Instructions for using the static electricity export system for composite hoses

In areas such as petrochemicals and hazardous chemical transportation, the accumulation of static electricity during the transportation of flammable media using composite hoses may lead to catastrophic accidents. As the core stabilizing device of composite hoses, the proper use and maintenance of the electrostatic discharge system are directly related to personnel stability and equipment integrity.

Core functions and principles of electrostatic discharge system

1. Mechanism of static electricity generation
When the medium flows inside the hose, static charges are generated by friction with the inner lining layer. When the accumulation of charge reaches a critical point (usually>3kV), it may trigger spark discharge and ignite flammable vapors.
2. System composition and working principle
Conductive inner lining layer: Made of carbon black modified rubber or metal coating, with a surface resistivity of ≤ 10 Ω· cm, it quickly conducts charges to the reinforcement layer.
Metal woven layer: Steel or copper wire woven mesh, forming a continuous conductive path with a resistance of ≤ 10 Ω (IEC60092-504 standard).
Grounding device: Connect the grounding wire (cross-sectional area ≥ 10mm ²) to the dock/ship grounding system to ensure stable charge release.

Preparation and inspection before use

1. System integrity verification
Conductivity test: Use a multimeter to measure the resistance of the braided layer at both ends of the hose, and the resistance should be less than 1 Ω.
Grounding resistance test: The resistance of the grounding system is tested using the four electrical methods and is ≤ 4 Ω (GB/T21431-2015 standard).
Appearance inspection: Confirm that the weaving layer is free of broken wires and rust, and that the inner lining layer is not damaged, resulting in exposed conductive layer.
2. Environmental adaptability confirmation
Humidity control: When the environmental humidity is less than 60%, auxiliary measures such as ion air neutralizers need to be added.
Dielectric conductivity: When transporting media with conductivity<50pS/m (such as aviation kerosene), anti-static additives should be used.

Operating procedures and standards

1. Connection and grounding
Step 1: Connect the hose flange to the conductive flange of the equipment/pipeline, ensuring that the metal contact area is ≥ 80%.
Step 2: Use a grounding wire to connect the braided layer of the hose to the grounding post, with a torque value of ≥ 10N · m.
Step 3: Verify that the total resistance of the system is ≤ 10 Ω using a ground resistance tester (refer to IMOMS7.1/Circ.1312).
2. Transportation process control
Flow velocity limitation: The initial flow velocity is ≤ 1m/s, gradually increasing to the design value (5m/s) to avoid turbulence (Reynolds number<3000).
Pressure monitoring: Keep the working pressure ≤ 80% of the marked value of the hose to prevent deformation of the inner lining layer from affecting conductivity.
Temperature management: When the medium temperature is greater than 60 ℃, a cooling system should be configured to avoid an increase in material resistivity.
3. Post homework processing
Power off operation: Close the valve first, keep it grounded for more than 3 minutes, and release all charges.
Cleaning and maintenance: Use neutral cleaning agent (pH 6.5-7.5) to clean the inner lining layer to avoid chemical residues affecting conductivity.

Maintenance and troubleshooting

1. Regular maintenance plan
Monthly maintenance:
 Clean the surface of the woven layer of oil and salt to avoid electrochemical corrosion;
 Check the torque of the grounding wire connection bolt and add conductive paste (such as molybdenum disulfide).
Quarterly maintenance:
 Use a megohmmeter to measure the resistivity of the inner lining layer. If it is greater than 10 Ω· cm, it needs to be replaced;
 Perform magnetic particle inspection on the woven layer to detect wire breakage defects (usability level ≤ 2).
2. Common fault diagnosis

Fault phenomenon: The grounding resistance suddenly increases to>10 Ω
Possible reasons: broken wires in the weaving layer, oxidation of the grounding wire, and damage to the inner lining layer;
Solution: Segmented detection and localization of fault points, replacement of damaged components.
Fault phenomenon: Static alarm during medium transportation
Possible reasons: excessive flow rate, low environmental humidity, and ineffective conductive additives;
Solution: Reduce the flow rate to below 3m/s, add a humidifier, and detect the conductivity of the medium.