Some standard content:
Valve settings
HG/T20570.18-95
Compiled by: China Huanqiu Chemical Engineering Corporation Approved by: Ministry of Chemical Industry
Implementation date: September 1, 1996 Prepared by:
Yang Yi of China Huanqiu Chemical Engineering Corporation
Reviewed by:
Gong Renwei, Process System Design Technology Center of Ministry of Chemical Industry
Scope of application
1.0.1 This regulation applies to the chemical process system specialty. The valves mentioned do not include safety valves, steam traps, sampling valves and pressure reducing valves, but include the setting of pipe fittings such as flow limiting orifice plates and blind plates that have similar functions to reading valves. Cut-off valves are the general name for these valves. The function of the cut-off valve is to cut off the fluid or change the flow direction of the fluid. It should be set according to the requirements of production (including normal production, start-up and shutdown and special working conditions), maintenance and safety, and economic rationality should also be considered.
1.0.2 Valve setting and selection of appropriate categories (not models). Valves are an important task for process system professionals when compiling PI diagrams. The contents described in this regulation take into account the general requirements of production and safety. When referring to this regulation for engineering design, system professionals should make choices based on the specific conditions of the project, local meteorological conditions, inter-factory cooperation, device operation requirements, fluid characteristics, special requirements of users and economic efficiency. 1.0.3 This regulation comprehensively introduces the valve settings for the listed situations. For detailed requirements of various chemical units, see the basic unit model of the PI diagram of the corresponding unit. 1.0.4 This regulation also introduces the characteristics of general industrial valves and factors to be considered in the selection of valves in engineering design.
2.0.1 Valve setting at the boundary
Valve setting
2.0.1.1 Cut-off valves should be installed at the device boundary (usually inside the device boundary) for process material and utility material pipelines, with the following exceptions:
1) Exhaust system.
(2) The discharge pipe when the emergency discharge tank is located outside the boundary; if a valve must be installed in these two situations, it is also necessary to seal it open (CSO).
(3) Material pipes that will not cause cross-contamination and accidents (4) Material pipes that do not require measurement.
Figure 2.0.1 Valve settings at the boundary
2.0.1.2 See the several methods of valve settings at the boundary shown in Figure 2.0.1. Among them, (1) is suitable for cutting off general materials; when cross-contamination may cause safety accidents such as explosions and fires or important product quality accidents, in order to prevent internal leakage of the valve, (2), (4), and 5) in Figure 2.0.1 are used with blind plates; (3) and (5) in Figure 2.0.1 are suitable for situations where the upstream or downstream line needs to be swept after feeding. Valve α can also be used for purging, draining, and checking for leakage. The detection and metering instrument can also be installed between the two valves in series. (5) in Figure 2.0.1 is applicable to places where pressure changes may be large, and the check valve can play an instantaneous shut-off role.
2.0.2 Setting of root valve
2.0.2.1 When a medium needs to be transported to multiple users, in order to facilitate maintenance or energy saving and antifreeze, in addition to the shut-off valve installed near the equipment, a shut-off valve is installed on the branch pipe close to the main pipe, which is called a root valve. It is usually used in public material systems (such as steam, compressed air, nitrogen, etc.). When a process material is led to multiple users (such as solvents), the same setting is required. The valve shown in Figure 2.0.2 is the root valve. When there are requirements such as energy saving and antifreeze, the distance between the root valve and the main pipe should be as small as possible. bzxz.net
To the user
Figure 2.0.2 Schematic diagram of root valve setting
2.0.2.2 Root valves should be installed on all public material pipeline branches in the chemical plant to avoid shutdown of the plant or the entire plant due to damage to individual valves. 2.0.2.3 Steam and overhead water pipes, even if they only lead to one device or one equipment, need to be equipped with root valves when the branch pipe exceeds a certain length to reduce dead zone, reduce energy consumption and prevent freezing. 2.0.2.4 Two or more steam-using equipment that are mutually backup should determine whether to install branch pipe root valves according to their importance in production.
2.0.2.5 The root valve of the public material branch pipe is set by the pipeline professional during the pipeline layout design, and the process system professional needs to review whether the branch is appropriate. The root valve is indicated on the public material PI diagram (distribution diagram). 2.0.3 Double valves
For storage tanks containing liquefied petroleum gas, other flammable, toxic, precious liquids, highly corrosive liquids (such as concentrated acid, caustic soda) and special requirements of 2.0.3.1
(such as malodorous media that cause serious environmental pollution), two valves (double valves) in series should be installed on the pipelines leading to other equipment at the bottom, regardless of whether there are valves near other equipment, and one of them should be close to the tank connection port. When the storage tank capacity is large or the distance is far, this valve is preferably a remote control valve. In order to reduce the number of valves, if the operation allows, several pipelines can be combined and connected to a pipe port as shown in Figure 2.0.3--1.
The drain valve of the container containing the above media should also be a double valve, as shown in Figure 2.0.3-1. The sampling valve and drain valve on the above media pipeline should be determined according to the frequency of operation and other conditions to decide whether to use double valves.
Figure 2.0.3-1 Double valve setting of the common valve for inlet and outlet of the tank bottom and double valve setting of the drain pipe
2.0.3.2 Equipment that needs to be cut off for maintenance, cleaning or regeneration during operation should be equipped with double valves, and a check valve should be set between the two valves. When the equipment is cut off from the system, the double valve is closed and the check valve is opened. Other measures can be taken to replace the double valve. The spare reboiler has a large valve diameter and strict requirements on the pressure drop. At this time, a single valve (generally a rising stem gate valve) can be installed and equipped with an 8-shaped blind plate. On one side of the reboiler, a separate drain valve should be set, as shown in Figure 2.0.5-1. For equipment that needs to switch regeneration, since the regeneration temperature is often much higher than the working temperature, if a reversible bend is installed at this time, it can be switched safely and avoid huge thermal stress. See Figure 2.0.32.
Regeneration medium inlet
Process material inlet
Process material outlet
Regeneration medium outlet
Figure 2.0.3-2 Schematic diagram of regeneration return elbow
The public material pipeline should not be fixedly connected to the process material pipeline as much as possible, and should be connected through a hose station with a quick 2.0.3.3
connector. When the operation requires direct connection, it should be connected with a double valve, with a check valve in the middle. The check valve opens when the feed is stopped, or is sealed open (CSO). In situations where the pressure may fluctuate, a check valve is added, as shown in Figure 2.0.3-3.
Process material pipe
Public material
As close as possible
Figure 2.0.3-~3 Connection of public material and process material pipeline If the pressure gauge of the public material is far away from this valve group, a pressure gauge can be installed between the two valves so that the pressure of the public material can be monitored on the spot when in use. This connection method is also suitable for occasions where auxiliary materials such as oxygen and hydrogen are frequently input into the process system. In order to avoid liquid materials from contaminating the water system, when water needs to be added frequently, the water pipe should be connected to the gas phase space of the equipment. In this case, double valves may not be installed. 2.0.3.4: When designing high-pressure waste heat boilers and steam systems, the chemical process system specialty can refer to and implement the relevant regulations of the State Electric Power Construction Bureau of the Ministry of Electric Power Industry: "Technical Regulations for the Design of Steam and Water Pipelines in Thermal Power Plants" (DLGJ233-81) (Trial): Articles 7-7 1: Pg ≥ 40* Two stop valves should be installed in series for drainage and drainage of pipelines. Articles 7-8: Two stop valves should be installed in series for the venting device of the Pg ≥ 40* pipeline. * Pressure unit is kg/cm (gauge).
When using, please pay attention to the latest version of the regulations 2.0.3.5 For hydrocarbons and toxic, harmful chemicals and other materials connected with other process materials, double valves are installed on the upstream and venting and draining pipes. Please refer to Table 2.0.3. Temperature and pressure conditions for double valves
Media name
Heavy hydrocarbons (kerosene, lubricating oil, asphalt, etc.) Reiter vapor pressure is lower than 1.05×105Pa (table), hydrocarbons with flash point lower than 37.8℃ (raw gasoline, etc.)
Working temperature
≥200
10'Pa (table)
Working pressure
Media name
Reiter vapor pressure is higher than 1.05×10°Pa (table ), hydrocarbons with a vapor pressure lower than 4.57X10°Pa (table) (butane, light naphtha, etc.) hydrocarbons with a vapor pressure higher than 4.57×10'Pa (table) (propane, etc.)
H., liquefied petroleum gas
Any flammable gas
Toxic gas and harmful chemical agents
2.0.4 Working temperature of public material station (public engineering station)
≥150
≥120
Continued Table 2.0.3
Working pressure 10°Pa (gauge)
2.0.4.1 The public material station (hereinafter referred to as the public station) in the chemical plant can be set up according to the coverage area of about 15m radius, and the plant public station outside the plant area is set up according to the design requirements. 2.0.4.2 The specifications of the cut-off valves for each medium range from DN15 to DN50 depending on the characteristics of the plant. The valves and joints of the public materials on the station can be intentionally inconsistent, but the order of arrangement of the media in each public station should be consistent, so as to avoid the expansion of accidents caused by connecting the wrong media in an emergency. 2.0.4.3 The water pipes of outdoor public stations in cold areas can be arranged as follows: (1) Multi-layer frame: valves are set according to conventional piping, cut off near the ground of the bottom floor and set up quick connectors, and water is drawn from the nearby water valve well when in use. If a fixed pipeline plus a drain valve is used, the drain valve should be set in the valve well.
(2) For storage tank areas or loading and unloading platforms, the valve well position can be adjusted appropriately in consultation with the water supply and drainage professionals, and the water supply valve can be installed in the valve well.
(3) Insulated together with the steam pipe.
2.0.4.4 In order to adapt to the use of pneumatic tools during maintenance, the diameter of the compressed air pipe and the cut-off valve on the public station can be appropriately increased, for example, from DN25 to DN50. 2.0.4.5 For equipment, the pipe joints that match the pipeline and the public station can be shared with the drain and vent ports of the equipment pipeline for small devices; for large devices, a dedicated public material connection port (UC) can be set on the equipment. This connection port and the vent valve should be located at the bottom and top of the vertical equipment or at both ends of the length direction of the horizontal equipment. 2.0.4.6 When the common material pipeline may be contaminated due to the backflow of process fluid, a check valve shall be installed downstream of the common material pipeline shut-off valve
To keep the condensed steam pressure in the top condenser as close to the tower top pressure as possible, the pressure drop of the tower top pipeline shall be minimized. Except for special needs of process control, no shut-off valve shall be installed on the pipeline from the tower top to the condenser.
2.0.5.2 The connecting pipeline between the reboiler (including the intermediate reboiler) and the tower body shall not be equipped with a shut-off valve, except for those required for process control or those that need to be cleaned during the operation of the device. When a valve is required on the connecting pipe between the thermosyphon reboiler and the tower body, a gate valve with the same diameter as the connecting pipe shall be used. An 8-shaped blind plate shall be installed between the valve and the reboiler. At the same time, the reboilers shall be equipped with their own drain valves, as shown in Figure 2.0.5-1.
A one-way thermosyphon reboiler should have a connecting pipe and a cut-off valve between the reboiler material inlet and the tower bottom discharge port, as shown in Figure 2.0.5-2. The diameter of this valve should be at least one area larger than the tower bottom discharge pipe
Figure 2.0.5-1 Spare thermosyphon reboiler process side valve setting 487
Reboiler
Connecting valve;
Figure 2.0.5-2
Reboiler
Figure 2.0.5-3
Discharge valve.
One-way reboiler valve setting
Throttle valve
Throttle valve setting for forced circulation reboiler
(Other conventional valves are omitted)
For a forced circulation reboiler, a throttle valve is installed on the pipeline from the reboiler to the tower, close to the tower body. This valve can be replaced by a flow-restricting orifice plate. However, this throttling valve can be eliminated when excessive flash evaporation does not reduce the efficiency improved by forced circulation or reduce the logarithmic mean temperature difference. See Figure 2.0.5-3. 2.0.5.3 Except for process control requirements, no shut-off valve is set on the side discharge and steam return pipeline of the stripping tower. 2.0.5.4 For towers where the feed composition may change, additional feed ports should be added according to the designed change range, and the shut-off valve of each feed port should be close to the feed pipe opening of the tower body. 488
Since decompression will produce two-phase flow materials (liquefied gas or saturated absorption liquid), the feed shut-off valve should also be as close to the feed pipe opening of the tower as possible.
2.0.5.5 No shut-off valve is set on the gas phase pipeline from the top of the tower to the bottom of another tower with a large number of plates and a tower body that is too long and connected in series in two sections. The cut-off valve or control valve added to the kettle liquid due to process control needs should be as close as possible to the pipe mouth of the receiving tower, as shown in Figure 2.0.5-4.
Figure 2.0.5-4 Schematic diagram of valve setting of series tower 2.0.6 Heat exchanger
2.0.6.1 Except for heat exchangers that need to be (or can be) cut off during control or device operation, cut-off valves are generally not added on the process material side.
2.0.6.2 If both sides of the heat exchanger are process fluids, a cut-off valve is only installed on one side according to the operation and control conditions. 2.0.6.3 When a heat exchanger needs to be bypassed due to production or maintenance, cut-off valves are installed on both the inlet and outlet pipes and the bypass. Bypass is usually required in the following situations:
Some processes in the production cycle do not require heat transfer and the heat exchanger should be cut off; (1)
Automatic or manual adjustment of process temperature;
(3) Temporary cut-off of the heat exchanger due to maintenance. 2.0.6.4 Steam Heating Equipment
(1) The heating steam inlet pipe should be equipped with a manual regulating valve or automatic control valve with good regulating performance. (2) A non-condensable gas discharge valve must be installed at an appropriate position. This valve should be located at the highest point on the equipment away from the steam inlet, as shown in Figure 2.0.6.
As small as possible
a-intake valve; b-non-condensable gas, discharge valve c-drain valve group. Figure 2.0.6 The non-condensable gas discharge valve of steam heating equipment should be set as small as possible
(3) In the case of coil heating, the check valve before the drain valve is used to discharge non-condensable gas, and no non-condensable gas discharge valve is required.
2.0.6.5 Water Cooling Equipment
(1) The cooling water is heated during operation and releases dissolved gas. An exhaust valve must be installed at an appropriate position of the heat exchange equipment (see 2.0.6.4). This valve is also used to discharge gas in the equipment when starting up, or to take in air when shutting down. (2) Each equipment’s water inlet and each cooling circuit inlet of the pump should be equipped with a shut-off valve. When the water volume needs to be adjusted, this valve should be an automatic valve or a manual valve with good adjustment performance. (3)
Gravity return water: No shut-off valve is installed at the water outlet. (4) Pressure return water: The water outlet should generally be equipped with a shut-off valve. Only several equipment that can be shut down at the same time can share a shut-off valve at the outlet.
(5) A drain valve is usually installed at the low point of the pipeline. When the drain valve on the pipeline cannot drain the water in the equipment, it is used to5—2
Reboiler
Figure 2.0.5—3
Discharge valve.
Valve settings for one-way reboiler
Throttle valve
Throttle valve settings for forced circulation reboiler
(Other conventional valves omitted)
A throttle valve is installed on the pipeline from the reboiler to the tower, close to the tower body. This valve can be replaced by a flow-restricting orifice plate. However, this throttle valve can be cancelled when excessive flash evaporation does not reduce the efficiency improved by forced circulation or reduce the logarithmic mean temperature difference. See Figure 2.0.5-3. 2.0.5.3 Except for process control requirements, no shut-off valve is installed on the side discharge and steam return pipeline of the stripping tower. 2.0.5.4 For towers where the feed composition may change, additional feed ports should be added according to the designed change range, and the shut-off valves of each feed port should be close to the feed pipe opening of the tower body. 488
Since decompression will produce two-phase flow materials (liquefied gas or saturated absorption liquid), the feed shut-off valve should also be as close to the feed pipe opening of the tower as possible.
2.0.5.5 A shut-off valve is not installed on the gas phase pipeline from the top of a tower with many plates and a long tower body to the bottom of another tower in series. The shut-off valve or control valve added to the kettle liquid due to process control needs should be as close to the pipe opening of the receiving tower as possible, as shown in Figure 2.0.5-4.
Figure 2.0.5-4 Schematic diagram of valve setting of series tower 2.0.6 Heat exchanger
2.0.6.1 Except for heat exchangers that need to be (or can be) shut off during control or device operation, shut-off valves are generally not installed on the process material side.
2.0.6.2 If both sides of the heat exchanger are process fluids, a shut-off valve is only installed on one side according to the operation and control conditions. 2.0.6.3 When a heat exchanger needs to be bypassed for production or maintenance, a shut-off valve shall be installed on the inlet and outlet pipes and the bypass. A bypass is usually required in the following situations:
Certain processes in the production cycle do not require heat transfer and the heat exchanger should be shut off; (1)
Automatic or manual adjustment of process temperature;
(3) Temporary shut-off of the heat exchanger for maintenance. 2.0.6.4 Steam heating equipment
(1) The heating steam inlet pipe shall be equipped with a manual regulating valve or automatic control valve with good adjustment performance. (2) A non-condensable gas discharge valve must be installed at an appropriate position. This valve should be located at the highest point on the equipment away from the steam inlet side, as shown in Figure 2.0.6.
As small as possible
a - air inlet valve; b - non-condensable gas, discharge valve c - steam trap group. Figure 2.0.6 The non-condensable gas discharge valve of steam heating equipment should be set as small as possible
(3) In the case of coil heating, the check valve before the steam trap is used to discharge non-condensable gas, and no non-condensable gas discharge valve is required.
2.0.6.5 Water cooling equipment
(1) The cooling water is heated during operation and releases dissolved gas. An exhaust valve should be installed at an appropriate position of the heat exchange equipment (see 2.0.6.4). This valve is also used to discharge the gas in the equipment when starting up, or to intake air when shutting down. (2) Each equipment’s water inlet and each cooling circuit inlet of the pump should be equipped with a shut-off valve. When the water volume needs to be adjusted, this valve should be an automatic valve or a manual valve with good adjustment performance. (3)
Gravity return water: no shut-off valve is installed at the water outlet. (4) Pressure return water: a shut-off valve should generally be installed at the water outlet. Only several equipment that can be shut down at the same time can share a shut-off valve at the outlet.
（5）A drain valve is usually installed at the low point of the pipeline. When the drain valve on the pipeline cannot drain the water in the equipment,5—2
Reboiler
Figure 2.0.5—3
Discharge valve.
Valve settings for one-way reboiler
Throttle valve
Throttle valve settings for forced circulation reboiler
(Other conventional valves omitted)
A throttle valve is installed on the pipeline from the reboiler to the tower, close to the tower body. This valve can be replaced by a flow-restricting orifice plate. However, this throttle valve can be cancelled when excessive flash evaporation does not reduce the efficiency improved by forced circulation or reduce the logarithmic mean temperature difference. See Figure 2.0.5-3. 2.0.5.3 Except for process control requirements, no shut-off valve is installed on the side discharge and steam return pipeline of the stripping tower. 2.0.5.4 For towers where the feed composition may change, additional feed ports should be added according to the designed change range, and the shut-off valves of each feed port should be close to the feed pipe opening of the tower body. 488
Since decompression will produce two-phase flow materials (liquefied gas or saturated absorption liquid), the feed shut-off valve should also be as close to the feed pipe opening of the tower as possible.
2.0.5.5 A shut-off valve is not installed on the gas phase pipeline from the top of a tower with many plates and a long tower body to the bottom of another tower in series. The shut-off valve or control valve added to the kettle liquid due to process control needs should be as close to the pipe opening of the receiving tower as possible, as shown in Figure 2.0.5-4.
Figure 2.0.5-4 Schematic diagram of valve setting of series tower 2.0.6 Heat exchanger
2.0.6.1 Except for heat exchangers that need to be (or can be) shut off during control or device operation, shut-off valves are generally not installed on the process material side.
2.0.6.2 If both sides of the heat exchanger are process fluids, a shut-off valve is only installed on one side according to the operation and control conditions. 2.0.6.3 When a heat exchanger needs to be bypassed for production or maintenance, a shut-off valve shall be installed on the inlet and outlet pipes and the bypass. A bypass is usually required in the following situations:
Certain processes in the production cycle do not require heat transfer and the heat exchanger should be shut off; (1)
Automatic or manual adjustment of process temperature;
(3) Temporary shut-off of the heat exchanger for maintenance. 2.0.6.4 Steam heating equipment
(1) The heating steam inlet pipe shall be equipped with a manual regulating valve or automatic control valve with good adjustment performance. (2) A non-condensable gas discharge valve must be installed at an appropriate position. This valve should be located at the highest point on the equipment away from the steam inlet side, as shown in Figure 2.0.6.
As small as possible
a - air inlet valve; b - non-condensable gas, discharge valve c - steam trap group. Figure 2.0.6 The non-condensable gas discharge valve of steam heating equipment should be set as small as possible
(3) In the case of coil heating, the check valve before the steam trap is used to discharge non-condensable gas, and no non-condensable gas discharge valve is required.
2.0.6.5 Water cooling equipment
(1) The cooling water is heated during operation and releases dissolved gas. An exhaust valve should be installed at an appropriate position of the heat exchange equipment (see 2.0.6.4). This valve is also used to discharge the gas in the equipment when starting up, or to intake air when shutting down. (2) Each equipment inlet and each cooling circuit inlet of the pump should be equipped with a shut-off valve. When the water volume needs to be adjusted, this valve should be an automatic valve or a manual valve with good adjustment performance. (3)
Gravity return water: no shut-off valve is installed at the water outlet. (4) Pressure return water: a shut-off valve should generally be installed at the water outlet. Only several equipment that can be shut down at the same time can share a shut-off valve at the outlet.
（5）A drain valve is usually installed at the low point of the pipeline. When the drain valve on the pipeline cannot drain the water in the equipment,
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