Ship Piping Requirements

Ship pipelines are pipes used to connect various mechanical equipment on ships and to transmit water, oil, gas and other related working fluids.
 

There are two main categories of marine piping: power piping and marine system piping. Power pipelines are various pipelines used to serve the main engine and auxiliary engines, including fuel oil, lubricating oil, cooling water, compressed air, exhaust, waste heat and other pipelines. Ship system piping supports the ship’s safety and stability and meets the normal living needs of the crew and passengers.

There are many system pipelines in the ship system, including the water supply system for supplying seawater and fresh water to the whole ship; the ballast water system for regulating the ballast of the ship; the bilge water discharge system for removing bilge water; the compressed air system for supplying compressed air; and fire protection systems for fire fighting. Many of the pumps and compressors used in these systems are electrically driven and can be automatically controlled.

Materials Used in Marine Piping

Material selection for steel ship pipelines depends on the fluid carried, working pressure and temperature, the corrosive environment (seawater, fuel, fresh water, steam or exhaust gas) and the rules that apply to the ship and the piping system. As noted above, the selection must be approved by the shipowner and the relevant classification society.

Carbon steel, seamless and stainless steel are not mutually exclusive categories. “Seamless” describes the manufacturing method, while carbon steel and stainless steel describe the material, so a seamless pipe can be made of either.

Carbon steel pipe: Often considered where its strength and cost suit the service. Depending on the system and the applicable rules, internal or external protection may be needed in seawater or humid environments.

Seamless steel pipe: Has no longitudinal weld seam and is often considered for higher-pressure, higher-temperature or critical services, where the design and the rules call for it.

Stainless steel pipe: Offers better corrosion resistance than carbon steel in many environments, so stainless steel ship piping may be considered where corrosion, cleanliness or fluid compatibility matters. The grade must still suit the medium, because stainless steel can suffer pitting or crevice corrosion in chloride-containing environments such as seawater. 

No single material suits every ship piping system. Confirm the final choice against the ship specification, the applicable classification society rules and the material certificates.

Ship Piping Inspection and Compliance

Checks start before ship piping installation and continue until the system is accepted.

Material documents: Check that pipes, fittings and valves match the approved material list. Confirm that mill test certificates and any required approval documents are available and can be matched to the markings on the delivered items.

Installation quality: Check pipe size and wall thickness against the drawings. Inspect fit-up and alignment, welds, flange connections, supports and insulation. Confirm that the routing leaves room for maintenance.

Testing: Depending on the system, the material and the applicable rules, installed piping may need non-destructive examination, pressure testing, and cleaning or flushing checks. The test type, test pressure and acceptance criteria are set by the class rules, the ship specification and the approved drawings, and should not be assumed.

Records: Keep inspection and test records so they can be reviewed by the shipowner or the classification society surveyor where required.

Read a full guide: Ship Piping Requirements

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