Determination of design temperature for equipment and pipelines
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In accordance with the reference principles for temperature design specified in HG/T20570.1, Table 1.0.8-1 is generally used; however, for certain designs, the equipment and design temperatures of the process system are determined based on conditions such as steam purging (for example: operating temperature of 60°C, design temperature of 210°C, determined according to the steam purging condition)； According to Table 1.0.8-1 in HG/T20570.1, 90°C can be used). As a result, the design temperature becomes higher, but this does not affect the selection of pipes. It does, however, affect the calculation of secondary stresses in the piping system or the assessment of loads at the pipe ends. Generally speaking, how do people deal with such issues? Are there any good methods for addressing them?
Conditions such as steam purging also fall within the range of normal operating conditions; therefore, the condition with the highest temperature should be selected
Is the design temperature based on the steam purge temperature? As I recall, aside from the oil pipelines made of stainless steel which require steam purging, steam purging is not permitted for other non-thermal pipelines. So when considering the design temperature, a margin is usually taken based on the normal operating temperature of the medium
This is an oil pipeline made of carbon steel, containing mainly aromatics with molecular weights ranging from C7 to C9. Is it necessary to consider a design temperature based on the purging conditions?
Based on the larger values, the purging condition is also one of the operating conditions
Generally, except for steam pipelines, it is not recommended to use steam for purging other pipelines. Generally, water is used for pressure resistance, and compressed air is used for purging
The design temperature of this pipeline is based on the highest operating temperature of the steam