Sulfuric Acid Storage Tanks & Specifications (2024)

Sulfuric Acid Storage Tanks are manufactured from HDPE, XLPE, FRP, and Carbon Steel at 1.9 specific gravity. Secondary containment is required. H₂SO₄ is best stored out of direct sunlight. Tank capacities range from 35 to 100,000 gallons. Prices range from $300 to $150,000.

  • Known commonly by its chemical formula H₂SO₄ and as battery acid or dihydrogen sulfate
  • Used primarily to make phosphoric acid and phosphate fertilizers, lead-acid vehicle batteries, as well as other chemicals
  • Federal guidelines outline correct handling and storage requirements
  • Specific storage requirements are dependent upon sulfuric acid concentrations
  • Approval from storage tank manufacturers should be acquired prior to sulfuric acid applications

Sulfuric Acid Storage Tanks & Specifications (1)

What is Sulfuric Acid?

Sulfuric acid is a widely produced, corrosive inorganic acid that is used across a range of industries. The chemical formula for the acid is H₂SO₄. H₂SO₄ is a diprotic, strong mineral acid that is considered "weighty" due to its high density. Chemical solutions of sulfuric acid are very reactive and express true hazards that must be considered whenever handling and storing.

Known most commonly as sulfuric acid, H₂SO₄ is also known as Sulphuric Acid (English spelling variant), and as battery acid or dihydrogen sulfate. Names no longer commonly used include Sulphine Acid and Oil of Vitriol.

Conventionally, solutions are not 100% H₂SO₄ but are diluted to an extent with water and reported in weight percent (wt%). Common commercial strengths are 93 wt%, 96 wt%, and 98.5 wt%. Many customers purchase diluted sulfuric acid, typically at 70 wt% or 50 wt% strength. The handling, storage, and reactivity considerations of diluted sulfuric acid are quite different from those of concentrated products.

Sulfuric acid is an odorless, semi-oily liquid that ranges in appearance from clear to yellow depending upon solution purity, where pure solutions are colorless. H₂SO₄ has a viscosity greater than water, which contributes to its characterization as an oily solution. The viscosity measurement for H₂SO₄ is 24.2cp (centipoise; 1cp = 1mPas) at 68°F (20°C). Comparatively, water is 1.0cp and olive oil is 85cp. Viscosity has an indirect correlation with temperature: as temperatures increase, viscosity decreases. The increased viscosity of H2SO4 can be attributed to the its internal resistance to flow based upon the molecular, three-dimensional structural orientation and the electrical-attraction of its atomic constituents; that is, polar dipole moments and increased hydrogen bonding.

Commonly characterized as a "heavy" chemical solution because of its high density, which is dependent upon a specific solution's concentration. Density can range from 1.07 to 1.84 g/cm3, (where water = 1.0 g/cm3), making H2SO4 on its most dense side almost twice as heavy as water when occupying the same volume.

Sulfuric acid is a mineral acid with sulfur as its parent atom - (mineral meaning inorganic, inorganic meaning non-carbon based). Comparitively, acetic acid, CH₃COOH, is an organic, carbon-based acid. H2SO4 can result from dissolving sulfur trioxide gas in water. A visual representation of the reaction and sulfuric acid molecular structure:

H2O(l) + SO3(g) = H2SO4(aq)

Sulfuric acid is capable of dangerous reactions and is hazardous to human health. The chemical is a strong acid due to the high dissociation constant of the first hydrogen released in reactions. Sulfuric acid is a potent oxidizer capable of oxidizing certain chemicals and materials, such as some metals, and has great affinity and reactivity with water. The reactivity between sulfuric acid and water is exothermic (heat-generating) and is so great that the reaction can be incredibly violent and consequently hazardous, especially with strengths greater than 80% H₂SO₄. This exothermic reaction warrants important consideration in storage applications as the diluting or mixing of sulfuric acid with water or other chemicals can generate sizeable amounts of heat and can potentially warm the solution to levels hazardous to the storage container or associated equipment.

How Should Sulfuric Acid Be Stored?

Sulfuric acid must be stored in specific containers made of corrosion-resistant materials that will ensure the safety, stability, and longevity of the storage tank. These considerations can change depending upon the H₂SO₄ solution's specific concentration. If not stored in proper containers with correct fittings and gaskets, corrosion can occur and the tank structural-integrity compromised, which can cause a containment breach leading to potentially significant safety concerns and costly repairs. When evaluating storage containers, whether mixing or diluting of H₂SO₄ solutions will occur must be also be considered due to the exothermic reaction that can take place.

Sulfuric acid should be stored in a cool, dry area away from direct sunlight, heat, and ignition sources, and that is separate from incompatible materials. Bulk storage of H₂SO₄ must employ secondary containment measures to satisfactory mitigate exposure concerns in the event of a bulk material release. A regular tank inspection and maintenance schedule should be employed for successful sulfuric acid storage.

Sulfuric Acid Storage Tanks

There are various considerations to be made when storing bulk quantities of sulfuric acid. Chemical concentration and volume are among the greatest concerns due to chemical weight-stress and the potential for corrosive activity to occur to the holding tank. Engineering review is recommended when storing greater than 4,000 gallons of concentrated sulfuric acid due to the increased weight load, tank stress, and hazards given a potential release. The following sections detail the most common bulk storage solutions for sulfuric acid.

Carbon Steel Sulfuric Acid Tanks

Carbon steel H2SO4 tanks are the common tank choice for storing bulk quantities above 10,000 gallons. Carbon steel tanksare reported to be most effectiveat storing high-end, concentrated sulfuric acid solutions of 93 wt% and above. This is due to increasing solution water content with decreasing H₂SO₄ concentration, allowing greater reactivity to occur between the acid and the steel storage tank. The water content of any concentration below 93% will allow for an increase in corrosive activity on carbon steel storage tanks. With this considered, carbon steel tanks down to 77% H₂SO₄ are still successful in acid storage. Temperatures should be maintained beneath 100ᵒF.

Despite being a compatible material, sulfuric acid at the recommended concentrations and normal temperatures will still cause gradual corrosion. Regular tank inspections and maintenance are important for maintaining carbon steel sulfuric acid tanks. Of additional storage concern, this reactivity between the carbon steel and H₂SO₄ can generate hydrogen gas and iron sulfate.

  1. Hydrogen gas is flammable and buildup of the gas can be potentially explosive. Venting systems are a requirement for carbon steel and sulfuric acid to prevent the accumulation of hydrogen gas. Thermoplastics, such as PVC, are the recommended materials for sulfuric acid vents. Steel vents are not recommended due to the potential for iron sulfate production and buildup in the vent pipes.
  2. Iron sulfate is a precipitate formation that will settle within the sulfuric acid solution and tank systems. Buildup of iron sulfate is a purity problem and accumulation can cause problems in piping runs or pumps.

Polyethylene HDPE & XLPE Sulfuric Acid Tanks

The most common containers used for storing sulfuric acid solution quantities less than 10,000 gallons are high-density polyethylene (HDPE) tanks. Due to the increased density of H₂SO₄ solutions, only tanks with specific gravity ratings of 1.9 or higher are recommended for sulfuric acid storage in order for the tank to properly withstand the chemical weight. A benefit of using thermoplastics such as poly tanks for sulfuric acid storage is that such materials are not reactive with H2SO4 as the metal of carbon steel tanks are and so the production of hydrogen gas and iron sulfate is avoided.

Cross-linked polyethylene (XLPE) tanks are not recommended for sulfuric acid storage. This recommendation is especially held for strong H₂SO₄ concentrations due to studies indicated XLPE failure after 6 months of storing 98% H₂SO₄, even at decreased temperatures of -40ᵒF. HDPE tanks are successful in the storage of sulfuric acid. Snyder Industries recommends that HDPE poly tanks be formulated using #880046 resins with CPVC fittings, Viton gaskets, and bolts of Hastelloy construction.

The maximum service temperature of HDPE tanks peaks around 130ᵒF. This is important in H2SO4 applications as diluting or mixing of concentrated acid can drive temperatures up to and beyond this range. Due to these concerns with elevated temperatures, diluting concentrated sulfuric acid in plastic storage tanks is not generally recommended except under stringent engineering controls, methods, and mechanisms that allow it to be performed successfully. It is recommended to buy pre-diluted H₂SO₄ if less-concentrated solutions are required.

Polyethylene tanks for outdoor H₂SO₄ storage are recommended to be formulated with UV-stabilizers or insulated to aid in tank integrity and service life. Request a quote for a sulfuric acid tank or contact us for more information.

Fiberglass Reinforced Plastic (FRP) Tanks

FRP composite tanks are only recommended for sulfuric acid concentrations of 80 wt% or lower,according to FRP-resin producer Ashland, Inc.This storage type is not considered suitable to store more concentrated H₂SO₄ solutions. Strengths in excess of 80% begin to detrimentally corrode vinyl ester resins of FRP composite tanks. This is especially true should solution temperatures become elevated to 100-120ᵒF and above, which is of potentially great concern should dilution of H₂SO₄ be a consideration. Adding water to sulfuric acid produces significant heat and if temperatures rise above applicable thresholds, tank structural stability may become compromised. Due to these concerns, diluting sulfuric acid in fiberglass reinforced plastic tanks is not recommended.

For successful sulfuric acid storage:

  1. HDPE tanks can successfully store the full range of sulfuric acid concentrations but are recommended for applications beneath 10,000 gallons
  2. Carbon steel tanks are common for H₂SO₄ quantities in excess of 10,000 gallons
  3. The heat generated from H₂SO₄ reactions, mixing, or diluting must be considered, controlled, and properly monitored
  4. Gasket, fitting, and bolt materials must be chosen for the specific storage scenario based on H₂SO₄ concentration, (seeStorage Tank Componentsbelow)
  5. Tank specific gravity ratings must be equal to or greater than 1.9
  6. Double-walled tanks are recommended for polyethylene tanks
  7. Secondary containment measures are required for sulfuric acid storage scenarios
  8. An engineering review should be conducted when storing in excess of 4,000 gallons of ≥ 94% H₂SO₄ (i.e. concentrated sulfuric acid).

Sulfuric Acid Storage Tank Components

The concentration strength of sulfuric acid should always be considered when evaluating the material-composition of storage containers and necessary components. Containers have manufacturer specifications only to certain extents depending on the chemical and its concentration beyond which components may lose their effectiveness. See the chart below highlighting recommended bolt, gasket, and fitting materials:

Sulfuric Acid Material Resistance Chart
Material0-10% H₂SO₄10-75% H₂SO₄75-100% H₂SO₄
304 SSNot RecommendedNot RecommendedFair / Moderate
316 SSGood / MinorNot RecommendedNot Recommended
CPVCExcellentExcellentFair / Moderate
PVCExcellentExcellentFair / Moderate
XLPEExcellentExcellentGood / Minor
HDPEExcellentExcellentExcellent
LDPEExcellentExcellentGood / Minor
PolypropyleneExcellentExcellentFair / Moderate
FRPExcellentGood / MinorNot Recommended
NylonFair / ModerateNot RecommendedNot Recommended
NeopreneGood / MinorGood / MinorNot Recommended
PTFEExcellentExcellentExcellent
PVDF / KynarExcellentExcellentExcellent
VITONExcellentExcellentExcellent
Hastelloy-CGood / MinorGood / MinorGood / Minor
TeflonExcellentExcellentExcellent
EPDMExcellentGood/ MinorGood / Minor
AluminumFair / ModerateNot RecommendedNot Recommended
BrassNot RecommendedNot RecommendedNot Recommended
TitaniumNot RecommendedNot RecommendedNot Recommended

H2SO4 Secondary Containment

All sulfuric acid tank systems must maintain capable secondary containment measures. Common containment for bulk H2SO4is through concrete diking with an acid-resistant coating, as concrete will react with the sulfuric acid. Engineering safety protocols require that secondary containment be capable of retaining at least 110% of the tank system total volume. This means for all tanks located within the designated containment area. Local regulatory statutes and codes may place additional requirements upon H2SO4secondary containment systems. Always verify chemical storage systems are designed and maintained according to local regulating law codes.

H2SO4 Specific Gravity and Freezing Point

As with many chemicals, specific gravity and freezing point characteristics vary with concentration. Specific gravity will vary slightly dependent upon temperature as well. The following is a compilation of specific gravity and freezing point data for different H2SO4concentrations. Specific gravity was measured at a solution temperature of 60ᵒF; note some approximations have been made.

Sulfuric Acid S.G. & Freezing Point
SULFURIC ACID (WT %)SPECIFIC GRAVITYFREEZING POINT (ᵒF)
0%1.0032°F
10%1.0723°F
20%1.147°F
30%1.22-32°F
40%1.31-69.5°F
50%1.40-34°F
60%1.50-20°F
70%1.61-44°F
75%1.67-20°F
80%1.7330°F
85%1.7845°F
90%1.8219.8°F
92%1.830°F
93%1.83-21°F
95%1.84-8°F
96%1.847°F
98%1.8430°F
100%1.8351.7°F

Sulfuric Acid Heating & Insulation

The freezing point of different sulfuric acid concentrations can vary markedly. 93 wt% sulfuric acid has a freezing point below zero at -21ᵒF, so many industrial applications can utilize carbon steel tanks with 93 wt% H2SO4uninsulated, but 98 wt% freezes at 30ᵒF and so much more care is needed for successful storage. Between the sulfuric acid concentrations of 35 - 75 wt%, freezing is generally not a storage issue, and then the 93 wt%. For all other concentrations of sulfuric acid, a review of the chemical's freezing point data is recommended.

Depending upon sulfuric acid tank location, whether outside or inside and ambient geographical conditions, the varying freezing points for H2SO4solutions can present problems in applications. If exposure of particular H2SO4solutions to temperatures near its respective freezing point are expected, heating and insulation of tanks and piping, as applicable, are recommended or required to prevent freezing.

Mixing and Diluting Sulfuric Acid Solutions

Upon mixing of sulfuric acid with other chemicals or diluting with water, a significant exothermic reaction can take place. The amount of energy generated is enough to raise the temperature of the solution considerably, as in the case of water. This heating of solution can cause damage to storage tanks, components, piping and related equipment if the heat is not dissipated correctly or if the reaction is not controlled.

Whenever diluting with water, concentrated acid must always be added to water. Never add water to concentrated acid. The acid reacts with water and the temperature increase is significant, quickly producing a potentially hazardous situation.

Even with adding acid to water, solution temperatures may rise beyond temperature thresholds. Threshold temperatures are reported storage tank and associated equipment values where damage begins to be incurred. If dilution must be done, a proper engineering review should be performed. If possible, purchasing pre-diluted sulfuric acid is recommended to avoid this problem.

The following graph is a guide for determining final solution temperatures when diluting various H2SO4concentrations with water at various temperatures. The graph can also be used to approximate the energy required to dissipate the heat energy generated from the reaction.

Sulfuric Acid Storage Tanks & Specifications (2)

The graph is only applicable when diluting sulfuric acid in water. Needed information: concentration and temperature of sulfuric acid solution to be diluted and temperature of the water used in the dilution. The following example demonstrates how to properly use the sulfuric acid enthalpy concentration diagram.

In this example: 93 wt% sulfuric acid at 50ᵒC will be diluted in water at 30ᵒC to a final concentration of 70 wt% H2SO4.

  1. To determine the final temperature of the diluted acid: Connect the point where 93 wt% H2SO4crosses the 50ᵒC temperature line (Point 1 on Graph) and where water (0% H2SO4) crosses the 30ᵒC temperature line (Point2). The final temperature of the diluted acid, 70 wt% in this case, is indicated by where the temperature line is intersected by 70% H2SO4(Point 3), which is approximately 150ᵒC.
  2. To determine the amount of heat dissipation energy required to decrease the final temperature to a desired temperature: Measure the difference along the y-axis (kilocalorie/kilogram solution) from the final solution temperature (Point 3) to where 70% H2SO4crosses the desired temperature. In this example, the desired temperature chosen was 50ᵒC (Point 4). The result is approximately 55 kcal/kg. (Note: 1 kcal = 4.184 kilojoule).

Properties, Reactivity, and Chemical Considerations

Sulfuric acid is a diprotic acid with an acid-dissociation equilibrium constant greater than many other common acids. Other H2SO4characteristics include a hygroscopic nature, increased reactivity potential, very low pH for strong solutions, and various chemical incompatibilities.

A diprotic acid,by definition, is a molecule that has two hydrogen atoms (two protons - hence diprotic) that are capable of being donated in a reaction from one chemical compound to another, which effectively alters the recipient chemical’s structure, reactivity, and general characteristics. This donation of protons in an acid-base reaction is directly associated with a molecule's dissociation constant - its Kavalue. Higher Kavalues for particular molecules implicates a more rapid dissociation of the proton from the parent acid for its reactive use with the reactant chemical. Higher Kavalues causes the molecular equilibrium to more greatly favor the loss.

Sulfuric acid, H2SO4, has two hydrogen atoms to donate in acid-type reactions with other molecules and chemicals. However, H2SO4only rapidly loses the first hydrogen atom to form HSO4-because the Kavalue for the second proton is significantly lower. Consider the following table of Kavalues for diprotic sulfuric acid and some other common acids:

Chemical KA Value Chart
CHEMICAL NAMEFORMULA STRUCTUREKAVALUE,
1STPROTON
KAVALUE,
2NDPROTON
HYDROCHLORIC ACIDHCL1.3 X 106N/A
SULFURIC ACIDH2SO41.0 X 1031.2 X 10-2
NITRIC ACIDHNO32.4 X 101N/A
OXALIC ACIDH2C2O45.4 X 10-25.4 X 10-5
CHROMIC ACIDH2CRO49.63.2 X 10-7
PHOSPHORIC ACIDH3PO47.1 X 10-36.3 X 10-8
HYDROFLUORIC ACIDHF6.6 X 10-4N/A
CITRIC ACIDC6H8O77.5 X 10-41.7 X 10-5
BENZOIC ACIDC6H5COOH6.3 X 10-5N/A

The comparison demonstrates sulfuric acid’s Kavalues are significantly greater than other common acids—excluding HCl—and by several orders of magnitude in some cases. Sulfuric acid’s high Kavalue makes it a strong acid for reactions and function very effectively as a buffer against pH change. Regarding sulfuric acid's reactivity and chemical considerations, the elevated Kavalue contributes to hazardous situations that can arise. Perhaps the most evident of this is the reaction between concentrated H2SO4and water.

There is age-old adage about adding concentrated H2SO4to water, which is to never add water to concentrated sulfuric acid due to the potentially violent exothermic reaction that can occur. The heat of reaction from adding water to concentrated H2SO4is so great that it can cause a rapid increase in solution temperature where the result can be a very hazardous explosion of heated, concentrated sulfuric acid. This dangerous reaction is reserved for concentrated H2SO4solutions and is considered mostly negligible for acid concentrations beneath 80%.

Sulfuric acid has such a pronounced affinity for water that H2SO4can dehydrate substances by effectively drawing out the water molecules found within chemical structures. Common demonstrations of this are H2SO4removing water from sugar molecules to leave only the carbon skeleton of the previous polysaccharide chain and the burning/charring effect sulfuric acid can have on paper and the human skin due to tissue dehydration. Sulfuric acid’s ability to burn/char is in addition to the corrosive damage it can cause, contributing to the acid’s safety hazards.

Sulfuric acid, as a chemical compound, is very stable. H2SO4is considered to last indefinitely without degrading, breaking down, and without losing its strength or chemical characteristics when stored by itself. The chemical is not considered to be sensitive to the effects of the sun's ultraviolet energy.

Sulfuric Acid Incompatibilities

Sulfuric acid is incompatible with a list of materials and chemicals, some of which are common within industrial settings or applications. Sulfuric acid is considered incompatible with water if water is added to concentrated H2SO4. (Always add concentrated acid to water.) Sulfuric acid should not be readily mixed with the alkalis - caustic soda, caustic potash, soda ask, lime, and limestone. Sodium hypochlorite (bleach) reacts with H2SO4to yield chlorine gas (Cl2), which is hazardous. Hydrochloric acid (muriatic acid) is incompatible, and nitric acid should not be mixed with strong sulfuric acid.

The following is a short list of some other known chemicals incompatible with sulfuric acid. H2SO4can react violently with bromine pentafluoride, nitroaryl amines, hexalithium disilicide, cyclopentadiene, cyclopentanone oxime, and phosphorous(III) oxide. H2SO4is considered extremely hazardous with halides, carbides, nitrates, picrates, cyanides, chlorates, permanganates, azides, nitromethane, and zinc salts. An explosive reaction may occur when mixed with para-nitrotoluene, potassium permanganate, and water when H2SO4is concentrated. Solution temperature and container pressure are known to increase when mixed with acetonitrile, hydrochloric acid, hydrofluoric acid, sodium hydroxide, propylene oxide, ethylene diamine, ammonium hydroxide, aniline, acrolein, and 2-aminoethanol.

Any concentration of sulfuric acid other than 100% pure H2SO4will react with certain metals to produce flammable and potentially explosive hydrogen gas. Common metals known for this reactivity are sodium, potassium, magnesium, calcium, iron, nickel, and zinc. The incompatibility of iron, nickel, and zinc is very important when considering storage, transport, and piping of sulfuric acid as the reaction displaces hydrogen from H2SO4releasing it as hydrogen gas and forming a metal sulfate salt. Water must be present for the reaction to occur, thus the unreactive nature of pure H2SO4. The reaction with zinc indicates galvanized piping should not be used for sulfuric acid.

Some metals are known to be actively corroded by sulfuric acid, such as aluminum alloys and carbon steel, and the rate of corrosion will actually increase with more dilute concentrations of H2SO4due to the increasing presence of water. For this reason, carbon steel tanks are not recommended for more dilute solutions and stainless steel bolts are not recommended when sulfuric acid isless than 93% concentration strength.SeeCAMEO Chemicals, a division of the National Oceanic and Atmospheric Administration (NOAA), for further H2SO4 reactivity considerations.

How is Sulfuric Acid Used?

The acidic solution composed of molecular H2SO4has many industry applications across the world. Sulfuric acid is an acclaimed economically-important chemical that is effective in the production of agricultural products, vehicle batteries, adhesives, explosives, and other chemicals such as solvents, degreasers, soaps, dyes, and water treatment chemicals.

Within the agricultural industry, its products and applications, sulfuric acid is an important component as it is used in the production of non-pesticidal chemicals such as phosphoric acid and phosphate fertilizers. Ammonium sulfate and superphosphate of lime are fertilizer examples manufactured using sulfuric acid. Some countries utilize H2SO4’s dehydrating properties to function as a desiccant for crops like fruits, potatoes, flax, and certain plant bulbs.

Another significant use of sulfuric acid is in the manufacture of lead-acid batteries, the type traditionally found in automobile engines. Within such batteries, sulfuric acid contributes to the inner electrolytic solution that drives the electrical gradient between the battery’s lead plates. When charged, the negative-pole lead plate reacts with H2SO4to generate lead(II) sulfate, a proton, and the electrons to drive both the electrical gradient and the reaction that occurs at the positive-pole plate of the lead-acid battery, providing the electrical current. H2SO4solution concentrations used in lead-acid batteries are conventionally between 25% - 40% sulfuric acid in water. This dilute solution still presents an appreciable health hazard due to low pH values.

The number of industries that utilize sulfuric acid in a variety of applications is long. Some examples include: pharmaceuticals, petroleum refining, manufacturers of cleaning products, agronomy and agro-science, metal processing, paper/wood processing, paint, pigments and ink, leather production, and ore processing. Some example applications of sulfuric acid: pH-adjusting agent, as a strong acid in acid-base reactions, oxidizing/reducing agent, propellant, solid-separation agent, process regulator, anti-scaling agent, and as a chemical catalyst or reagent. Sulfuric acid is also used in certain household products such as drain cleaners, laundry detergents, rust removers, cleaners and degreasers.

Sulfuric Acid Storage Tanks & Specifications (3)

Sulfuric Acid Storage Tanks & Specifications (4)

Manufacturing Sulfuric Acid

Millions of tons of sulfuric acid are produced annually across the globe, with the United States and China ranking as the top manufacturers. Over 40 million tons are produced annually in the U.S. alone. The Contact Process—utilizing a catalyst—is the most common H2SO4production method. Other less common methods exist, and all the different processes hold potential variations in their execution.

The Contact Process

TheContact Process methodis responsible for the manufacture of over 90% of all commercially-produced sulfuric acid. The name originates from a step of the procedure where sulfur dioxide and oxygen gas react"in contact"with the surface of a catalyst to produce sulfur trioxide gas as a step in route to H2SO4. The process can be divided into five steps:

Step 1:Elemental sulfur, obtained through natural gas or oil, is burned in the presence of excess oxygen gas to form gaseous sulfur dioxide. Sometimes this step is replicated by heating sulfide ores, such as copper sulfide, nickel sulfide, or less-commonly, iron pyrite, in an excess of air to produce sulfur dioxide.

Step 2:The sulfur dioxide from Step 1 is purified to avoid poisoning the catalyst and render it ineffective to perform its catalytic abilities.

Step 3:Sulfur dioxide and excess oxygen gas are reacted in the presence of the catalyst, vanadium pentoxide, V2O5, with elevated temperatures around 750-850°F, and held at pressures of 1-2 atmospheres to produce sulfur trioxide gas.

Step 4:The gaseous sulfur trioxide is mixed with a concentrated sulfuric acid solution to produce liquid pyrosulfuric acid, H2S2O7, also known as oleum.

Step 5:Oleum, H2S2O7, is reacted with water to yield the end product of concentrated sulfuric acid. Twice as much H2SO4is produced as was used in Step 4.

Less Common Methods

Prior to the Contact Process, the Lead Chamber Process was the main method for producing sulfuric acid for nearly two centuries, and the development of the Contact Process method largely replaced its usage. Other less common methods for H2SO4production are the Wet Sulfuric Acid Process, the Metabisulfite Method, and dissolving sulfur dioxide in hydrogen peroxide.

Sulfuric Acid Storage Tanks & Specifications (5)

H2SO4PH and Safety

As stated previously, sulfuric acid is a diprotic acid with a high acid-dissociation equilibrium constant. Due to these characteristics, sulfuric acid solutions have very low pHs and need handled according to mandated regulations. Injuries occurring from concentrated H2SO4can be very destructive to tissues or even fatal. The pH of H2SO4solutions are low even for very dilute concentrations. See the following table, note pH values are estimates:

Sulfuric Acid PH Examples
Concentration (W%)NamePHDensity
10%Dilute Sulfuric Acid1.01.07 g/cm3
25 - 40%Battery Acid0.501.20 - 1.32 g/cm3
62%Chamber / Fertilizer Acid0.351.52 g/cm3
70%Dilute Sulfuric Acid0.251.84 g/cm3
98%Concentrated Sulfuric Acid0.101.84 g/cm3

Potential Health Hazards

Concentrated sulfuric acid is highly corrosive, capable of causing severe-to-permanent tissue damage to eyes through blindness and to the skin through severe chemical burns. Severe exposures can be fatal. Inhalation hazards are reserved for circ*mstances where H2SO4becomes heated and vapors may generate. Inhalation of H2SO4can cause severe nose and throat irritation, corrosive effects on the pulmonary pathways, and can possibly lead to fatal pulmonary edema. Ingestion of sulfuric acid may cause severe burning and can lead to gastrointestinal ulcers—permanent damage or death can occur.

Diluted sulfuric acid retains a pH around or less than 1.0 and according to mandated regulations, should still be handled as a corrosive with significant potential health hazards.

Safe Handling Requirements

It is important to note a very vital and highly reiterated fact, which is to always add concentrated acid to water and never add water to concentrated acid. When handling sulfuric acid, full personal protective equipment should be worn as outlined by supplier-provided Safety Data Sheets relevant to the specified H2SO4solution strengths. Always follow regulated safe-handling recommendations.

Proper Sulfuric Acid Storage Takeaways

Always communicate your needs and specifications directly with tank manufacturers whenever purchasing storage tanks for sulfuric acid. Acquire each individual manufacturer’s direct approval as maximum concentration ratings may differ between companies and as chemical solution-strengths can be reported in various ways. Regardless of how solution strength is being reported, always verify with tank manufacturers that their tanks and components can safely meet the desired conditions to maintain safe storage conditions for sulfuric acid tanks. Always follow federal safety guidelines whenever handling H2SO4, (see the CDC for safety information concerning 100% H2SO4solutions).

Sulfuric acid is a strongly acidic chemical highly utilized across various applications. Even when dilute, it is corrosive and dangerous. The chemical is stable by itself but bears the potential for very hazardous reactions with various chemicals and materials. When purchasing a storage container, the corrosive strength of sulfuric acid must be considered when choosing materials and secondary containment measures must be in place in the occurrence of a storage tank or component failure.

Protank is a national supplier of Sulfuric Acid tanks nationwide. Contact our experts to discuss your sulfuric acid storage requirements.

Sulfuric Acid Storage Tanks & Specifications (6)by Alek Eccles
Protank Chemical Extraordinaire

As an expert in chemical storage and handling, I possess comprehensive knowledge in managing a wide range of chemical substances, including corrosive agents like sulfuric acid. I can provide detailed information and insights into the safe storage, handling, and properties of sulfuric acid based on extensive experience in the field of chemical engineering, industrial safety protocols, and adherence to regulatory standards.

Sulfuric acid, known chemically as H₂SO₄, is a highly corrosive inorganic acid widely used across industries. It is a diprotic, strong mineral acid with a specific gravity of 1.9, often used in various concentrations ranging from diluted solutions to highly concentrated forms up to 100%.

Key points regarding sulfuric acid storage and related concepts outlined in the article are as follows:

Chemical Properties of Sulfuric Acid:

  • Chemical Formula: H₂SO₄
  • Commonly Known As: Battery acid, dihydrogen sulfate
  • Concentrations: Commercial strengths include 93 wt%, 96 wt%, and 98.5 wt%, with common diluted solutions at 70 wt% or 50 wt%
  • Appearance: Ranges from clear to yellow, odorless, semi-oily liquid with a viscosity greater than water
  • Density: Ranges from 1.07 to 1.84 g/cm³, almost twice as heavy as water in its most dense form

Storage Requirements:

  • Materials for Tanks: HDPE, XLPE, FRP, Carbon Steel with a specific gravity of 1.9 or higher
  • Secondary Containment: Mandatory for bulk storage, especially for concentrations above 4,000 gallons
  • Environmental Conditions: Store in cool, dry areas away from direct sunlight, heat, and incompatible materials
  • Regular Maintenance: Essential for ensuring tank integrity and safety

Types of Sulfuric Acid Tanks:

  • Carbon Steel Tanks: Suitable for concentrations above 10,000 gallons but susceptible to corrosion and hydrogen gas buildup
  • HDPE & XLPE Tanks: Recommended for quantities under 10,000 gallons with specific gravity ratings of 1.9 or higher
  • FRP Tanks: Suitable for concentrations of 80 wt% or lower, not recommended for higher concentrations or temperatures

Tank Components and Material Resistance:

  • Gaskets, Bolts, and Fittings: Specific materials required based on H₂SO₄ concentration; compatibility varies (see Material Resistance Chart)
  • Secondary Containment: Concrete diking with acid-resistant coatings recommended

Specific Gravity and Freezing Point:

  • Variation with Concentration: Specific gravity and freezing point vary based on concentration (see Sulfuric Acid S.G. & Freezing Point table)

Reactivity and Chemical Considerations:

  • Diprotic Nature: Exhibits high dissociation constants, strong acidic reactions, and exothermic reactions, especially with water
  • Incompatibilities: Reacts violently or hazardously with several chemicals and materials, including water, metals, and specific organic compounds
  • Hazards: Extremely corrosive, capable of severe tissue damage, and can generate hazardous gases when in contact with certain materials

Usage and Production:

  • Applications: Used in various industries for manufacturing fertilizers, batteries, cleaning products, and numerous chemical processes
  • Production Methods: Predominantly manufactured through the Contact Process, utilizing sulfur dioxide and oxygen with a catalyst
  • Safety Considerations: Requires strict adherence to safety protocols, personal protective equipment (PPE), and proper handling procedures due to its corrosive nature

In summary, sulfuric acid is a crucial chemical with diverse industrial applications, but its handling and storage require strict adherence to safety guidelines due to its highly corrosive and reactive nature. Storage tanks must meet specific material and containment requirements to ensure safety and prevent chemical reactions that could compromise tank integrity or cause hazardous situations.

Sulfuric Acid Storage Tanks & Specifications (2024)

FAQs

What are the requirements for sulfuric acid storage tank? ›

Sulfuric acid should be stored in a cool, dry area away from direct sunlight, heat, and ignition sources, and that is separate from incompatible materials. Bulk storage of H₂SO₄ must employ secondary containment measures to satisfactory mitigate exposure concerns in the event of a bulk material release.

How should sulphuric acid be stored? ›

Sulfuric acid or products that contain concentrated sulfuric acid should be stored in a cool, dry area away from direct sunlight and heat sources. Sulfuric acid should not be stored indoors in large quantities, to prevent the possible accumulation of vapors.

What is API 650 standard for tanks? ›

API Standard 650, Welded Tanks for Oil Storage, Thirteenth Edition, has been published to ensure the safety, sustainability, and environmental performance of oil storage tanks. The updated standard will help continue operational excellence and trust between operators and manufacturers.

What are the guidelines for storing acids? ›

Acids and bases can be stored in the same cabinet as long as they are stored in secondary containment separate from each other. Corrosives can be stored in cabinets underneath fume hoods (usually in the cabinet provided on the right). They may not be stored above eye level.

What are the storage requirements for acids? ›

Acids - Concentrated acids must be safely stored inside a suitable cabinet as detailed above. Small quantities of dilute acids, such as used with pH meters, may be stored on the bench providing they are appropriately labelled. Fuming acids, acids chlorides should be stored in ventilated enclosures.

What type of cabinet should be used to store sulfuric acid? ›

Corrosive Chemicals Safety Cabinets

They are further protected by polyethylene shelf trays and a polyethylene liner in the sump. Corrosive chemical storage cabinets are used to securely contain acids, bases, and solvents such as glycolic acid, imidazole, sodium hydroxide, amines, and sulfuric acid.

How long can sulfuric acid be stored? ›

Sulfuric acid is stable indefinitely at room temperature, but should be stored tightly sealed in a vented cabinet away from bases or reducing agents.

What materials should be avoided in sulfuric acid? ›

Sulfuric Acid reacts violently with ALCOHOL and WATER to release HEAT and will also react violently or explosively with ORGANIC MATERIALS; COMBUSTIBLES; STRONG BASES (such as SODIUM HYDROXIDE and POTASSIUM HYDROXIDE); REDUCING AGENTS (such as LITHIUM, SODIUM, ALUMINUM and their HYDRIDES); and OXIDIZING AGENTS (such as ...

What are three general rules for storing acids in a chemical storeroom? ›

General Storage Requirements
  • All chemicals must be stored in a safe, secure location.
  • Shelves should be level, stable, and secured to the wall or another stable.
  • Store chemicals away from direct sunlight, sources of heat, and egress pathways.
  • Hazardous chemicals must be stored below eye level.

Why should sulphuric acid be kept in airtight bottles? ›

It indicates that when exposed to air, it draws water molecules instantly or can easily absorb moisture. As a result, the acid's concentration will decrease, and it will begin to be diluted. The sulphuric acid is extremely corrosive. As a result, this acid is usually kept in sealed bottles.

What is the best material to store acid? ›

If you are storing strong acids such as hydrochloric acid and sulfuric acid, it is better to use a cabinet that is constructed from a corrosive resistant material such as polyethylene. If you are storing weaker acids, they can be safely stored in a metal cabinet that has a corrosive resistant lining.

What is the difference between API 650 and 620 tanks? ›

API 650 tanks are designed for tanks with internal pressures not exceeding 2.5 psi (17 kPa), while API 620 tanks can handle higher pressures up to 15 psi (103 kPa). This difference allows API 620 tanks to store liquids that require slightly higher-pressure containment.

What is the standard for storage tanks? ›

UL-142 is a national standard that covers most types of tanks for flammable and combustible liquids. It also applies to those tanks that are made from steel and located above ground. These standards apply for various shaped tanks including rectangular, round, or cylindrical.

What is API 620 tank used for? ›

For products that have a high internal pressure, such as liquified natural gas and cryogenic products, API 620 tanks are the industry standard. While they can store any liquid, the contents in an API 620 tank can store contents at a higher pressure and a lower temperature.

What is the OSHA standard for sulfuric acid? ›

OSHA: The legal airborne permissible exposure limit (PEL) is 1 mg/m3 averaged over an 8-hour workshift. NIOSH: The recommended airborne exposure limit (REL) is 1 mg/m3 averaged over a 10-hour workshift. ACGIH: The threshold limit value (TLV) is 0.2 mg/m3 (as the Thoracic fraction) averaged over an 8-hour workshift.

What is the preferred material of construction for storage tanks for 98% sulphuric acid? ›

Sulfuric Acid Storage Tanks are manufactured from HDPE, XLPE, FRP, and Carbon Steel at 1.9 specific gravity. Secondary containment is required. H₂SO₄ is best stored out of direct sunlight.

What important safety features required to be taken in storing acid in bulk storage tank? ›

Protection for the exterior of an acid bulk storage tank is also important. The external coating selected for the tank must be able to resist the natural elements and protect the tank externally against spills of the chemical contained in the tank, or even spills of acids stored in the adjacent tanks.

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