HG/T 20512-2000 Instrument piping and wiring design regulations (with clause explanation)
Some standard content:
Industry Standard of the People's Republic of China
Design Code for Instrument Tubing and Wiring
Design Code for Instrument Tubing and WiringHG/T20512-2000
Editor: Design Institute of Nanhua Group CorporationApproval Department: State Bureau of Petroleum and Chemical IndustryImplementation Date: June 1, 2001National Chemical Engineering Construction Standard Editing Center (formerly the Engineering Construction Standard Editing Center of the Ministry of Chemical Industry) Beijing
This regulation applies to the piping and wiring design of the measuring pipelines, power supply and signal transmission systems of the measuring and control instruments of chemical plants.
When implementing this regulation, it shall also comply with the provisions of the relevant current national standards. 235
Basic Principles
2.0.1 The design of piping and wiring engineering shall ensure that the instrument measurement is accurate, the signal transmission is reliable, the lag is reduced, the economy, safety and practicality are achieved, the pipelines (lines) are neat and beautiful, and the construction and maintenance are convenient. 2.0.2 When designing piping and wiring, corresponding measures should be taken for environments with fire and explosion hazards, dust, corrosion, high temperature, humidity, vibration, static electricity, lightning strikes and electromagnetic field interference. 236
Selection of measuring pipelines
3.1 Material of measuring pipelines
The material of measuring pipelines (including valves and pipe fittings) should be comprehensively considered according to the physical properties, temperature, pressure level of the measured medium and 3.1.1
environmental conditions, and shall not be lower than the requirements of the "Pipeline Material Grade Table" specified in the project. 3.1.2
Material.
The material of the measuring pipeline for non-corrosive media should be carbon steel or stainless steel. The material of the measuring pipeline for corrosive media should be selected with the same or higher anti-corrosion performance as the process pipeline or equipment. The material of the high-pressure pipeline should comply with the relevant regulations for high-pressure pipelines. When the measuring pipeline inevitably needs to pass through a corrosive place, even if the measured medium is not highly corrosive, its material should be comprehensively considered according to the medium passing through it and the environmental corrosion protection requirements. Measuring pipelines, pipe fittings and valves should be made of the same material or metal materials with similar corrosion potentials. 3.1.6
The sampling pipeline material of the analytical instrument should be stainless steel. 3.2 The diameter of the measuring pipeline
The diameter of the measuring pipeline can be selected according to Table 3.2.1. 3.2.1
Diameter selection table for measuring pipelines
Place of use and nominal pressure (MPa)
Low-pressure system containing dust (PN≤0.25)PN6.3
PN≤16
Outer diameter×wall thickness (mmxmm) (metric)
Weight 22×3 (or steel pipe)
Nominal diameter×wall thickness (in/in) (imperial)
Φ12×1.5, Φ14×2, Φ18×3, Φ22×31/2/0.065, 5/8/0.095, 3/4/0.12Φ12×2.Φ14×3, Φ18×4.Φ22×4Φ14×4.Φ19×5
Note: Attention should also be paid to the influence of medium temperature. 1/2/0.083、3/8/0.083
3.2.2 The diameter of the sampling pipeline of the analytical instrument should be Φ6×1, Φ8×1, Φ10×1. The diameter of the return pipeline and the discharge pipeline of the fast loop can be appropriately enlarged and should also meet the requirements of the manufacturer. 238
Selection of pneumatic signal pipeline
The material and type of the pneumatic signal pipeline can be selected according to Table 4.0.1. Table 4.0.1
Material and type
Copper tube
PVC sheathed copper single tube
PVC sheathed copper pipe and cable
Stainless steel tube
Polyethylene single tube
Polyethylene pipe and cable
Nylon single tube
Nylon pipe and cable
Note: "○" indicates applicable;
Piping behind the instrument panel
Pneumatic signal pipeline selection table
Control room
"*" indicates not applicable.
General location
Corrosive location
4.0.2 The diameter of the pneumatic signal pipeline should be 06×1. In special cases, such as large diaphragm head regulating valve and cylinder valve with larger diameter. For control devices with short switching time and long transmission distance, Φ8×1 or Φ10×1 can also be selected. 4.0.3 The operating temperature range of nylon and polyethylene pipes (cables) should meet the requirements of the manufacturer. They should not be used in places with large changes in ambient temperature, fire hazards, and important occasions. 4.0.4 When production equipment has anti-static requirements, it is prohibited to use nylon and polyethylene pipes (cables). 4.0.5 For production equipment with a take-over box, multi-core pipes and cables should be used from the control room to the take-over box. The number of spare cores of nylon and polyethylene pipes and cables should not be less than 20% of the number of working cores. The number of spare cores of stainless steel and copper pipes and cables should not be less than 10% of the number of working cores. From the take-over box to the regulating valve or field instrument, the pipeline should use PVC sheathed copper pipes or stainless steel pipes.
5 Laying of measuring pipelines and pneumatic signal pipelines 5.0.1 The laying of measuring pipelines and pneumatic signal pipelines should avoid places with high temperature, process medium discharge ports, easy leakage, mechanical damage, corrosion, vibration, and obstruction of maintenance. 5.0.2 The measuring pipeline and pneumatic signal pipeline should not be laid underground, but should be laid overhead. The fixing should be beautiful and firm, with fewer bends and crosses. The laying of pneumatic pipelines should be relatively concentrated and kept horizontal and vertical. 5.0.3 For the measured media that are easy to freeze, condense, solidify, crystallize, and vaporize, the measuring pipeline should take heating or insulation measures. Specifically, it shall be implemented in accordance with the "Design Regulations for Heating and Insulation of Instruments and Pipelines" (HG20514). The sampling pipeline of the analytical instrument and the measuring pipeline from the measuring point to the field instrument should be as short as possible, and the length should not be greater than 5.0.4
15m.
The laying of the measuring pipeline should avoid the generation of additional static pressure head, density difference and bubbles in the pipeline. 5.0.5
5.0.6 When the measuring pipeline is laid horizontally, it should have a slope of 1/10~1/100, and its inclination direction should ensure that the entrained gas or condensate can be removed. If the condensate or gas is difficult to return to the process pipeline (or equipment) by gravity, for the liquid phase measured medium, an exhaust device should be installed at the highest point of the measuring pipeline. For the gas phase measured medium, a liquid discharge device should be installed at the lowest point of the measuring pipeline. When the measured medium contains sediment or dirt, a sewage discharge device should be installed at the lowest point of the measuring pipeline. 5.0.7 When designing the discharge port, toxic, corrosive and seriously polluting media shall not be discharged arbitrarily, and must be discharged to the designated location or closed discharge system in the device. 5.0.8 For measuring pipelines with a pressure greater than 10MPa, a safety pressure relief facility (discharge valve or joint with pressure relief hole) should be installed, and the discharge port should face the safe side.
Selection of wires and cables
Wire and cable core cross-sectional area
The core cross-sectional area should meet the requirements of the detection and control circuits for line impedance, as well as the requirements for the mechanical strength of the cable during construction.
The core cross-sectional area can be selected according to Table 6.1.2. 6.1.2
Occasions of use
Control room main power supply box to distribution box or cabinetControl room distribution box to field power supply box
Control room distribution box to field instrument (power line)Field power supply box to field instrument (power line)Control room to field wiring box (signal line)Field wiring box to field instrument (signal line)Control room to field instrument (signal line)
Control room to field instrument (alarm interlock line)Control room to field solenoid valve
Control room to motor control center MCC (interlock line)Intrinsically safe circuit
Wire and cable core cross-sectional area selection table
Copper core wire cross-sectional area
Note: For the cross-sectional area of wiring inside the instrument panel (box, cabinet), see Article 8.0.1 of these regulations. Cross-sectional area of copper core cable
Two-core and three-core
Four-core and above
6.1.3 The cross-sectional area of thermocouple compensation wire should be 1.5~2.5mm2. If multi-core compensation cable is used, the cross-sectional area of its core can be 0.75~1.0mm2 under the condition that the line resistance meets the measurement requirements.241
The cross-sectional area of the core of the grounding wire should be selected in accordance with the relevant provisions of the "Instrument System Grounding Design Regulations" (HG20513)6.1.4
.
The cross-sectional area of the core of the power distribution line should be selected in accordance with the relevant provisions of the "Instrument Power Supply Design Regulations" (HG20509)6.1.5
6.2 Types of wires and cables
6.2.1 In general, copper core polyvinyl chloride insulated wires should be used for wires; copper core polyvinyl chloride insulated and polyvinyl chloride sheathed cables should be used for cables.
6.2.2 In cold regions and places with high or low temperatures, the temperature range allowed for the use of wires and cables should be considered. 6.2.3 In places with fire hazards, flame-retardant cables should be used. 6.2.4 In explosion-hazardous areas, when adopting intrinsically safe systems, control cables for intrinsically safe circuits should be selected. The distributed capacitance and inductance of the cables used must meet the requirements of intrinsically safe circuits. 6.2.5 When adopting a DCS or PLC detection and control system, or when the manufacturer has special requirements for signal lines, shielded cables should be selected for signal circuits. The selection of shielding types should comply with the provisions of Table 6.2.5. Table 6.2.5
Shielding type selection table for shielded cables for DCS (PLC) signals Serial number
Cable specifications
Connecting signal
Analog/digital signal
Analog/digital signal
Thermocouple compensation cable
Thermocouple compensation cable
Thermal resistor
Thermal resistor
Separate shielding
Note: 1. ☆ indicates need. 2. The data communication cable in the DCS should be selected according to the requirements of the manufacturer. Total shielding
6.2.6 If the instrument manufacturer has special requirements for the instrument signal transmission cable, it should be selected according to the manufacturer's requirements or provided by the manufacturer. For example, the signal transmission cable for shaft vibration and shaft displacement signals should use a cable with separate shielding and total shielding.
The model of the thermocouple compensation wire should correspond to the thermocouple graduation number and can be selected according to Table 6.2.7. 6.2.7
Thermocouple category
Platinum 30-Platinum 6
Platinum 10-Platinum
Nickel-chromium-nickel-silicon
Nickel-chromium-copper-nickel
Iron-copper-nickel
Copper-steel-nickel
Tungsten 3-Tungsten 25
Tungsten 3-Tungsten 26Www.bzxZ.net
Nickel-chromium-silicon-nickel-silicon
Compensation wire model selection table
Graduation number
WRe3-WRe25||tt| |WRe5-WRe26
Name and model of compensation conductor
KC, KX
WC3/25
WC5/26
Select the type of compensation conductor according to the place where the compensation conductor is used: ordinary type is selected for general places: 6.2.8 for high temperature places
Select high temperature resistant type: flame retardant type is selected for fire hazard places; shielded type should be selected for places using DCS or PLC: intrinsically safe type is selected when using intrinsically safe system.
Laying of wires and cables
General provisions
7.1.1. Wires and cables should be laid in a concentrated manner along a short route, avoiding heat sources, moisture, process medium discharge ports, vibration, static electricity and electromagnetic field interference, and should not be laid in a position that affects operation and hinders equipment maintenance. When it cannot be avoided, protective measures should be taken.
7.1.2 Wires and cables should not be laid in parallel above high-temperature process pipelines and equipment or below process pipelines and equipment with corrosive liquids.
7.1.3 Different types of signals should not share a cable. Wires and cables should be placed in metal protective tubes or in covered metal junction bridges. When instrument signal cables are laid crosswise with power cables, they should be at right angles; when laid parallel to power cables, the minimum allowable distance between the two should comply with the provisions of Table 7.1.3. Minimum spacing between instrument cables and power cables laid in parallel (mm) Table 7.1.3
Length of parallel laying (m)
Power cable voltage and working current
125V,10
250V,50A
200~400V,100A
400~500V,200A
3000~10000V,800A
Note: Instrument signal cables include compensation wires laid in steel pipes or covered metal bus bridges. 7.1.4 The wiring of intrinsically safe circuits must be laid separately from the wiring of non-intrinsically safe circuits. ≥500
7.1.5 When intrinsically safe circuits and non-intrinsically safe circuits are laid in parallel, the minimum allowable distance between the two shall comply with the provisions of Table 7.1.5.
Current of non-intrinsically safe circuits
Voltage of non-intrinsically safe circuits
More than 440V
Below 440V
Below 220V
Below 110V
Below 60V
Minimum spacing between intrinsically safe circuits and non-intrinsically safe circuits in parallel (mm)Minimum spacing for parallel laying (mm)
More than 100A
Below 100A
The communication bus should be laid separately and protective measures should be taken. In the case of many on-site detection points, it is advisable to use an on-site junction box. Below 50A
The number of spare cores of multi-core cables should be 10%~15% of the number of working cores. The on-site junction box should be set up in a location close to the detection point, where the instrument is concentrated and easy to maintain. The same junction box should not be used to transmit different types of signals. For explosion-hazardous places, a junction box with the corresponding explosion-proof grade must be selected. Cables of outdoor junction boxes should not enter or exit from the top of the box. The line entry method of the control room should comply with the "Control Room Design Regulations" (HG20508). 7.2 Cable bridge laying method
10A or less
In the process device area, the cable bridge should be laid overhead. When the cable bridge is installed on the process pipe rack7.21
, it should be arranged on the side or above the process pipe rack with better environmental conditions. The material of the cable bridge should be selected according to the environmental characteristics of the laying site. 7.2.2
1 In general, galvanized carbon steel cable bridge can be used. 2 In environments containing dust, water vapor and general corrosion, plastic spraying or hot-dip galvanized carbon steel cable bridge can be used. 3 In severely corrosive environments, when there is no electromagnetic interference, fiberglass cable bridge can be used; when there is electromagnetic interference, carbon steel cable bridge with zinc-nickel alloy coating or high-efficiency anti-corrosion paint can be used. A fiberglass bridge with metal shielding net can also be used.
4 The same material bridge should be used for the same device. The AC power supply line and safety interlock line in the bridge should be separated from the instrument signal line by metal partitions. 7.2.33 Different types of signals should not share a cable. Wires and cables should be placed in metal protective tubes or in covered metal bridges. When instrument signal cables are laid across power cables, they should be at right angles; when laid parallel to power cables, the minimum allowable distance between the two should comply with the provisions of Table 7.1.3. Minimum spacing between instrument cables and power cables laid in parallel (mm) Table 7.1.3
Length of parallel laying (m)
Power cable voltage and working current
125V,10
250V,50A
200~400V,100A
400~500V,200A
3000~10000V,800A
Note: Instrument signal cables include compensation wires laid in steel pipes or covered metal bridges. 7.1.4 The wiring of intrinsically safe circuits must be laid separately from the wiring of non-intrinsically safe circuits. ≥500
7.1.5 When intrinsically safe circuits and non-intrinsically safe circuits are laid in parallel, the minimum allowable distance between the two shall comply with the provisions of Table 7.1.5.
Current of non-intrinsically safe circuits
Voltage of non-intrinsically safe circuits
More than 440V
Below 440V
Below 220V
Below 110V
Below 60V
Minimum spacing between intrinsically safe circuits and non-intrinsically safe circuits laid in parallel (mm)Minimum spacing for parallel laying (mm)
More than 100A
Below 100A
The communication bus should be laid separately and protective measures should be taken. In the case of a large number of on-site detection points, it is advisable to use an on-site junction box. The number of spare cores of multi-core cables below 50A should be 10%~15% of the number of working cores. The field junction box should be set up near the detection point, where the instrument is concentrated and convenient for maintenance. The same junction box should not be used to transmit different types of signals. For explosion-hazardous places, junction boxes with corresponding explosion-proof grades must be selected. The cables of the junction box installed outdoors should not enter and exit from the top of the box. The line entry method of the control room should comply with the "Control Room Design Regulations" (HG20508). 7.2 Cable bridge laying method
Below 10A
In the process device area, the cable bridge should be laid overhead. When the cable bridge is installed on the process pipe rack7.21
, it should be arranged on the side or above the process pipe rack with better environmental conditions. The material of the cable bridge should be selected according to the environmental characteristics of the laying site. 7.2.2
1 In general, galvanized carbon steel cable bridge can be used. 2 In environments containing dust, water vapor and general corrosion, plastic-sprayed or hot-dip galvanized carbon steel bus bridges can be used. 3 In severely corrosive environments, when there is no electromagnetic interference, fiberglass bus bridges can be used; when there is electromagnetic interference, carbon steel bus bridges with zinc-nickel alloy plating or high-efficiency anti-corrosion paint can be used. Fiberglass bus bridges with metal shielding nets can also be used.
4 Bus bridges of the same material should be used for the same device. The AC power lines and safety interlock lines in the bus bridge should be separated from the instrument signal lines by metal partitions. 7.2.33 Different types of signals should not share a cable. Wires and cables should be placed in metal protective tubes or in covered metal bridges. When instrument signal cables are laid across power cables, they should be at right angles; when laid parallel to power cables, the minimum allowable distance between the two should comply with the provisions of Table 7.1.3. Minimum spacing between instrument cables and power cables laid in parallel (mm) Table 7.1.3
Length of parallel laying (m)
Power cable voltage and working current
125V,10
250V,50A
200~400V,100A
400~500V,200A
3000~10000V,800A
Note: Instrument signal cables include compensation wires laid in steel pipes or covered metal bridges. 7.1.4 The wiring of intrinsically safe circuits must be laid separately from the wiring of non-intrinsically safe circuits. ≥500
7.1.5 When intrinsically safe circuits and non-intrinsically safe circuits are laid in parallel, the minimum allowable distance between the two shall comply with the provisions of Table 7.1.5.
Current of non-intrinsically safe circuits
Voltage of non-intrinsically safe circuits
More than 440V
Below 440V
Below 220V
Below 110V
Below 60V
Minimum spacing between intrinsically safe circuits and non-intrinsically safe circuits laid in parallel (mm)Minimum spacing for parallel laying (mm)
More than 100A
Below 100A
The communication bus should be laid separately and protective measures should be taken. In the case of a large number of on-site detection points, it is advisable to use an on-site junction box. The number of spare cores of multi-core cables below 50A should be 10%~15% of the number of working cores. The field junction box should be set up near the detection point, where the instrument is concentrated and convenient for maintenance. The same junction box should not be used to transmit different types of signals. For explosion-hazardous places, junction boxes with corresponding explosion-proof grades must be selected. The cables of the junction box installed outdoors should not enter and exit from the top of the box. The line entry method of the control room should comply with the "Control Room Design Regulations" (HG20508). 7.2 Cable bridge laying method
Below 10A
In the process device area, the cable bridge should be laid overhead. When the cable bridge is installed on the process pipe rack7.21
, it should be arranged on the side or above the process pipe rack with better environmental conditions. The material of the cable bridge should be selected according to the environmental characteristics of the laying site. 7.2.2
1 In general, galvanized carbon steel cable bridge can be used. 2 In environments containing dust, water vapor and general corrosion, plastic-sprayed or hot-dip galvanized carbon steel bus bridges can be used. 3 In severely corrosive environments, when there is no electromagnetic interference, fiberglass bus bridges can be used; when there is electromagnetic interference, carbon steel bus bridges with zinc-nickel alloy plating or high-efficiency anti-corrosion paint can be used. Fiberglass bus bridges with metal shielding nets can also be used.
4 Bus bridges of the same material should be used for the same device. The AC power lines and safety interlock lines in the bus bridge should be separated from the instrument signal lines by metal partitions. 7.2.3
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