Overview
ISO 15749-2:2004 - Ships and marine technology - Drainage systems on ships and marine structures - Part 2: Sanitary drainage, drain piping for gravity systems - specifies requirements for the design of sanitary drain lines that rely on gravity to convey wastewater to a collector tank or sewage treatment plant. It complements ISO 15749-1 (planning and basic requirements) and ties into later parts for sewage disposal. The standard covers allowable pipe materials, nominal bores, routing, gradients, testing and operation, and interface with collector tanks or sewage treatment plants.
Key topics and technical requirements
- Scope & application
- Applies specifically to sanitary drainage in gravity systems on ships and marine structures.
- Wastewater lines downstream of sewage treatment plants are handled by ISO 15749-4.
- Operating pressure
- Design requirement: internal operating pressure shall not exceed 0.5 bar.
- Permitted pipe materials
- Steel (seamless, welded, threaded), CuNiFe (CuNi10Fe1,6Mn), spigot-and-socket types, and PVC‑U (where allowed).
- Plastic pipes must be approved per IMO Resolution A.753 (18).
- Nominal bores & flow rates
- Nominal bore selection is flow-rate based; example: water closet ≈ 2.5 l/s → NB 100.
- Tables in the standard give sizes for single branches, collecting branches, gravity delivery lines and manifolds.
- Routing, gradients and layout
- Lines must be self‑draining with evenly distributed gradients. Typical gradients:
- Branch lines (except WCs): 1:100 to 1:66.7
- Water-closet branches, manifolds, mains: 1:66.7 to 1:50
- Branches should be short; mid-ship wastewater routed at least one deck downwards.
- Odour control and maintenance
- All sanitary items and floor drains must have an odour seal.
- Cleaning openings required where sections cannot be cleaned otherwise; mandatory for galleys and WCs.
- Collector tanks & treatment
- Tank sizing and holding times must consider ISO 15749-1 minimum volumes and trading-area requirements.
- Testing & operation
- Acceptance, leakage tests and operational instructions are referenced to ISO 15749-1.
Practical applications & users
Who uses ISO 15749-2:2004:
- Marine and naval architects, ship plumbing designers, and shipyards designing sanitary gravity drainage.
- Marine engineers and classification societies for approval and compliance checks.
- Ship operators and inspectors for retrofit, maintenance and testing procedures.
Practical uses:
- Selecting pipe material and nominal bore for sanitary branches and mains.
- Defining gradients, routing and cleaning access to ensure reliable gravity drainage.
- Integrating collector tanks and sewage treatment plant interfaces and ensuring regulatory compliance.
Related standards
- ISO 15749-1 (sanitary drainage-system design - planning & basic requirements)
- ISO 15749-3, -4, -5 (other parts covering vacuum systems, sewage disposal pipes, deck/cargo drainage)
- IMO Resolution A.753 (18) (plastic pipe approval)
- Relevant pipe standards cited (e.g., ISO 4200, ISO 65, ISO 9329-1, ISO 9330-1)
Open preview (PDF)Ships and marine technology — Drainage systems on ships and marine structures — Part 2: Sanitary drainage, drain piping for gravity systems
