Wu Xiuxia

The R&D and application of steel for China's ships and offshore engineering equipment have made constant breakthroughs in recent years,domestically manufactured sheettype LNG marine Invar steel,duplex stainless steel for super large chemical tankers,low temperature steel for offshore engineering equipment,crack arresting steel for large container ships,sheet for large cruise ships have achieved industrial application in succession,meeting the demand of the rapid development of domestic shipbuilding companies.The increase of orders for high-tech ships and offshore engineering equipment has also put forward new requirements for high-quality shipbuilding and offshore engineering equipment steel,and high strength,high toughness,good corrosion resistance and easy weldability have become the new development direction of steel for the shipbuilding industry.Industry insiders said that in this situation,the majority of steel enterprises should not only make refined highend products on the market demand,but also pay more attention to further improve the quality of the hull plate,improve the whole ship procurement and segment distribution mode and meet shipbuilding enterprises’new requirements for marine steel after completing the intelligent manufacturing line upgrade.Only in this way,can steel enterprises and shipbuilding enterprises build a"win-win chain" and jointly achieve transformation and upgrading.

High-end ships call for homemade highend marine steel

This year,China's shipbuilding enterprises have actively undertaken high-tech,high value-added ship orders,and made fresh headway in 9000CEU methanol ready PCTC,5000TEU methanol dual-fueled large container ship,23000TEU LNG dualfueled VLCS,93000m3 very large liquid ammonia carrier,large LNG carrier and other fields.With the increase of the proportion of high value-added ship orders in China's shipbuilding industry,the demand for marine high-strength plates and small varieties of steel is gradually increasing.Principals of material departments and procurement departments of many shipbuilding enterprises called on steel enterprises to cooperate with shipbuilding enterprises to step up R&D of new products to roll out more competitive products to shipbuilding enterprises.

A principal of the China State Shipbuilding Equipment and Materials Corporation Limited said that in recent years,CSSC shipbuilding enterprises have undertaken a batch of high-end ship orders including PCTC and dualfueled ships,and these orders have large demand for mid-and-highend ship plates,and he expected steel companies could conduct longerrange technical planning,further strengthen R&D and application for low temperature toughness steel plate production technology.A source of COSCO Shipping Kawasaki Shipbuilding Heavy Industry Co.,Ltd.said that COSCO Shipping intends to join hands with domestic highquality steel enterprises to tackle joint problems in crack arresting steel for large container ships,Invar steel,ultra-low temperature high-manganese steel (HMS) and other high-end steel.The head of the purchasing department of Dalian Shipbuilding,a subsidiary of China State Shipbuilding Corporation,said that since 2006,Dalian Shipbuilding has formed a stable cooperative relationship with Anshan Iron and Steel Group Corpopration(Angang).The two sides complement each other's advantages and achieve many results in the field of R&D of new hull plate products.

"For a long time,the lack of integrity of hull plate delivery is a'pain point' that ship companies need to get through." A source of Jiangsu New Times Shipbuilding said that if steel enterprises can not achieve integrity delivery,it means that the shipyard’s hull plate reserve cycle is longer,capital pressure,inventory pressure and cost pressure are greater.He said that compared with before the COVID-19 outbreak,the average arrival rate of hull plate contracts has increased,but many steel companies still need to strengthen the integrity of the delivery,especially the ordered remaining plate can not be supplied by batch and on time.

As we all know,the shipbuilding industry is a major consumer of steel,shipbuilding steel requires strong compatibility,need simultaneous supply of steel plate from thick to thin,wide to narrow,from high steel to low steel grade,some varieties also need to be delivered by the number of sheets.For example: a batch of 10,000 tons of hull plate orders generally cover 2000-3000 specifications.If this batch of hull plate is divided into several construction cycles for delivery,some steel enterprises may make part of the hull plate delivery miss the deadline taking into account convenience of organizing their own production.However,the ship production has strict schedule requirements,and failure of the normal arrival of the remaining hull plate will affect the delivery of the whole ship.

An increasing number of shipbuilding enterprises recognize and call on steel enterprises to adopt the segmented customized distribution mode.The so-called customized distribution mode requires hull plate suppliers pile up and gather batches according to the varieties and specifications required by different sections of the hull,and ship one section after gathering batches of one section.This steel plate distribution method can reduce the inventory of shipbuilding enterprises,improve their capital turnover efficiency,and shorten the shipbuilding cycle,but it puts forward higher requirements for the production organization and warehousing logistics of steel enterprises.In the past,very few domestic steel companies could meet the requirements of the shipbuilding companies.However,in recent years,some steel enterprises have significantly improved the requirements in the variety,quality and service of hull plates,and the production line is fully equipped,making it possible to meet the client’s customized needs with full specification coverage and segmented distribution.

More and more steel enterprises are exploring the "whole ship procurement,segmented distribution"supply method commonly used in Japan and South Korea,but this distribution method is a real ordeal to the comprehensive strength of steel enterprises."We hope that steel enterprises can improve the level of lean management,realize the customized distribution of hull plates,achieve on-demand distribution without increasing the inventory of shipbuilding enterprises,and realize the seamless connection between steel and the production plan of ship enterprises." A source of China Merchants Industry Nanjing Jinling Shipyard Procurement Department said that shipbuilding enterprises are willing to achieve real-time information exchange with steel enterprises,mutually see each other’s production state,facilitate the formulation and adjustment of production plans.

"The customized distribution of hull plates timely supply the required steel plates according to the shipbuilding period,which can meet the material supply demand of modern shipyards,and is an urgently needed service mode for shipyards." A principal of the Yangzijiang Shipyard said the company’s cooperation with Nanjing Iron and Steel by adopting the ship segment customerized distribution mode has reduced the shipyard’s inventory cost,more effectively guaranteed timely delivery and quality of hull plates,produced a certain synergy,saved the manufacturing cost of both sides,and improved thekir production efficiency.Yangzhou COSCO Shipping Heavy Industry applauded the practice of some steel enterprises,and pointed out that failure of supply by batch and on time of the remaining plates is still widespread,it is suggested that steel enterprises take measures to make each hull plate distributed on time.

We learn that some domestic shipbuilding enterprises and steel enterprises have acted as early birds by stepping up cooperation and innovation in the steel inventory optimization and other aspects and setting up the information sharing platform.For example,the customized distribution supply chain cooperation platform developed by Nanjing Iron and Steel enables shipyards to monitor the order production of steelmakers in real time,making the ordering and supply more timely and accurate.

Luo Tiejun,vice President of the China Iron and Steel Association (CISA),said the shipbuilding industry has in recent years sped up the intelligent upgrade,rolledout higher requirements for steel quality stability and customized distribution,shipyards and steelmakers should establish closer cooperation and forge strategic partners in production and distribution schedule coordination,to reduce the inventory,withstand market fluctuations,and avoid frequent urgent reminders.

Ships and production line upgrades require higher steel quality

With the increase of orders for large-scale ships and high-tech ships and the introduction of intelligent production lines by more and more shipyards,they have new requirements on the quality,shape,tolerance control accuracy and surface "smoothness" of hull plates.

In recent years,the proportion of CSSC Guangzhou Shipbuilding International’s luxury passenger ro-ro ship and PCTC products have increased gradually.At present,the company contracted to build 7000CEU,8600CEU and other passenger ro-ro ships,accounting for more than 25%,or even close to 30%.an executive of the company said that the passenger roro ship has a large demand for sheets,and the flatness requirement of the ship section is more stringent,so GSI introduced the intelligent production line of sheet section.The intelligent production line has higher requirements for the processed steel.Therefore,we hope that the steel enterprises will further improve the flatness of the steel plate.

Ships under construction at China Merchants Industry Nanjing Jinling Shipyard are mainly passenger ro-ro ships.A source of the company noted the stress and deformation of hull plate is a major problem in the construction process of ro-ro ships.From the construction feedback in recent years,the stress and deformation of wide plate is relatively higher,and it is hoped that steel enterprises can do more work on the deformation control of stress tooling and wide plate stress.

Sheets of the ro-ro ship involve numerous specifications and stringent steel plate thickness tolerance requirements,e.g.,in a 12.5m long hull plate,the requirements of the thinnest and the thickest difference can not exceed 0.25 mm.Rolling such high precision steel plate has to use a large reversible four-roll finishing mill to control the accuracy to the size tolerence of the hair thickness,as it were,"a seven-foot strong man doing embroidery",how difficult it is! This requires steel companies conduct stricter quality control.

An industry insider said that at present,China's shipbuilding industry is taking the road of connotative highquality development,the ship order structure is further optimized,and the proportion of high-tech ships continues to increase.In addition,a number of backbone shipyards in China have established or are promoting the application of automatic production lines and assembly lines,and some enterprises have built intelligent production lines and intelligent workshops,and intelligent production lines have more stringent requirements for shipbuilding steel.Therefore,meeting the new requirements of intelligent manufacturing line for shipbuilding steel should be one of the focus of steel enterprises in the future.