Is it necessary to conduct low-temperature impact tests on No. 20 steel pipes used in Beijing and Tianjin areas?
Thread Content
Page 19 of GB20580-2020, Clause 5.0.2, Paragraph 4: “For storage containers installed outdoors without insulation, where the minimum design temperature is determined by the local ambient temperature, the following provisions shall apply: 2) For storage containers in which the volume of liquid contained accounts for more than 1/4 of the container’s total volume, the minimum design temperature may be set as the lowest value of the monthly average minimum temperatures.” (1) How should the term “determined by” be understood? (2) The lowest ambient temperature in Tianjin is -3.6°C. In accordance with the provisions of 5.1.3, 5.1.4, and 5.1.5 in GB150 and P53, steel pipes of grade 20 are subjected to impact tests at 0°C, and the lower limit for operating temperature is 0°C. For a carbon steel storage tank operating at temperatures of 30–60°C, can grade 20 steel pipes and forgings be used in this equipment? If it is used, is a low-temperature impact test required? At what temperature does it need to be done?
In accordance with Clause 5.0.2, Paragraph 4, Page 19 of GB20580-2020, when steel pipes are installed in outdoor storage containers without insulation and the minimum design temperature is determined by the local ambient temperature, the relevant requirements must be met. Therefore, when using No. 20 steel pipes in Tianjin and Beijing areas, it is necessary to take the ambient temperature into account and carry out design in accordance with regulations. For a carbon steel storage tank operating at temperatures of 30–60°C, if Grade 20 steel pipes and forgings are to be used, low-temperature impact tests are required. According to GB150, and clauses 5.1.3, 5.1.4, and 5.1.5 of P53, steel pipe grade 20 is subjected to impact tests at 0°C, with the lower operating temperature limit being 0°C. Therefore, a low-temperature shock test needs to be conducted at 0°C. .
This post was last edited by AtlantisH on 2023-4-11 at 11:10. The tank wall temperature is affected by the working medium and the ambient temperature; when the tank wall temperature may drop below 0°C and this minimum value is determined by the ambient temperature, then the minimum design temperature is controlled by the local ambient temperature. The lowest metal design temperature specified by standards can be used; for equipment that operates continuously, the influence of ambient temperature generally need not be considered, unless the flow rate is very low and unable to keep up with the rate of heat loss. 20 seamless tubes cannot be used below 0°C; 10 seamless tubes or 20 forgings must be used instead. Low-temperature impact testing can be conducted at the minimum metal design temperature, or at the lowest operating temperature permitted by standards (for example, for 10 seamless steel tubes and 20 forged products as specified in 9948, this temperature is -20°C)