M64 – Design of integrated cargo and ballast systems on tankers

APPLICATION FIELD

IACS UR M64, “Design of integrated cargo and ballast systems on tankers,”

This rule is for tankers where cargo oil pumps, cargo piping, and ballast piping are arranged to share common equipment.

This kind of integrated arrangement typically appears on tankers that aren’t required to carry the full segregated ballast tank (SBT) piping duplication mandated by MARPOL Annex I apply for crude and product carriers.

In particulat, it apply for smaller tankers operating under a clean ballast tank (CBT) or crude oil washing (COW) arrangement, where using the same pumps and piping for both cargo and ballast duty, with appropriate safeguards, is permitted rather than requiring a second, fully separate ballast system.

M64 governs the piping design consequences of choosing that integrated arrangement rather than the fully segregated one.

PIPE CLASS / SYSTEM TYPE

M64 doesn’t classify pipes under P2.2. it’s a machinery/system-design UR, not a piping classification rule.

The cargo and ballast piping involved is still classified and constructed under P1/P2 in the ordinary way (cargo oil piping typically Class III, ballast piping typically Class II or III depending on where it runs).

What M64 adds is a system-design layout clarification: because the same physical piping and pump equipment is being asked to carry both cargo oil and ballast water at different times, the rule addresses how that switch-over is achieved without contaminating ballast water with oil residue or vice versa, a concern that has nothing to do with pressure classification and everything to do with system segregation and changeover procedure.

RELATED RULES

• Direct sibling: UR P1/P2 govern the pipe strength, classification and construction of the cargo and ballast piping itself; M64 sits on top of that as a system-arrangement requirement specific to the integrated configuration.
• Statutory backdrop: MARPOL Annex I, particularly the regulations governing segregated ballast tanks and the conditions under which cargo pumps and piping may instead be used for ballast duty (the clean ballast tank framework), is the underlying international instrument that makes an integrated cargo/ballast system a permitted option in the first place for qualifying tankers.
• Cross-reference (as noted by IACS): UR F32, “Fire detecting system for unattended machinery spaces,” is flagged alongside M64, relevant where the pump room serving the integrated system operates unattended.
• Historical cross-reference: IACS’s own listing for M64 also flags E8 and F31  both of which have since been deleted or absorbed into other URs (E8’s content, for instance, was merged into what’s now UR M61 on starting arrangements). Anyone tracing these cross-references today should follow them to their current location rather than treat E8/F31 as live requirements in their own right.

DESCRIPTION

A fully segregated ballast system, the MARPOL default for larger tankers, sidesteps this problem entirely by never letting cargo oil and ballast water share a pump or a pipe, the two systems simply never touch.

An integrated system deliberately gives that separation up, usually for smaller tankers where duplicating the entire pumping and piping plant would be a significant cost and space issues relative to the risk involved, and where MARPOL itself permits the alternative arrangement. But giving up physical separation means the safety case shifts entirely onto the changeover procedure and the piping arrangement that supports it a pump or pipe run that carried cargo oil an hour ago has to be verifiably clean before it’s trusted to handle ballast water that may ultimately be discharged to the sea, and the reverse has to hold true as well.

IMPORTANT NOTE

• Given the MARPOL backdrop, the core consequence of getting an integrated system’s segregation wrong isn’t a piping non-conformity, it’s the possibility of producing a pollution during the ballasting or de-ballasting, which is the specific pollution scenario the segregated ballast tank regime was designed to prevent in the first place; 

• The historical cross-references to E8 and F31 in IACS’s own listing are a useful reminder that older UR cross-references can go stale as the numbering scheme evolves, worth checking that any cited related requirement is still current before relying on it.