As you well know, any discharge of oil mixtures with oil content exceeding 15 ppm from the machinery space is prohibited into sea under the Regulations of MARPOL 73/78 Annex I. Furthermore, any ship of 10,000 tons gross tonnage and above shall be provided with arrangements for an alarm and for automatically stopping any discharge of oily mixture when the oil content in effluent exceeds 15 ppm. Therefore, it is not allowed that any discharge pipe is directly connected to overboard discharge line with by-pass from oily water separators. Even if there is no fixed direct discharge piping arrangement, it is, also, prohibited that the discharge piping is connected easily by means of rubber hoes or some portable pipes as a temporary arrangement. However, in case that there is a branch pipe on the overboard discharge line for the purpose of operation test of oily water separator and is not any connecting pipe at the discharge side of bilge pump, it is acceptable. It has been reported that ships with a temporary discharge arrangement were suspected of oil discharge into sea under the port state control and sustained heavy losses with detention.
You are kindly requested to check the discharge arrangements in your fleet. In case where you find suspected arrangements with connection such as rubber hoses or portable pipes to overboard discharge, please dismantle branch pipes on discharge line permanently and/or fix blind flanges by welding in order to avoid unexpected suspicion by PSC.
In this connection, we have instructed all surveyors to examine carefully the piping arrangement of the discharge system at each classification survey, every periodical class and IOPP surveys. If the attending surveyors find temporary discharge arrangements at surveys, they will instruct you to deal with this matter by permanent measures.
We would very much appreciate your cooperation with us at every survey.
If you have any question, please don't hesitate to contact us.


Department in charge : Survey Department
Tel:+81 3 5226 2027 Fax:+81 3 5226 2029
e-mail : svd@classnk.or.jp
Attached : Sample of discharge arrangement