Overview
EN ISO 15749-2:2004 - Ships and marine technology - Drainage systems on ships and marine structures - Part 2: Sanitary drainage, drain piping for gravity system - specifies requirements for the design of sanitary drain lines using gravity drainage on ships and marine structures. It covers acceptable pipe materials and dimensions, routing and gradients, nominal bore sizing based on wastewater flow, cleaning and odour-control provisions, and interfaces with collector tanks or sewage treatment plants. For planning and basic requirements, see ISO 15749-1; for sewage disposal lines downstream of treatment, see ISO 15749-4.
Key topics and requirements
- Scope: Design of sanitary drain lines in gravity systems that convey wastewater by gravity to a collector tank or sewage treatment plant.
- Operating pressure: Sanitary drain and vent pipes shall be designed so internal pressure does not exceed 0.5 bar.
- Approved pipe materials:
- Steel (seamless, welded, threaded)
- CuNiFe alloys (CuNi10Fe1.6Mn)
- Spigot-and-socket steel or CuNiFe pipes
- PVC-U (subject to IMO Resolution A.753 approval for plastic pipes)
- Nominal bores (NB): Sizes and permitted materials are listed (common NBs include 32, 40, 50, 65, 80, 100, 125, 150). Branch and collecting pipe sizes are determined from flow-rate tables.
- Flow-rate sizing: Nominal bores are calculated from standard flow rates for single branches (e.g., water closet ≈ 2.5 l/s → NB 100; urinal ≈ 0.5 l/s → NB 32–50). Collecting branches and gravity delivery lines use sum-flow tables to select NB.
- Routing and gradient:
- Drain lines must be self-draining; branch gradients typically from 1:100 to 1:66.7, main sewers 1:66.7 to 1:50.
- Branches should be short; wastewater from midships should discharge at least one deck height down to both sides or center.
- Operational features:
- All sanitary fixtures and floor drains require odour seals.
- Cleaning openings are mandatory where sections cannot otherwise be cleaned, notably in galleys and water-closet runs.
- Testing and operation: Acceptance and leakage testing follow ISO 15749-1 procedures.
Applications and practical value
- Use this standard when designing or installing sanitary gravity drainage on:
- Commercial ships, ferries, offshore platforms, and other marine structures
- Newbuild plumbing systems, refits, and upgrades
- Integration with collector tanks and onboard sewage treatment plants
- Practical benefits include consistent pipe selection, reliable self-draining layouts, compliance with classification societies, and safer sewage handling aboard vessels.
Who should use this standard
- Marine and naval architects
- Shipbuilders and shipyards
- Marine engineers and piping designers
- Classification societies and surveyors
- Ship operators, shipboard maintenance teams, and regulatory compliance specialists
Related standards
- ISO 15749-1 - Sanitary drainage-system design (planning/basic requirements)
- ISO 15749-4 - Sewage disposal pipes (post-treatment discharge)
- IMO Resolution A.753 - Approval guidelines for plastic pipes on ships
Keywords: EN ISO 15749-2:2004, sanitary drainage, gravity drainage, drain piping, ships, marine structures, collector tank, sewage treatment plant, PVC-U, CuNiFe, steel pipes, nominal bore.
