Recently, the Jingtang Company’s 9Ni steel for the fuel tanks of liquefied natural gas (LNG) ships was delivered to customers in batches, with its surface quality, remanence, performance, welding and other indicators fully meeting the usage requirements. This single fuel tank project supplied by Jingtang is also the shipyard’s first project in the LNG tank field.

9Ni steel is recognized as one of the wide and thick plate varieties with the highest technological content and production difficulty at home and abroad, and known as the “diamond of steel”. Compared with other types of steel, 9Ni steel has extremely strict requirements for its molten steel purity, surface quality and steel plate remanence. It is mainly used to manufacture LNG tanks because it has the highest toughness for use in cryogenic environments. Only a few domestic manufacturers have the capacity to produce 9Ni steel.

Jingtang carried out the certification of its 9Ni steel in August 2021, and the leading officials of the Company took the lead in setting up a special research team. During the R&D and certification, they actively communicated with various classification societies, worked out the approved production and testing schedule of the 9Ni steel factory, and completed a high-quality comprehensive approval report which was submitted to the classification societies. During the trial production of 9Ni steel, aiming at the key technological problems in the smelting cycle, surface quality control, heat treatment and remanence, Jingtang organized special research on key technological links such as smelting, rolling and heat treatment. In September 2021, the smelting and blanking were completed; in December 2021, the laboratory rolling, heat treatment and sampling performance placement were completed, and the classification societies observed the flaw detection, sampling, standard conversion and sample welding; in March 2022, the NK Classification Society Certificate was obtained, and in April, the CCS, ABS, DNV and LR Classification Society Certificates were gained.

In order to meet the customer's requirements, Jingtang and the Beijing Shougang Marketing Center intervened in advance, deeply communicated with the shipyard and discussed details of the technology, quality and delivery cycle many times. Through the strict evaluation and audit of customers, Jingtang was successfully selected as a cooperative supplier. In order to ensure smooth delivery as stipulated in the contract, Jingtang’s Medium and Heavy Plate Division cooperated with the Manufacturing Department, Beijing Shougang Marketing Center and other departments on setting up a special research team to establish a detailed tracking account for each billet and steel plate in order to master the information of the whole process production; focusing on SPC, they strengthened the management and control of the key characteristics of the products in order to ensure the stability of temperature control, size control and other indicators through the precise control of the process parameters. Every steel plate is operated carefully and inspected meticulously, enabling the quality to be effectively guaranteed.