What about the selection of equipment flanges, pipe flanges, and manholes? Should the hydrostatic test pressure be taken into consideration?
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During the equipment design process, standard equipment flanges have a maximum allowable operating pressure at a corresponding temperature； Should we consider the pressure for the hydrostatic test at this time? For example, if the design pressure of the equipment is 1.6 Mpa and the design temperature is 100 degrees, I choose a 16MnⅡ equipment flange. At 100 degrees, the maximum allowable operating pressure is 1.6 Mpa; however, the pressure calculated for the hydrostatic test is 2 Mpa, which exceeds 1.6 Mpa. Is the selection of this flange appropriate? Similarly, pipe flanges and standard manholes also have corresponding maximum allowable working pressures; is it necessary to take into account the hydrostatic test pressure? There’s also opening reinforcement – should we calculate whether it can withstand the pressure of the hydrostatic test? I would appreciate it if the experts could give some advice. If there is no need to consider the hydrostatic test pressure, I’m hoping to know which standards or books mention similar provisions ； Thank you so much!
There is no need to consider the hydrostatic test pressure; since the hydrostatic test represents a short-term load, the maximum overall membrane stress can reach 0.9 times the yield limit, after applying the welding joint factor. Based on GB/T150.1, Section 4.6 – Pressure test
It is good to note, during the design process, that flanges have a maximum allowable operating pressure. I only learned about this thing after working in design for a year; fortunately, at that time the products designed were of a lower category, and the temperature did not exceed 100 degrees. First, make sure you are selecting according to the corresponding pressure level specified in the standards. Then, as you said, the design temperature is 100 degrees, but the temperature at which pressure tests are conducted on the equipment is usually room temperature; therefore, for the pressure tests, the maximum allowable operating pressure for the flanges used will be higher than the 100 degrees you mentioned. Combined with reply #2 too :)
Please refer to the interpretation of the pressure test standards in GBT150.1; hydrostatic testing needs to be taken into account. The equipment flanges shall follow the values at 20 degrees Celsius as specified in Tables 6 and 7 of NBT47020. Pipe flanges are designed for values that are 1.5 times those at 20 degrees Celsius or 38 degrees Celsius; generally, the pressure tests for pressure vessels do not exceed these values for pipe flanges.
Thank you for your advice:handshake
The equipment flanges shall follow the values at 20 degrees Celsius as specified in Tables 6 and 7 of NBT47020. Pipe flanges are designed for values that are 1.5 times those at 20 degrees Celsius or 38 degrees Celsius; generally, the pressure tests for pressure vessels do not exceed these values for pipe flanges. Why didn’t I find this sentence in the explanation for 150? On which page is it? Thank you
This post was last edited by zjq1962 on 2020-5-4 15:01. Could you provide the source of these words? What were the exact words? The standard requires that stress verification of the pressure-bearing components be carried out when the test pressure exceeds the specified value.
Clause 4.6.3 of GB150.1-2011 states: “If a test pressure higher than that specified in 4.6.2.2 and 4.6.2.3 is used, the stress levels of all pressure-bearing components under the test conditions shall be checked prior to the pressure resistance test; for example, for shell components, the maximum overall membrane stress σT shall be checked...” In other words, if the pressure is not higher than the specified value, no such check is necessary.
The value of the hydrostatic test is calculated based on the maximum allowable working pressure when that pressure is applied. Its value must be at least 1.25 times the maximum allowable operating pressure. The maximum allowable operating pressure does not require consideration of hydrostatic testing, whereas hydrostatic testing can only be determined based on the maximum allowable operating pressure.
The flange standards already take into account the issue of pressure testing; during design, standard flanges can be selected based on the pressure and temperature values