Date post: | 16-Dec-2015 |
Category: |
Documents |
Upload: | davis-golston |
View: | 215 times |
Download: | 2 times |
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
2
3
© North Slope Training Cooperative—revised May 2011. All rights reserved.
Administration and Safety
Emergency Procedures
Restrooms/Breaks/Smoking
Safety Minute
3
4
© North Slope Training Cooperative—revised May 2011. All rights reserved.
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?
4
5
© North Slope Training Cooperative—revised May 2011. All rights reserved.
Goal
To create a safe environment for employees working in areas where the possibility of static electricity generation exists.
5
6
© North Slope Training Cooperative—revised May 2011. All rights reserved.
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.
6
7© North Slope Training Cooperative—revised May 2011. All rights reserved.
Static Electricity and Its Hazards
7
8
© North Slope Training Cooperative—revised May 2011. All rights reserved.
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.
8
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.
9
© North Slope Training Cooperative—revised May 2011. All rights reserved.
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.
9
10
© North Slope Training Cooperative—revised May 2011. All rights reserved.
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.
10
BP ASH, pages 198-199
11
© North Slope Training Cooperative—revised May 2011. All rights reserved.
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.
11
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.
12
© North Slope Training Cooperative—revised May 2011. All rights reserved.
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.
12
13
© North Slope Training Cooperative—revised May 2011. All rights reserved.
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.
13
NFPA 77 3.3.16 and 5.3.3.1
14
© North Slope Training Cooperative—revised May 2011. All rights reserved.
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.
14
15
© North Slope Training Cooperative—revised May 2011. All rights reserved.
Static Electricity Generation in Oil/Gas Industry
15
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
16
© North Slope Training Cooperative—revised May 2011. All rights reserved.
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
16
17
© North Slope Training Cooperative—revised May 2011. All rights reserved.
Why Static Electricity is Dangerous
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
17
18
© North Slope Training Cooperative—revised May 2011. All rights reserved.
Why Static Electricity is Dangerous
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
18
19
© North Slope Training Cooperative—revised May 2011. All rights reserved.
Why Static Electricity is Dangerous
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
19
20
© North Slope Training Cooperative—revised May 2011. All rights reserved.
Static Build-up During Transfer Operations
20
21© North Slope Training Cooperative—revised May 2011. All rights reserved.
Control Measures
21
22
© North Slope Training Cooperative—revised May 2011. All rights reserved.
Reducing the Hazards of Static Electricity
22
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
23
© North Slope Training Cooperative—revised May 2011. All rights reserved.
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
24
© North Slope Training Cooperative—revised May 2011. All rights reserved.
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
25
© North Slope Training Cooperative—revised May 2011. All rights reserved.
Bonding and Grounding
This is an example of grounding two objects with the earth and bonding them to each other.
25
BP ASH, pages 198-199; 238; 241
26
© North Slope Training Cooperative—revised May 2011. All rights reserved.
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.
26
27© North Slope Training Cooperative—revised May 2011. All rights reserved.
Safe Work Practices
27
28
© North Slope Training Cooperative—revised May 2011. All rights reserved.
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.
28
Connection of static bonding and grounding equipment to a tanker truck during the loading process
ASH, pages 165-168; BP ASH, pages 65-69
29
© North Slope Training Cooperative—revised May 2011. All rights reserved.
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.
29
Connection of static bonding and grounding equipment to a tanker truck during the loading process
ASH, pages 165-168; BP ASH, pages 65-69
30
© North Slope Training Cooperative—revised May 2011. All rights reserved.
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.
30
31
© North Slope Training Cooperative—revised May 2011. All rights reserved.
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.
31
32
© North Slope Training Cooperative—revised May 2011. All rights reserved.
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.
32
33
© North Slope Training Cooperative—revised May 2011. All rights reserved.
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.
33
34
© North Slope Training Cooperative—revised May 2011. All rights reserved.
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.
34
35
© North Slope Training Cooperative—revised May 2011. All rights reserved.
Summary
Definition of Static Electricity
Static Electricity Hazards
Why Static Electricity is Dangerous
Static Electricity Control Measures
Safe Work Practices
35