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Monday, June 15, 2020

Hot-Dip Galvanizing

Introduction

The second hot-dip procedure includes the application of zinc onto a “fabricated or assembled” shape. This means the steel is shaped into the final product, a structural beam, a large diameter pipe, or a small fastener, and then dipped into molten zinc to apply a zinc coating. These items are coated either one at a time or, in the case of small parts, as several parts contained in a “basket”. Hence, the terms “batch” or “after fabrication” are applied to this process. In a sense, the general or “batch” process is the same as the continuous process in that the objective is to apply a continuous coating of corrosion-resistant zinc onto the surface of the steel. However, the practices to achieve this result are very different. The typical batch procedure involves three points before the concentration of the part (s) into the molten zinc bath:

Hot-Dip Galvanizing (HDG) Process

Whether an artful sculpture glowing under the Sun or a Strong or powerful bridge arching over a running river, hot-dip galvanizing protects the steel from corrosion for generations throughout the world.  Updated and latest technologies and innovative chemistry continue to expand this over 150-year old process and techniques, which promote its regular use in myriad applications as well as innovative ideas for new ones. Prior to get into the details of hot-dip galvanizing's benefits, it is important for us to know and understand how the coating is applied. The galvanizing process consists of three basic steps:

  1.  Surface preparation
  2. Galvanizing
  3. Inspection.  

Commonly, hot-dip galvanized steel is known for its superior corrosion protection, especially in extreme environments.  Though corrosion resistance is genetic any time galvanizing is utilized, more and more pacifiers, and select hot-dip galvanized steel for secondary reasons, including lowest initial cost (cost reduction initiative), durability, longevity, versatility, and sustainability. Hot-dip galvanizing is the best method of protecting and preserving the steel against corrosion. During the process, a series of regular layers of iron and or zinc alloy form on the metal. Such type of layers has unique mechanical properties, which ensure the best conditions for adhesion. This is a type of “active protection”, and where the steel and zinc have bonded, the zinc is oxidized in favour of the steel.

There are two different processes/ways for applying a zinc coating to steel by the hot-dip method. Hot-dip galvanizing of steel involves the application of a zinc coating by a process where the steel is immersed in molten zinc. Since zinc melts at 419.4 C (787 F) and has to be heated to a temperature of approximately 455 C (850 F) or higher for the galvanizing process to be implemented correctly, the operation is referred to as the “hot-dip” process. There are two common methods for applying the zinc in hot-dip galvanizing. The first step includes the application of zinc onto steel sheet as it passes as a continuous ribbon through a bath of molten zinc at extremely high speeds – hence, the term “continuous/regular” hot-dip galvanizing. As 1- Number coil is processed through the coating bath, another is welded to the trailing edge of the first one. The process is exactly “continuous”, as the coating line may operate for days without disruption delay. The other method involves the application of a zinc coating to the surface of steel parts after they have been fabricated. This process is not continuous in that the parts are immersed as a discrete “batch” into the zinc bath - hence, the names “batch”, “after fabrication” or “general” galvanizing are used interchangeably. Parts as small as fasteners, to as large as bridge structural girders, can be galvanized by the batch method.

Continuous Galvanizing

As described above, the continuous/regular galvanizing process is utilized to apply a zinc coating to the surface or layer of steel sheet, as the sheet passing through a zinc bath as a continuous, flat strip of steel. The coated sheet is then blanked or sheared and formed into a final part. The sheet thickness might be as thin as 0.25 mm (0.010 inches) or less, to as thick as 6.3 mm (0.25 inch). The lines in operation around the world today are typically made to be “light-gauge”, “intermediate-gauge or “heavy-gauge lines. The product from the light-gauge lines is generally utilized for various applications in the construction industry (roofing sheets, building sidewall panels, flashing, etc.) The largest application for a product made on intermediate-gauge lines is automotive body panels. Product from the heavy-gauge lines might be used for culvert, automotive structural parts, grain bins, etc.

In this process, the steel sheet is passed through the molten zinc bath at speeds as high as 200 meters per minute (>600 feet per minute). As it comes out from the coating bath, it extends out excess molten zinc. The desired thickness of the coating is attained by the use of “gas knives”. These knives frequently utilize air as the gas and are directed at both sides of the sheet to discard excess zinc.  After that, the steel is then cooled and the zinc solidifies onto the layer of the steel. The continuous galvanizing process used to produce coated steel sheet involves a series of complex steps, one of which is designed to anneal the steel to soften it and make it more form able.

One of the most important features of the continuous galvanizing process is the formation of a strong bond between the steel and zinc coating. As the steel is passed through the zinc bath at high speeds, it is actually in the bath less than 2 seconds; and in some cases, less than 1 second. During this short time, the molten bath and steel react to make an intimate metallurgical bond between them by a process including diffusion. This bond is an intermetallic compound, called the “alloy layer”. This thin alloy bonding zone, which is usually only 1 to 2 micrometers thick, is very important because after the coating is applied and cooled to room temperature, the sheet product is recoiled and shipped to a customer. At the customer’s plant, the coated sheet is formed into the desired shape. For example, the sheet might be deep drawn to form a canister, it might be stamped into a car fender, or it might be roll-formed into a roofing panel. For the forming operation to be done strongly, both the steel and zinc have to be well-bonded to one another. This is the aim of the alloy surface. If this bond zone is not formed, or not formed appropriately, during the hot-dip method process, the steel and zinc would not “stick” together during the various crucial forming steps that the coated sheet might undergo.

As can be observed, an appropriate bonding zone must form during the hot-dip process activity. However, it is equally essential that this alloy bond layer remains thin and be of the correct composition. The reason is that the bond layer is very hard and brittle. These are inherent characteristics of the alloy layer. There is no way metallurgically to make the bond zone soft, adaptable and manageable. By making an alloy surface or layer of the correct composition it will be thin, and the coated-steel sheet can be formed into many intricate shapes without loss of adhesion between the steel and zinc coating. If the alloy surface becomes extra thick, cracks become in the alloy layer during the process of forming and the steel and zinc coating would contribute to disbond. In short, it is very essential for the steel and zinc to make and develop or form an appropriate bonding zone, and that this zone intact thin. This is readily completed by the producers of hot-dip galvanized sheet. It includes 2- basic control key points:
  • The extension or addition of a controlled amount of ALUMINIUM (approximately 0.15 to 0.20%) to the molten zinc coating bath.
  • The control of the steel sheet temperature at the point where it makes entry into the molten zinc and control of the temperature of the zinc coating bath. Nevertheless, when the process is properly controlled, the coated-steel sheet made by the hot-dip galvanizing process is a well-engineered product; one that is being used today for the manufacture of many sophisticated end products

Surface Preparation for General Galvanizing

The second hot-dip procedure includes the application of zinc onto a “fabricated or assembled” shape. This means the steel is shaped into the final product, a structural beam, a large diameter pipe, or a small fastener, and then dipped into molten zinc to apply a zinc coating. These items are coated either one at a time or, in the case of small parts, as several parts contained in a “basket”. Hence, the terms “batch” or “after fabrication” are applied to this process. In a sense, the general or “batch” process is the same as the continuous process in that the objective is to apply a continuous coating of corrosion-resistant zinc onto the surface of the steel. However, the practices to achieve this result are very different. The typical batch procedure involves three points before the concentration of the part (s) into the molten zinc bath:

1.    Caustic cleaning/De-greasing 

2.    Pickling

3.     Fluxing

Caustic cleaning/De-greasing

It involves the use of a hot alkali solution to effect the removal of organic contaminants such as oils and greases. These surface contaminants need to be removed before pickling so that the surface can be “wetted” by the pickling solution. A hot alkali solution, moderate acidic bath, or biological cleaning bath removes organic contaminants or layers such as dirt, paint markings, grease, and oil from the metal layer. The Epoxies, vinyl’s, asphalt, and or welding slag, which cannot be removed by de-greasing, must be removed before galvanizing by grit-blasting, sand-blasting, or other mechanical means.

Pickling involves the immersion of parts into an acid solution (typically either heated sulfuric acid or ambient temperature hydrochloride acid) to remove surface scale or rust (both oxides of iron). The term “scale” is typically used to describe the oxides of iron that form at high temperatures such as during hot rolling, annealing in air, or welding. The rust is the product of corrosion of the steel layer when it becomes wet. Both types of iron oxide required to be discarded before the application of the zinc coating.

Fluxing contains involves the application of a particular chemical coating onto the layer of the steel part. This “flux” work the same as fluxes utilized during the soldering process. The fluxing chemical zinc ammonium chloride (Cl4H8N2Zn) is particularly designed and made to chemically discard the last ashes of oxides as the steel is being absorbed into the molten zinc, and enables the steel to dampen or wetted by the molten zinc. Fluxing can be either “dry” or “wet”. The Dry fluxing includes absorption and or immersion of the steel part into a melted solution of the flux. After discarding, the flux solution is dried before the absorption into the zinc bath. In damp and wet fluxing, a blanket of melted zinc ammonium chloride (Cl4H8N2Zn) is floated on top of the molten zinc bath. The part to be coated is then immersed or absorbed through the molten flux as it is being processed into the coating bath. (Wet fluxing works because zinc ammonium chloride (Cl4H8N2Zn) has a melting point (290 °C (554 °F; 563 K)) below that of molten zinc and it is less solid than molten zinc, and thus, floats on the bath layer or surface.)

As with regular galvanizing process, the application of the zinc coating in batch galvanizing includes absorption of the steel into a bath of molten zinc. However, in contrast with the continuous process wherein the steel is immersed for a very brief time, the batch process requires that the part be immersed for much longer times, typically measured in minutes, not seconds. There are two reasons for needing longer immersion times. Immersion of a relatively cold thick-walled large pipe, for example, means that as the steel is first immersed, it freezes a skin of zinc onto its surface. For the coating to bond metallurgically to the steel, the pipe has to be heated to “remelt” the zinc.) Then, additional time is required to develop the iron/zinc alloy bond zone. In contrast with the regular procedure where the alloy surface has to be kept very thin to contain subsequent forming into the final shape, for batch-galvanized parts, the alloy layer can be allowed to grow much thicker. A thicker alloy bond layer is often desired to provide a longer life to the final product, i.e., a longer life before the onset of rust. as zinc itself, the alloy surface or layer is galvanic ally protective to the steel part; thus, a thicker alloy layer means longer life performance. Yes, the alloy surface is hard and breakable, but since the part is already assembled, there is no requirement for extra forming. The brittle alloy bond is not deleterious. It will not cause coating damage during shipment and subsequent handling at the job site.

The alloy layer is perhaps as much as 50% of the total coating thickness and it consists of two or more distinct zinc/iron layers. Every specific layer combines to make the “total” alloy layer zone. Every layer generally has a quite particular amount of iron and zinc. As one might expect, the layer closest to the steel has the highest iron content while the layer immediately adjacent to the pure zinc outer layer has the lowest iron content. Remember, the alloy layer grows by an intermixing diffusion reaction between the atoms of the steel and zinc. In fact, for batch galvanized parts, the additional immersion time is often needed to achieve the final required thickness of the protective coating (the thickness is a combination of the alloy surface and the pure zinc external coating metal). As a result of the capability to accommodate long concentration duration, the final thickness of the coating (pure zinc + alloy layer) on batch galvanized parts is often considerably thicker than the coating on continuous galvanized sheet product. At least, the thickness can be much thicker if desired/required. This is one major difference between the batch galvanizing process and the continuous galvanizing process.

There are production issues that often need to be considered concerning the maximum alloy layer thickness that can be achieved during batch galvanizing. As the alloy layer thickens, its rate of growth slows down because diffusion through the thickening alloy layer takes longer, resulting in a practical limit to the final thickness. When this type of behaviour is experienced, the practical maximum coating thickness is less than when the alloy continues to grow as a compact layer.

Zinc Bath Composition for General Galvanizing

From the historical point of view, the zinc bath utilized for natural or ordinary galvanizing having between 0.5 and 1.0% lead. As for a lead, it had had two main effects. First, it caused the formation of the typical, attractive large spangled surface, which through the years was “the way to identify galvanized coatings”. And the second, the lead was profitable to accommodate “free drainage” of excess zinc as the part was discarded from the zinc bath. In some instances, today, bismuth is being substituted for lead to achieving free drainage of the excess zinc. Alloys that contain bismuth for use by the general galvanizing industry are available today from several zinc suppliers.

Another alloying addition to zinc that is receiving some attention today as a way to further improve the coating performance is the addition of nickel to the galvanizing bath. The influence of nickel is important concerning the development of the zinc/iron alloy layer, especially when galvanizing high silicon- containing steels. This development is still quite new and all the metallurgical aspects related to the addition of small amounts of nickel are still being discovered. The addition of 0.15 to 0.20% ALUMINIUM to the coating bath, a required addition to the coating bath when continuous galvanizing, is not a typical practice for general galvanizing. In general galvanizing, the development of a thick alloy layer is important to the achievement of the required coating thickness. ALUMINIUM acts as an inhibitor and interferes with this action.

Part Thickness

Another difference in the two processes, batch vs. continuous, depicts the thickness of the steel that can be galvanized without experiencing “heat distortion” or exaggeration of the steel. In the steady and regular process, very thin steel can be coated. The reason that this can be accomplished is that during continuous galvanizing, the steel sheet is held under some amount of tension while being processed. Tension needs to be applied to “pull” the ribbon of steel through the coating line, and to maintain the flatness of the sheet. Distortion or misuse of the sheet can develop during exposure to the high thicken, toughen temperatures. Tension protect distortion and allows good control, even application of zinc onto the very thin sheet, which differently would not be possible if it were not flat. In the batch process, the products immersed in the coating bath are not constrained by the application of outside forces. The part has to be designed to be dimension ally stable during the exposure to the bath temperature. This is accomplished by using both thicker sheets of steel and part design principles that prevent heat-generated distortions. Also, temporary bracing can be used for thin-walled parts to minimize distortions caused by the heating. Stated simply, one cannot easily batch galvanize parts fabricated using thin steel sheet, nor can one continuous galvanize heavy steel plate.

Conclusion

Both regular and batch galvanizing methods and techniques have been in use for many years. Both processes provide a corrosion-resistant zinc coating onto steel that has been a proven value-added method for protecting the attributes of the steel product in a multitude of applications. Through the years, both processes have undergone advances in technology that continue to expand the markets for galvanized steel.


Hydrochloride Acid (HCl)


Advantages


  • Reduce heating costs since pickling solutions are used at room temperature
  • More extensive scale removal
  • Less penetration of hydrogen by diffusion
  • Less deposition of iron salts on the pickled layers

Disadvantages

  • Fumes when heated above ambient temperatures
  • Acid recovery systems are expensive
  • More corrosive toward equipment
  • Magnesium Higher disposal costs than sulfuric acid

HAZARDS IDENTIFICATION

Risks to Health:

  • Corrosive.
  • Causes severe skin, eye
  • Digestive tract burns
  • Harmful if swallowed.
  • Mist or vapour extremely irritating to eyes and respiratory tract.

Regulatory Status


HCL is considered a "Hazardous substance" as defined by the OSHA Hazard Communication Standard, 29 CFR 1910.1200.


Potential Acute Health Effects


HCL Routes of Exposure: Inhalation, ingestion, skin contact, eye contact


Inhalation: 

Corrosive. May cause damage to mucous membranes in the nose, throat, lungs and bronchial system.


Ingestion: 

Corrosive. Harmful if swallowed. May produce burns to the lips, oral cavity, upper airway, esophagus and digestive tract.


Skin Contact: 

Corrosive. Causes severe burns.


Eye Contact: 

Corrosive. Causes severe burns. Vapour, mists or spray may cause eye damage, effect sight or cause blindness.


Target Organs: 

Skin, respiratory system, eyes, lungs


Chronic Health Effects:

Corrosive. 

Prolonged contact causes serious tissue damage.


FIRST AID MEASURES


First Aid Procedures:


Inhalation: 

Remove to fresh air. If breathing is difficult, administer oxygen. If the victim is not breathing properly, do mouth-to-mouth resuscitation.


HCL Routes of Exposure: 

Inhalation, ingestion, skin contact, eye contact. Get medical attention immediately


Ingestion: 

Do not induce vomiting. If vomiting starts, always low down the head so that vomit does not enter into the lungs. Never practice giving anything by mouth to senseless person. Get Medical Attention Immediately.


Skin Contact: 

Flush or wash continuously the affected area with a severe quantity of water for at softly least 15-20 minutes.


Remove contaminated clothing and shoes. Wash clothing before reuse. Get medical attention immediately.


Eye Contact: 

  • Check for and remove contact lenses. Immediately flush or wash eyes with soft but enough stream of water for at least 15-20 minutes, by lifting lower and upper eyelids infrequently.
  • General Advice: In the case of a critical unwanted event, accident or if you feel uncomfortable, search for medical advice ASAP (SDS or show the label where possible).
  • Always make sure that medical staff know the material(s) or substance involved and take precautions to Show this safety data sheet to the medical person is in charge of the treatment.

 

Notes to Doctors: Treat symptomatically. Keep the victim of any hazardous substance or material under continuous observation.


FIRE FIGHTING MEASURES

  • HCL Flammable Properties: This material or substance is not flammable.
  • Appropriate Extinguishing Media: Water, DCP, foam, CO2
  • Hazardous Combustion Products:  Hydrogen chloride (HCL), Chlorine (Cl-). May break down upon heating to produce corrosive and/or toxic fumes/mists.
  • Specific Hazards: HCL originated fire may cause and produce irritating, corrosive, and/or toxic gases/fumes.
  • Special Protective Equipment for Firefighters: in case of any fire, wear OSHA approved or equivalent self-contained positive pressure breathing apparatus and full protective safety gear.


Particular Methodology:

Utilize water spray to cool down the unused containers of the substance. Then cool containers those are exposed to flames with flooding/huge quantities of water until the fire is extinguished. In such circumstances of fire and/or explosion incident, do not breathe fumes


Accidental Release Measures


How to Take Personal Precautions

In case of any accidental release of such hazardous gas, chemical or substance, immediately Ventilate that particular area of leak or spill. Make isolation to that hazards area and keep all unauthorized and unprotected people away from the area of the leak or spill. Wear proper recommended personal protective equipment (PPE) as per the requirement. Be sure not to contact with eyes, skin, and clothing/uniform kit.


How to Adopt Environmental Precautions


To protect the environment from its release:

  • Prevent further leakage if it is safe to do so.
  • Do not contaminate water.
  • Avoid discharge HCL or any chemical into the drainage system, water reservoirs or on the ground.
  • In case of severe large spillage, barrier if needed.


Methods for Cleaning Up Operation:

  • Devour or ingest the spill with vermiculite, dry sand, earth, cloth, etc.
  • Place in a properly non-combustible container for disposal.
  • Do not utilize combustible materials, such as sawdust.
  • Clean contaminated surface completely.
  • Subdue spill area and washings with soda ash or lime.
  • Never return spills in genuine containers for re-use.
  • Clean up in as per all applicable regulations of the state.


HANDLING AND STORAGE OF CHEMICAL/GAS/SUBSTANCE


Handling:


  • Wear appropriate recommended personal protective equipment (PPE).
  • Use only in well-ventilated areas.
  • Provide proper air exhaust system in workrooms.
  • Avoid contact directly with skin, eyes and clothing.
  • Do not breathe in vapours and or spray mist.
  • Do not drink or absorb.
  • When using and working with such chemicals or gashouse substance, do not eat, smoke, or drink.
  • Keep away from conflicting and unsuits materials.
  • Always Handle carefully as per good industrial hygiene and safety practice.


Wash completely after handling.


  • Carefully observe all warnings and precautions listed for the product. 
  • Read SDS.
  • Use and adopt caution when mixing with water.
  • NEVER add water to acid. ALWAYS add acid to water while stirring or electrifying to prevent the release of excessive heat, steam, and fumes

Storage:


  • Always store in a cool, dry, well-ventilated area away from unsuitable materials.
  • Store in Genuine container.
  • Always keep chemical containers tightly closed and upright state.
  • Keep away from eatable items such as food, drink and animal feeding stuff.
  • Always keep all chemicals out of the reach of children.
  • Avoid its misuse.

EXPOSURE CONTROL AND PERSONAL PROTECTION


Exposure Limits as per OSHA:

Ceiling: 5 ppm 7 mg/m3


Engineering Controls


  • Ensure proper ventilation system.
  • Ventilation rates should be suitable as per the conditions. If applicable, always make well use of process enclosures, local exhaust ventilation system, or other engineering controls to intact and keep airborne levels below to recommended exposure limits.
  • If the exposure limits have not been well established, maintain airborne levels to an ALARP level.
  • The explosion-proof exhaust ventilation system should be used.
  • Personal Protective Equipment (PPE)

Eye/Face Protection:


Wear safety goggles and a face shield.


Skin Protection


Wear proper chemical resistant clothing (CRC) (with long sleeves) and suitable chemical resistant gloves.


Respiratory Protection (RP)


If it is not possible to maintain the airborne concentrations below recommended exposure limits (where applicable) or to an ALARP level by engineering controls, an approved respirator must be worn.  

 

Respirator type:


  • Chemical respirator with Acid Gas Cartridge (AGC).  
  • Utilize a positive-pressure air-supplied respirator device if there is any danger for an uncontrolled release, exposure levels are not known, or any other conditions where air-purifying respirators may not provide suitable protection.

General Hygiene Review:

  • Avoid direct contact with skin, eyes and clothing. 
  • When using and working with such chemicals or gashouse substance, do not eat, smoke, or drink.
  • Always practice good personal hygiene initiatives, such as washing after handling the material and before eating, drinking, and/or smoking.
  • Randomly wash work clothing and protective equipment to remove contaminants.
  • Provide proper washing facilities such as eyewash station and a safety shower.

PHYSICAL AND CHEMICAL PROPERTIES


Physical State:                                      Liquid                   

Appearance:                                         Transparent

Color:                                                  Colorless

Odor:                                                   Pungent, irritating

Molecular Formula:                              HCl

Molecular Weight:                                36.46

pH:                                                       0.1 (1.0 N Solution)

Specific Gravity:                                   1.18

Freezing/Melting Point:                         -25 °C (-13 °F)

Boiling Point:                                        50.5 °C (123 °F)

Flash Point:                                           Not applicable

Auto Ignition Temperature:                    Not applicable

Flammable Limits in Air

(% by Volume):

Upper:                                  Not applicable

Lower:

Solubility:                                             Miscible with water

Vapor Pressure:                                     25 kPa at 25°C (estimate)

Vapor Density:                                      1.3 (estimate)

Odor threshold (ppm):                   0.25-10 ppm


TOXICOLOGICAL INFORMATION


Toxicological Data:

Oral Rat LD50:                   240 mg/kg (estimate)

Oral Rabbit LD50:              900 mg/kg

Inhalation Rat LC50:          3124 mg/L 1 H


Acute Effects:


  • Highly corrosive.  
  • May harm deep tissue damage.  
  • Extreme harmful if swallowed.                         


Chronic Effects:


  1. Highly Corrosive.
  2. Lengthy or repeated skin contact may cause serious tissue destruction.         

DISPOSAL INFORMATION    


Disposal Instructions: Disposal of this substance and its container to hazardous waste collection. Consume the substance or chemical under controlled conditions in an approved heating system.  All wastes should be handled carefully following state regulations.    


Contaminated Packaging of the Chemicals


Always follow label warnings signs even after container is emptied. Offer clean packaging material to local recycling facilities.


Waste Codes   


D002: Waste corrosive substance (pH ≤ 2 or pH ≥12.5)


TRANSPORT INFORMATION


This chemical substance/chemicals is considered a "Hazardous Chemical" as defined by the OSHA Hazard Communication Standard, 29 CFR 1910.1200.


Sulfuric Acid


Sulfuric Acid and its Uses


Sulfuric Acid (H2SO4) is a clear, colourless and odourless liquid. It is easily soluble in water and can cause serious destructions/damages, particularly at when the chemical is at high-centralization levels. If we look it from historically, it is known as oil of vitriol, sulfuric acid started to be produced on a large scale in the 18th century. Sulfuric Acid (H2SO4) is Utilized for a wide range of functions both industrially and domestically. Produced basically in Asia and North America, sulfuric acid (H2SO4) is used in the production of:


  • Agricultural usage purposes (Fertilizers)
  • Drain cleaners (sanitation)
  • Detergents (soaps)
  • Synthetic resins
  • Medical purposes (Pharmaceuticals)
  • Petroleum catalysts
  • Insecticides (fumigation and pesticides)
  • Antifreeze
  • Batteries (energy)
  • Paint, enamels, and printing inks


The Extreme Health Hazards Associated with Sulfuric Acid


  • Evaporated sulfuric acid (H2SO4) is highly corrosive and can cause serious skin burns when not handled appropriately.
  • This chemical is unique because it not only chemical burns but also secondary thermal burns as a result of dehydration.
  • This hazardous substance can destroy skin, paper, metals, and even stone in some cases.
  • In the case of direct contact with the eyes, it can cause complete blindness.
  • If this chemical ingested, may cause internal burns, irreversible organ destruction, and possibly leads to death.
  • Continuously exposure to Sulfuric Acid Aerosols (SAA), even at a low dose, can cause a person’s teeth to erode.
  • In the laboratory or industrial settings, it’s mandatory to use appropriate personal protective equipment (PPE) when handling Sulfuric Acid (H2SO4).
  • At home, we are most likely to encounter concentrated amounts of Sulfuric Acid (H2SO4) when using an Acidic Drain Cleaner(ADC). It’s essential to follow the safety instructions, precautions and took all initiatives on the drain cleaner label to avoid these serious hazards risks.

Safe Handling of Sulfuric Acid (H2SO4)


When handling pure Sulfuric Acid (H2SO4) in a laboratory or industrial usage, or when using products that contain concentrated Sulfuric Acid (H2SO4), it’s necessary to prioritize safety precautions and take proper initiatives. The following personal protective equipment (PPE) should be worn when using or working with Sulfuric Acid (H2SO4):

  • Standardized Respirator
  • Long rubber gloves
  • Safety shoes
  • Good quality Industrial apron
  • Chemical safety glasses
  • Full Face protective shields
  • Safety Precautions for Sulfuric Acid (H2SO4) Exposure


Exposure to Sulfuric Acid (H2SO4) can develop as body contact, ingestion, or inhalation of vapours. Every type of chemical, substance or gaseous exposure can pose fatal hazards to our health and should be handled appropriately by a medical practitioner (specialist) to reduce damage and risks to health.


Skin Contact


If Sulfuric Acid (H2SO4) contacts with the skin, immediately flush the affected area softly with lukewarm water for at least 30 uninterrupted minutes. Seek medical attention immediately.


Eye Contact


If Sulfuric Acid (H2SO4) gets into your eyes, immediately flush the eye(s) with water for at least 30 minutes. Seek medical attention immediately.


Ingestion:

If you ingest Sulfuric Acid (H2SO4), rinse your mouth immediately with water. Do not induce vomiting. Continually rinse your mouth with water and seek medical attention as soon as possible.


Inhalation:

If you inhale Sulfuric Acid (H2SO4) aerosols, seek fresh air and medical attention immediately.


Proper Sulfuric Acid Storage and Disposal


Sulfuric Acid (H2SO4) or products that contain concentrated sulfuric acid should be stored in a cool, dry area away from direct sunlight and heat sources. Sulfuric Acid (H2SO4) should not be stored indoors in large quantities, to prevent the possible accumulation of vapours. Chemicals containers should be regularly inspected and observed by MSDS professional experts for signs of damages or leakages.


Sulfuric Acid (H2SO4)


Advantages


  1. Acid can be renewed more frequently
  2. Higher temperature will allow lower down acid concentrations to pickle adequately
  3. Ease of recovering iron sulfate
  4. The rate of pickling can be controlled by varying the temperature

Disadvantages


  • Greater acid attack on the base metal.
  • Greater hydrogen diffusion into the steel
  • Pickling residues are more adherent
  • Acid solutions must be heated

Alkali


Alkali name                                    Formula                              Ionic Formula

Sodium hydroxide                          NaOH                                 Na+(aq) OH-(aq)

Calcium hydroxide                         Ca(OH)2                             Ca2+(aq) 2OH-(aq)

Lithium hydroxide                          LiOH                                  Li+(aq) OH-(aq)


Acerbic or Acid ingestions can effect and cause functional and histological destruction to any surface come in contact.  Any alkaline agent with a pH greater than 7.0 is considered Acid. Some household cleaning agents have powerful alkalis. Alkali substances and or acids can cause liquefactive necrosis and can be particularly corrosive at high pH values as the necrosis continues until the alkali becomes neutralized. This substance pathway is particularly destructive to human tissue within the esophagus. There are many products, both household and industrial, that contain chemicals with caustic potential. Bleach is the most common household alkali, which has a pH of 11 and is 3% to 6% sodium hypochlorite solution. Household caustics are usually less concentrated; therefore, they are usually benign. On the other hand, industrial-strength bleach has a greater concentration of sodium hypochlorite, this may cause more extensive damage, including gastric and esophageal necrosis.


As per observation under OSHA precautionary notes that abrasive blasting generates high levels of noise, which may result in “substantial” hearing loss for workers. Due to such type of hazard, the workforce should always wear appropriate hearing protection (protective equipment). brasive blasting also generates or produces a large quantity of dust, which may be hazardous and toxic depending on the materials used. Frequently utilized abrasive substance includes silica, coal slag, crushed glass or glass beads, and or steel grit. The severe and excessive inhalation of silica dust can result in various health circumstances and can result in silicosis, lung cancer and other breathing chronic and acute problems, coal slag may result in lung damage, and steel grit can cause lung destruction. And the slags also may consist “trace amounts of hazardous metals such as arsenic, beryllium and cadmium,” the agency states.


How to be Stay Safe


It’s up to employers to keep their workforce safe and secure from abrasive blasting critical hazards. Before starting a job, employers should identify possible hazards and assign a competently trained person to ensure essential and mandatory corrective actions, precautions and initiatives and controls are adopted.


Engineering Controls


OSHA recommends several engineering controls for abrasive blasting, including the use of less-toxic abrasive blasting material, using abrasives that can be delivered with water to reduce dust, installing barriers to isolate blasting areas and keeping employees away from the blaster. Using ventilation systems to remove dust also is suggested.


Administrative controls


Practice good housekeeping by regularly cleaning using wet methods or HEPA-filtered vacuuming, OSHA states. Also, the agency recommends decontaminating equipment, scheduling blasting when as few workers as possible are onsite, refraining from performing abrasive blasting in high winds, and refraining from using compressed air (which creates more dust) to clean.

OSHA suggests that employers prohibit workers from eating, drinking or using tobacco near blasting areas, and provide shower and changing areas so workers can clean up before changing into their street clothes, which helps prevent workers from bringing dust home.


Sandblasting blasting:Health and Safety Risks


Sandblasting is a technique used in the industrial and crafts sectors to smooth rough surfaces or remove paint or other material. It is a mechanical process which exploits the action of abrasive material such as sand, propelled at high pressure and which necessarily requires the presence of an operator to coordinate the processing, the ultimate goal of which is a completely clean surface ready to be finished off. This procedure can cause a lot of damage to the health of the workers involved as the large amount of dust which develop finds its way into the respiratory system very easily where it is deposited and it becomes very difficult to expel


Sandblasting surface cleaning operations pose multiple risks to the health and safety of the worker and the respiratory system in particular. Sandblasters are continuously exposed to and inhale the dust and particles which develop during abrasion. As blasting is carried out on metal, plastic coatings, paints, and similar products, it goes without saying that the microparticles contain elements which are hazardous for the human body and which are absorbed through the breathing process. These elements, cause inflammation of the respiratory tract, at first, generating illnesses of varying degrees which, in some cases, become chronic and thus are no longer treatable with traditional medicine. Thereafter, continuous, long-term exposure can cause a build-up of these micro-particles in the respiratory system, predominantly the lungs and bronchi, which may lead to particular types of rarely curable cancer and consequently to death. Not all sandblasters face the certainty of developing tumours – there is a wide variety of personal protective equipment available on the market to protect workers from inhaling hazardous substances.


Health Effects of Crystalline Silica Exposure


An employee may establish any of three kinds of silicosis, build upon the airborne concentration of crystalline silica:


  • Chronic silicosis, which usually happens after more than ten (10 years) of exposure to crystalline silica at relatively low absorption.
  • Quick silicosis, which may result from exposure to a high level of crystalline silica concentrations of and develops more than 10-years after the initial exposure.
  • Acute silicosis, which happens where exposure absorption is the highest and can cause symptoms to establish within a few weeks to 4 or 5 years after the initial exposure.

Acute Effects


Silicosis symptoms are shortness of breath, fever, and cyanosis (bluish skin), pneumonia, or tuberculosis. The abundance of mycobacterial or fungal infections often complicate silicosis and may be fatal in many cases.


LEAD


Health Problems Caused by Lead Exposure


When Lead is absorbed and stored in our bones, blood, and tissues. It does not halt there forever, rather it is reserved there as a means of continual internal extreme exposure.  With time, our bones demineralize and the internal disclosure and destructions may increase as a result of larger releases of lead from the bone tissue. There is the worry that lead may activate from the bone among women going through menopause or climacteric. Post-menopausal women have been observed to have higher blood lead levels than premenopausal women.  Severe health effects from short-term overexposure and Lead poisoning can happen if a person is exposed to extreme levels of lead over a short period. When this occurs, symptoms can be, abdominal pain, constipated, tiresome, headachy, irritable, loss of appetite, memory loss, pain or tingling in the hands and or feet, weak

Because these symptoms may be lead poisoning can be easily detected. High levels of exposure to lead may cause anemia, weakness, and kidney failure and brain damage. Moreover, a very high level of lead exposure can cause death.

Lead exposure can destroy an undergrowth or developing baby’s nervous system. Even low-level of lead absorption in the undergrowth or developing babies have been found to affect behaviour and intelligence. Severe exposure to Lead can cause miscarriage, stillbirths, and infertility (in both men and women).


Health effects from prolonged exposure to Lead


A person who is exposed to lead for the long duration may have:


  1. Abdominal pain
  2. Constipated
  3. Depressed
  4. Distracted
  5. Forgetful
  6. Irritable
  7. Nauseous/Sick
  8. People with excessive exposure to lead may also be at risk for high blood pressure, heart disease, kidney disease (failure), and reduction in fertility.

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