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About OCNS

The Offshore Chemical Notification Scheme (OCNS) applies to all chemicals used in the exploration, exploitation and associated offshore processing of petroleum on the UK Continental Shelf.

It incorporates "operational" chemicals/products* which, through their mode of use, are expected in some proportion to be discharged. This includes rig washes, pipe dopes, jacking greases and hydraulic fluids used to control wellheads and blow-out preventers.

As well as those chemicals used in the actual production of hydrocarbons, those generated offshore (such as sodium hypochlorite) must also be notified.

Default product templates for these types of chemicals are available in our Downloads section.

* The word "chemicals" when used subsequently refers to fully formulated products used offshore, whether these are comprised of one or more distinct chemical substances. 

Chemicals not covered

The scheme does not apply to chemicals that might otherwise be used on a ship, helicopter or other offshore structure. Products used solely within domestic accommodation areas - such as additives to potable water systems, paints and other coatings, fuels, lubricants, fire-fighting foams, hydraulic fluids used in cranes and other machinery - are also exempt.

If there is any doubt about whether or not a chemical should be included in a UK risk assessment, then operators are advised to consult the UK's Department of Energy and Climate Change or Cefas. All queries regarding risk assessment in the Netherlands should be directed to State Supervision of Mines.

How does the process work?

Our OCNS team conduct work for both the UK and the Netherlands, using the Chemical Hazard and Risk Management (CHARM) model  as the primary tool to rank offshore chemicals according to their calculated Hazard Quotients (the ratio of Predicted Environmental Concentration (PEC) to Predicted No Effect Concentration (PNEC)).

Inorganic chemicals and organic chemicals with functions for which the CHARM model has no algorithms are ranked using the Cefas OCNS hazard groups.

All products currently registered by Cefas for either the Netherlands or the UK are presented on the ranked lists. The lists use a banding system to rank organic chemicals of similar function according to the Hazard Quotients.

The minimum data set of actual values and the parameters used by Cefas to calculate them will be disclosed to chemical suppliers on "templates". The supplier may then pass these on to operators to enable the calculation of site-specific risk assessments for any chemicals they may want to use. Some chemicals are generated/used in situ on offshore installations, e.g. sodium hypochlorite, and don't fall under the remit of any one supplier. Templates for such chemicals are available in our downloads section.

Once classified, a product will typically remain on the List of Notified Chemicals for three years after which it becomes due for re-certification. However, products being used for a field trial or those containing substances recommended for substitution may have a shorter validity. When products are due for re-certification, a full Harmonised Offshore Chemical Notification Format (HOCNF) registration form and SDS must be resubmitted.

Web links for OSPAR, the relevant regulators, Marine Scotland and others may be found in our Downloads section.

© Crown Copyright 2015
Last Modified: 27 April 2014