ISO 15749-3:2004

Overview

ISO 15749-3:2004 provides design requirements for sanitary drain lines in vacuum drainage systems on ships and marine structures. It covers the functional description of vacuum systems, permitted pipe materials and dimensions, layout and installation rules, capacity and air‑consumption calculations, collector tank considerations, testing and cleaning provisions. For planning and basic system requirements, ISO 15749-1 is referenced.

Key Topics

• Vacuum system operation
  • Wastewater is transported as a sewage “plug” by pressure difference to a collector tank or sewage treatment plant. Operating absolute pressure is specified between 0.4 and 0.7 bar (negative pressure −0.3 to −0.6 bar).
  • Vacuum water closets have integrated mechanisms (flush ≈ 1.2 L).
• Pipe materials and sizes
  • Permitted materials: steel, CuNiFe, spigot & socket steel, PVC‑U (plastic pipes subject to IMO A.753 approval).
  • Typical nominal bores: NB 40, NB 50, and NB 100 (for main sewers). Example steel dimensions: NB40 OD 48.3 mm s≥2.3 mm; NB50 OD 60.3 mm s≥2.3 mm; NB100 OD 114.3 mm s≥3.2 mm.
• Fittings and testing
  • Fittings must be suitable for vacuum use; shut‑offs provide smooth passage. Tightness and acceptance tests are specified in Annex B.
• Laying and routing rules
  • Horizontal gradient ≈ 2:1 000 toward suction point. Water traps at intervals ≤ 40 m before riser branches.
  • Riser branches: max 3 vacuum toilets/valves on same deck, branch length ≤ one deck (≈3 m) unless manufacturer approves.
  • Feeding angle into manifolds ≤ 45°; no tees/90° at feed in direction; bend radius ≥ 3× outer diameter.
• Capacity and air demand
  • Pipe sizing tables define how many vacuum mechanisms each branch/manifold may serve (e.g., NB50 manifolds up to 32).
  • Air capacity (sewage) is calculated using the number of water closets, per‑activation air consumption (typically ~60 L), user frequency and leakage factor.

Applications

• Intended for ship designers, marine plumbing engineers, shipyards, equipment manufacturers and classification societies specifying vacuum sanitary drainage and vacuum sewage piping on vessels and offshore structures.
• Use cases: cruise ships, ferries, naval vessels, offshore platforms - where water saving, compact piping and hygiene control are required.

Related Standards

• ISO 15749‑1 (Sanitary drainage‑system design) - planning basics
• ISO 15749‑2, ‑4, ‑5 (other drainage applications)
• IMO Resolution A.753 (plastic pipes on ships) and referenced ISO material standards (pipe/fitting specifications)

Keywords: ISO 15749-3, vacuum drainage systems, sanitary drainage, ships, marine structures, vacuum sewage, marine plumbing, pipe materials, design guidance.