NRB - Not Required Back
An NRB is, in a nutshell, an oil worker who is 'Not Required Back' onto a Platform having incurred the displeasure of a core crew worker there. A permanent record detailing the name of the NRB'd individual will be made and held in company records. That person will be black-balled from ever working on board the platform again. In extreme cases involving deliberate sabotage or loss of life the NRB could be enforced on all offshore platforms in the North Sea. This is almost unheard of though, partly because the other installations are under different company's control.
The NRB usually does not affect core-crew workers. They are almost always under contract and tend to have more official disciplinary channels.
There are two schools of thought on the NRB system. One holds that it serves as a hard and effective yardstick to prevent bullys, dangerous workers and potential sociopaths from upsetting and disrupting the workforce as well as the platform itself. This is no small consideration. On board an offshore platform there are no police nearby to step in nor any fast exits apart from overboard. Having a malignant presence on board stirring up trouble is the last thing anyone wants and an NRB can nip such things in the bud. In addition it acts as a powerful means of deterring such behaviour in the first place knowing the NRB is in place.
Sometimes the individual can appeal verbally or in writing against the NRB and have it dismissed. Other times the NRB could be removed after a set period of time.
The other school of thought holds that the NRB system is wide open to abuse and heavy-handedness by a platforms core-crew supervisors and crew. A classic example is an oil worker could arrive on a platform. His work may be at the standard required but a clash of personality could ensure with a senior worker on board.
This controversial NRB measure was mentioned at Parliament by an MP in 2008. The consensus seemed to be there the NRB system is wrong / unfair and needs to stop.
However an oil company who operates an board an oil / gas platform may now officially deny NRB's exist and pay lip-service to this consensus. Yet will simply change the term to other, more acceptable, variants. 'No more work' being one. 'Down-manned' being a classic; Vague, neutral and considered a'catch-all'.