Overview
EN ISO 15749-3:2004 - Ships and marine technology - Drainage systems on ships and marine structures - Part 3: Sanitary drainage, drain piping for vacuum systems (ISO 15749-3:2004) is a technical standard adopted by CEN that specifies design requirements for sanitary drain lines in vacuum sewage systems used on ships and marine structures. It complements ISO 15749-1 (planning and basic requirements) and addresses materials, pipe dimensions, installation practice, testing and system layout for vacuum-operated sanitary drainage.
Key topics and requirements
- Scope and function: Covers design of drain lines that convey wastewater as sewage “plugs” by vacuum pressure to a collector tank or sewage treatment plant. Downstream pressure/disposal piping is covered in ISO 15749-4.
- Operating pressure: Typical absolute pressure range 0.4–0.7 bar (permissible negative pressure approx. −0.3 to −0.6 bar).
- Sanitary fixtures: Vacuum-operated water closets (approx. 1.2 l flush) and other sanitary items connected via vacuum valves are addressed.
- Pipe materials & nominal bores:
- Steel (seamless, welded, threaded) - NB 40, 50, 100 with specified OD and wall thickness.
- CuNiFe / CuNi10Fe1.6Mn and spigot/socket pipes - NB 40, 50.
- PVC‑U (IMO A.753 approval required for plastic on ships) - NB 40, 50.
- Fittings and valves: Components must be suitable for vacuum use; shut-off valves must provide smooth passage. Tightness testing referenced in Annex B.
- Laying and routing:
- Pipes may run in any direction but avoid frequent direction changes.
- Horizontal gradient ≈ 2:1 000 toward suction point.
- Water traps every ≤ 40 m before riser branches.
- Riser branches: max three vacuum toilets/valves per riser (same deck), riser length ≤ one deck (~3 m) unless manufacturer consents.
- Feeding angles to manifolds ≤ 45°; no tees or 90° elbows into manifolds.
- Bend radius ≥ 3 × outer diameter.
- Cleaning & maintenance: Cleaning openings and access (hex plugs, blank flanges, ball valves, molded PVC fittings) must be provided where cleaning otherwise impossible.
- System capacity & manifolds: Guidance on maximum numbers per branch and manifold sizing; main sewers for >6 manifolds should be NB 100.
Applications and users
This standard is essential for:
- Naval architects and ship designers planning sanitary vacuum drainage systems
- Marine mechanical/plumbing engineers and shipbuilders specifying piping and fittings
- Classification societies and shipyards evaluating conformity and safety
- Operators and ship maintenance teams implementing installation, testing, cleaning and commissioning procedures
- Suppliers of vacuum toilets, vacuum valves, collector tanks and sewage treatment plants
Keywords: EN ISO 15749-3:2004, vacuum drainage systems, sanitary drainage, ships, marine structures, drain piping, vacuum-operated water closet, PVC-U, CuNiFe, steel pipes, marine piping systems.
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