The components of the pressure pipeline are generally standard parts, so the design of the pressure pipeline components is mainly the selection of its standard parts, and the determination of the pressure level of the pipeline is also the determination of the standard part level.
The pressure rating of the pipeline: the parameter that can be determined by the nominal pressure rating and wall thickness rating of the standard pipe fittings in the pipeline and can reflect the pressure characteristics of the pipeline is called the pressure rating of the pipeline. In order to simplify the description, the nominal pressure level of the pipe fittings in the pipeline is often called the pressure level of the pipeline.
The determination of the pressure level is the foundation of the pressure pipeline design and the core of the design. It is a design prerequisite for the layout of pressure pipelines and stress checking of pressure pipelines, and it is also an important factor that affects the investment in pipeline infrastructure and reliability of pipelines.
Steel pipes are divided into thick-walled pipes and thin-walled pipes. The formula for calculating the internal pressure is different. The pipe with K=D/d ≤1.2 is called thin-walled pipe; the pipe with daok=D/d>1.2 is called thick-walled pipe.
The allowable maximum internal pressure of thin-walled pipe [P] Calculation formula:
[P] =2[ σ ]φS / (d+S),where: [σ ]--permissible stress of the material; φ--weld coefficient,For seamless tubes, φ=1; S--tube wall thickness; d--tube inner diameter.
[P] = [σ] (K^2-1)/ (K^0.5 K^2), Where: K=D/d