HG/T 20570.1-1995 Determination of design pressure and design temperature of equipment and piping systems
Some standard content:
Determination of design pressure and design temperature of equipment and piping systems
HG/T20570.195
Preparing unit:
China Chengda Chemical Engineering Corporation
China Huanqiu Chemical Engineering Corporation
Approving department: Ministry of Chemical Industry
Implementation date: September 1, 1996 Preparer:
Hu Guanyun of China Chengda Chemical Engineering Corporation
Yang Yi of China Huanqiu Chemical Engineering Corporation
Reviewer:
Zeng Qingxiang
Gu Gong Renwei and Feng Shuyuan of Process System Design Technology Center of Ministry of Chemical Industry
1 Principles for determining design pressure and design temperature of equipment 1.0.1 Scope of responsibilities
1.0.1.1 The process system major is responsible for determining the design pressure of containers, towers and heat exchangers (hereinafter referred to as equipment or containers).
1.0.1.2 When the process system professional determines the equipment design pressure, it should be as economical and reasonable as possible on the basis of meeting the safety requirements.
1.0.1.3 The process system professional determines the design pressure of the container based on the maximum pressure that may be reached at the top of the container under normal working conditions provided by the chemical process professional and the additional system conditions that should be considered by this professional (such as system pressure changes, the impact of the relative position of the safety valve in the system on the design pressure, etc.). 1.0.1.4 The process system specialist shall, together with the chemical process specialist and other related specialists, determine the design pressure of the following special equipment according to specific conditions and special requirements (this design pressure is higher than the design pressure determined according to Table 1.0.4):
(1) The discharge of highly toxic substances is subject to environmental restrictions or directly affects personal and environmental safety; (2) Certain occasions, such as asphalt, paraffin, phthalic anhydride and other condensable materials or certain slurries, which may solidify in the safety device and discharge system during discharge; and water or other materials may freeze during discharge, clogging the discharge system;
(3) Certain precious materials, where it is necessary to reduce discharge losses; (4) Chemical reactions or other reasons may cause a sharp increase in working pressure. 1.0.1.5 When necessary, the process system specialist shall propose the design pressure and design temperature of the equipment components based on the working conditions provided by the chemical process specialist. bzxz.net
1.0.1.6 The process system professional does not determine the equipment design temperature, but needs to provide the normal or maximum (or minimum) working temperature during normal operation to the equipment professional based on the data published by the chemical process professional so that the equipment professional can determine the equipment design temperature. If the process system professional really needs to propose the equipment design temperature, the process system professional can refer to the provisions of 1.0.8 to determine the equipment design temperature. 1.0.2 Glossary
1.0.2.1 Pressure
Except where otherwise specified, all pressures in this provision refer to absolute pressure. 1.0.2.2 Maximum working pressure
The maximum pressure that may be reached at the top of the container during normal operation is also called the maximum normal working pressure. This value is usually proposed by the chemical process professional. (1) Internal pressure container
refers to the maximum pressure that may appear at the top of the container during normal operation. (2) Vacuum container
refers to the maximum vacuum degree that may appear at the top of the container during normal operation. (3) External pressure vessel
refers to the maximum internal and external pressure difference that may occur at the top of the vessel during normal operation. 1.0.2.3 Maximum pressure
is the reference pressure used to determine the design pressure of the vessel. It is the pressure that may be reached at the top of the vessel after adding the additional conditions of the process working system in the process to the maximum working pressure of the vessel. This value is determined by the process system specialty. 1.0.2.4 Design pressure
refers to the maximum pressure set at the top of the vessel (including the additional conditions of the process system), which, together with the corresponding design temperature, is used as the condition for the equipment design load proposed by the process system specialty to the equipment specialty. Its value shall not be lower than the maximum pressure. For equipment with special requirements (such as the case of 1.0.1.4), the design pressure shall be jointly agreed upon by the process system specialty and relevant specialties such as chemical process. In a system with a safety relief device, the design pressure of special equipment is higher than the maximum working pressure except for fire. The safety relief device is only used to protect the equipment in the event of fire. 1.0.2.5 Pump closing pressure
refers to the discharge pressure of the centrifugal pump when the outlet valve is closed and the corresponding flow rate is zero. 1.0.2.6 Safety valve opening pressure (i.e. safety valve set pressure) The static pressure at the safety valve inlet when the safety valve disc begins to rise and the medium is continuously discharged. For details, see "Setting and Selection of Safety Valves" (HG/T20570.2--95). 1.0.2.7 Maximum (minimum) working temperature
refers to the maximum (minimum) metal temperature of the component metal that may occur during the normal operation of the container. 1.0.3 Scope of application
1.0.3.1 This regulation is only applicable to the determination of the design pressure of pressure vessels within the following ranges: (1) 0.1MPa (gauge) ≤ design pressure ≤ 35MPa (gauge): (2) Vacuum degree is higher than 2kPa (200mm water column) (gauge). 1.0.3.2 This regulation is only applicable to the determination of the design pressure of atmospheric pressure vessels within the following ranges: (1) Design pressure is lower than 0.1MPa (gauge); (2) Vacuum degree is lower than or equal to 2kPa (200mm water column) (gauge). 1.0.4 Principles for determining equipment design pressure
1.0.4.1 Principles for selecting equipment design pressure are shown in Table 1.0.4.2
Working under normal pressure
Not equipped with safety relief device
Equipped with safety valve
Equipped with bursting disc
Equipped with safety valve on the outlet pipeline
Design pressure selection table
Design pressure
The design pressure is normal pressure, and is checked with normal pressure plus system additional conditions
Generally, 1.00~1.10 times the maximum pressure (table) 1.05~1.10 times the maximum working pressure (when the maximum working pressure is too high, the lower limit can be taken, otherwise the upper limit can be taken), and not less than the opening pressure of the safety valve
Not less than the maximum calibrated bursting pressure For details, see "Burst Pressure Setting and Selection of Plates" (HG/T20570.3-95)
Not less than the opening pressure of the safety valve plus the pressure drop of the fluid from the container to the safety valve
When the container is located on the inlet side of the pump and there is no safety relief device
When the container is located on the outlet side and there is no safety relief device
No jacket
Vacuum container
Jacket C
With internal pressure
With a clamp
Jacket vacuum
With a safety relief device
No safety relief device
Container wall
Jacket wall
When the medium is butane, butene, butadiene
Stored at room temperature
When the saturated vapor pressure of the medium is 50℃, it is less than
, hydrocarbon Type
Liquid gas 1.57MPa (table)
or mixed liquid
medium is liquid propane or saturated petroleum gas at 50℃
(mixture of propylene and
and vapor pressure is greater than 1.57MPa (table), less than propane or propylene and butene
1.62MPa (table)
etc.:
medium is liquid propylene or saturated medium at 50℃) container
and vapor pressure is greater than 1.62MPa (table), less than 1.94MPa (table)
take the design pressure when there is no safety relief device, and check with 0.10MPa (table) external pressure
take the closing pressure of the pump
design external pressure is 1 .25 times the maximum internal and external pressure difference or 0.1MPa (gauge) for comparison, whichever is smaller. Design for full vacuum conditions [i.e. the design external pressure is 0.1MPa (gauge)]. Design as external pressure vessel, the design pressure is the pressure value specified for the unjacketed vacuum vessel, plus the design pressure inside the jacket, and the stability under the jacket test pressure (external pressure) must be checked. The design internal pressure is selected as specified for the internal pressure vessel. The design external pressure shall not be less than the maximum internal and external pressure difference that may be generated during operation.
0.79MPa (gauge)
1.57MPa (gauge)
1.77MPa (gauge)
2.16MPa (gauge)
1.0.4.2 The steam surface condenser under low pressure is designed for full vacuum conditions. 1.0.4.3 For storage pressure vessels containing liquefied petroleum gas with a volume greater than or equal to 100m3, the design temperature shall be determined by consultation between the equipment designer and the process system designer, but shall not be lower than 40°C. The maximum working pressure and design pressure shall be determined based on the design temperature and the corresponding saturated vapor pressure of the medium. 1.0.4.4 In chemical production, when the same equipment needs to withstand a variety of different working conditions (such as some reactors need to adapt to the various working conditions of various chemical processes such as purging, pressure testing, temperature reduction, chemical reaction, catalyst regeneration, etc.), the design pressure of such equipment shall be determined in accordance with the provisions of 1.0.4 and 1.0.6, and the corresponding change time of working pressure and working temperature at each stage and the change of medium shall be explained to the equipment professionals. 1.0.5 Selection of the highest pressure of equipment in various systems 1.0.5.1 Centrifugal pump system
(1) The highest pressure of the equipment upstream of the last shut-off valve on the pump output side a. If the design pressure of the container on the suction side is selected according to Table 1.0.4, the highest pressure of the equipment on the pump output side is equal to the highest pressure of the container on the pump suction side plus the pump outlet closing pressure difference plus (or minus) the static pressure head. b. If there are special requirements, the highest pressure on the pump output side shall be jointly agreed upon by the process system professionals and relevant professionals.
(2) The highest pressure of the equipment downstream of the last shut-off valve on the pump output side shall be the maximum working pressure given by the chemical process professionals and the highest pressure after adding the system additional conditions. 1.0.5.2 Positive Displacement Pump System
The output pressure of the pump is mainly limited by the strength of the pump casing and the torque of the driver. Therefore, the term "closing pressure" is usually not used for positive displacement pumps, but "stop pressure" (i.e., the pressure difference required to stop the driver). The "stop pressure" is usually much higher than its normal working pressure. Therefore, the equipment on the output pipeline of the positive displacement pump should not be designed according to the "stop pressure". The maximum pressure of the equipment on the output pipeline of the positive displacement pump is the maximum working pressure of the equipment proposed by the chemical process specialty plus the additional conditions of the system. 1.0.5.3 Refrigeration System
The chemical process specialty usually provides the maximum working pressure expected to be reached by the refrigeration system during operation. However, after stopping, the pressure on the high-pressure side will decrease and the pressure on the low-pressure side will increase until the pressure on both sides of the system is equal. The pressure at this time is the "stop pressure".
The maximum working pressure on the high-pressure side is usually the value specified by the process, which is higher than the "stop pressure". The maximum working pressure on the low-pressure side is the "stop pressure" plus a certain margin, which depends on the heat input during the system shutdown and the heat of the refrigerant. Mechanical properties. During long-term parking, the maximum working pressure on the low-pressure side shall be the equilibrium pressure of the refrigerant at the highest expected ambient temperature, or shall be selected in accordance with the provisions of 1.0.5.6. The "parking pressure" is calculated by throttling from the high-pressure side to the low-pressure side. 4
The maximum working pressure plus the system additional conditions, that is, as the maximum pressure of the refrigeration system, the high-pressure side and the low-pressure side are determined separately.
1.0.5.4 Compressor system
Compressor systems that handle steam and steam mixtures and other systems with multiple equipment in series should select the maximum equipment pressure according to a group of equipment (between two shut-off valves) that are subject to the same overpressure source, and the following aspects should be noted: (1) The safety valve should be located as close to the normal temperature as possible in the group; (2) The maximum working pressure of the equipment immediately upstream of the safety valve is the key to determining the maximum pressure of the remaining equipment in the system. High pressure benchmark;
(3) The opening pressure of the safety valve is equal to the design pressure of the upstream equipment minus the pressure drop from the equipment to the safety valve at the maximum normal flow rate.
1.0.5.5 Tower system
The tower system includes the tower, reboiler, top condenser and reflux tank. The maximum pressure of the tower should be determined based on the maximum working pressure of the top of the tower specified by the chemical process specialty and the additional conditions of the system. 1.0.5.6 Containers for liquefied gases
(1) For pressure vessels containing liquefied gases with a critical temperature higher than 50°C, when designed with reliable cold preservation facilities, the maximum pressure is the saturated vapor pressure of the liquefied gas at the highest possible working temperature: if there is no cold preservation facility, the maximum pressure shall not be lower than the saturated vapor pressure of the liquefied gas at 50°C. (2) Containers containing critical temperature For pressure vessels for liquefied gases below 50℃, if they are designed with reliable cold-keeping facilities and can ensure low-temperature storage, their maximum pressure shall not be lower than the saturated vapor pressure at the highest temperature actually measured. For pressure vessels without measured data or cold-keeping facilities, their maximum pressure shall not be lower than the gas pressure at 50℃ when the liquefied gas contained is at the specified maximum filling volume. (3) Pressure vessels containing mixed liquefied petroleum gas at room temperature shall be designed at 50℃. When its saturated vapor pressure at 50℃ is lower than the saturated vapor pressure of isobutane at 50℃, the saturated vapor pressure of isobutane at 50℃ shall be taken as the maximum pressure; when it is higher than the saturated vapor pressure of isobutane at 50℃, the saturated vapor pressure of propane at 50℃ shall be taken as the maximum pressure. If it is higher than the saturated vapor pressure of propane at 50℃, the saturated vapor pressure of renes at 50℃ shall be taken as the maximum pressure.
1.0.6 Principles for final determination of equipment design pressure According to Table 1.0.4, the design pressure determined in the table is the preliminary design pressure of each equipment. The initially determined design pressure also needs to be adjusted according to the relative position of the equipment and the safety relief device in each safety system to obtain the final determined design pressure of the equipment, that is, as the basis for equipment calculation for the equipment specialty, the adjustment principle is as follows:
1.0.6.1 The design pressure (finally determined) of the equipment equipped with a safety relief device and its upstream equipment can be determined according to the design pressure selection table in Table 1.0.4. 1.0.6.2 The design pressure (finally determined) of the equipment downstream of the safety relief device is equal to the opening pressure (or the upper limit of the calibrated pressure) of the safety relief device, or the design pressure determined according to Table 1.0.4, whichever is greater.
1.0.7 Selection of design pressure of equipment in typical systems 1.0.7.1 Selection of equipment design pressure for process systems with safety valves (single equipment is no longer equipped with safety valves) (1)
The design pressure of the equipment located downstream of the safety valve is shown in Figure 1.0.7-1. E101
Distillation tower
Heat exchanger
Reflux tank
Figure 1.0.7-1 Schematic flow chart (—)
The design pressure of the equipment in the system should be considered according to the state that the fluid in the system does not flow when the control valve is closed, and the pressure drop of the pipeline and equipment is zero (i.e. △P0). The design pressure of the reflux tank F101 should be: PD,-PD,+AP
APF—system pressure drop;
PD,—safety valve opening pressure;
-Reflux tank design pressure:
-static pressure head.
(1.0.7-1)
The design pressure of the equipment located upstream of the safety valve is shown in Figure 1.0.7-2. E101
Distillation tower
Heat exchanger
Reflux tank
Figure 1.0.7-2 Schematic flow chart (II)
The system equipment design pressure should reflect the safety valve opening pressure, liquid static pressure head and the pressure loss of pipelines and equipment under the design flow and scaling conditions. The design pressure PD of equipment E101 should be: PD,=PD+(4P)max+AP
AP——liquid static pressure head;
PD, a safety valve opening pressure
a pressure loss of pipelines and equipment,
(1.0.7-2)
The design pressure of equipment with safety valve in the centrifugal pump system is shown in Figure 1.0.7-3. a.
Centrifugal pump
Heat exchanger
Heat exchanger
Figure 1.0.73 Schematic flow chart (III)
When the safety valve is used only for fire protection
Equipment (such as heat exchanger) design pressure - pump outlet closing pressure C103
Heat exchanger
6. When the safety valve is used to protect the equipment in any other situation other than fire or occurring simultaneously with it (such as thermal expansion), the equipment design pressure should be the opening pressure of the safety valve plus the pipeline pressure drop (α). When the pump suction container design pressure is higher than the normal working pressure of the suction container More [that is, there is a high pressure difference between the pump outlet closing pressure and the normal discharge pressure, so that the design pressure of the equipment (such as a heat exchanger) can be set at the pump outlet closing pressure without causing leakage of the safety valve. The equipment design pressure is as follows: Equipment (such as a heat exchanger) design pressure - pump outlet closing pressure (6) When the design pressure of the pump suction container is not much higher than the normal working pressure of the suction container (the suction container design pressure is low), the equipment design pressure is as follows: Equipment (such as a heat exchanger) design pressure - 1.1 × pump outlet closing pressure (4) The design pressure of the equipment located downstream of the positive displacement pump outlet safety valve is determined according to the system type. In all cases, for a full flow system, even if a buffer is installed at the pump, the residual pulse cannot be completely discharged. The equipment design pressure should be able to withstand this residual pulse to avoid leakage of the safety valve in the system. The system is shown in Figure 1.0.7-4.
Positive displacement pump
Figure 1.0.7-4: Schematic flow chart (IV)
In the system, the design pressure of the full-flow equipment downstream of the safety valve is as follows: Equipment (such as heat exchanger) design pressure = safety valve opening pressure C101
Heat exchanger
Whether the pump is equipped with a buffer or not, the opening pressure of the safety valve on the outlet pipe of any single-cylinder pump or double-cylinder pump a.
should be at least 20% higher than the maximum working pressure at the design flow rate of the pump. 6For a pump with three or more cylinders, a buffer is installed on the pump outlet pipe, and the opening pressure of the safety valve on its outlet pipe should be at least 15% higher than the maximum working pressure at the design flow rate of the pump. c. For a pump with one or two cylinders, a buffer is installed on the outlet pipe, and the opening pressure of any safety valve on the full-flow equipment in the pump discharge system should be at least 15% higher than the maximum working pressure, and the equipment design pressure should be adapted to it.
d. For a pump with three or more cylinders, the design pressure of the full-flow equipment in the outlet loop as in clause c shall allow for at least a 12% increment between the opening pressure of any safety valve and the maximum working pressure. 1.0.7.2 Selection of design pressure for equipment in the pump loop (1) Design pressure of equipment in a centrifugal pump loop system a. The centrifugal pump loop has a relief protection system, and the design pressure of the full-flow equipment is as specified in 1.0.7.1(3). 6. The design pressure of equipment in a centrifugal pump loop without a relief protection system is shown in Figure 1.0.7-5. There is equipment (such as a heat exchanger) at the outlet of the centrifugal pump, and there is a control valve upstream of the equipment (such as a heat exchanger), and no valve downstream. 9
Centrifugal pump
Heat exchanger
Figure 1.0.7-5 Schematic flow chart (V)
Heat exchanger
Heat exchanger
In the system, the design pressure of the equipment (such as the heat exchanger) shall be based on the maximum working pressure at the pump outlet minus the pressure drop along the way (the pressure drop at the maximum normal flow rate). The design pressure of the equipment (such as the heat exchanger) = (MNOP-AP) × 1.1 Where
MNOP—maximum working pressure at the pump outlet;
△PF—pressure drop along the way from the pump to the heat exchanger. (1.0.7-3)
(a) For the system described above, when there is a shut-off valve downstream of the pump, the situation is similar to that specified in 1.0.7.1(3), and the design pressure shall be determined in accordance with the provisions of 1.0.7.1(3). (6) For the system described above, but the system is prone to blockage, the design pressure of the equipment (such as the heat exchanger) shall be increased to equal the maximum pressure of the system.
(2) The design pressure of equipment in the volumetric pump loop system is specified in 1.0.7.1(4). 1.0.7.3 Design pressure of tower system equipment
When determining the design pressure of equipment in the tower system, factors such as the pressure drop in the tower (APT) and the static liquid column (HD) should be considered. A typical tower system is shown in Figure 1.0.7-6. The design pressure of the equipment in Figures 1.0.7-6 is as follows: Tower design pressure = DPr (referring to the design pressure of the tower top, determined according to the principle of determining the equipment design pressure in 1.0.4) Tower bottom design pressure = DP+△P+HD
Safety valve opening pressure P = DP-AP
(1.0.7-4)
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