Cathodic protection of reinforcing steel in atmospherically exposed concrete structures
Some standard content:
ICS 25.220.99
National Standard of the People's Republic of China
GB/T 28721—2012
Cathodic protection of reinforcing steel in atmospherically exposed concrete structures2012-09-03Issued
General Administration of Quality Supervision, Inspection and Quarantine of the People's Republic of ChinaAdministrative Committee of Standardization of the People's Republic of China
Implementation on 2013-02-01
Normative references
3 Terms and definitions
4 General
4.2 Quality management
4.3 Personnel
5 General provisions for condition assessment and maintenance of buildings or structures
Appearance inspection and layer survey
Chloride analysis
Carbonation depth measurement
Concrete cover thickness and steel bar location
Reinforcement electrical continuity
Reinforcement/concrete potential
Concrete resistivity
Integrity requirements
Cement-based cap layer
New structures
6 Cathodic protection system
System composition
Power supply
DC power supply device
Monitoring sensor
Monitoring equipment
Data management system
Junction box
? Installation procedure
7.1 Electrical continuity
7.2 Performance monitoring system
7.3 Connection of steel bars in concrete
7.4 Concrete maintenance items related to cathodic protection components
GB/T28721—2012
GB/T 28721—2012
Surface preparation before anode installation
Anode installation
Anode connection
Implementation of anode covering, surface sealant or decorative coatingElectrical installation
Testing during installation
8Commissioning
Visual inspection
Measurements before energization
Initial energization·
Initial commissioning…·
Initial performance evaluation
Protection criteria.
Protection Adjustment of irrigation
System records and documents
Quality and test records
Installation and commissioning report
Operation and maintenance manual
Operation and maintenance
Cycle and procedures
10.2 System review
10.3 System review report
Appendix A (informative appendix)
References
Design process
This standard was drafted in accordance with the rules given in GB/T1.1-2009. This standard was proposed by the China Petroleum and Chemical Industry Federation. This standard is under the jurisdiction of the National Anti-Corrosion Standard Promotion Technical Committee (SAC/TC381). GB/T 28721--2012
This standard was drafted by: Suzhou Thermal Engineering Research Institute Co., Ltd., China Industrial Anti-Corrosion Technology Association, Nanjing Water Conservancy Research Institute, Daya Bay Nuclear Power Plant Operation and Management Co., Ltd., Sinopec Northwest Oilfield Branch Engineering Research Institute Anti-Corrosion Center. The main drafters of this standard are: Gao Yuzhu, Ge Yan, Li Jike, Shan Longxin, Lin Bin, Liu Shuang, Zhu Xichang, Li Yan, Zhou Bo, Yan Yonggui, Wang Mo, Yang Dongming,
1 Scope
Cathodic protection of steel bars in concrete in atmospheric environment GB/T 287212012
This standard specifies the terms and definitions, general principles, building and structure condition assessment and maintenance, cathodic protection system, installation procedures, trial operation, system records and documents, operation and maintenance of steel bars in concrete in atmospheric environment. This standard applies to cathodic protection of steel bars in concrete in atmospheric environment. 2 Normative references
The following documents are indispensable for the application of this document. For any dated referenced document, only the dated version applies to this document. For any undated referenced document, the latest version (including all amendments) applies to this document. GB4208 Degrees of protection of enclosures (IP code) GB/T10123 Basic terms and definitions for corrosion of metals and alloys GB/T12706 (all parts) Extruded insulated power cables and accessories with rated voltages of 1 kV (U.=1.2 kV) to 35 kV (U=40.5 kV)
GB19212.5 Safety of transformers, reactors, power supply units and similar products with a power supply voltage of 1100 V or less - Part 5: Special requirements and tests for isolating transformers and power supply units with built-in isolating transformers GB/T19 285 Inspection of buried steel pipeline corrosion protection engineering GB/T50344 Technical standard for building structure inspection CB3220 Technical conditions for constant potential instrument for ship JGJ/T23 Technical specification for testing concrete compressive strength by rebound method BSEN1504-9 Definitions, requirements, quality control and evaluation of conformity for products and systems for protection and repair of concrete - Part G: General provisions for the use of products and systems 3 Terms and definitions The terms and definitions defined in GB/T 10123 and the following terms and definitions apply to this document. 3.1 Zone Zone Cathodic protection system. Part II.
Drain point
The connection point between the cathode cable and the steel bars of the protected building or structure, through which the protection current flows back to the power supply. 3.3
Anode
An electrode used for cathodic protection of steel bars of buildings or structures, which is provided with protection current by an external power supply, GB/T 28721--2012
Reference electrode
An electrode with a stable and reproducible potential, used as a reference when measuring the potential values of other electrodes. 3.5
Polarization potentialpolarized potentialThe potential at the building/electrolyte or structure/electrolyte interface is the sum of the steel bar corrosion potential and the cathodic potential. The corrosion potential is the potential of the corrosion surface in the electrolyte relative to the reference electrode under open circuit conditions. 3.6
On potential
The potential of the structure's steel bars to the electrolyte measured when the cathodic protection system is continuously running. 3.7
Off potential
The potential of the structure's steel bars to the electrolyte measured at the moment of power failure. 3.8
Iugginprobe
A probe that reduces the influence of ohmic potential drop on potential measurement. 3.9
Battery probe
Macro cel! probe
A corrosion probe that can distinguish the anode and cathode with the naked eye. 4 General
4.1 Design
The design process refers to Appendix A. The system design should at least include the following: design calculations, material and equipment lists; construction details; installation, commissioning, operation and maintenance details. 4.2
Quality management
The documents and materials for the design, manufacture, installation, commissioning, operation and maintenance of the system and its components shall be archived in full. Manufacturing and construction shall be carried out according to the quality plan. The system shall be subjected to visual inspection, mechanical test and electrical test during the installation, commissioning and operation stages. 4.3 Personnel
The design, installation, commissioning, operation and maintenance management of the cathodic protection system shall be carried out under the supervision of trained personnel with reliable professional knowledge and experience.
5 Assessment and maintenance of the condition of buildings or structures 5.1 General provisions
Before deciding to implement cathodic protection, the condition of the materials of the building or structure, the integrity of the structure, whether it needs maintenance and how to maintain it, etc. shall be evaluated in accordance with the requirements of BS EN 1504-9. GB/T 28721—2012
5.1.2 After deciding to implement cathodic protection, the following 5.2~5.10 requires additional investigation to confirm whether cathodic protection measures are suitable and provide information required for system design. 5.2 Data
Review relevant drawings, instructions and records to determine the location, quantity, type and electrical continuity of steel bars, as well as the composition and quality of concrete.
5.3 Appearance inspection and layered investigation
Inspect the appearance of the building or structure, analyze the type of defects, causes, impact range and environmental characteristics of the surrounding country.
Inspect the previous maintenance area of the building or structure to understand the maintenance methods and materials used. 5.3.2
Inspect the concrete protective layer within the scope of the proposed cathodic protection of the building or structure. 5.3.3
Record defects such as cracks, honeycombs or the worst structural joints. 5.4 Chloride analysis
Determine the chloride content in the concrete according to the provisions of GB/T50344. 5.5 Carbonation Depth Measurement
Determine the carbonation depth of concrete in accordance with the provisions of JGJ/T 23. 5.6 Concrete Protective Layer Thickness and Rebar Position 5.6.1Measure the concrete protective layer thickness and the size and position of the reinforcement. 5.6.2Inspect and evaluate the influence of small iron wires, metal fibers, metal plates, plastic plates and other conductive and non-conductive materials on the concrete surface on the cathodic protection effect.
5.6.3Evaluate the possibility of short circuit between the reinforcement and the anode. 5.7 Rebar Electrical Continuity
Test the following in accordance with the requirements of 7.1:
Electrical continuity between the components of the building or structure in each area of the cathodic protection system; b) Electrical continuity between the reinforcement in the components; e) Electrical continuity between the reinforcement and other metal components. 5.7.2
During the maintenance and installation stage, the electrical continuity of the reinforcement should be further checked in accordance with the method of 7.1. 5.8 Steel/concrete potential
Before measuring the steel/concrete potential, the electrical continuity of the steel hoop should be checked to ensure that the steel bars in the area of the steel/concrete potential measurement are electrically continuous.
5.8.2 Use a portable reference electrode to measure the steel/concrete potential in the damaged and undamaged areas. The measuring points should be arranged in a grid with a grid spacing of no more than 500mm.
5.8.3 It is not necessary to test the steel/concrete potential of the entire building or structure, but the area designed to install the reference electrode should be carefully tested so that the reference electrode is placed at the most negative potential when no cathodic protection is applied. 5.9 Resistivity of concrete
The resistivity of concrete shall be determined in accordance with the provisions of GB/T19285,3
GB/T28721—2012
5.10 Integrity requirements
5.10.1 Repair
Damaged or deteriorated concrete matrix shall be repaired before the installation of the cathodic protection system. 5.10.2 Removal of concrete
5. 10. 2. 1
5, 10. 2. 2
Repair materials with a resistivity exceeding 50% to 200% of the resistivity of the bulk concrete shall be removed. Wires, nails or other metal parts electrically connected to the anode in the concrete surface layer shall be removed. It is not necessary to remove concrete that has been contaminated or carbonized by chlorides but is in good appearance. 5. 10. 2. 3
5.10.3 Rebar treatment
5. 10. 3. 1
5. 10.3.2
Loose corrosion products on the surface of the reinforcement should be cleaned. The surface of the reinforcement should not have non-metallic coatings and insulating adhesives. Concrete repair
5. 10. 4. 1
5. to. 4. 2
Concrete should be repaired in accordance with BSEN1504-9. To avoid short circuit between the anode and the reinforcement, the thickness of the concrete protective layer should be appropriately increased. Cement-based materials used for soil-mixing repair should meet the following requirements: 5. 10. 4. 3
a) Do not contain metallic materials (including fibers or powders); b) The mechanical properties should be close to those of the original concrete; c) The resistivity should be within the range of 50% to 200% of the resistivity of the bulk concrete. 5.10.4.4 Before installing the anode, a special curing film should not be used on the surface of the repair area. 5.11 Cement-based cover layer
5.11.1 After completing the concrete repair and anode installation, a cement-based cover layer should be laid on the surface where the anode is installed. The cover layer material and implementation method should comply with the provisions of BSEN1504-9. The average value of the bond strength between the cover layer and the original concrete should not be less than 1.N/mm and the minimum value should not be less than L.0 N/mm2 or the test failure surface is on the original concrete. 5.11.2 The implementation of the cover layer can be combined with concrete repair. The resistivity of the repair material should be within the range of 50%~200% of the resistivity of the bulk concrete. The maximum resistivity of the anode cover layer should not exceed 100kⅡ·cm. 5,11.3 The resistance between the anode and the steel bar should be monitored during construction to prevent short circuit. 5.11.4 The curing film should be removed or degradable. 5.12 New structures
For new structures, the following assessments should also be performed: a) Check the electrical continuity of the steel bars according to 7.1; b) Monitor the sensors and cables to avoid damage during concrete pouring and vibration; c) Connect, position and insulate metal fixtures and accessories to avoid adverse effects of the cathodic protection system; d) Insulating gaskets and fixtures should have sufficient rigidity to ensure that the anodes are in place to prevent short circuits between the anodes and the steel bars during concrete pouring and vibration;
e) The resistance between the anodes and the steel bars should be monitored during concrete pouring to prevent short circuits. 4
6 Cathodic protection system
6.1 System composition
GB/T28721--2012
The cathodic protection system mainly consists of a DC power supply device, electrodes, monitoring sensors, monitoring equipment, cables, junction boxes, etc. 6.2 Power supply
When AC power is available, a DC power supply device can be provided through a transformer-rectifier. When there is no AC power, other forms of power, such as diesel, wind power or turbine generators, can be used to provide AC power to the transformer rectifier. The controllable DC power supply device can also be directly generated by thermoelectric or solar generators and wind power or turbine generators, and provided to the intermittently charged battery system after rectification, and the system provides power to the DC controller. 6.3 DC power supply device
The DC power supply device shall meet the following requirements: It should be independent and continuously adjustable.
The enclosure protection level shall comply with the provisions of GB420R. b
It should have a power switch, fuse or circuit breaker and leakage current protection device. d)
The main transformer should be an isolation transformer that complies with the provisions of GB19212.5. c)
The DC output voltage does not exceed 60V
When the DC power supply device is located in a place that is easily accessible to people or animals and no isolation measures are taken, the DC output voltage should not exceed 24 V.
It should have stepless constant voltage, constant current or constant potential control function from zero to the maximum rated output range. It should have the function of current on and off to carry out "instantaneous power-off potential measurement, and can be equipped with a device interface for using portable instruments to measure the following parameters: output voltage, output current: the potential of steel bars/concrete relative to the reference electrode; the potential of steel bars/concrete for the potential decay sensor; the potential of current density probe or battery probe/steel. At least one positive terminal and one negative terminal are provided for cable connection. j
k) When using multi-channel equipment, each channel should be fully labeled. 1)
All electrical tests should be carried out in accordance with the methods specified in CB*3220. 6.4 Anode
Performance requirements
The output current of the anode should meet the design requirements and should not cause the concrete at the electrode/concrete interface and the performance of the anode to decrease. 6. 4. 2
Anode material
The anode can be made of active titanium or anode materials with better performance. 5
GB/T 28721—2012
Anode Installation
6.4.3.1 Installation on Concrete Surface
6.4.3.1.1:
Active titanium anodes shall be distributed on the concrete surface in a mesh or grid pattern. 6.4.3.1.2 Titanium conductive strips shall be used to connect the anodes by spot welding. 6.4.3.1.3 Anode/cable connection joints shall be firm and the contact resistance shall be less than 0.010. Before pouring concrete, non-metallic fasteners shall be used to fix the anodes to the concrete surface or steel bars to ensure that there is no short circuit between the anodes and the steel bars.
6.4.3.2 Installation in the Concrete Cover 6.4.3.2.1 Anodes shall be solid or mesh strips or lock grids. 6.4.3.2.2 The size and distribution of anodes shall meet the requirements of protection current density and maximum anode output current density. 6.4.3.3 Installation in buildings or structures
Anodes shall be buried in buildings or structures in the following manner: 6. 4. 3. 3. 1
a) Strip, mesh, grid or tubular anodes shall be buried in cement-based repair mortar; b) Anodes shall be used in combination with graphite-based conductive backfill; c) When used for cathodic protection of new structures, they shall be installed in concrete structures, and when used for old structures, they shall be installed in repaired concrete. 6.4.3.3.2 When backfill is used as part of the anode system, the working current density of the backfill and the output current density of the anode shall meet the design requirements.
When using graphite backfill, the graphite shall be regarded as an anode to calculate the minimum spacing between anodes and steel bars. 6.4.3.3.3
6.5 Monitoring sensor
6.5.1 Basic requirements
6.5.1.1
The monitoring sensor should be installed at the most negative potential when no cathodic protection is applied, to evaluate the effect of cathodic protection. The reference electrode can be used to measure the steel bar/concrete potential to judge the performance of the system. 6.5.1.2
6.5.1.3
Potential decay electrode, current density probe, macro cell probe, etc. can also be used in conjunction with the reference electrode. 6.5.2 Fixed reference electrode
It is advisable to use a double-tube silver/silver chloride (Ag/AgCl, 0.5mol/KCl) gel electrode and a manganese dioxide (Mn/MnOa, 0.5mol/INaOH) reference electrode.
6.5.3 Portable reference electrode
Portable reference electrode can be used temporarily on the concrete surface directly or through Luggin capillary. 6.5.3.1
6.5.3.2 Reference electrode used directly on the concrete surface should have a replaceable sponge to ensure good contact between the electrode and the concrete. 6.5.3.3 Double-tube silver/silver chloride gel electrode and manganese dioxide electrode are preferred. 6.5.4 Other sensors
6.5.4.1 Potential decay probe
6.5.4.1.1 Potential decay probe can be used to measure the change of potential of steel/concrete in a limited time (between power on and off), usually not more than 24 hours. This type of probe is not suitable for measuring the absolute potential of steel/concrete or long-term potential decay exceeding 24 hours. 6
6.5.4.1.2 Potential decay probe suitable for permanent installation in concrete are graphite, activated titanium and zinc. 6.5.4.2 Current density probe and macro cell probe 6.5.4.2.1 Current density probe and macro cell probe can be used to determine the protective current density of the steel bar. GB/T 28721--2012
6,5.4.2.2 Current density probe and macro cell probe shall be made of steel with the same composition as the steel bar and buried in concrete. It can also be made by cutting a section of steel bar.
6.5.4.2.3 Macro cell probe shall be enclosed in a mortar cylinder with high oxygen ion content. The chloride content in the cylinder shall be at least 5 times the average chloride content at the position of the concrete steel bar in the building or structure. 6.5.4.2.4 Whether the active corrosion area is adequately protected can be confirmed by whether the net current direction between the macro cell and the main bar changes after the cathodic protection system is energized.
6.5.4.3 Luggin probe (bridge)
6. 5. 4. 3. 1
A Luggin probe consists of an ionic conductive medium enclosed in a rigid or semi-rigid insulating material. 6.5.4.3.2 The material used for the Luggin probe shall be suitable for burial in concrete and shall be protected from complete drying. 6.5.4.3.3 A portable reference electrode may be used to measure the potential of steel bars buried deep in a building or structure through a Luggin probe. 6.6
Monitoring equipment
Digital meter
6. 6. 1. 1
Digital meter shall meet the following requirements:
Minimum resolution 1 mV;
Accuracy ±1 mV or better;
Input impedance not less than 10 M0.
6. 6. 1. 2
The accuracy and resolution of the zero resistance ammeter or other device should be such that the current can be measured with an accuracy of less than ±1% of the measured value. 6.6.2 Data recorder
The data recorder shall meet the following requirements:
It shall have multi-channel input or multiplexer;a
It shall be equipped with software that can identify the test location, sensor, DC power supply system and anode area;6)
The minimum input impedance is 10 Mn;
The resolution is at least 1 mV when the measuring range is 2 000 mV;d)
The accuracy is ± 5 mV or higher:
It shall be able to collect the steel bar/concrete potential within 0.1 s~0.5 s after power failure;The portable data recorder shall be able to be used in outdoor and field environments;g
The fixed data recorder shall be placed in a box suitable for the field environment and climatic conditions in accordance with the requirements of 6.3 and 6.5, and connected to the sensor, DC power supply device, etc. in accordance with the requirements of 6.8, and shall have the function of connecting to the network. 6.7
Data management system
The data management system shall be able to process the data and files for checking, processing and evaluating the effect of cathodic protection. 6.7.2 The processing content shall include at least the following information: anode area layout; b) sensor type and location; DC power supply device parameters; GB/T 28721—2012; d) initial (before trial operation) sensor readings; trial operation data: sensor data after trial operation; output data of DC power supply device after trial operation; g) event records (such as inspection date, changes in system operation, etc.). 6.7. 3
The data measured by the sensor shall comply with the provisions of 8.6. 6.8 Cables
Cable abbreviation identification
6. 8. 1. 1
Single-core cables
Single-core cables should be coded with corresponding colors according to their functions: anode cables are red;
cathode cables are black;
6. 8. 1. 2
Measurement ground cables are gray, but they can be black if the specifications of the measurement cables and cathode cables are different; reference electrode cables are green, and
other monitoring sensor cables are yellow.
Multi-core cables
Multi-core cables should be identified by color or numbers. 6.8.2
Current, voltage and temperature
Cable current, voltage and temperature shall meet the following requirements: be able to withstand current greater than 25% of the design current within the temperature increase range; a)
1) When the current reaches 125% of the maximum design current, the voltage drop shall meet the voltage output and anode/cathode voltage requirements of the DC power supply device, and the current distribution shall be uniform;
The temperature range shall comply with the provisions of GB/T12706. c
6,8, 3, 1
Dimensions, insulation and environmental suitability
The minimum core wire cross-sectional dimensions of multi-core cables buried in concrete or in pipes and cable ducts shall meet the following requirements: 1. 0 mm for anode and cathode cables;
b) 0.5 mm for monitoring cables;
Data network cables shall meet network requirements. 6.8.3.2
The minimum core wire cross-section size of a single-core cable is 2.5 mm2. 68.3.3 The cable should be selected according to the design function and installation requirements. The selected cables should be wrapped with at least 7 strands, and their insulation and protective layers should meet the requirements of GB/T 12706. 6.8.3.4 The cable connected to the anode should be suitable for an acidic environment with a pH value of less than 2, and the cable installed in the concrete should be suitable for an alkaline environment with a pH value of more than 13.
6.9 Junction box
The design of the junction box should be carried out in accordance with the requirements of GB4208. The type of connector in the junction box, as well as the worst external environment and mechanical exposure conditions that the junction box will encounter should be considered during the design. 82 When backfill is used as part of the anode system, the working current density of the backfill and the output current density of the anode shall meet the design requirements.
When graphite backfill is used, the graphite shall be regarded as the anode to calculate the minimum distance between the anode and the steel bar. 6. 4. 3. 3. 3
6. 5 Monitoring sensor
6.5. 1 Basic requirements
6. 5. 1. 1
Monitoring sensors shall be installed at the most negative potential when no cathodic protection is applied to evaluate the effectiveness of cathodic protection. Reference electrodes can be used to measure the steel bar/concrete potential to determine the performance of the system. 6. 5. 1. 2
6. 5. 1. 3
Potential decay electrodes, current density probes, macro cell probes, etc. can also be used in conjunction with reference electrodes. 6.5.2 Fixed reference electrode
It is advisable to use a double-tube silver/silver chloride (Ag/AgCl, 0.5 mol/KCl) gel electrode and a manganese dioxide (Mn/MnOa, 0.5 mol/INaOH) reference electrode.
6.5.3 Portable reference electrode
The portable reference electrode can be used directly on the concrete surface or temporarily through a Luggin capillary. 6.5.3.1
6.5.3.2 The reference electrode used directly on the concrete surface should have a replaceable sponge to ensure good contact between the electrode and the concrete. 6.5.3.3 It is advisable to use a double-tube silver/silver chloride gel electrode and a manganese dioxide electrode. 6.5.4 Other sensors
6.5.4.1 Potential decay probes
6.5.4.1.1 Potential decay probes can be used to measure the change in potential of steel bars/concrete in a limited time (between power on and off), usually not exceeding 24 hours. This type of probe is not suitable for measuring the absolute potential of steel bars/concrete or long-term potential decay exceeding 24 hours. 6
6.5.4.1.2 Potential decay probes suitable for permanent installation in concrete include graphite, activated titanium and zinc. 6.5.4.2 Current density probes and macro cell probes 6.5.4.2.1 Current density probes and macro cell probes can be used to determine the protective current density of steel bars. GB/T 28721--2012
6,5.4.2.2 The current density probe and macro cell probe shall be made of steel with the same composition as the steel bar and buried in the concrete. It can also be made by cutting a section of steel bar.
6.5.4.2.3 The macro cell probe shall be enclosed in a mortar cylinder with high oxygen ion content. The chloride content in the cylinder shall be at least 5 times the average chloride content at the position of the concrete steel bar in the building or structure. 6.5.4.2.4 Whether the active corrosion area is adequately protected can be confirmed by whether the net current direction between the macro cell and the main bar changes after the cathodic protection system is powered on.
6.5.4.3 Luggin probe (bridge)
6. 5. 4. 3. 1
A Luggin probe consists of an ionic conductive medium enclosed in a rigid or semi-rigid insulating material. 6.5.4.3.2 The material used for the Luggin probe shall be suitable for burial in concrete and shall be protected from complete drying. 6.5.4.3.3 A portable reference electrode may be used to measure the potential of steel bars buried deep in a building or structure through a Luggin probe. 6.6
Monitoring equipment
Digital meter
6. 6. 1. 1
Digital meter shall meet the following requirements:
Minimum resolution 1 mV;
Accuracy ±1 mV or better;
Input impedance not less than 10 M0.
6. 6. 1. 2
The accuracy and resolution of the zero resistance ammeter or other device should be such that the current can be measured with an accuracy of less than ±1% of the measured value. 6.6.2 Data recorder
The data recorder shall meet the following requirements:
It shall have multi-channel input or multiplexer;a
It shall be equipped with software that can identify the test location, sensor, DC power supply system and anode area;6)
The minimum input impedance is 10 Mn;
The resolution is at least 1 mV when the measuring range is 2 000 mV;d)
The accuracy is ± 5 mV or higher:
It shall be able to collect the steel bar/concrete potential within 0.1 s~0.5 s after power failure;The portable data recorder shall be able to be used in outdoor and field environments;g
The fixed data recorder shall be placed in a box suitable for the field environment and climatic conditions in accordance with the requirements of 6.3 and 6.5, and connected to the sensor, DC power supply device, etc. in accordance with the requirements of 6.8, and shall have the function of connecting to the network. 6.7
Data management system
The data management system shall be able to process the data and files for checking, processing and evaluating the effect of cathodic protection. 6.7.2 The processing content shall include at least the following information: anode area layout; b) sensor type and location; DC power supply device parameters; GB/T 28721—2012; d) initial (before trial operation) sensor readings; trial operation data: sensor data after trial operation; output data of DC power supply device after trial operation; g) event records (such as inspection date, changes in system operation, etc.). 6.7. 3
The data measured by the sensor shall comply with the provisions of 8.6. 6.8 Cables
Cable abbreviation identification
6. 8. 1. 1
Single-core cables
Single-core cables should be coded with corresponding colors according to their functions: anode cables are red;
cathode cables are black;
6. 8. 1. 2
Measurement ground cables are gray, but they can be black if the specifications of the measurement cables and cathode cables are different; reference electrode cables are green, and
other monitoring sensor cables are yellow.
Multi-core cables
Multi-core cables should be identified by color or numbers. 6.8.2
Current, voltage and temperature
Cable current, voltage and temperature shall meet the following requirements: be able to withstand current greater than 25% of the design current within the temperature increase range; a)
1) When the current reaches 125% of the maximum design current, the voltage drop shall meet the voltage output and anode/cathode voltage requirements of the DC power supply device, and the current distribution shall be uniform;
The temperature range shall comply with the provisions of GB/T12706. c
6,8, 3, 1
Dimensions, insulation and environmental suitability
The minimum core wire cross-sectional dimensions of multi-core cables buried in concrete or in pipes and cable ducts shall meet the following requirements: 1. 0 mm for anode and cathode cables;
b) 0.5 mm for monitoring cables;
Data network cables shall meet network requirements. 6.8.3.2
The minimum core wire cross-section size of a single-core cable is 2.5 mm2. 68.3.3 The cable should be selected according to the design function and installation requirements. The selected cables should be wrapped with at least 7 strands, and their insulation and protective layers should meet the requirements of GB/T 12706. 6.8.3.4 The cable connected to the anode should be suitable for an acidic environment with a pH value of less than 2, and the cable installed in the concrete should be suitable for an alkaline environment with a pH value of more than 13.
6.9 Junction box
The design of the junction box should be carried out in accordance with the requirements of GB4208. The type of connector in the junction box, as well as the worst external environment and mechanical exposure conditions that the junction box will encounter should be considered during the design. 82 When backfill is used as part of the anode system, the working current density of the backfill and the output current density of the anode shall meet the design requirements.
When graphite backfill is used, the graphite shall be regarded as the anode to calculate the minimum distance between the anode and the steel bar. 6. 4. 3. 3. 3
6. 5 Monitoring sensor
6.5. 1 Basic requirements
6. 5. 1. 1
Monitoring sensors shall be installed at the most negative potential when no cathodic protection is applied to evaluate the effectiveness of cathodic protection. Reference electrodes can be used to measure the steel bar/concrete potential to determine the performance of the system. 6. 5. 1. 2
6. 5. 1. 3
Potential decay electrodes, current density probes, macro cell probes, etc. can also be used in conjunction with reference electrodes. 6.5.2 Fixed reference electrode
It is advisable to use a double-tube silver/silver chloride (Ag/AgCl, 0.5 mol/KCl) gel electrode and a manganese dioxide (Mn/MnOa, 0.5 mol/INaOH) reference electrode.
6.5.3 Portable reference electrode
The portable reference electrode can be used directly on the concrete surface or temporarily through a Luggin capillary. 6.5.3.1
6.5.3.2 The reference electrode used directly on the concrete surface should have a replaceable sponge to ensure good contact between the electrode and the concrete. 6.5.3.3 It is advisable to use a double-tube silver/silver chloride gel electrode and a manganese dioxide electrode. 6.5.4 Other sensors
6.5.4.1 Potential decay probes
6.5.4.1.1 Potential decay probes can be used to measure the change in potential of steel bars/concrete in a limited time (between power on and off), usually not exceeding 24 hours. This type of probe is not suitable for measuring the absolute potential of steel bars/concrete or long-term potential decay exceeding 24 hours. 6
6.5.4.1.2 Potential decay probes suitable for permanent installation in concrete include graphite, activated titanium and zinc. 6.5.4.2 Current density probes and macro cell probes 6.5.4.2.1 Current density probes and macro cell probes can be used to determine the protective current density of steel bars. GB/T 28721--2012
6,5.4.2.2 The current density probe and macro cell probe shall be made of steel with the same composition as the steel bar and buried in the concrete. It can also be made by cutting a section of steel bar.
6.5.4.2.3 The macro cell probe shall be enclosed in a mortar cylinder with high oxygen ion content. The chloride content in the cylinder shall be at least 5 times the average chloride content at the position of the concrete steel bar in the building or structure. 6.5.4.2.4 Whether the active corrosion area is adequately protected can be confirmed by whether the net current direction between the macro cell and the main bar changes after the cathodic protection system is powered on.
6.5.4.3 Luggin probe (bridge)
6. 5. 4. 3. 1
A Luggin probe consists of an ionic conductive medium enclosed in a rigid or semi-rigid insulating material. 6.5.4.3.2 The material used for the Luggin probe shall be suitable for burial in concrete and shall be protected from complete drying. 6.5.4.3.3 A portable reference electrode may be used to measure the potential of steel bars buried deep in a building or structure through a Luggin probe. 6.6
Monitoring equipment
Digital meter
6. 6. 1. 1
Digital meter shall meet the following requirements:
Minimum resolution 1 mV;
Accuracy ±1 mV or better;
Input impedance not less than 10 M0.
6. 6. 1. 2
The accuracy and resolution of the zero resistance ammeter or other device should be such that the current can be measured with an accuracy of less than ±1% of the measured value. 6.6.2 Data recorder
The data recorder shall meet the following requirements:
It shall have multi-channel input or multiplexer;a
It shall be equipped with software that can identify the test location, sensor, DC power supply system and anode area;6)
The minimum input impedance is 10 Mn;
The resolution is at least 1 mV when the measuring range is 2 000 mV;d)
The accuracy is ± 5 mV or higher:
It shall be able to collect the steel bar/concrete potential within 0.1 s~0.5 s after power failure;The portable data recorder shall be able to be used in outdoor and field environments;g
The fixed data recorder shall be placed in a box suitable for the field environment and climatic conditions in accordance with the requirements of 6.3 and 6.5, and connected to the sensor, DC power supply device, etc. in accordance with the requirements of 6.8, and shall have the function of connecting to the network. 6.7
Data management system
The data management system shall be able to process the data and files for checking, processing and evaluating the effect of cathodic protection. 6.7.2 The processing content shall at least include the following information: anode area layout; b) sensor type and location; DC power supply device parameters; GB/T 28721—2012; d) initial (before trial operation) sensor readings; trial operation data: sensor data after trial operation; output data of DC power supply device after trial operation; g) event records (such as inspection date, changes in system operation, etc.). 6.7. 3
The data measured by the sensor shall comply with the provisions of 8.6. 6.8 Cables
Cable abbreviation identification
6. 8. 1. 1
Single-core cables
Single-core cables should be coded with corresponding colors according to their functions: anode cables are red;
cathode cables are black;
6. 8. 1. 2
Measurement ground cables are gray, but they can be black if the specifications of the measurement cables and cathode cables are different; reference electrode cables are green, and
other monitoring sensor cables are yellow.
Multi-core cables
Multi-core cables should be identified by color or numbers. 6.8.2
Current, voltage and temperature
Cable current, voltage and temperature shall meet the following requirements: be able to withstand current greater than 25% of the design current within the temperature increase range; a)
1) When the current reaches 125% of the maximum design current, the voltage drop shall meet the voltage output and anode/cathode voltage requirements of the DC power supply device, and the current distribution shall be uniform;
The temperature range shall comply with the provisions of GB/T12706. c
6,8, 3, 1
Dimensions, insulation and environmental suitability
The minimum core wire cross-sectional dimensions of multi-core cables buried in concrete or in pipes and cable ducts shall meet the following requirements: 1. 0 mm for anode and cathode cables;
b) 0.5 mm for monitoring cables;
Data network cables shall meet network requirements. 6.8.3.2
The minimum core wire cross-section size of a single-core cable is 2.5 mm2. 68.3.3 The cable should be selected according to the design function and installation requirements. The selected cables should be wrapped with at least 7 strands, and their insulation and protective layers should meet the requirements of GB/T 12706. 6.8.3.4 The cable connected to the anode should be suitable for an acidic environment with a pH value of less than 2, and the cable installed in the concrete should be suitable for an alkaline environment with a pH value of more than 13.
6.9 Junction box
The design of the junction box should be carried out in accordance with the requirements of GB4208. The type of connector in the junction box, as well as the worst external environment and mechanical exposure conditions that the junction box will encounter should be considered during the design. 83 Double-tube silver/silver chloride gel electrodes and manganese dioxide electrodes are preferably used. 6.5.4 Other sensors
6.5. 4.1 Potential decay probes
6.5.4.1.1 Potential decay probes can be used to measure the change in potential of steel bars/concrete in a limited time (between power on and off), usually not exceeding 24 hours. This type of probe is not suitable for measuring the absolute potential of steel bars/concrete or long-term potential decay exceeding 24 hours. 6
6.5.4.1.2 Potential decay probes suitable for permanent installation in concrete include graphite, activated titanium and zinc. 6.5.4.2 Current density probes and macro cell probes 6.5.4.2.1 Current density probes and macro cell probes can be used to determine the protective current density of steel bars. GB/T 28721--2012
6,5.4.2.2 The current density probe and macro cell probe shall be made of steel with the same composition as the steel bar and buried in the concrete. It can also be made by cutting a section of steel bar.
6.5.4.2.3 The macro cell probe shall be enclosed in a mortar cylinder with high oxygen ion content. The chloride content in the cylinder shall be at least 5 times the average chloride content at the position of the concrete steel bar in the building or structure. 6.5.4.2.4 Whether the active corrosion area is adequately protected can be confirmed by whether the net current direction between the macro cell and the main bar changes after the cathodic protection system is powered on.
6.5.4.3 Luggin probe (bridge)
6. 5. 4. 3. 1
A Luggin probe consists of an ionic conductive medium enclosed in a rigid or semi-rigid insulating material. 6.5.4.3.2 The material used for the Luggin probe shall be suitable for burial in concrete and shall be protected from complete drying. 6.5.4.3.3 A portable reference electrode may be used to measure the potential of steel bars buried deep in a building or structure through a Luggin probe. 6.6
Monitoring equipment
Digital meter
6. 6. 1. 1
Digital meter shall meet the following requirements:
Minimum resolution 1 mV;
Accuracy ±1 mV or better;
Input impedance not less than 10 M0.
6. 6. 1. 2
The accuracy and resolution of the zero resistance ammeter or other device should be such that the current can be measured with an accuracy of less than ±1% of the measured value. 6.6.2 Data recorder
The data recorder shall meet the following requirements:
It shall have multi-channel input or multiplexer;a
It shall be equipped with software that can identify the test location, sensor, DC power supply system and anode area;6)
The minimum input impedance is 10 Mn;
The resolution is at least 1 mV when the measuring range is 2 000 mV;d)
The accuracy is ± 5 mV or higher:
It shall be able to collect the steel bar/concrete potential within 0.1 s~0.5 s after power failure;The portable data recorder shall be able to be used in outdoor and field environments;g
The fixed data recorder shall be placed in a box suitable for the field environment and climatic conditions in accordance with the requirements of 6.3 and 6.5, and connected to the sensor, DC power supply device, etc. in accordance with the requirements of 6.8, and shall have the function of connecting to the network. 6.7
Data management system
The data management system shall be able to process the data and files for checking, processing and evaluating the effect of cathodic protection. 6.7.2 The processing content shall include at least the following information: anode area layout; b) sensor type and location; DC power supply device parameters; GB/T 28721—2012; d) initial (before trial operation) sensor readings; trial operation data: sensor data after trial operation; output data of DC power supply device after trial operation; g) event records (such as inspection date, changes in system operation, etc.). 6.7. 3
The data measured by the sensor shall comply with the provisions of 8.6. 6.8 Cables
Cable abbreviation identification
6. 8. 1. 1
Single-core cables
Single-core cables should be coded with corresponding colors according to their functions: anode cables are red;
cathode cables are black;
6. 8. 1. 2
Measurement ground cables are gray, but they can be black if the specifications of the measurement cables and cathode cables are different; reference electrode cables are green, and
other monitoring sensor cables are yellow.
Multi-core cables
Multi-core cables should be identified by color or numbers. 6.8.2
Current, voltage and temperature
Cable current, voltage and temperature shall meet the following requirements: Able to withstand current greater than 25% of the design current within the temperature increase range; a)
1) When the current reaches 125% of the maximum design current, the voltage drop shall meet the voltage output and anode/cathode voltage requirements of the DC power supply device, and the current distribution shall be uniform;
The temperature range shall comply with the provisions of GB/T12706. c
6,8, 3, 1
Dimensions, insulation and environmental suitability
The minimum core wire cross-sectional dimensions of multi-core cables buried in concrete or in pipes and cable ducts shall meet the following requirements: 1. 0 mm for anode and cathode cables;
b) 0.5 mm for monitoring cables;
Data network cables shall meet network requirements. 6.8.3.2
The minimum core wire cross-section size of a single-core cable is 2.5 mm2. 68.3.3 The cable should be selected according to the design function and installation requirements. The selected cables should be wrapped with at least 7 strands, and their insulation and protective layers should meet the requirements of GB/T 12706. 6.8.3.4 The cable connected to the anode should be suitable for an acidic environment with a pH value of less than 2, and the cable installed in the concrete should be suitable for an alkaline environment with a pH value of more than 13.
6.9 Junction box
The design of the junction box should be carried out in accordance with the requirements of GB4208. The type of connector in the junction box, as well as the worst external environment and mechanical exposure conditions that the junction box will encounter should be considered during the design. 83 Double-tube silver/silver chloride gel electrodes and manganese dioxide electrodes are preferably used. 6.5.4 Other sensors
6.5. 4.1 Potential decay probes
6.5.4.1.1 Potential decay probes can be used to measure the change in potential of steel bars/concrete in a limited time (between power on and off), usually not exceeding 24 hours. This type of probe is not suitable for measuring the absolute potential of steel bars/concrete or long-term potential decay exceeding 24 hours. 6
6.5.4.1.2 Potential decay probes suitable for permanent installation in concrete include graphite, activated titanium and zinc. 6.5.4.2 Current density probes and macro cell probes 6.5.4.2.1 Current density probes and macro cell probes can be used to determine the protective current density of steel bars. GB/T 28721--2012
6,5.4.2.2 The current density probe and macro cell probe shall be made of steel with the same composition as the steel bar and buried in the concrete. It can also be made by cutting a section of steel bar.
6.5.4.2.3 The macro cell probe shall be enclosed in a mortar cylinder with high oxygen ion content. The chloride content in the cylinder shall be at least 5 times the average chloride content at the position of the concrete steel bar in the building or structure. 6.5.4.2.4 Whether the active corrosion area is adequately protected can be confirmed by whether the net current direction between the macro cell and the main bar changes after the cathodic protection system is powered on.
6.5.4.3 Luggin probe (bridge)
6. 5. 4. 3. 1
A Luggin probe consists of an ionic conductive medium enclosed in a rigid or semi-rigid insulating material. 6.5.4.3.2 The material used for the Luggin probe shall be suitable for burial in concrete and shall be protected from complete drying. 6.5.4.3.3 A portable reference electrode may be used to measure the potential of steel bars buried deep in a building or structure through a Luggin probe. 6.6
Monitoring equipment
Digital meter
6. 6. 1. 1
Digital meter shall meet the following requirements:
Minimum resolution 1 mV;
Accuracy ±1 mV or better;
Input impedance not less than 10 M0.
6. 6. 1. 2
The accuracy and resolution of the zero resistance ammeter or other device should be such that the current can be measured with an accuracy of less than ±1% of the measured value. 6.6.2 Data recorder
The data recorder shall meet the following requirements:
It shall have multi-channel input or multiplexer;a
It shall be equipped with software that can identify the test location, sensor, DC power supply system and anode area;6)
The minimum input impedance is 10 Mn;
The resolution is at least 1 mV when the measuring range is 2 000 mV;d)
The accuracy is ± 5 mV or higher:
It shall be able to collect the steel bar/concrete potential within 0.1 s~0.5 s after power failure;The portable data recorder shall be able to be used in outdoor and field environments;g
The fixed data recorder shall be placed in a box suitable for the field environment and climatic conditions in accordance with the requirements of 6.3 and 6.5, and connected to the sensor, DC power supply device, etc. in accordance with the requirements of 6.8, and shall have the function of connecting to the network. 6.7
Data management system
The data management system shall be able to process the data and files for checking, processing and evaluating the effect of cathodic protection. 6.7.2 The processing content shall at least include the following information: anode area layout; b) sensor type and location; DC power supply device parameters; GB/T 28721—2012; d) initial (before trial operation) sensor readings; trial operation data: sensor data after trial operation; output data of DC power supply device after trial operation; g) event records (such as inspection date, changes in system operation, etc.). 6.7. 3bZxz.net
The data measured by the sensor shall comply with the provisions of 8.6. 6.8 Cables
Cable abbreviation identification
6. 8. 1. 1
Single-core cables
Single-core cables should be coded with corresponding colors according to their functions: anode cables are red;
cathode cables are black;
6. 8. 1. 2
Measurement ground cables are gray, but they can be black if the specifications of the measurement cables and cathode cables are different; reference electrode cables are green, and
other monitoring sensor cables are yellow.
Multi-core cables
Multi-core cables should be identified by color or numbers. 6.8.2
Current, voltage and temperature
Cable current, voltage and temperature shall meet the following requirements: be able to withstand current greater than 25% of the design current within the temperature increase range; a)
1) When the current reaches 125% of the maximum design current, the voltage drop shall meet the voltage output and anode/cathode voltage requirements of the DC power supply device, and the current distribution shall be uniform;
The temperature range shall comply with the provisions of GB/T12706. c
6,8, 3, 1
Dimensions, insulation and environmental suitability
The minimum core wire cross-sectional dimensions of multi-core cables buried in concrete or in pipes and cable ducts shall meet the following requirements: 1. 0 mm for anode and cathode cables;
b) 0.5 mm for monitoring cables;
Data network cables shall meet network requirements. 6.8.3.2
The minimum core wire cross-section size of a single-core cable is 2.5 mm2. 68.3.3 The cable should be selected according to the design function and installation requirements. The selected cables should be wrapped with at least 7 strands, and their insulation and protective layers should meet the requirements of GB/T 12706. 6.8.3.4 The cable connected to the anode should be suitable for an acidic environment with a pH value of less than 2, and the cable installed in the concrete should be suitable for an alkaline environment with a pH value of more than 13.
6.9 Junction box
The design of the junction box should be carried out in accordance with the requirements of GB4208. The type of connector in the junction box, as well as the worst external environment and mechanical exposure conditions that the junction box will encounter should be considered during the design. 82 Data recorder
The data recorder shall meet the following requirements:
It shall have multi-channel input or multiplexer;a
It shall be equipped with software with functions such as identification of test location, sensor, DC power supply system and anode area;6)
The minimum input impedance is 10 Mn;
The resolution is at least 1 mV when the measuring range is 2 000 mV;d)
The accuracy is ± 5 mV or higher:
It shall be able to collect the steel bar/concrete potential within 0.1 s~0.5 s after power failure;The portable data recorder shall be able to be used in outdoor and field environments;g
The fixed data recorder shall be placed in a box suitable for the field environment and climatic conditions in accordance with the requirements of 6.3 and 6.5, and connected to sensors, DC power supply devices, etc. in accordance with the requirements of 6.8, and shall have the function of connecting to the network. 6.7
Data management system
The data management system shall be able to process the data and files for checking, processing and evaluating the effect of cathodic protection. 6.7.2 The processing content shall include at least the following information: anode area layout; b) sensor type and location; DC power supply device parameters; GB/T 28721—2012; d) initial (before trial operation) sensor readings; trial operation data: sensor data after trial operation; output data of DC power supply device after trial operation; g) event records (such as inspection date, changes in system operation, etc.). 6.7. 3
The data measured by the sensor shall comply with the provisions of 8.6. 6.8 Cables
Cable abbreviation identification
6. 8. 1. 1
Single-core cables
Single-core cables should be coded with corresponding colors according to their functions: anode cables are red;
cathode cables are black;
6. 8. 1. 2
Measurement ground cables are gray, but they can be black if the specifications of the measurement cables and cathode cables are different; reference electrode cables are green, and
other monitoring sensor cables are yellow.
Multi-core cables
Multi-core cables should be identified by color or numbers. 6.8.2
Current, voltage and temperature
Cable current, voltage and temperature shall meet the following requirements: Able to withstand current greater than 25% of the design current within the temperature increase range; a)
1) When the current reaches 125% of the maximum design current, the voltage drop shall meet the voltage output and anode/cathode voltage requirements of the DC power supply device, and the current distribution shall be uniform;
The temperature range shall comply with the provisions of GB/T12706. c
6,8, 3, 1
Dimensions, insulation and environmental suitability
The minimum core wire cross-sectional dimensions of multi-core cables buried in concrete or in pipes and cable ducts shall meet the following requirements: 1. 0 mm for anode and cathode cables;
b) 0.5 mm for monitoring cables;
Data network cables shall meet network requirements. 6.8.3.2
The minimum core wire cross-section size of a single-core cable is 2.5 mm2. 68.3.3 The cable should be selected according to the design function and installation requirements. The selected cables should be wrapped with at least 7 strands, and their insulation and protective layers should meet the requirements of GB/T 12706. 6.8.3.4 The cable connected to the anode should be suitable for an acidic environment with a pH value of less than 2, and the cable installed in the concrete should be suitable for an alkaline environment with a pH value of more than 13.
6.9 Junction box
The design of the junction box should be carried out in accordance with the requirements of GB4208. The type of connector in the junction box, as well as the worst external environment and mechanical exposure conditions that the junction box will encounter should be considered during the design. 82 Data recorder
The data recorder shall meet the following requirements:
It shall have multi-channel input or multiplexer;a
It shall be equipped with software with functions such as identification of test location, sensor, DC power supply system and anode area;6)
The minimum input impedance is 10 Mn;
The resolution is at least 1 mV when the measuring range is 2 000 mV;d)
The accuracy is ± 5 mV or higher:
It shall be able to collect the steel bar/concrete potential within 0.1 s~0.5 s after power failure;The portable data recorder shall be able to be used in outdoor and field environments;g
The fixed data recorder shall be placed in a box suitable for the field environment and climatic conditions in accordance with the requirements of 6.3 and 6.5, and connected to sensors, DC power supply devices, etc. in accordance with the requirements of 6.8, and shall have the function of connecting to the network. 6.7
Data management system
The data management system shall be able to process the data and files for checking, processing and evaluating the effect of cathodic protection. 6.7.2 The processing content shall include at least the following information: anode area layout; b) sensor type and location; DC power supply device parameters; GB/T 28721—2012; d) initial (before trial operation) sensor readings; trial operation data: sensor data after trial operation; output data of DC power supply device after trial operation; g) event records (such as inspection date, changes in system operation, etc.). 6.7. 3
The data measured by the sensor shall comply with the provisions of 8.6. 6.8 Cables
Cable abbreviation identification
6. 8. 1. 1
Single-core cables
Single-core cables should be coded with corresponding colors according to their functions: anode cables are red;
cathode cables are black;
6. 8. 1. 2
Measurement ground cables are gray, but they can be black if the specifications of the measurement cables and cathode cables are different; reference electrode cables are green, and
other monitoring sensor cables are yellow.
Multi-core cables
Multi-core cables should be identified by color or numbers. 6.8.2
Current, voltage and temperature
Cable current, voltage and temperature shall meet the following requirements: Able to withstand current greater than 25% of the design current within the temperature increase range; a)
1) When the current reaches 125% of the maximum design current, the voltage drop shall meet the voltage output and anode/cathode voltage requirements of the DC power supply device, and the current distribution shall be uniform;
The temperature range shall comply with the provisions of GB/T12706. c
6,8, 3, 1
Dimensions, insulation and environmental suitability
The minimum core wire cross-sectional dimensions of multi-core cables buried in concrete or in pipes and cable ducts shall meet the following requirements: 1. 0 mm for anode and cathode cables;
b) 0.5 mm for monitoring cables;
Data network cables shall meet network requirements. 6.8.3.2
The minimum core wire cross-section size of a single-core cable is 2.5 mm2. 68.3.3 The cable should be selected according to the design function and installation requirements. The selected cables should be wrapped with at least 7 strands, and their insulation and protective layers should meet the requirements of GB/T 12706. 6.8.3.4 The cable connected to the anode should be suitable for an acidic environment with a pH value of less than 2, and the cable installed in the concrete should be suitable for an alkaline environment with a pH value of more than 13.
6.9 Junction box
The design of the junction box should be carried out in accordance with the requirements of GB4208. The type of connector in the junction box, as well as the worst external environment and mechanical exposure conditions that the junction box will encounter should be considered during the design. 8
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