Pipeline pressure rating issue
Thread Content
I selected pipes with a pressure rating of 6.3 MPa based on the table in the process manual that lists common pressure ratings and wall thicknesses (taken from the Chemical Pipeline Center Station), for use with steam at 4.2 MPa and 280°C. However, the hydrostatic test is conducted at a pressure higher than 6.3 MPa – will this be sufficient?
The water pressure can be calculated using the hydrostatic test formula: P_water pressure = 1.5 × P × allowable stress at normal temperature / allowable stress at operating temperature
Please refer to the pressure-temperature conversion tables in the flange standards; the reference temperatures for European and American standards are different. Therefore, a conversion is necessary when the design temperature differs from the standard temperature specified in the flange standards. If this factor has already been taken into account, the selected grade can withstand the hydrostatic test pressure
If 20# steel is used, the pressure should not exceed 3.9 MPa (at 280°C).
It is best to select the pipeline grade based on the temperature and pressure curve
It is possible to check the maximum impact-free pressure at the specified temperature and pressure in HG20592; as long as it meets the requirements, that’s sufficient