Application areas for 3.5Ni and 9Ni steels
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GB150-2011 lists 3.5Ni (08Ni3DR) steel and 9Ni (06Ni9DR) steel among the plate materials. Apart from being used in LNG tanks, in what other applications are these two types of steel generally utilized, or what equipment are they used to manufacture? 2. There are no corresponding pipes for these two types of steel. 3.5Ni steel does have corresponding forgings, while 9Ni steel does not have any corresponding forgings. What materials are used for the pipes and forgings in LNG tanks? 3. For the low-temperature pressure vessels used in low-temperature methanol washing, sheet metal, pipes, and forgings are generally employed; it seems that these materials are not suitable for manufacturing pressure vessels. If anyone is familiar with this topic, please share some information
1. Design temperature: 3.5Ni (08Ni3DR) steel: -70~-100°C (Personally, I think -65~-95°C)； 9Ni(06Ni9DR) steel: Used for low-temperature containers at -100 to -196°C (I personally think it’s -95 to -190°C). It can be used for low-temperature equipment. 2. There are already corresponding forgings for 9Ni steel: NBT47009-2017 06Ni9D forgings. Steel pipes can be 304 stainless steel pipes. 3. The low-temperature pressure vessels for low-temperature methanol washing are selected with materials corresponding to design temperatures of -40 (-30)/-45/-50/-70. Plate 16MnDR/15MnNiDR/15MnNiNbDR/09MnNiDR ； Tube: 16Mn/09MnD/09MnD/09MnNiD; forgings: 16MnD etc./16MnD/10Ni3MoVD/09MnNiD is sufficient. The quality of the materials can be slightly improved depending on the actual circumstances.
For low-temperature pressure vessels designed for temperatures below -70 degrees, should 3.5Ni and 9Ni be chosen, or should stainless steel be used instead? Are there any examples of its use in engineering? Except for the LNG tanks
Before the development of 3.5Ni and 9Ni, for low-temperature pressure vessels designed for temperatures below -70 degrees, stainless steel or low-temperature materials of foreign grades were used as materials. Due to reasons such as project duration and cost, 304 stainless steel is used more frequently.