north slope training cooperative © north slope training cooperative—revised may 2012. all rights...

North Slope Training Cooperative

© North Slope Training Cooperative—revised May 2012. All rights reserved.

Static Electricity for Non-Electrical Workers (Unqualified)

NSTC-27

2© North Slope Training Cooperative—revised May 2011. All rights reserved.

Course Overview

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Administration and Safety

Emergency Procedures

Restrooms/Breaks/Smoking

Safety Minute

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Introductions

Name

Company and/or position

What are some of your common experiences of static electricity?

What potential hazards from static electricity are there in your work area or facility?

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Goal

To create a safe environment for employees working in areas where the possibility of static electricity generation exists.

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Objectives

Explain how static electricity is generated and its hazards.

Describe the control measures that prevent or reduce the generation of static electricity.

Apply those control measures to specific work situations where there is a potential danger from static electricity.

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Static Electricity and Its Hazards

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Chemical Safety Board Case Study

The tank had a loose linkage on a liquid level gauging system float that separated and created a spark that ignited the naphtha vapors.

Heat from the fire ruptured other tanks and destroyed the tank farm.

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In July 2007 an explosion and fire occurred at Barton Solvents in Wichita, Kansas where a 15,000 gallon, vertical storage tank was being filled with naphtha.

Because of its low electrical conductivity, naphtha can produce ignitable vapor-air mixtures inside tanks.

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Chemical Safety Board Case Study

Three months later at another Barton Solvents facility in Des Moines, Iowa, an explosion occurred while a 300 gallon steel tank was being filled with ethyl acetate, a flammable solvent.

The Iowa discharge came from steel parts of the fill nozzle and hose assembly that were not bonded and grounded.

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What Is Static Electricity?

Static electricity is an electrical charge imbalance either positive or negative between two objects.

The charge is created by contact and separation (friction) of dissimilar insulating surfaces.

Electrons move to the surface of the material with the greatest ability to hold them.

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BP ASH, pages 198-199

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How Is Static Electricity Generated?

Static electricity is generated by the contact of dissimilar materials.

It can occur at solid to solid, solid to liquid, or liquid to liquid interfaces.

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When there is a great enough charge imbalance, the electrons will flow as a spark or static discharge. This often occurs when touching a metal object after walking across a carpeted floor.

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How Is Static Electricity Generated?

Movement enhances the transfer of electrons from one material to the other. Some materials lose electrons (positive charge) and some gain electrons (negative charge).

Static electricity can be generated when material is moved from one place to another through pipes, by filtering, or by pouring.

Other factors influencing the accumulation of static electricity include low humidity, and the low conductivity of a flammable liquid.

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Static Electric Discharge

Static electric discharge is a release of static electricity in the form of a spark that might be capable of causing ignition.

The discharge usually occurs in the gap between the two charged bodies, e.g. liquid to liquid, metal to liquid, metal to metal, human body to metal, etc.

The energy of a spark discharge is highly concentrated in space and time.

Sparks from ungrounded charged conductors, including the human body, are responsible for most fires and explosions ignited by static electricity.

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NFPA 77 3.3.16 and 5.3.3.1

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Static Electricity Generation in the Oil/Gas Industry

In the oil/gas industry, a static charge can result from contact and separation of inflowing liquids through a pipe.

Examples would include:

oil/gas flowing through a pipeline into a tanker,

fuel flowing from a gasoline pump through a hose and nozzle into a vehicle.

flammable liquid flowing through a hose into a storage tank.

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Static Electricity Generation in Oil/Gas Industry

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Static Producing Situations Examples

Liquid flow through pipes and filters Fueling vehicles, filling a tank

Settling of solid particles in liquidRust and sludge particles settling in a tank

Gas bubbling through liquidAir in a liquid rises to the surface or gas bubbles during a filling operation

Splashing by the break-up of jets or bubbles

Splash filling of tanks, high speed ejection of liquids from nozzles

Air movement Using fans to ventilate a tank

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Why Static Electricity is Dangerous

Personal injury from electric shock which can vary from a slight tingling sensation to immediate electrocution and result in:

Burns and shrapnel wounds

Blindness and hearing loss

The severity of injury depends on the:Amount of current and its path through the body

The length of time the body remains in the circuit

The current’s frequency

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Damage to electrical equipment or electronic devices

Risk of fire or explosion in a flammable atmosphere

Gases or vapors

Mists, dusts or fibers

Hybrid mixtures of two or more flammable materials

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Static electricity is often the cause of fire and explosions when circumstances rule out other forms of ignition

Steam cleaning equipment

Tank-filling operations

Using plastic containers for sampling

Ventilating vessels or tanks

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Static electricity is often the cause of fire and explosions when circumstances rule out other forms of ignition

Steam-cleaning equipment

Tank filling operations

Using plastic containers for sampling

Ventilating vessels

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Static Build-up During Transfer Operations

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Control Measures

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Reducing the Hazards of Static Electricity

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Hazards Control Measures

Accumulation of static build-up

Reduce build-up through the use of anti-static mats, clothing, and footwear, anti-static additives, grounding and bonding

Electrostatic (spark) discharge

Reduce chance of a discharge by the use of anti-static mats, clothing, and footwear, anti-static additives, grounding and bonding

Ignitable atmosphere Eliminate flammable atmospheres by eliminating vapor space, purging, or inerting

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Bonding is the process of connecting two or more conductive objects to each other by means of a conductor to minimize potential differences between conductive objects. Bonding equalizes the potential between objects.

Bonding23

BP ASH, pages 198-199; 238

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Grounding is the process of connecting one or more conductive objects to the ground to minimize potential differences between objects and the ground. Grounding dissipates an electric charge to ground.

Grounding24

BP ASH, pages 198-199; 241

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Bonding and Grounding

This is an example of grounding two objects with the earth and bonding them to each other.

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BP ASH, pages 198-199; 238; 241

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Personal Protection

An electrostatic discharge can injure workers and damage sensitive instrumentation and electronic devices.

Use anti-static work bench and floor mats, anti-static wrist straps, clothing, and footwear to reduce the chance of an electrostatic discharge.

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Safe Work Practices

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Commercial Fuel Transfer

Follow company procedures for fuel transfer.

Procedures will vary according to the product being transferred.

Tank trucks should be bonded to the fill system.

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Connection of static bonding and grounding equipment to a tanker truck during the loading process

ASH, pages 165-168; BP ASH, pages 65-69

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Commercial Fuel Transfer

All bonding and grounding should be in place prior to starting transfer operations.

Use deflectors or drop tubes to avoid splashing during filling.

Keep nozzle in contact with fill pipe while filling.

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Connection of static bonding and grounding equipment to a tanker truck during the loading process

ASH, pages 165-168; BP ASH, pages 65-69

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Fueling Passenger Vehicles

Static electricity can be highest during cold or dry conditions.

Static build-up may occur if the driver re-enters the vehicle during fueling and then returns to the nozzle.

If this occurs, discharge any potential static by touching a metal part of the vehicle with a bare hand before touching the nozzle again.

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Fueling Passenger Vehicles

Leave your cell phone in the vehicle and focus on the task.

Fuel slowly as higher velocity creates more static.

If a fire occurs when refueling, leave the nozzle in the fill pipe, and back away from the vehicle. Notify someone immediately.

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Filling Portable Fuel Containers

Use only approved portable fuel containers.

Place the container on the ground while filling.

Never fill a container while it is inside a vehicle, in the trunk, in the bed of a pickup or on the floor of a trailer.

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Filling Portable Fuel Containers

Manually control the nozzle and fill the container slowly.

Keep the nozzle in contact with the rim of the container opening while filling.

Place cap tightly on the container after filling. Do not use containers that don’t seal properly.

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Transporting Portable Fuel Containers

If gasoline spills on the container, make sure it has evaporated before it is placed in the vehicle.

Report all spills to the filling station attendant.

Secure the filled container against tipping or sliding back and forth while being transported. This type of movement can cause a build-up of static electricity inside or outside of the container.

Never leave filled containers in direct sunlight or inside the vehicle.

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Summary

Definition of Static Electricity

Static Electricity Hazards


Static Electricity Control Measures

Safe Work Practices

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north slope training cooperative © north slope training cooperative—revised may 2012. all rights...

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