Dedicated sea water ballast tanks shall have an efficient corrosion prevention system in accordance with SOLAS Chapter II-1/3-2 and IMO Resolution MSC.215(82): Performance Standard for Protective Coat-ings (PSPC) for Dedicated Seawater Ballast Tanks in All Types of Ships and Double-Side Skin Spaces of Bulk Carriers. Any maintenance or repair of the applied coating system shall be documented and added on the technical coating file onboard vessel. The CTF file is a subject for annual inspection scope. //DNV-RU-SHIP Pt.3 Ch.3 4.1 and Pt.7.Ch.1.4

All ballast tanks shall be connected to at least two drainage pumps. Ballast pumps are required to have product certificates. Control and monitoring system for valves and pumps, together with the sea discharge connection to the shell are subjects for class approval. //DNV-RU-SHIP Pt.4 Ch.6 Sec.1 and Pt.4 Ch.6 Sec.4

Air pipes for ballast tanks shall be at least one pipe size bigger than filling pipes. I.e., the sectional area of air pipes shall be at least 25% bigger than on filling pipes to avoid structural damage in case of overfilling the tanks. Automatic stop of ballast pumps at high level alarm or automatic closing of ballast filling line may be accepted as an alternative solution. //DNV-RU-SHIP Pt.4 Ch.6 Sec.8

Ballast pipes shall be of pipe class II or III depending of the location and size of the pipe. The pipes and valve bodies fitted on ship’s side and bottom shall be of class II, i.e. material declaration and radiograph-ic testing of 10% of welding seams shall be documented. //DNV-RU-SHIP Pt.4 Ch.6 Sec.2 Pt.4 Ch.6 Sec.10
Two non-return valves in series shall be installed between sea and ballast system in compartments to avoid unintentional water ingress. The allowed piping thicknesses for steel pipes are defined in DNV-RU-SHIP Pt.4 Ch.6 Sec.9.1 Table 2. Due to the corrosive environment ballast pipes shall have a corrosion allowance. Fire redundance requirements and list of allowed mechanical joints can be found DNV-RU-SHIP Pt.4 Ch.6 Sec.9.5 Table 9. Inlet and overboard discharge pipes shall be joined by butt welding. //DNV-RU-SHIP Pt.4 Ch.6 Sec.7 and Pt.4 Ch.6 Sec.9

Fore peak tank (often used for ballast) may have one pipe penetration through collision bulkhead below bulkhead deck. A manually operable valve, which is operable from above the bulkhead deck shall be fitted directly on the bulkhead. The emergency operation location shall be accessible under all service conditions and cannot be a cargo space. The valve shall be of screw-down type. A butterfly valve, which is supported by a seat or flanges can be accepted on cargo vessels. Valves made of grey cast iron or similar materials are not accepted. //DNV-RU-SHIP Pt.4 Ch.6 Sec.3.1.4

Last modified: Thursday, 4 May 2023, 4:05 PM