On the selection of pipeline materials for extremely cold regions
Thread Content
Dear colleagues in the chemical industry: The highest temperature over 24 hours: 30℃； Hottest week temperature: 26℃ ； I recently received a project located in Ukraine, and the weather data is as follows: design winter temperature –29℃ ； Lowest temperature over 24 hours: -29℃ ； Coldest week temperature: -24℃ ； Annual average humidity: 74% ； Maximum humidity: 89% ； Frost depth: 1.0m. The question under discussion is: how should the material for pipes and pipe fittings be selected? Also, how should equipment and structural materials be selected? Furthermore, with these temperature data available (some sources provide the extreme minimum temperatures and the average temperature for the coldest month), which of these should be used as the basis for selecting the pipeline material?
I’ll also post a thread to stimulate discussion – the average temperature in the coldest month of a certain project in Xinjiang is -19.4°C, with an extreme minimum temperature of -37°C℃； 20# steel is used for seamless steel pipes, Q235B is used for welded steel pipes, and Q345B is used for steel structures.
I have discussed this issue with SEI, global experts; when selecting materials, it is sufficient to choose those that are suitable for the design temperature specified in the manufacturing process. Low ambient temperatures are generally not taken into consideration, as even for utility process media, the operating temperature during normal operation does not reach such low levels. And even if the ambient temperature is reached during shutdown, the pipes are not under external loads such as operating pressure at that time, so the internal stresses do not exceed the allowable strength and safety is not compromised. Follow the WeChat official account of Pressure Pipeline Professionals to subscribe to more such information every day. The minimum operating temperature for 20/Q235B is -20°C.
So, this one of yours is suitable.
SA333.GR 6 is generally sufficient; or materials equivalent to China’s 16MnDR class will also work
Use specialized low-temperature steel… the kind with a D after its grade.
Think! on the third floor The answer was quite good. In fact, the lowest temperature permissible for the material can be easily found, but determining what value to use for this minimum temperature is a matter that requires careful consideration. The key issue is figuring out how to set the design temperature based on the temperature of the medium, the ambient temperature, and various operating conditions – and that is what truly reflects skill level. Additionally, please share your views on what is meant by environmental temperatures with different names, such as extreme minimum temperature, extreme maximum temperature, average temperature of the coldest month, etc.; everyone is encouraged to speak up.