IACS has developed Rec.177 to provide comprehensive guidance on shipbuilding quality standards for machinery piping systems, for use during a ship’s new construction phase.
The recommendation is designed to improve the quality standards of machinery piping systems in terms of fabrication, installation, commissioning and function tests as well incorporating remedial standards to address situations where the prescribed quality standards have not been met. Furthermore, these standards can be applied to cover repairs/modifications and piping system retrofits onboard ships in service, so ensuring a through-life approach to enhancing and maintaining the quality standards of machinery piping systems.
The purpose of machinery piping systems is to convey different fluids at various temperatures and pressures to all parts of the ship, including to nearly every enclosed space on a vessel. As such, and because these systems are a means through which many of a ship’s control systems operate, it is crucial that these systems are designed to meet high quality standards in order to mitigate against the possibility of failure.
Rec.177 focuses primarily on machinery piping systems covered by those Classification Society rules which address critical functions such as ship propulsion, electricity generation and navigational safety.
Furthermore, this recommendation builds upon, and complements, IACS current Rec.47 which sets down guidance on ship-building quality standards for the hull structure itself.
Key highlights of the Rec.177 include:
I. Terminology: Clear and precise definitions related to machinery piping have been provided.
II. General Requirements:
- Qualification of welders/operators and Non-Destructive Testing (NDT) operators
- Procedures: Welding procedures (for metallic pipes) and plastic coating or lining procedures (for steel-plastic composite pipes), Procedures for bonding, NDT, and installation
- Requirements for Quality Management Systems of shipyards
III. Quality Standards: Detailed quality standards are outlined for the following items:
- Materials: General requirements, surface conditions, and remedial measures for defects
- Workshop Fabrication:
- Cutting: Permitted cutting methods for different materials, roughness of cut edges, cut end perpendicularity, length tolerance.
- Bending: Longitudinal weld seam arrangement, heat temperature range, post-heat treatment, minimum thickness, bending radius, bending surface quality, wall thickness thinning rate, roundness, reduction in cross-sectional area, creasing, angle deviation, shape, and position deviation.
- Edge preparation and assembly: Cleaning, misalignment tolerance, distance between welds, tack weld, typical edge preparations
- Preheating and Post-heat treatment of welding
- Typical weld profile and weld surface quality
- NDT and acceptance criteria: NDT methods, NDT requirements, acceptable standard levels
- Weld remedy standards
- Installation onboard: Pipe support, pipe support spacing, gap between piping, flushing.
The publication of Rec.177 is yet another example of IACS’ ongoing commitment to supporting the maritime industry through the development of guidelines that improve safety across all aspects of ship construction
… said IACS Secretary General, Robert Ashdown
