Blasting Operator Safety

24.2.2 Blasting Operator Safety

Other than the personal protective equip- ment (PPE) an abrasive blasting operator wears the Deadman’s Handle (Deadman’s Valve). It is perhaps the most important safety feature of the equipment ( Figure

24.1 ). It is a handle attached to the nozzle. When it is depressed by the hand holding the nozzle, it allows the equipment to operate. Releasing the handle immediately stops operation of the blasting equipment. Inspec- tors need to ensure it is operable and in use during blast operations.

Figure 24.2 Operator Safety PPE

It is also critical that the operator has a good supply of clean, fresh air to breathe. Two common ways to provide this are:

Safety 24-3

• Air delivery at low pressure from the blast

points below typical storage temperatures,

pot via a filter. The disadvantage is the air

73ºF (23ºC) and are the most hazardous to

is the same used for blasting (often poor

store and/or use. When concentrations of

quality).

these volatile vapors are sufficient, even hot

• Air delivery, at relatively low pressure,

surfaces can ignite them.

from a remote air-driven pump located well away from contaminated or dust-

Adequate ventilation is essential to keep

laden air.

the solvent content of the air below the lower explosive limit (LEL), with the addi-

tional benefit of facilitating coating cure. Coating inspectors, supervisors, and workers

24.3 Spray Application Safety

Static electricity discharges may also ignite are usually well aware of typical worksite

solvent vapors. To reduce this hazard, hazards (mechanical equipment, cranes, lad-

ground the spray equipment and ensure con- ders, staging, etc). However, they may not

nections are electrically continuous.

realize the extent of the toxic and fire/ explosion hazards inherent when spray

Spray finishing also creates a certain

applying coatings.

amount of overspray, hazardous vapors, and toxic fumes. This is true even under ideal

When coating application is being done, all conditions and there is no way to avoid it personnel on site must be aware of the tre-

entirely. Mitigate hazards to personnel by mendous damage that can result from a

ensuring they use respirators appropriate for small quantity of a vaporized volatile sub-

the specific vapors and fumes. stance (it is both a health and explosion

hazard). Personnel need to be aware of the Even if the concentration of flammable gas hazards to health inherent in solvent fumes,

or vapors in the air is below the LEL, it may toxic fumes, finely atomized metals, vapor

still be far above the safe limit for breath-

mists, and dust dispersed in the air. These

ing. Workers should not exceed the maxi- are all both health and explosion hazards.

mum allowable concentration (MAC) of hazard exposure during an eight-hour work-

Workers have been killed by explosions day. The MAC applies to vapors, gases, while painting in confined places. One acci-

mists, and solids. MAC data are published dent occurred when the workers, because of

annually in the US in the Archives of Indus-

a toxic hazard, were properly breathing fresh trial Hygiene. These same MACs are often air through masks. They were killed sud-

adopted in other countries. denly by an explosion. The concentration of

toxic vapor in the air was in the explosive In general, aromatic solvents, such as range, so when an extension light bulb broke

xylene and toluene, are more hazardous than the vapor ignited killing several men.

aliphatic solvents, such as mineral spirits. Unfortunately, mineral spirits are rarely used

Flash point indicates the fire or explosion in high-performance coatings, but relatively hazard of a flammable substance. Coatings

hazardous solvents are still widely used. and their solvents are sometimes categorized

Aromatic solvents are used almost exclu- according to their flash-point temperature.

sively in some synthetic paints, such as lac- Low flash point solvents are those with flash

24-4 Safety

degree in oleoresinous paints, such as phe- is contaminated by a compressor or opera- nolic varnish and some alkyds.

tions elsewhere in the plant. Always ensure filters and warning monitors are fitted in line

Allowable concentrations for the aliphatic before use by the sprayer or brush painter.

solvents are greater than for the aromatic solvents, but in every case the MAC for

There are four primary types of protective breathing is far less than the LEL. This

respirators available:

means that while an airspace may be consid-

• Air-supplied helmets or hoods

ered safe from fire or explosion, it can still

• Air-supplied masks

be extremely dangerous to personnel. Sup- ply exposed workers with fresh air masks

• Organic vapor (cartridge) respirator s

that connect to a source of clean, cool, fil-

• Filtering face-piece respirator s (“paper” or

tered air.

“dust” masks)

Air-Supplied Helmet / Hood Respirators

The common use of low flash point solvents cover the entire head and neck area and sup-

such as methyl ethyl ketone (MEK) or ace- ply the wearer with clean, dry air at low

tone as universal thinners can be extremely pressure through a filtered air supply. These

hazardous, particularly in enclosed spaces. respirators provide the most complete means

Protect both spray and brush painters against of protection because they protect the wearer breathing dangerous concentrations of coat-

from heavy concentrations of vapor, fumes, ings containing lead or chromates. In addi-

dust, and dirt that can harm respiratory tion to adequate ventilation, spray removal,

organs, eyes, ears, and skin. respirators, and air filters, ensure workers

They are used where other types of respira- clean themselves thoroughly before eating

tors are either impractical or do not provide and before leaving the job. Workers must

sufficient protection. The continuous supply thoroughly clean contaminated clothing

of dry fresh air ensures mist or fog do not before reuse.

form inside the hood or helmet.

24.3.1 Respirators

These respirators are commonly required

A respirator is a mask worn over the mouth when coating work takes place in confined and nose to prevent the inhalation of over-

spaces, such as tanks, and may be mandatory spray fumes and vapor. Respirators are nec-

when certain coatings (e.g., those containing essary for two reasons:

isocyanates) are spray applied.

• Inhaling paint overspray and solvent

Air-supplied mask respirators operate

fumes is not healthy.

from an external air supply and may cover

• Use of respiratory protection is dictated by

the nose and mouth only or may cover the

governing regulatory agencies such as

full face. They do not provide the degree of

protection against splashes, etc., that a hel- It is critical to ensure that air-supplied res-

OSHA and NIOSH.

met/hood respirator does. If a full-face respi- pirators deliver fresh and pure air. The

rator is not used, workers must wear eye common practice of using plant air (air taken

protection, such as goggles. from a factory supply) is dangerous if the air

Safety 24-5

Organic-vapor respirators cover the nose and mouth and incorporate cartridges designed to remove organic vapors by chem- ical absorption. Use the correct cartridges and install replacement cartridges as needed.

Some organic-vapor respirators are designed to remove solid particles from the air before the air passes through the chemical car- tridge. They are usually used in finishing operations that use standard materials, but are not recommended for use in commercial coating operations.

For organic-vapor respirators to be effective, ensure there is a complete seal between the mask and the face. Workers should wear separate safety goggles or other eye protec- tion as required. Because the cartridges have

a limited life and must be replaced, maintain records of respirator/cartridge use.

Sprayers or helpers may use dust respira- tors, but in most coating applications they are not effective and are probably illegal. The cartridges of these respirators remove only solid particles from the air (i.e., con- taminants produced from surface prepara- tion operations like sanding, grinding, or buffing) and are not designed to remove vapors. Workers should wear separate safety goggles or other eye protection when required.

Safety recommendations for proper PPE are usually on the coating manufacturer’s MSDS. Workers should always wear the clothing specified (i.e., gloves, masks, and long-sleeve shirts).

Airless spray equipment safety precau- tions are essentially the same as conven- tional air spray equipment, with one very important addition. Airless spray operates

high pressure through a very small opening. The atomization of the material is so effec- tive that liquids can pass through a mem- brane (e.g., human skin) without breaking it. This is exactly the same principle the high- pressure devices the military uses, instead of hypodermic needles, to give military person- nel medical shots. The hazard of acciden- tally injecting coating materials into the body is a very real danger.

Injection of solvents or other fluids through the skin damages local tissue and can get into the blood stream. Localized swelling occurs and continues to occur until the pres- sure is relieved. Proper treatment involves cutting open the skin of the affected area to release the pressure and the toxic chemicals. The resulting wound may be very signifi- cant. If accidental injection is not treated immediately, it can result in the loss of a limb, or may even be fatal.

An accidental injection is highly unlikely if all safety precautions are observed. How- ever, remember to take anyone accidentally injected to a doctor immediately, even if the injury seems minor. Delay may cause loss of

a finger, arm, or leg, or even death. When working with or near airless spray

equipment, treat an airless spray gun as if it is

a loaded gun. Safety authorities in the US recognize the danger and require that airless spray guns: (1) carry a safety warning, and (2) have a safety spacer at the tip of the noz- zle. The spacer reduces the possibility of coating injection ( Figure 24.3 ).

24-6 Safety

involved in coating operations need to know and understand. Most owner/operators require workers to attend a detailed class for confined spaces safety. Those who need per- mit-required confined space training are:

• Permit issuer or company area supervisor • Quality assurance manager • Permit recipient or on-site supervisor • Authorized on-site attendant or standby • Authorized on-site linkman (as needed for

communication) • Authorized on-site entrants

• Authorized alternates (as needed)

Figure 24.3 Airless Spray Gun with Spacer

Use all equipment in accordance with

24.4.1 Confined Spaces Terminology

OSHA or Health and Safety at Work Act, or The following are terms related to permit- the governing standards for the specific

required confined spaces that inspectors country where the jobsite is located.

need to know and understand to ensure Some additional rules for airless spray safety

safety is enhanced and observation of all are:

regulations:

• Never leave a pressurized unit unattended. • The designated authority is the senior Shut off the unit, relieve the pressure,

person in charge (or appointed representa- make sure the spray gun’s trigger safety is

tive, possibly the inspector) of the coating engaged, and the power shut off.

operation.

• Ensure all fluid connections are high-pres- • Confined space is any space that is not sure-rated airless spray fittings, and are

routinely or continuously occupied, is securely tightened and checked before

enclosed or can be sealed thereby limiting each use.

ventilation; has a restricted entry or exit; and could contain or produce dangerous

• Ensure the fluid hose is electrically concentrations of airborne contaminants grounded to reduce the hazard of static

or asphyxiants.

electricity sparking. • Explosive atmosphere is any atmosphere • Ensure the coating and solvent manufac-

that contains a concentration of flammable turers’ safety precautions and warnings

or combustible material that could are followed.

explode when exposed to a source of igni- • Report any unsafe condition or practice to

tion.

the safety supervisor immediately. • Flammable material is any material that will ignite when there is a proper mixture

24.4 Confined Space Safety

of gases, vapors, and air.

Confined spaces that require permits to enter

• Oxygen deficiency is any atmosphere that

have inherent hazards that all personnel

has an oxygen concentration of 19.5% or

Safety 24-7

• Oxygen enriched atmosphere is any tains flammable material that has not been atmosphere having 22% or more oxygen

cleared and prepared for cutting using content.

conventional construction methods. • Hazardous/toxic atmosphere is any sub-

• Emergency is any occurrence (including stance or atmosphere that has the capacity

failure of hazard control or monitoring to produce personal injury, illness or death

equipment) or event(s) internal or external to humans through ingestion, inhalation,

to the confined space, that could endanger or body-surface absorption.

entrants.

• Acceptable environmental condition is a • Engulfment is when a person is sur- confined space workplace where uncon-

rounded and effectively captured by a liq- trolled hazardous atmospheres and/or

uid or finely divided solid substance. physical hazardous conditions are not

• Permit issuer is the person responsible present.

for issuing confined space entry- or work- • Entry/work permits are part of the sys-

permits.

tem that controls all work performed in • Permit recipient is an on-site supervisor and around permit-required confined

(possibly the inspector) who receives the spaces. All work in these spaces must be

permit for the group performing the work. approved by the responsible operations

person. Pre-entry job site “check list” • Standby/attendant is the person respon- system is a part of the procedures by

sible for protecting others and their equip- which the on-site job supervisor conducts

ment from hazards associated with the a pre-entry on-site job assignment orienta-

confined space entry and associated works tion meeting to include contents of entry

such as “hot work” (work generating a and work permits, personnel and work

flame or spark, such as welding or grind- assignments, safety check results, and

ing). The attendant is stationed outside the emergency rescue procedures.

space. This person monitors the autho- rized entrants specifically listed on the

• Safe Clearance procedure is a process confined space entry permit. that secures potential physical hazards.

• Linkman is the alternate person assigned • Blanking and blinding is the absolute

responsibility for the communication link closure of a pipeline, or duct, by fastening

between the standby and the workers a solid plate or cap across the bore (open-

inside the permit-required confined space. ing), completely covering it.

• Entrant is the person(s) authorized to • Double block and bleed is the closure of

enter the permit-required confined space a line, duct, or pipe by locking and tagging

to do the assigned work. Alternates must any drain or vent that is open to the atmo-

be trained in the permit-required confined sphere and located in the line between two

space entry regulations and be ready to act locked-closed valves. Lock out/tag out

as stand-ins for other workers. (LOTO) is covered later in the chapter.

• Operating area is any area under the • Standoff Blind is used to isolate an

supervision of operations personnel, enclosed space. The blind is used to cap

including, but not limited to, loading the side of the system that must be sealed

docks, tank farms, offshore platforms, off, but leaves the other side of the system

separators, vapor recovery units, or fire open to the atmosphere.

foam houses, etc.

• Hot tap is any connection made to a pipe- • Personal entry is when any part of a per- line, tank, or other equipment, that con-

24-8 Safety

an enclosed space, including ensuing work • The oxygen level is 16.1% to 19.4% in that space.

• A 10% to 19% LEL • Rescue teams are the contractor’s pre-

• Less than a IDLH level of toxicity approved and pre-arranged personnel

responsible for rescuing people inside the

This space requires full life support or car-

permit-required confined space in an

tridge respirators and standby personnel.

emergency.

Class C: a measured/tested confined space Permit-required confined spaces can become

with potential hazards from work proce- unsafe as a result of:

dures, but one that does not require any spe-

• Atmospheric contamination by toxic or

cial modification of the work procedures

flammable vapors, oxygen deficiency, or

and/or atmosphere. Authorized or unauthor-

excess oxygen

ized entrants could cause a hazard to arise

• Physical hazards, such as agitators or

through their actions, such as welding while

moving parts located inside the space

in the confined space. The conditions are:

• The inadvertent admission of liquids, • Oxygen level is 19.5% to 21.8% gases, or solids during occupancy • Has a 10% LEL or less • An event or occurrence that isolates the

occupants from help in case of need or • The toxicity level is less than contamina- rescue.

tion levels

• If a ladder is used as a means of access

to the scaffold, it shall be securely The four types of confined spaces include:

24.4.2 Types of Confined Spaces

attached and shall comply with the Class A: a measured/tested confined space

section on ladders. that has conditions immediately dangerous

This space does not require full life support to life or health (IDLH). These conditions

or a cartridge respirator, but does require include, but are not limited to:

standby personnel.

• Oxygen deficiency of 19.5% or less

Class D: a documented low-hazard confined

• Oxygen enrichment of 23.5% or greater

space that can be entered without the need

for life support or an attendant. Entrants can

• Explosive or flammable atmospheres,

10% or greater of LEL

perform repetitive entries but not any pro- cess or procedure which may cause a hazard,

• Acute IDLH concentrations of toxic sub- stances.

i.e. hot work, without obtaining a new or amended work or entry permit.

This space requires full life support equip- ment and standby personnel.

Inspectors need to know the pre-job check- list for permit-required confined spaces.

Class B: a measured/tested dangerous con- These are some of the items that should be fined space that is not immediately life

on the checklist:

threatening. Its conditions include:

• Know the job-site assignments, the on-site • The potential to cause injury and illness if

supervisor, the standby person, the link- preventive and/or control measures such

man (if needed), the entrants, and the as isolation, ventilation, and/or respirators

alternates

Safety 24-9

• Know the location of personnel assign-

the classification of the confined space, its

ments

configurations, and the hazards of the mate-

• Know the length of work assignments,

rials used and processes of the work to be

working hours, and job

done. Two common hazards are:

• Know if the work is hot work • Flammable atmospheres • Know the proper place to park personal

• Toxic substances

vehicles

The term “flammable atmosphere” refers

• Know what restrooms, water fountains,

to the fuel to air ratio which can ignite only

and break facilities are for the workers

when components in the atmosphere are

• Know the emergency phone numbers,

within certain limits. Facts about a flamma-

wash stations, rescue team, etc.

ble atmosphere follow:

• Know the terminal location • It cannot ignite when the ratio of oxygen

• Know the contractor’s personnel to combustible material in the air is nei- • Inspect the contractor’s equipment

ther too rich nor too lean for combustion to occur.

• Know all on-site personnel’s responsibili- ties

• It cannot ignite when the (LEL) is the minimum concentration of flammable

• Confirm that the on-site supervisor’s daily vapors in the air below which propagation report is filled out and accurately docu- of flame does not occur. ments the work to be performed

• The upper explosive limit (UEL) is the • Confirm that the on-site supervisor wit- maximum concentration of flammable nesses required vapor/atmosphere testing vapors in air above which fire does not and that the official work permit is issued occur on contact with an ignition source, and signed often referred to as “too rich to burn.”

• Go over the on-site safety guidelines and • The LEL and UEL explosive limits for facility-specific requirements for person- most petroleum products are between 1% nel, testing, and safety equipment and 10% hydrocarbon vapors by air vol-

• Ensure any authorized outside contractor

ume.

adheres to requirements for permit- • Combustible gases or vapors accumulate required confined space entry when there is inadequate ventilation in

• Discuss the work to be performed, the pro-

confined spaces.

cedures, and the specifications • Flammable gases (such as acetylene,

• Discuss any restrictions at the job-site butane, propane, hydrogen, methane, nat- • Discuss the emergency procedures, res-

ural or manufactured gases, or vapors cue plan, terminals list of phone numbers,

from liquid hydrocarbons) can be trapped local and terminal fire departments num-

in confined spaces; since many gases are bers, hospital and ambulance services, etc.

heavier than air, they seek lower levels in storage tanks and various other vessels.

24.4.3 Hazards in a Confined Work

• In a closed-top tank, lighter-than-air gases

Space

can rise and develop a flammable concen-

Conditions in and around permit-required

tration if trapped above the opening.

confined spaces vary greatly depending on

24-10 Safety

Toxic substances may be present in permit-

• Ethyl chloride

required confined spaces; these are classi-

• Trichloroethane

fied as:

• Corrosives (either acutely toxic or chroni-

• Chloride

cally toxic)

Irritants are substances that cause minor or

24.5 Lock Out/Tag Out

transient, and possibly painful, injuries that Before anyone enters a permit-required con- heal without scars and produce no known

fined space, it is necessary to complete a after effects.

lock out/tag out isolation procedure and Corrosives are substances that destroy tis-

ensure an on-site supervisor approves the sue and leave permanent scars. Examples of

process. The Lock out/Tag out Isolation pro- corrosive substances are hydrofluoric acid,

cess shall be determined for each type of sulfuric acid, and caustics such as lye.

confined space. Class A and Class B spaces Acutely toxic (primary) substances, with a

shall be determined by the designated safety only a single dose or short-term exposure,

professional.

can cause symptoms ranging from a simple To completely isolate Class A and Class B headache or nausea, to disablement or death.

spaces, the pipe should first be blanked at Examples of acutely toxic substances are:

the flanges with valves locked or closed as

• Chlorine

appropriate. Blanks should be capable of

• Ozone

withstanding the maximum working pres-

sure or load of the line (following required safety factors). Each blank should have a

• Hydrochloric acid

• Hydrofluoric acid

gasket on the pressure side to ensure a leak

• Sulfuric acid

proof seal. The gaskets should be made of a

• Nitrogen dioxide

chemically non-reactive material.

• Ammonia

In addition to blanking, pumps and compres-

• Sulfur dioxide

sors that serve the lines entering the con-

• Hydrogen sulfide

fined space should be locked out to prevent accidental activation. Two types of isolation

Chronically toxic (secondary) substances are

are needed:

those that can produce physiological impair- ment with long latency, such as cancer, or

• Electrical

with gradual progression, such as pulmonary

• Mechanical

obstructive disease. In some cases, these Electrical isolation prevents accidental acti- substances can adversely affect reproductive

vation of moving parts that could be hazard- organs. Some examples of chronically toxic

ous. Ensure the circuit breakers and/or substances are:

disconnects are locked in the open (off)

• Benzene

position with a key-type padlock. The only

• Carbon tetrachloride

key should remain with the person working

Safety 24-11

on the unit. If there is more than one worker, each person should place his/her own lock on the circuit breaker. In addition to the lockout system, there should be an accompa- nying tag that identifies the operation and prohibits activation of the system.

To mechanically isolate moving parts, such as linkage, drive belts, or chains, the con- trols or levers should be disconnected. Equipment with moving parts should be blocked to prevent accidental mechanical movement.

In summary, to prevent unexpected hazards from developing, make sure all electrical and mechanical operating systems that might endanger workers are locked out, blanked off, misaligned, and tagged out.