How to Prevent Hand-Arm Vibration Syndrome (HAVS)

D0 you know vibration can cause long-term painful damage to your hands, fingers and arm? And that shocks and jolts from driving certain types of vehicles can cause severe back pain? There are a few types of vibration that are encountered in the work place. But the most common are:

 

Hand-arm vibration

Hand-arm vibration comes from the use of hand-held power tools and is the cause of significant ill health (painful and disabling disorders of the blood vessels, nerves and joints).

Whole body vibration

Whole-body vibration (WBV) is transmitted through the seat or feet of employees who drive mobile machines, or other work vehicles, over rough and uneven surfaces as a main part of their job. Large shocks and jolts may cause health risks including back-pain. Advice on reducing the risks of back and muscle pain caused by shocks/vibrations when driving certain types of vehicle.

Are You at Risk?

Personnel who regularly use hand-held or hand guided power tools and machines are at risk. These machines or tools include but are not limited to:

• Concrete breakers, concrete pokers; Sanders, grinders, disc cutters;
• Hammer drills; Chipping hammers; Chainsaws, brush cutters, hedge trimmers,
• Powered mowers; Scabblers or needle guns,
• If you hold work pieces, which vibrate
• You are particularly at risk if you regularly operate: “hammer action tools for more than about 15 minutes per day; or some rotary and other action tools for more than about one hour per day”.

Early signs and symptoms to look out for?

• Tingling and numbness in the fingers (which can cause sleep disturbance)
• Not being able to feel things with your fingers;
• Loss of strength in your hands (you may be less able to pick up or hold heavy objects);
• Fingers going white (blanching) and becoming red and painful on recovery (particularly in the cold and wet, and probably only in the tips at first).

Preventing Whole-body vibration

To prevent whole-body vibration, kindly do the following:

• Avoid risky behaviors;
• Evaluate the risks that cannot be avoided
• Combat the risks at source;
• Adapt the work to the individual, e.g. workplaces design; work equipment choice and working methods;
• Adapt to technical progress
• Replace any dangerous vehicles with non-dangerous vehicles
• Adhere to prevention policies, conditions, and the influence of factors relating to the working environment;
• Give appropriate instructions to employees.

Protection against Hand-arm vibration?

It is employers’ responsibility to protect its personnel against HAVS and carpal tunnel syndrome, but you should help by asking your employer if your job could be done in a different way without using vibrating tools and machines. If this cannot happen:

• Ask to use suitable low-vibration tools;
• Always use the right tool for each job (to do the job more quickly and expose you to less hand-arm vibration);
• Check tools for wear and tear before using them ;
• Make sure cutting tools are kept sharp so that they remain efficient;
• Reduce the amount of time you use a tool in one go, by doing other jobs in between;
• Avoid gripping or forcing a tool or work piece more than you have to;
• Store tools so that they do not have very cold handles when next used;
• Encourage good blood circulation by:
  • Keeping warm and dry (when necessary, wear gloves, a hat, waterproofs and use heating pads if available);
  • Giving up or cutting down on smoking because smoking reduces blood flow; and
  • Massaging and exercising your fingers during work break.

Key Messages

• Hand Arm Vibration Syndrome (HAVS) is preventable, but once the damage is done it is permanent;
• HAVS is serious and disabling, and nearly 2 million people are at risk;
• Damage from HAVS can include the inability to do fine work and cold can trigger painful finger blanching.

HSE Quotes

Safety is like a member of your family. Treat it with disrespect and it will leave you exposed to harm. Treat it with respect and nurture it as you go and will remain with you always – from Sue C

Brief about HSE Safety Triangle

In 1969, a study of industrial accidents was undertaken by Frank E. Bird, Jr., who was then the Director of Engineering Services for the Insurance Company of North America. He was interested in the accident ratio of 1 major injury to 29 minor injuries to 300 no-injury accidents first discussed in the 1931 book, Industrial Accident Prevention by. H. W. Heinrich. 

Since Mr. Heinrich estimated this relationship and stated further that the ratio related to the occurrence of a unit group of 330 accidents of the same kind and involving the same person, Mr. Bird wanted to determine what the actual reporting relationship of accidents was by the entire average population of workers. H.W. Heinrich’s classic safety pyramid is now considered the foremost illustration of types of employee injuries.

There Bird analyzed 1,753,498 accidents reported by 297 cooperating companies. These companies represented 21 different industrial groups, employing 1,750,000 employees who worked over 3 billion hours during the exposure period analyzed. The study revealed the following ratios in the accidents reported: 

For every reported major injury (resulting in fatality, disability, lost time or medical treatment), there were 9.8 reported minor injuries (requiring only first aid). For the 95 companies that further analyzed major injuries in their reporting, the ratio was one lost time injury per 15 medical treatment injuries.

Forty-seven percent of the companies indicated that they investigated all property damage accidents and eighty-four percent stated that they investigated major property damage accidents. The final analysis indicated that 30.2 property damage accidents were reported for each major injury.

Part of the study involved 4,000 hours of confidential interviews by trained supervisors on the occurrence of incidents that under slightly different circumstances could have resulted in injury or property damage. Analysis of these interviews indicated a ratio of approximately 600 incidents for every reported major injury.

In referring to the 1-10-30-600 ratio detailed in a pyramid it should be remembered that this represents accidents reported and incidents discussed with the interviewers and not the total number of accidents or incidents that actually occurred. 


Bird continues, as we consider the ratio, we observe that 30 property damage accidents were reported for each serious or disabling injury. Property damage incidents cost billions of dollars annually and yet they are frequently misnamed and referred to as "near-accidents”. Ironically, this line of thinking recognizes the fact that each property damage situation could probably have resulted in personal injury. This term is a holdover from earlier training and misconceptions that led supervisors to relate the term "accident" only to injury.

The 1-10-30-600 relationships in the ratio indicate clearly how foolish it is to direct our major effort only at the relatively few events resulting in serious or disabling injury when there are so many significant opportunities that provide a much larger basis for more effective control of total accident losses.

It is worth emphasizing at this point that the ratio study was of a certain large group of organizations at a given point in time. It does not necessarily follow that the ratio will be identical for any particular occupational group or organization. That is not its intent. The significant point is that major injuries are rare events and that many opportunities are afforded by the more frequent, less serious events to take actions to prevent the major losses from occurring. Safety leaders have also emphasized that these actions are most effective when directed at incidents and minor accidents with a high loss potential.

There is always a large variation between the most serious and no claim incident, as shown in both pyramids. 

In 2003, ConocoPhillips Marine conducted a similar study demonstrating a large difference in the ratio of serious accidents and near misses. The study found that for every single fatality there are at least 300,000 at-risk behaviors, defined as activities that are not consistent with safety programs, training and components on machinery. These behaviors may include bypassing safety components on machinery or eliminating a safety step in the production process that slows down the operator. With effective machine safeguarding and training, at-risk behaviors and near misses can be diminished. This also reduces the chance of the fatality occurring, since there is a lower frequency of at-risk behaviors. The variation can be explained by distance or time – for example, the injury was missed by one second or by one inch. Machine safety can make a material. The difference in widening the variation, favorably impacting frequency and severity of claims and, therefore, workers’ compensation premiums. 

Define Hazardous Area Classification (HAZAC)

The scope of this guide is to drawn the guidelines of several different Recommended practice(s) for the Area Classification of a process plant. The area classification is required for the installation of the electrical equipment with  the related specific protection kind within a process area. The basic definition, and the following modifications is based mainly on the 1996 NFPA 70, The national Electrical Code (NEC) and the API 505 Recommended Practice (API RP 505). Once that a location has been classified, requirements for electrical equipment and associated wiring should be determinate from applicable publications (e.g. NFPA 70 and API Recommended Practice 14F (API RP 14F) and local regulations.

The final scope of the document is to achieve the classification of both permanently and temporarily installed electrical equipment. The application is designed in relation to their potential risk of ignition source in presence of an ignitable mixture of “fuel”, or a flammable/ignitible substance, and Oxygen (Air) under normal atmospheric conditions.

Reference Atmospheric Conditions
Pressure	101.3 Kpa	14.7 Psia
Temperature	20°C (293.15 K)	68°F

The document provides that is no relevant changes related to the change of the atmospheric conditions from the reference point. On the basis provided earlier, the guide is developed on the recommended practice based on the petroleum facility zones (where ignitable liquids, gases, and vapors are processed, handled and loaded).

References, Codes and Reference Standards:

Actually, there are many Reference standards and industrial codes as reference for the plant area classification. Part of them are developed on the same basis, others are very particular and applied in specific plant type (e.g. Drilling Facilities, Petroleum and petrol chemical plants).

The Hazardous Area Classification presents in this guide is based on the following items as reference:

 API:

API RP 505  Recommended Practice for Classification of Locations for Electrical Installation at Petroleum Facilities Classified as Class I, Zone 0, Zone 1 and Zone 2 (2002).

API RP 500 Recommended Practice for Classification of Locations for electrical Installation at Petroleum Facilities Classified as Class I, Division 1 and Division 2.

IEC:

IEC 60079-10 Electrical Apparatus for explosive gas atmospheres- Part 10: Classifications of hazardous Area.

IEC 60079-12 Classification of Mixtures of Gases or vapors with air according to their maximum experimental Gaps (MEGs) and minimum ignition currents ratio (MIC).

IEC 60079-20 Electrical Apparatus for explosive gas atmospheres- Part 20: Data for flammable gases and vapors, relating to the use of electrical apparatus.

NFPA:

NFPA 30: Flammable and Combustible Liquids Code

NFPA 70: National Electrical Code

NFPA 325: Guide to fire Hazard Properties of Flammable Liquids, Gases, and volatile Solids

NFPA 497: Recommended practice for the Classification of Flammable Liquids, Gases or Vapors and of Hazardous (classified) Locations for Electrical Installations in Chemical Process Areas.

The complete list of the codes, recommended practice, and standards relevant to the hazardous area classification is present at the end of the chapter.

 Basic Definitions:

The following list of definition is based on the reference codes and practice guideline listed before. The reference standard is assigned to each definition.

Boiling Point – The temperature of a liquid boiling at the reference atmospheric conditions. (IEC 79-10, Mod.)

Area Classification – See Further paragraph named (“Area Classification and Definition”).

Class I, Zone 0 – See Further paragraph named (“Area Classification and Definition”).

Class I, Zone 1 – See Further paragraph named (“Area Classification and Definition”).

Class I, Zone 2 – See Further paragraph named (“Area Classification and Definition”).

Combustible Liquid(s) – See Flammable Liquid(s) definition.

Enclosed Area – A three-dimensional space enclose by more than two-third (2/3) of the possible projected plane surface area and of sufficient size to allow the entry of personnel. For a common building, this would required two-third (2/3) of the walls, ceiling, and/or floor be present.

Explosive gas atmosphere – A mixture with air, under the reference atmospheric conditions, of a flammable material in the form of gas or vapor which, after ignition, combustion spreads throughout the unconsumed mixture. (API 505-3.2.20)

Flammable  – Capable of an easy ignition, burning intensely or spreading flame rapidly.

Flammable (Explosive) limit(s)  – The lower (LFL) and upper (UFL) percentages by volume of concentration of gas in gas-air mixture that will form an ignitible mixture.   (NPFA 325)

Flammable Liquid(s) – See Further paragraph named (“Flammable liquid Classification”).

Flash Point  – The minimum temperature of a liquid at which sufficient vapor is give off to form an ignitible mixture with air, near the surface of the liquid, or within the vessel used, as determinate by the test procedure and apparatus specified in NFPA 30.

Grade of Release  – There are three basic grade of release, as listed below, in order of decreasing likelihood of the explosive gas atmosphere being present.(1)

1-     Continuous

2-     Primary

3-     Secondary

Other grades of release may be possible by combination of the basic ones listed.(IEC 79-10, Mod.)

(1)    It is important to underline that there isn’t any relationship with the type of release discussed earlier like” puff” and “plume”.

Grade of Release: Continuous – See Further paragraph named (“Area Classification and Definition”).

Grade of Release: Primary – See Further paragraph named (“Area Classification and Definition”).

Grade of Release: Secondary – See Further paragraph named (“Area Classification and Definition”).

Gas Group(s) – For the Classification, the ignitible gases or vapors are classified in several different groups. The subdivision of the gases is related to the gases physical and chemical properties.

Hazardous (classified) Location(s) – A location where fire and explosion hazards may exist due to flammable gases or vapors, flammable liquids, combustible dusts, or ignitible fibers of flyings. (API 505-3.2.10.5)

Heavier-than-air Gases of Vapors – Formally those gases of vapors with a relative density above 1.2 as to be regarded as Heavier-than-air gases. (IEC 79-10, Mod.)

Highly volatile liquid(s) (HVL) – See Further paragraph named (“Flammable liquid Classification”).

Ignitible (Flammable) Mixture  – A gas-air mixture that is capable of being ignited by an open flame, electric arc or spark, or device operating above the ignition temperature of the gas-air mixture.  (See “Flammable (Explosive) Limits”) (API 505-3.2.32)

Ignition (Auto ignition) Temperature  (AIT) – The lowest temperature of a heated surface at which, under specific conditions, the ignition of a flammable substance, or mixture in the form of gas or vapor will occur. (IEC 79-10, Mod.)

Lighter-than-air Gases or Vapors  – Formally those gases or vapor with a relative density below 0.8 as to be regarded as Lighter-than-air substances. (IEC 79-10, Mod.)

Maximum Experimental Safe Gap (MESG)  – The maximum gap of the joint between the two parts of the interior chamber of a test apparatus that, when the internal mixture is ignited  and under specific conditions, prevents the ignition of the external gas mixture by propagating through a 25 mm (984 mils) long joint, for all concentrations of the tested gas or vapor in air. (API 505-3.2.38)

Minimum Ignition Current (MIC) – The minimum current that, in a specified spark test apparatus and under specific condition, is capable of igniting the most easily ignitible mixture. (API 505-3.2.39)

Minimum Ignition Current Ratio (MIC Ratio) – The minimum energy required from a capacitive spark discharge to ignite the most easily ignitible mixture of a gas or vapor divided by the minimum current required from and inductive spark discharge to ignite methane under the same test conditions. (NFPA 497)

Normal Operation(s) – The situation when the equipment is operating within its design parameters. (IEC 79-10, Mod.)

Protected Fire Vessel – Any fired vessel that is provided with equipment (such flame arresters, stack temperature shutdown, forced draft burners, with safety controls, and spark arresters) designed to eliminate the air intake and exhaust as sources of ignition. (API 505-3.2.48)

Release, Source of – A point or location from which a flammable gas, vapor or liquid may be released into the atmosphere such that an ignitible gas atmosphere could be formed. (IEV 426-03.06, Mod.)

Release Rate – The quantity of flammable gas or vapor emitted per unit time from the source of release. (IEC 79-10, Mod.)

Vapor Pressure –  The pressure exerted when a solid or liquid is in equilibrium with its own vapor. It is a substance properties linked to the environment condition and determinate by ASTM D 323-82. (IEC 79-10, Mod.)

Vapor-tight Barrier – Is a wall, or barrier that will not allow the passage of significant quantities of gas or vapor at atmospheric pressure. (API 505-3.2.54)

Ventilation – Natural or artificial movement of air and its replacement with “fresh air”.

Ventilation, Adequate – Ventilation that is sufficient to prevent the accumulation of enough quantities of an ignitible mixture into a specific location.

Volatile Flammable Liquid – A flammable liquid whose temperature is above its flash point, or a Class II combustible liquid having a vapor pressure not exceeding 276 Kpa (40 Psia) at 37.8°C(100°F) whose temperature is above its flash point. (API 505-3.2.58)

Basic Condition for Fire(s) and Explosion(s):

As discussed earlier, to occur, a fire and/or and explosion needs three basic elements, without any of them, or specific conditions for each of them, the event cannot occur. The three main elements are: (1) A fuel, not necessary an common combustible (e.g. Dust, or Mill Dust), (2) a combustible (e.g. Air or Oxygen). (3) An igniter source with enough energy to ignite the flammable mixture (e.g. Electrical equipment, free flames, or hot surfaces). Other than the presence of each of these elements, there are two additional conditions needed to obtain a fire or an explosion: (4) The concentration of the fuel within the mixture must be between its own Upper and Lower Flammable Limit. (5) The three basic elements must be in same location, or they must have a position that allows them to complete their own role.

In classifying a particular location, the likelihood of the presence of a flammable gases or vapor is a significant factor in determinate the zone classification (See Further paragraph named “Area Classification and Definition”). Otherwise a distinction must be made: the presence of the flammable mixture could be distinguished between “normal conditions” and “extraordinary condition”. The term “extraordinary condition” doesn’t mean only a catastrophic event like a violent breakage of an item or similar, but also an ordinary maintenance operation. There is obviously an objection: If an item, or a location, needs a frequent maintenance, the act itself will go under the “normal condition”. (API 505.4.2 refers to these condition adopting the phrase “Normal and Abnormal Condition”).

As said, the mixture, to occur into an explosion and/or a fire, must have a concentration within its range of flammability. It is quite important to know or to reach an approximation of the quantities of flammable mixture are present inside the different location, to determinate the extension of the area. As more the released quantities are high, as more the area affected by the hazard is wide.

Another relevant parameter to take into account is the ventilation. The ventilation of a specific location can reduce sensibly the hazard connected to a ignitible substance release, even in major case. A good ventilation, natural and/or artificial), especially inside enclosed location, is the fist measure to adopt to reduce the risk of Fires.

Especially for preliminary studies, even before the engineering starts, where the knowledge of the plant and the area is almost unknown, found even and approximate form of these parameters (Likelihood, Concentration, and Ventilation of a specific area) could be really hard, and in the best case the approximation is totally aloof from reality. In fact, the hazardous area classification is commonly  made during the entire development of the plant, from the first plot plan revised by the process company to the final general plot plan of the engineering phase, reviewing continuously the data and the area classification.