Drainage – Machinery Space

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Key Legislation:

For more detail on the Legislation relevant to this page, please use the following links:
Supporting Legislation:
Definition of Machinery Space Drainage: Machinery space drainage can be defined as any drainage not associated with the oil and gas production process, i.e. hazardous and non-hazardous drains would generally fall outside this definition (see Hazardous and Non-Hazardous Drains). Examples of machinery space drainage will include FPSO and vessel/MODU bilges, etc.
Consent Needed: Consent is needed for a United Kingdom Oil Pollution Prevention Certificate (UKOPP) or IOPP Certificate for a foreign flagship unit.Note: Offshore installations may obtain a temporary exemption from the requirements to have a UKOPP certificate under an informal agreement between Oil & Gas UK and the MCA. These exemptions are based on the grounds of cost and technical difficulties versus the small amounts of machinery space discharge involved pending MCA review leading to a more formal and final arrangement. New installations will need to demonstrate their “equivalence” to other offshore installations where temporary exemptions are being issued. Any new installations seeking to obtain a UKOPP certificate is unlikely to satisfy the certifying body unless they fully comply with the requirements.Hazardous and non-hazardous drainage that is not machinery space drainage (i.e. oily drainage resulting from process operations) is covered by the OPPC Regulations (see OPPC Summary Table and Hazardous/Non-Hazardous Drainage for more information).If all drainage (including any minor machinery space drainage) is treated via the hazardous and non-hazardous drainage system that deals with all the process drainage, it is expected that this will fall under the OPPC Regulations and require an OPPC permit rather than a UKOPP certificate (see Hazardous and Non-Hazardous Drains).
How to Apply: For a first certificate for UKCS registered MODUs, the operator must request Maritime and Coastguard Agency (MCA) to conduct survey of oily water drainage and treatment systems; MCA then issue the certificate. For renewal of certificate, the operator must request Classification Societies to re-survey the machinery space drainage and treatment systems; Classification Societies then renew the certificate.
Who to Apply to: The first certificate will be issued by the Maritime and Coastguard Agency (MCA website). Thereafter, certificate is renewed by the Classification Societies.
When to Apply: Once the unit is commissioned for first certificate, renewed every 5 years.
Limits Placed on Discharging of Machinery Space Drainage:

The North West European waters have been designated as a Special Area under Annex I of MARPOL. Within North West European waters ships of 400 GT or above (including MODUs) are permitted to discharge processed water (i.e. Oily Drainage Water) from machinery spaces as long as the following conditions are satisfied:

  • The water does not originate from the cargo pump room bilges
  • The water is not mixed with cargo oil residues
  • The ship is proceeding on a voyage
  • The oil content of the effluent, without dilution, does not exceed 15 ppm of the mixture
  • The ship has in-operation oil filtering, oil content measuring equipment and alarm devices of a design approved in accordance with the “Guidelines and Specifications for Pollution Prevention Equipment for Machinery Space Bilges of Ships”
  • The oil filtering system is equipped with a stopping device which will ensure that the discharge is automatically stopped if the oil content of the effluent exceeds 15 ppm of the mixture

With respect to MODUs, the requirements of the regulations “shall be considered met” by the regulatory authority “if the discharge of processed bilge water from machinery spaces is undertaken when there is a positive water movement past the installation, i.e. at times of the day when the tidal flow is at its greatest, and provided there is no visible sheen”.
Oily Water Discharges: Record all discharges, together with date, time and method of discharge, disposal route, any system failures and accidental oil spills, in the Oil Record Book.
What to Report: Regular reporting is not required, although backdated entries in the Oil Record Book must be maintained for at least 3 years. Inspections will be undertaken periodically to ensure compliance.
Who to Report to:
When to Report:
Non Compliance: Non compliance would constitute a breach of United Kingdom/International Oil Pollution Prevention Certificates requirements and might be a discharge of drainage water at more than 15 ppm or failure to properly keep the Oil Record Book. If a discharge outside of legal requirements is made then it should be recorded in the Oil Record Book which must be kept available for inspection.
Certificate Renewal: Certificate must be renewed every 5 years, following inspection by the Classification Societies.
Oil Record Book: MCA Marine Information Notice (MIN) 400: MARPOL – Amendments to Annex I: Effect on the Oil Record Book Parts I and II (PDF document)The form of the Oil Record Book Parts I and II that must be used should be compliant and in accordance with that detailed in MARPOL (consolidated edition 2006) Annex I, Appendix III: Form of the Oil Record Book.Shipowners/Ship Managers/Masters must have the correct edition of Oil Record Book Parts I and II on board and in use from January 2011. This version must be used from that date.