Replacement with low-temperature steel pipes
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For low-temperature pipelines, with temperatures around -30 degrees, the pipes were originally made of the American standard A333 material. However, this material is not available in stock; 16Mn is also unavailable, with only 15CrMo and 20G available. 15CrMo is generally used as a high-temperature steel – but what is its performance when used for low-temperature applications? If any experts are aware of this, please advise! Thank you first
It cannot be used, as GB150 does not specify its minimum operating temperature; its minimum operating temperature must be above 20 degrees
Are you using it on pressure pipelines or pressure vessels? In terms of performance, 15CrMoG is a heat-resistant steel with high strength but poor plasticity and toughness; it is mainly used in environments where the operating temperature is above 450°C to prevent the spheroidization of pearlite. It clearly cannot be used in cryogenic equipment with high requirements for low-temperature toughness. Additionally, for 20# steel, it is possible to check whether the actual operating conditions fall under those of low temperature and low stress; if so, 20# steel can be used.
The fact that the goods are not available in the warehouse is not a reason to look for alternatives; 15CrMo and 20G certainly cannot be used in low-temperature environments. 16Mn must meet the requirements for low-temperature impact resistance, and design approval must be obtained.
I think it’s not appropriate; superalloy steel has poor low-temperature brittleness, and on top of that, its cost is too high!
This post was last edited by tjsyhx@163.com on 2019-4-8 15:47. It is not recommended for use. Furthermore, if it really could be replaced, there would be no need to establish so many standards and so many materials...... right? ! It is recommended to follow the relevant standards and specifications strictly 【After all, too many chemical accidents have sounded the alarm for us time and again! ! 】. ASTM A333 Gr.6 is commonly available in stock. GB/T 6479 grades Q345D and Q345E are available in stock to some extent. GB/T 18984 grade 16MnDG requires customization. GB150.2 grades 09MND and 09MnNiD also require customization. All of these grades can be manufactured upon order, though the lead time will be longer; the quantity, on the other hand, is not a problem.
For occasional use, you can try using stainless steel as a substitute…
Firstly, material substitutions cannot be made arbitrarily; projects in the design phase must obtain written approval from the design agency. No relevant guidelines have been found regarding the minimum operating temperature for 15CrMo and 20G steel pipes. The corresponding minimum operating temperatures for 10, 20, and Q345D steel pipes are -10°C, 0°C, and -20°C respectively. For detailed information, please refer to the attached drawings