy replacement and to avoid use of duplicate keys
  • Spare keys available
  • Master keys available
  • Coloured tagplates

Download Netherlocks NDL valve interlock product sheet (includes exploded view and GA drawings)