Seamless Steel Pipe for Ship Building: Sizes, Chemical Composition, Mechanical Properties

The seamless steel pipe for ship building usage are mainly used for Level 1& Level 2 pressure pipe in piping system, boiler and super-heated unit of shipbuilding. 

The main grades of steel pipe for ships include 320, 360, 410, 460, and 490. 

These are internationally recognized ship pipe grades. The number represents the minimum yield strength (MPa). For example, 320 indicates a yield strength of 320 MPa or higher. These grades are used in various ship piping systems. The standard specification is ISO 9329-1.

Other:

CCS Grade A/B/D/E: China Classification Society material. A/B represents general strength, D/E represents high strength, and Grade E has excellent low-temperature impact toughness. 
ABS Grade A/B/D/E: American Bureau of Shipping material. The grading method is similar to CCS, but the requirements are slightly different. 
Uses I, II, III: ASTM A106 is sometimes used, but it must meet the additional inspection requirements of the ship regulations. 

Sizes for ship seamless steel pipe:

Outer diameter: 8mm-1240mm
Wall thickness: 1mm-200mm

Types of steel tubes	Out diameter		Wall thickness
Cold-rolled tubes	Tube sizes (mm)	Tolerances (mm)	Tube sizes (mm)	Tolerances (mm)
	＞30-50	±0.3	≤30	±10%
	＞50-219	±0.8%
Hot-rolled tubes	＞219	±1.0%	＞20	±10%

Chemical compisition:

Models of steel tubes	Chemical compisition (%)
	C	Si	Mn	P	S
320	≤0.16	≤0.35	0.40-0.70	≤0.035	≤0.035
360	≤0.17	≤0.35	0.40-0.80	≤0.035	≤0.035
410	≤0.21	≤0.35	0.40-1.20	≤0.035	≤0.035
460	≤0.22	≤0.35	0.80-1.40	≤0.035	≤0.030
490	≤0.23	≤0.35	0.80-1.50	≤0.035	≤0.030

Mechanocal properties:

Models of steel tubes	Tensile strength (MPa)	Yield strength (MPa)	Elongation (%)
320	320-410	≥195	≥25
360	360-480	≥215	≥24
410	410-530	≥235	≥22
460	460-580	≥265	≥21
490	490-610	≥285	≥21

Standards for Shipbuilding Steel Pipes:

Shipbuilding pipes must be certified by the classification society. Manufacturers must submit their products and production processes to the classification society for review. Only after obtaining factory approval and product type approval certificates can their products be used in shipbuilding. Steel pipes are marked with the classification society's inspection mark upon leaving the factory.

China Classification Society Material and Welding Specifications - China Classification Society (CCS)
Det Norske Veritas (DNV) Specifications - Det Norske Veritas (DNV)
Lloyd's Register (LR) Specifications - Lloyd's Register (LR)
Germanischer Lloyd (GL) Specifications - Germanischer Lloyd (GL)
American Bureau of Shipping (ABS) Specifications - American Bureau of Shipping (ABS)
Bureau Veritas (BV) Specifications - Bureau Veritas (BV)
RINA Specifications - RINA
NK Classification Society (NK) Specifications - Nippon Kaiji Kyokai (NK)
GB/T 5312 - Chinese National Standard

Read more: Comprehensive Introduction to Seamless Carbon Steel Pipes for Ships