HG/T 20585-2011Technical requirements for steel low-temperature pressure vessels (English PDF)

1.0.1

This standard is applicable to the steel low temperature pressure vessels with design temperature lower than or equal to -20°C.

1.0.2

Unless otherwise specified, the other application scope, normative references and definitions of this standard are the same as those of "Steel Pressure Vessels" GB 150.

3.0.1 Lowest operating temperature

It refers to the lowest metal temperature that may appear during the normal operating process of vessels.

3.0.2 Lowest environment temperature

It is the lowest value of the "monthly average lowest air temperature" over the years in this area.

"Monthly average lowest air temperature" means the quotient of the sum of lowest temperature at all the days in the current month divided by the number of days in that month.

3.0.3 Lowest design temperature

It refers to the set lowest metal temperature of the pressure parts under the normal operating conditions, regarded as the design load conditions together with corresponding design pressure.

1 Where each part of the vessel may generate different temperatures during the operating process, the predicted different temperatures may be regarded as the design temperature for each corresponding part.

2 Where the vessel walls directly contact the working medium and have external insulation, the lowest temperature of medium or the value of normal operating temperature of medium minus the possible downward fluctuating value of temperature shall be regarded as the design temperature.

3 Where there are heat transfer processes at both sides of the vessel wall, the design temperature may be determined according to the lowest temperature of the wall temperature calculated according to the heat transfer or the measured wall temperature, in consideration of the temperature fluctuating value.

4 As for the pressure vessels subject to the low temperature of environment, where their design temperature is controlled by the environment temperature, the lowest design temperature shall be determined according to the following principles.

1) As for the storing vessels containing compressed gas and without insulation facilities, the design temperature shall be the value of lowest environment temperature minus 3°C;

2) As for the storing vessels containing the liquid accounting for more than 1/4 of the vessel and without insulation facilities, the design temperature shall be the lowest environment temperature;

3) As for the vessels with insulation facilities, in which the materials are frequently in the flow conditions, the design wall temperature shall be determined through calculation analysis or with reference to the examples, in comprehensive consideration of the temperature of material, flow, vessel size and heat dissipation conditions;

4) Except the vessels specially set for the emergency shutdown, the consideration for the influence of environment temperature to the vessel wall temperature shall be based on the normal operating conditions.

Generally, the design temperature is not determined by the unexpected temperature drop under the accident states or the natural temperature drop after shutdown.