General Precautions Against Electrostatic Hazards

Why Do We Need to Worry about Static Electricity?

In this lesson, you will learn more about how static electricity is formed and why you must be aware of static electricity risks when handling flammable fluids.

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How Does Different Material Behave in Terms of Static Electricity?

Conductivity differs between different materials. To know how to handle your equipment onboard, you will learn more about the classification of materials in this lesson.

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What Are the Sources of Static Electricity Onboard?

In this lesson, you will learn more about static accumulators and the importance of interting when handling flammable fluids.

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What Precautions Can Be Implemented to Mitigate the Risks Posed By Static Electricity?

What can you do to minimize the risks of static electricity? In this lesson, you will learn more about precautions to prevent incidents that electrostatic discharges may cause.

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Step 1 of 43 minutes read

General Precautions Against Electrostatic Hazards

Whenever a flammable atmosphere could potentially be present, the following measures must be taken to prevent electrostatic hazards:

  • The bonding of metal objects to the metal structure of the ship to eliminate the risk of spark discharges between metal objects that might be electrically insulated. This includes metallic components of any equipment used for dipping, ullaging, and sampling.
  • The removal from tanks or other hazardous areas of any loose conductive objects that cannot be bonded.
  • Restricting the linear velocity of the cargo to a maximum of 1 metre per second at the individual tank inlets during the initial stages of loading, i.e. until: The filling pipe and any other structure on the base of the tank has been submerged to twice the filling pipe diameter in order that all splashing and surface turbulence has ceased, and, any water collected in the pipeline has been cleared. It is necessary to load at this restricted rate for a period of 30 minutes or until two pipeline volumes (i.e. from shore tank to ship’s tank) have been loaded into the tank, whichever is the lesser.
  • Continuing to restrict the product flow to a maximum of 1 m/s at the tank inlet for the whole operation unless the product is ‘clean’. A ‘clean’ product, within this context, is defined as one which contains less than 0.5% by volume of free water or other immiscible liquid and less than 10 mg/l of suspended solids.
  • Avoiding splash filling by employing bottom entry using a fill pipe terminating close to the bottom of the tank.

Additional precautions for Static Accumulator oils

The following additional precautions should be taken against static electricity during ullaging, dipping, gauging or sampling of static accumulator oils:

Banning the use of all metallic equipment for dipping, ullaging and sampling during loading and for 30 minutes after completion of loading. After the 30 minute waiting period, metallic equipment may be used for dipping, ullaging and sampling, but it must be effectively bonded and securely earthed to the structure of the ship before it is introduced into the tank, and must remain earthed until after removal. 

Banning the use of all non-metallic containers of more than 1 litre capacity for dipping, ullaging and sampling during loading and for 30 minutes after completion of loading. Non-metallic containers of less than 1 litre capacity may be used for sampling in tanks at any time, provided that they have no conducting components and that they are not rubbed prior to sampling. Cleaning with a high conductivity proprietary cleaner, a solvent such as 70:30% IPA:toluene mix, or soapy water, is recommended to reduce charge generation. To prevent charging, the container should not be rubbed dry after washing. 

Operations carried out through a correctly designed and installed sounding pipe are permissible at any time. It is not possible for any significant charge to accumulate on the surface of the liquid within the sounding pipe and therefore no waiting time is required. However, the precautions to be observed against introducing charged objects into a tank still apply and if metallic equipment is used it should be bonded before being inserted into the sounding pipe. Detailed guidance on precautions to be taken during ullaging, dipping and sampling of static accumulator oils is given in Section 12.8.2.3 of ISGOTT 6th edition published by the ICS and OCIMF . These precautions should be rigidly adhered to in order to avoid hazards associated with the accumulation of an electrical charge on the cargo which could form part of the links of the chain of events leading to a fire or explosion.