Abcaring4safety

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Hazard Recognition and Intervention Module

Static Electricity (SE)

This module does not cover SE prevention by means of design and construction, nor does it cover prevention of other spark type ignition sources such as from Hot Work like welding (see HR&IM Work Permitting)

This module deals with the risk for SE incidents, related work practices by process Operators and maintenance Technicians- and with potential incident prevention Inspiring Work Practices (IWP)

27-02-2014

Free

Draft for review

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Disclaimer and conditions of use

ABCARING4SAFETY Theo van der Smeede Rotterdam-Rozenburg, The Netherlands 27-02-2014

Disclaimer:

  Separateness notice: This Hazard Recognition and Intervention Module (HR&IM) is freely available on the ABCARING4SAFETY website for end-users only. This in an effort of trying to help people improving or maintaining Health, Safety, Security and Environmental (HSSE) performance at their operations. End-users of this module, including Incident Prevention Elements (IPE), Lay-outs, Inspiring Work Practices (IWP) and Theo van der Smeede’s Key Lessons provided herein, retain ultimate responsibility for adapting, adopting, and using all or parts of it’s contents. End-users take a conscious decision to utilize this module or not, accept full responsibility and accountability for usage and agree with this disclaimer and conditions of use by utilizing this HR&IM;

  The names, titles and/or content of HSSE Management Systems, Work Practices, Lay-outs and IWP are included as examples. They do not necessarily match one-to-one with a particular system used by a particular company. End-users of this information are referred to the relevant documents of the company they work with;

  End-users of this module are responsible and accountable for pictures/video’s/illustrations/text if added to this module and/or used in conjunction with this module by them. This taking into account ownership and copy-right issues of these items if any;

  Local laws and/or regulations always prevail to anything covered in this module;

  In no event, under no circumstances and under no legal theory or practice, shall ABCARING4SAFETY nor it’s founder and owner, Theo van der Smeede be liable to End-users of this module or to any other party/person for events/incidents including injuries, illnesses, loss of life, environmental pollution, work stoppages, loss of profits, loss of goodwill, or any other direct, indirect, special, incidental, or consequential deaths, injuries, illnesses, damages and costs. This includes situations in which the causes of these incidents can be allocated to the use, less than adequate (LTA) use or misuse of the contents of this module.

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Target audience and expected outcomes

After reviewing this module you should be able to:

  Explain what Static Electricity (SE) is o  Explain how accumulated positive “+” and negative “-” ions generate a

voltage difference between two materials / objects / bodies

o  Explain how a “Spark Bridge” between these objects can be dangerous depending spark energy, flash point / explosive range of the combustibles / flammables and other conditions

  Explain how process- and maintenance activities shall take this information into account in order to prevent SE type incidents

The ultimate outcome: NO Fires nor Explosions

The Team leader best reviews this module with the Process Operators and /or Maintenance Technicians in her / his Team. See also the “Do’s” for these Toolbox

type sessions on the ABCARING4SAFETY website

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1.  Static Electricity

1  Definition of Static Electricity (SE)

2  Is Static Electricity dangerous, a HAZARD?

3  How is SE produced / generated?

4  Can Static Electricity (SE) accumulate?

5  Can SE lead to fire / explosions?

6  Incidents

7  Example of SE accumulation / build-up

2.  Key Hazard examples

3.  Example Inspiring Work Practices (IWP)

Content

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1.1 Example definition of Static Electricity (SE)

Static Electricity (SE) is electricity formed by an imbalanced situation in between electrical charged bodies.

Example: Charges got stuck on one body* e.g. negative (-) and

on another body* e.g. positive (+) charges / ions

* Body with positive or negative charges can be anything such as a pipe, tank truck loading arm, liquid inside a storage tank, powder in a storage bin, your personal body, a bucket, tool and sample- or gauging device

Generation of SE can be caused by several events such as by flow of liquids through a pipe, filtering, splashing, spraying mist on an object, separating two different solid materials, contact between two differently charged objects etc. Think about combing your hair for example. See also the next page

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1.2

YES, SE can be the (ignition) source for fires and explosions!

The following elements are needed for an ignition hazard to be present:

1.  A combustible / flammable atmosphere (mixture), (fuel in air);

2.  Static Electricity is generated, for example by friction between two materials;

3.  The electrical charges are accumulated on the surface of these materials;

  There is a difference in potential / voltage between the two charges, (+ ions on one material and – ions on the other);

4.  A gap is created / exists in between the two materials / objects in which a spark can be created between the + and the – bodies;

5.  Electrostatic discharge (ESD) takes place including spark formation;

6.  Spark has enough energy, some materials ignite at very low spark energy levels.

Is Static Electricity (SE) dangerous?

Combustibles

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1.3

Example activities and processes that produce SE charges:

o  Contact and then separating solid materials, (e.g. combing your hair);

o  Flowing materials through pipes or hoses;

o  Filling a tank truck or land storage tank with refinery products such as gasoline;

o  Movement of people, liquids, dust / other isolating (non-conductive) materials;

o  Filtering combustible / flammable materials through a metal screen (the smaller the screen mazes, the higher the SE generation);

o  Splashing liquids like loading a tank railcar when the loading arm’s outlet is not submerged;

o  The production of mist like spraying paint / coating;

o  Moving liquids, ascending gasses and descending water droplets in e.g. a storage tank;

o  Draining, sampling without assuring that all parts are equally connected to each other such that potential charges “flow away” / be earthed before a gap / spark bridge is formed ….

Message: Waiting periods / times are different! This depending materials handled, their characteristics with regard to accumulation of electrical charges, the processing method (e.g. filtering), weather conditions and alike.

Electrical charges need to disappear / flow away to earth / equalize.

This should all be made clear to you through formal work practices / procedures and education !

How is Static Electricity (SE) produced / generated?

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1.4

YES, SE accumulates / assembles in particular on isolating materials! Examples:

1.  Refined products such as gasoline, jet fuel, kerosene, solvents like toluene, xylene, heptanes, diesel, naphtha, polymers and plastics;

2.  Many powders used in industry.

Can Static Electricity (SE) accumulate?

Combustibles

Not easy on:

Raw materials like wood, crude oils, bitumen, alcohols, ketones, water and metals.

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1.4 KEY HAZARD WARNING Static Electricity can also accumulate on conductors such

as metal if:

You have ungrounded, bad earth connections or insufficient bonding / connections in between conductors for example.

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Take an open metal bucket with solvent on a rubber / plastic floor

Other examples of SE hazards:   Metal fittings with non-conductive hoses (without metal wires inside the rubber);   Metal scaffold on rubber wheels;   Floating / flying debris in a vacuum truck’ tank;   Corroded connections and people on isolated / non conductive shoes.

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Exercise

Is it true that static electricity charges are accumulated in good conductors like metal and water?

Is it true that static electricity is always fatal due to electrical execution?

Is it true that spiral wounded hoses must form a conductive connection through metal couplings and equipment such that the whole set is earthed / grounded?

Static electricity can be formed by high pressure cleaning, the use of steam hoses/lances, spraying paint etc. A fire or explosion may happen if combustible / flammable materials are also present in air.

Please read the descriptions below and indicate if the statement is True or False. Discuss in your team after your initial conclusions

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Answer examples

Is it true that static electricity charges are accumulated in good conductors like metal and water? Normally it’s not unless metal is badly grounded / earth connections are corroded etc.

Is it true that static electricity is always fatal due to electrical execution?

Is it true that spiral wounded hoses must form a conductive connection through metal couplings and equipment such that the whole set is earthed / grounded?

Static electricity can be formed by high pressure cleaning, the use of steam hoses/lances, spraying paint etc. A fire or explosion may happen if combustible / flammable materials are also present in air.

Please read the answer examples below, clarify to each other, discuss in your team and determine if you agree or not

 

 

 

 

Can SE lead to fire or explosions ?

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1.5

Three components of the Fire Triangle

Combustible / flammable materials such as organic (hydrocarbon) vapor / gas or dust

Some metal dusts / thin shavings are also combustible

Combustibles

Air because of the Oxygen (O2)

Ignition source such as:

1.  Sparks from welding, grinding, electrical arches and static electricity;

2.  Hot surfaces

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1.5 KEY HAZARD EXAMPLE

Flammable liquids in the form of mist or aerosols may ignite far below the official flashpoint!

Remember that the official flashpoint laboratory test starts with a colder liquid which is slowly heated up until the combustible / flammable material produce enough vapor that can be ignited if an ignition source is present.

When you have small droplets, dense mist and / or aerosols you already have a combustible / flammable / explosive mixture in the air.

See also HR&IM “Fires, Explosions and Bleve’s”

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Incidents 1.6 Operator killed on top of a storage tank while

sampling the product before the product

was settled out and electrically discharged.

For this product the official waiting time was

30 minutes

Operator Severely burned over his entire body

when a flash occurred during flushing of

solvent in an open bucket. The bucket was

not earthed.

Electrical discharge (getting rid of the charge difference (+ and -) depends on so many factors that settling and waiting times must be carefully defined with a lot of contingency time and must be

strictly respected.

Even weather conditions like air humidity play a role!

Note: Using an open bucket with low flash materials is hazardous anyway!

SE is a so-called “hidden hazard”; You’ll be hit without even seeing it!

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1.7 Example of SE accumulation / build-up

+ +

+ +

+ +

+

Earth connection

A difference in electricity voltage is created between the liquid and storage tank

during the emptying / filling operation of the tank

Hatch

Liquid positive

Tank wall negatively charged

Atmospheric connection

Accumulation of electrical charge is worsened by

splashing!

Patience after product movement is KEY !!! Liquid has to settle out, water droplets need to sink, gas bubbles need to

ascend and the difference in electrical charges need to disappear before any work is considered near the tank / truck / rail car etc. , (see your local procedure)

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+++ +

+ ++

Hatch

An example Inspiring Work Practice (IWP) includes that:

1.  People are kept away from the tank during transfer of combustible liquid such as filling or emptying a storage tank. This is also true for storage tanks with (internal) floating roofs with open hatches;

2.  Minimum waiting times are defined, after product transfer has been stopped, for each storage tank, tank truck, railcar tank and ship compartment and for the product type such that static electricity / electrical potential is equalized / drained to ground. Products differ in conductivity, i.e. accumulate higher or lower electrical charges;

3.  People do not remove clothing near-by open hatches. They use special safety footwear, first touch a metal / earthed object close to the hatch before opening hatches to equalize potential differences between their body and the tank;

4.  Any equipment such as measuring /gauging devices and sample equipment are selected and used as per local procedure. This taking into account conductivity of the device’ material and potential need for bonding / holding it against the vessel near the hatch if the devices are conductive.

1.7 Example of SE accumulation / build-up

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Exercise Ignition due to static electricity: Please read the

descriptions below and indicate if the statement is True or False. Discuss in your team after your initial conclusions

Is it true that the items listed below are all needed for electrostatic ignition of combustibles / flammables?

Generation of static electricity

Build-up of an electrical charge / accumulation of electricity

A space gap in between 2 differently charged objects/materials

Nitrogen

Spark with enough energy

Combustible / flammable gas, vapor or mist (due to splashing)

Oxygen, for example from air

The concentration of combustibles / flammables above the flashpoint within the explosive range, (in between LEL and UEL)

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Answer examples Ignition due to static electricity: Please read the answer

examples below, clarify to each other, discuss in your team and determine if you agree or not

Is it true that the items listed below are all needed for electrostatic ignition of combustibles / flammables?

Generation of static electricity

Build-up of an electrical charge / accumulation of electricity

A space gap in between 2 differently charged objects/materials

Nitrogen

Spark with enough energy

Combustible / flammable gas, vapor or mist (due to splashing)

Oxygen, for example from air

The concentration of combustibles / flammables above the flashpoint within the explosive range, (in between LEL and UEL) Flashpoint not always true, (think about the page 13 Key Hazard)

     

       

 

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Exercise

Ignition due to static electricity: Please read the descriptions below and indicate if the statement is True or False. Discuss in your team after your initial conclusions

Can you imagine static electricity building up, leading to ignition, when an open bucket is filled with solvent while electrically isolated from the process equipment?

Examples of the electrical isolation: 1.) Bucket is equipped with a plastic handle and hung-up on the drain valve; 2.) Bucket is handhold by the Operator without any conductive bonding with the process equipment.

An Operator was severely burned over his whole body when solvent vapors were ignited during draining / flushing into an open bucket

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Answer examples

Ignition due to static electricity: Please read the answer examples below, clarify to each other, discuss in your team and determine if you agree or not

Can you imagine static electricity building up, leading to ignition, when an open bucket is filled with solvent while electrically isolated from the process equipment?

Examples of the electrical isolation: 1.) Bucket is equipped with a plastic handle and hung-up on the drain; 2.) Bucket is handhold by the Operator without any conductive bonding with the process equipment.

 

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Exercise

Is the description below True or False? Discuss in your team after your initial conclusions

Static electricity is a so called “hidden hazard”, you don’t see it but it’s there. That’s one of the reasons why it’s so important to follow safe work practices, procedures and safety rules to the letter / without any deviations. You’ll be hit by the hazard without even seeing it!

A Tank truck loader was killed during sampling, after loading and before the electrical charge was drained to ground. The highly combustible / flammable vapors ignited

Earth connection

+ + +

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Answer examples

Please read the answer examples below, clarify to each other, discuss in your team and determine if you agree or not

Static electricity is a so called “hidden hazard”, you don’t see it but it’s there. That’s one of the reasons why it’s so important to follow safe work practices, procedures and safety rules to the letter / without any deviations. You’ll be hit by the hazard without even seeing it!

Earth connection

+ + +

 

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2 KEY HAZARD EXAMPLES

- Static Electricity accumulators such as refined oil products and powders

- Combustible mist, small droplets lowering the ignition temperature to < flashpoint

- Dust clouds, transferring combustible powders with air

- Moving materials, turbulence in liquids, splashing, spraying liquids

- gas bubbles ascending from liquids, water droplets sinking

- Steam jets

- Filters and even more, partly plugged / small screen filters are increasing charge

- People’s activities such as moving, sampling, (un)loading, draining, flushing

- People’s activities such as using hoses, buckets, ropes and isolated tools

- Lack of good earth connections, lack of conductive bonding of all equipment

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- Combustible / flammable atmosphere with aerosols, dust, gasses or vapors

Example Inspiring Work Practices (IWP)

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Describing exactly what the hazards are and how to deal with them step-by-step. The IWP takes contingencies (e.g. extra waiting times) into account and spells out, e.g.:

1.  What equipment to use for activities such as sampling or draining; 2.  Assuring that conductors are not isolated by non-conducting materials (also true

for hoses and tools); 3.  The work method / how to do the job, including how to check and assure

conductive bonding, grounding and earth connections of all equipment and tools; 4.  People based rules like for expected behaviors, clothing and footwear etc.; 5.  Waiting times before approaching potentially hazardous areas and before doing

any work.

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Describing exactly how emptying / filling trucks, railcars, ships, storage tanks is done (e.g.):

1.  Proper bonding / grounding of all equipment involved; 2.  No splash filling, no spraying; 3.  Bottom filling / loading arm extended to the bottom of the truck / railcar 4.  Varying flow rates, slow until fill nozzle is fully submerged; 5.  No modifications without proper risk assessment by subject matter experts,

review and approval by management. Not adding filters for example! 6.  Dedicated and well selected equipment for sampling / gauging; 7.  Adherence to waiting times and other subjects in work practices / procedures;

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Target audience and expected outcomes

Are you now able to:

  Explain what Static Electricity (SE) is o  Explain how accumulated positive “+” and negative “-” ions build up a

voltage difference between two materials / objects / bodies

o  Explain how a “Spark Bridge” between these objects can be dangerous depending spark energy, flash point / explosive range of the combustibles / flammables and other conditions

  Explain how process- and maintenance activities shall take this information into account in order to prevent SE type incidents

The Team leader best reviews this module with the Process Operators and /or Maintenance Technicians in her / his Team. See also the “Do’s” for these Toolbox

type sessions on the ABCARING4SAFETY website

Please raise / resolve questions and discuss how to use the information in day-to-day activities