PSI - Issue 59

Teguh Muttaqie et al. / Procedia Structural Integrity 59 (2024) 222–229 Muttaqie et al. / Structural Integrity Procedia 00 (2019) 000 – 000

223

2

1. Introduction Liquefied natural gas (LNG) is a clean energy source that has received significant attention because of the low carbon dioxide emissions when burned compared to other fossil fuels. International Maritime Organization (IMO) regulatory requirements of January 1, 2020 target ship emissions on a global scale, specifically limiting the sulfur (sulfur oxide, SOx) content in marine fuels to a limit of 0.5%, from 3.5% previously (Prabowo et al., 2016; IMO, 2019; Suryanto et al., 2023). This regulation further boosts the potential of LNG as a promising alternative fuel. In LNG tank applications for temperatures around - 265°F ( -160 °C), Alloys SUS304, Al5083 -O and Ni-9% steel have been considered as materials for cryogenic applications. Type 304 stainless steel is widely used in cryogenic structures due to its advantageous mechanical properties and better ductile-brittle transition at low temperatures. This steel type is part of the 300 series type austenitic stainless steels containing chromium and nickel. Stainless steel in the austenitic group has different compositions and properties, but many common characteristics. It is one of the few structural materials that exhibits high toughness and high fatigue strength at both room and cryogenic temperatures (Kim et al., 2006; Cao et al.,2016; Prabowo et al., 2018, Nubli et al., 2022; Sari et al., 2023; Tuswan et al., 2023). In order to study related LNG storage materials, it is worth considering the impact behavior exhibited by materials used for liquefied gas tanks at low temperatures in the design process (Cooper et al., 2015; Zheng et al., 2018; Bader and Samir, 2022). The effects of thermal aging on the material properties during operational service should also be studied (Byun et al., 2020). In LNG storage material requirements such as ASME Section VIII (ASME, 2019) require Charpy V-notch impact testing in the weld deposit when the minimum design temperature is in the cryogenic regime (Kim et al., 2014; Park et al., 2018). The energy necessary to break a sample during impact is measured using the Charpy V-notch impact testing technique, which is frequently used to assess the strength of a material. This type of testing is particularly important for evaluating materials that have a ductile-to-brittle transition, such as ferritic steels, and can help to determine the temperature at which this transition occurs. Charpy testing is also commonly used to assess the toughness of large, forged components like pressure vessels used in independent tanks for instance. However, to ensure the structural integrity of these components, a curve showing the relationship between impact energy and temperature is necessary. In this study, the application of Charpy V-notch impact testing is used to review the impact behavior of SUS 304 for LNG tank structures under cryogenic temperature conditions. The results of the test can be used to improve the design and manufacture of materials and components, and to ensure that they meet the required standards for performance and safety. 2. Structural Application In cryogenic applications such as LNG storage tanks, the material used must be able to withstand thermal cycling over a certain temperature range. In this application, the material undergoes thermal cycles between room temperature and cryogenic service temperature. According to the IMO (International Maritime Organization) classification (IMO, 1993), the currently existing LNG Carriers (LNGC's) can be classified as one of the membrane types. Additionally, to expand the distribution of LNG to remote areas within a region, it is also feasible to transport it using ISO tanks in sizes of 20 and 40 feet (Muttaqie et al., 2022; Lee et al., 2023). The illustration of this LNG tank can be seen in Figure 1. Type 304 stainless steel has proven to be a reliable and durable choice for LNG storage tanks, providing strength even in the most challenging conditions. By knowing the characteristic of type 304 stainless steel in the construction of LNG tanks, engineers can ensure that the tanks meet the necessary standards and safety, and can support the growing demand for sustainable energy sources. 3. Test specimen Impact testing is a widely used method for evaluating the toughness and resistance of materials to sudden and high-energy impacts. In impact testing, a test specimen is subjected to a sudden load, and the energy absorbed by the