Demand for Ship Plate Varieties and Analysis of Ship Plate Certification at Home and Abroad

With the improvement of domestic shipbuilding capacity, it is gradually making breakthroughs from quantity to quality, gradually changing the product structure dominated by bulk carriers, and improving the shipbuilding capabilities of large container ships , liquefied gas ships , drilling ships and other high value-added ships. The demand for plate varieties is developing in the direction of high strength , high toughness and corrosion resistance .
Therefore, as an important variety in the production of medium and heavy plates, analyzing the demand for ship plates, including the variety and specification changes, has important implications for product development and equipment transformation in various steel mills .

1. Analysis of Shipbuilding Industry's Requirements for Types and Specifications of Ship Plates

" Ship Industry Adjustment and Revitalization Plan " issued by the State Council in June 2009 supports the optimization and upgrading of the three major ship types, and the development of ships that meet new specifications , new standards, and energy-saving and environmental protection requirements. It proposes the goal of optimizing and upgrading China's ship product structure. To expand the market share of high-tech ships and marine engineering equipment, there is also a big increase in the variety and specification requirements of marine steel [ 1 ] .
1 . 1 Changes in demand for shipboard varieties in the shipbuilding industry
In terms of varieties, it has developed from general strength grades A , B , D and high strength grades AH32 , AH36 , DH32 , DH36 to E , EH32 , EH36 , to high strength grades AH40 , DH40 , EH40 , FH40 and super high strength grades 420 , 460 , 500 , 550 , 690 steel grades of high- strength steel grades, and even special ship steels ( LNG ships) with higher strength requirements and -196* impact tests .

1 . 1 . 1 high toughness ship plate
With the continuous improvement of China's ability to build high-tech ships, the design and development capabilities of large-scale liquefied natural gas ships , large-scale liquefied petroleum gas ships , large-scale car carriers , scientific research ships, etc. The demand for steel products is also increasing significantly. For example, the use of low-temperature pressure vessel plates for large LNG carriers must not only meet the requirements for high-strength ship plates, but also meet the performance requirements of -163* for low-temperature pressure vessels . Ship types such as new container ships require that the types of ship plates will cover almost all classes, with more than 1,200 types , and will develop towards F -class and class steel ship plates and profiles . 1 . 1 . 2 high-strength ship boards
High-strength steel is generally used in large bulk carriers , container ships , oil tankers and offshore engineering ships . Due to the increasing demand for high-tech ships, the demand for low-alloy and high-strength ship plates is increasing . According to estimates, high-strength ship plates required by large shipyards in China account for about 30% of the total ship plates .
1 . 1 . 3 Steel for marine boiler vessels
Steel for marine boiler vessels is mainly used in storage tanks such as LNG and LPG carriers, with a yield strength ranging from 235MPa to 500MPa , and is included in boiler vessel steel and low-temperature steel in ship regulations . 1 . 1 . 4 Corrosion-resistant ship plates
In May 2011 , at the 87th meeting of the International Maritime Organization (IMO ) Maritime Safety Committee ( MSC ) held in London, the performance standard for alternative measures for protective coatings for cargo oil tanks of crude oil tankers was officially adopted, which is applicable between January 1 , 2013 and A construction contract will be signed later . The marine corrosion-resistant steel standard is the only alternative to the current crude oil tanker cargo oil tank protective coating performance standard .
IMO passes the new regulations, the shipyard can choose the PSPC coating mode or the corrosion-resistant steel mode . At present, only Japan has announced the breakthrough of corrosion-resistant ship plate technology at home and abroad . Neither IMO nor the ship regulations of various countries have stipulated specific detection methods and evaluation methods for ship plate corrosion resistance . 1 . 2 Changes in shipbuilding industry's demand for ship plate specifications 1 . 2 . 1 Large-scale ships require wide ship decks
Large-scale shipbuilding plates for shipbuilding are developing towards 5m plate width and 5m plate length specifications. The varieties of ship plates cover almost all grades, and at the same time, the quality , specifications , and dimensional accuracy of marine steel are required to be higher .

Domestic and foreign ship plate certification
The classification societies of various countries do not distinguish shipbuilding steel from marine engineering steel, and the steel grades in practical applications are also grades in general specifications.
2 . 1 High-strength hull structure steel
2 . 1 . 1 Delivery status and certified maximum thickness
1 for the certification status of high-strength ship plates .

Table 1 Certification status of high-strength ship plates

steel mill	Certified ship plate maximum level	delivery status	Maximum thickness /m	mBill maximum thickness /mm		Remark
Angang	FH40-Z35	tm	100	CC	300	E40 and below have passed the 100kJ/mm large input energy welding certification
	DH36-Z35	NR	40	CC
	EH36	N	100	IC
Hunan Iron and Steel	FH40-Z35	N	100	CC	300
Xinyu	FH40-Z35	tm	50	CC	250	Passed in February 2009
	EH40	tm	36
Shaogang				CC	250
	EH36-Z35	N	60
	FH36	tm	100
Dillingen, Germany				CC	400 or IC
		QT	150
Japan JFE Fukuyama Plant	FH40	tm	80	CC	300	E36 and below include Fatigue Damage Approval ( AFD )
Japan JFE Kurashiki Plant	FH36-Z35	tm	100	CC	310
Pohang, South Korea	EH36	tm	50	CC

Note: TM stands for temperature deformation controlled rolling; NR stands for normalizing rolling; QT stands for quenching + tempering; N stands for normalizing; CC stands for continuous casting slab; IC stands for ingot .

 

2 . 3 Steel for marine boilers and pressure vessels
Many domestic steel mills have certified ship plate steel for marine boilers and pressure vessels, and its grade and thickness are no worse than those of foreign steel mills.
2 . 4 low temperature ductile steel
4 for certification status of low temperature ductile steel . Low-temperature ductile steel is mainly used in the construction of liquid cargo tanks of liquefied gas carriers and hull structures near liquid cargo tanks .
Certification status of ultra-high-strength steel ship plates

steel mill	Certified ship plate maximum level	delivery status	Maximum thickness /mm	Corresponding blank thickness /mm
Baosteel	E550-Z35	QT	50	CC 300
Angang	F550-Z35	tm	80	CC 300
Wuyang	E690-Z35	QT	140	IC
Dillingen, Germany	F550	tm QT	75 150	CC 400 or IC
Japan JFE Fukuyama Plant	E420	tm	50	CC 300
Japan JFE Kurashiki Plant	E420-Z35	tm	50	CC 310
	E690-Z35	QT	108	CC or IC
Swedish SSAB	E690	QT	80	CC

Table 3 Boiler and pressure vessel plate certification status

Table 3 Boiler and pressure vessel plate certification status
steel mill	Certified ship plate maximum level	delivery status	Maximum thickness /mm	billet
Angang	510-0N	CR , N , TM	90	CC
Wuyang	490-1FN	N	100	IC
Jigang	510-1FN	N	50	CC
Xinyu	510-1FN-Z35	tm	60	CC
Dillingen, Germany	510-1	N	30	CC or IC
Japan JFE Kurashiki Plant	510-1	N or TM	50	CC or IC
Swedish SSAB	510 - 1 FN	CR , N , TM	50	CC

Table 4 Certification status of low temperature ductile steel

steel mill	Certified ship plate maximum level	delivery status	Maximum thickness /mm
Angang	9Ni	QT	40
Nangang	9Ni
Dillingen, Germany	9Ni	N+N+T	42
Swedish SSAB	4 - 4L	N	50
Japan JFE Fukuyama Factory	4 - 4L	tm	40
Japan JFE Kurashiki Plant	9Ni - Z35	QT	35

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