CHEMICAL NEWS

DuPont Announces Availability of Teflon® Nonstick Coatings in Six Different Colors

SpecialChem - Mar 22, 2013

CHICAGO - The superior nonstick performance and durability of DuPont™ Teflon® nonstick coatings is now commercially available in the United States in six delectable new colors.

The 2012 introductory colors, which included Hot Chili (a spicy red), Lavender Blue (a rich blue), Champagne Gold (a classic shimmer) and Ivory (an elegant neutral), are joined now by Spicy Olive (a stylish green) and Aubergine Purple (a vibrant eggplant). The palette will satisfy consumers' taste for style and individuality, as well as their appetite for something fresh in their kitchens. During the Housewares Show, the colors can be seen at DuPont booth S3910.

"The new colors will turn heads at retailer's shelves and in America's kitchens," said David W. DeVoe, North American consumer Marketing Manager, DuPont™ Teflon® consumer finishes. "In addition to looking great, consumers will continue to enjoy all of the benefits of cooking on a coating that offers superior durability and nonstick performance. And, just like Teflon® nonstick coatings for cookware and bake ware, the new Color Collection is made without using PFOA."

Each color was created to inspire cooks to purchase and use cookware and bake ware that reflect their personal taste and kitchen design and enhance the presentation of their traditional and seasonal dishes:

• Hot Chili - The color is bright, fun and cannot be overlooked at the point-of-sale. It engages experimentally minded individuals and will leave no one cold.
• Lavender Blue - Friendly and familiar, this distinctive hue enhances the presentation of cakes, bakes and desserts.
• Champagne Gold - This color is classy, combining luxury with understatement. The high-quality appearance leaves an impression of natural elegance.
• Ivory - Simple yet elegant, Ivory is one of the world's most versatile colors. Its minimalist feel impresses those with an eye for style, while its calm, soft tone creates an aura of pure relaxation.
• Spicy Olive - Spicy Olive has the flair of urban plazas and cobblestone streets filled with street cafes and live music, appetizers and snacks.
• Aubergine Purple - This color signals glory and splendor, pure joy of life. This warm and inspiring hue is an invitation to spoil you with color.

About DuPont™ Teflon® Brand

The origin of the DuPont™ Teflon® brand began with the discovery of polytetrafluoroethylene (PTFE) in 1938 by DuPont chemist Roy Plunkett after which in 1945, DuPont selected, coined the term and registered as a trademark the Teflon® brand. Teflon® nonstick coating systems were first commercialized for cookware more than 50 years ago in the United States and have, along with other additives, been used in paints, fabrics, carpets, home furnishings, clothing and so much more.

CHEMISTRY'S SURPRISES

Chemical engineering is an uneasy amalgam of industrial chemistry and mechanical engineering. In the U.S., it had its rudimentary beginnings with a course taught at the Massachusetts Institute of Technology by Lewis N. Norton in 1888. Since then, our profession has expanded away from its roots. Today, I think most chemical engineers are more comfortable with mechanical engineering than chemistry. So, let's consider some of the chemistry that you might want to re-remember. 

Here's one of my favorites: the Brønsted–Lowry theory of acids. Strictly speaking, it states that a compound is an acid if it can donate a proton (H+) and a base if it can accept a proton. Sounds like cash flow from senior economics, doesn't it? In simple terms, Brønsted–Lowry means that to every other compound or material, a compound is either an acid or a base. When I worked at Anheuser-Busch, I was fascinated by the large craters etched into our otherwise impervious concrete pads. Acid produced by bacteria-eating molasses that had spilled during tank filling created them. That was Brønsted at work! Concrete has a pH of about 12. A typical organic acid produced by bacteria is probably in the 5–6 range. To concrete, even pH-7 rain is an acid.
Now and then, Le Chatelier's principle — a stress imposed on a chemical system at equilibrium will shift the equilibrium to relieve the stress — has bitten a few forgetful engineers in the hindquarters. At Millennium Inorganic Chemicals, we inherited a 1,500°C gas-phase reactor designed by DuPont; flue gas, oxygen and titanium tetrachloride, caged in nitrogen, are heated in the middle of the plug-flow reactor. Jamming so much nitrogen on the reactant side of an equation, with only oxygen present, caused mischief: nitric acid ate our lined tank at the other end of the process. So, we switched from nitrogen to argon during startup.

Our gas-phase reactors proved another interesting chemical principle: gas-phase reactions always are the purest, except possibly for gas/solid reactions with selective catalysts. 

Biocatalytic processes can pose special complications. Jim Dye briefly touched upon this in his kinetics class: In 1778, Carl Wilhelm Scheele introduced Schweinfurter (Prussian) green. This copper arsenate dye became popular in wallpaper — even more so when it was discovered that the dye killed bedbugs! In places with a cool, damp climate (like much of Europe), mold can grow on the wallpaper. The mold consumes the starch used in the paste to put up the wallpaper. It also takes up arsenic from the dye, which through a complex series of biochemical reactions is turned into trimethylarsine oxide and then reduced to poisonous trimethylarsine, which is excreted as a gas. People living in rooms with the wallpaper grew sick and even died. Prussia banned the dye in 1838, England and France much later. It was not until 1945 that a chemist identified trimethylarsine as the culprit. For more information on this tale, see: www.cas.umt.edu/geosciences//faculty/moore/G431/lectur17.htm
Water solubility often gets chemical engineers in trouble. Members of upper Group 1 in the periodic table, e.g., Na–K, are nearly always soluble. Away from Group 1, carbonates, phosphates, sulfates, and hydroxides generally are insoluble. In the transition elements, with the exception of Pb and Ag, chlorides, nitrates and acetates are soluble. 

Then, there's the eruption that results when you drop a Mentos candy into a carbonated beverage. Some chemists argue it stems from bubbles forming on the surface of the Mentos, but I think they're all wet. I've seen the same effect with a root beer float and by adding saccharine to hot tea: it's surface tension. When two soluble components are added together, surface tension decreases (per the Gibbs isotherm equation). The opposite result occurs when two insoluble or semi-soluble components are mixed together. Because Mentos are soluble in the pop, the surface tension drops and a geyser erupts. TV's MythBusters concluded that the pitting of the Mentos candy creates abundant sites for nucleation (http://dsc.discovery.com/tv-shows/mythbusters/videos/diet-coke-and-mentos-minimyth.htm). They forgot that you still have to get the carbon dioxide to form. The extensive surface area is a factor, just like the saccharine in my tea. This may seem far afield from our business but it isn't. Improper use of a surface-tension-decreasing foam was to blame for a fatality at Millennium.

ALCOHOL VS QUATS AS SANITIZERS

What are quat-based hand sanitizers? How do they work?

Quat-based hand sanitizers are made with quaternary surfactants that destroy the cell integrity of bacteria and germs.  

— Dan Renner, Director of Marketing, Kutol Products Co., Sharonville, Ohio 

Quat-based sanitizers have additives to increase their antimicrobial effectiveness.

— Katharina Versluis, Marketing Manager, Gent-l-kleen Products Inc., York, Pa.

Quats are Quaternary Ammonium Compounds (QUATS) and the more common ones used are benzethoniumchloride (BEC) or benzalkoniumchloride (BZK). QUATS are typically found in hard surface type sanitizing applications ‚Äì inanimate, nonliving surfaces. This versus alcohol which is used in sanitizing applications on living tissue, i.e. skin. 

Studies have shown that QUATS are more irritating to the skin and they are not good for the environment. Further to this, the FDA has not approved the use of QUATS as a leave on application; they must be rinsed off. In recent years, the FDA has been enforcing its rulings requiring companies who manufacture QUAT based products to remove or change claims that market the product as a leave on hand sanitizer.  

QUATS work by breaking down the cell walls and ultimately killing the germ, thus contact time is important to ensure kill. Alcohol (at the FDA recommended level of at least 60 percent) kills germs on contact which usually means within the 15 seconds that it was tested to. Currently, the FDA guidelines state that hand sanitizers must contain at least 60 percent ethyl alcohol and BSCs should look for this on the label as a standard.  And, as of this date, the FDA has not approved non-alcohol based hand sanitizers for use as leave-on products; again, they must be rinsed off.

— Lori Huffman, Head of Marketing, North America, STOKO An Evonik Brand, Greensboro, N.C.

Do non-alcohol-based hand sanitizers, such as quat-based sanitizers, have benefits over alcohol-based products? Any facilities I should or should not use quat-based sanitizers?

Yes, quat-based hand sanitizers are not flammable, do not sting on cuts and chapped hands and have a pleasant scent versus alcohol based sanitizers.  Schools and prisons are ideal for quat-based sanitizers, where the dangers of alcohol based products may be a concern.— Dan Renner, Director of Marketing, Kutol Products Co., Sharonville, Ohio 

Quat-based products have a greater risk of causing contact allergies and can leave a sticky residue on skin. Additionally, these sanitizers can become more easily contaminated. Depending on the percentage of Ethyl Alcohol in the product, alcohol-based sanitizers have have been proven to kill 99.99 percent or more of (bacteria) micro-organisms.

— Katharina Versluis, Marketing Manager, Gent-l-kleen Products Inc., York, Pa.

Because the FDA has not approved QUATS as a leave on product, together with issues of less desirable skin compatibility and environmental friendliness, we do not recommend sanitizers that contain these ingredients.  

— Lori Huffman, Head of Marketing, North America, STOKO An Evonik Brand, Greensboro, N.C.

WALNUT SHELLS IN INDUSTRY

Walnut shells are used in many polishing and/or deburring applications. Walnut shell media is used for polishing or cleaning fine metals, alloys, mechanical parts, shell cartridges, eye glass lens, rocks, stones, coral, ivory, beans, and seeds.

Jewelers use walnut shell media treated with rouge in both tumbling and vibratory applications for polishing gems and fine jewelry.

When polishing the media size should be small enough to freely pass through openings or large enough to avoid lodging in openings or crevices.

Ground walnuts shells are a type of abrasive blast media used for cleaning. Typical substrates are metals, fiberglass, woods, plastics and stone. The walnut shells are ground to various sizes from coarse to extra fine depending on the application. The walnut shells are used in the same manner as typical blast media. Walnut shells are durable and can be re-used in many applications. Walnut shells can remove matter from surfaces without scratching or pitting underlying material.

Walnut shell is used in many applications as a filler or extender. Paint and coating materials, resins, pigments, plywood, adhesives, ceramics, dynamite, tile and livestock feed just to name a few. Media sizes vary from coarse walnut shell to walnut shell flour.

Walnut shell is used as lost circulation material to combat typical operational problems associated with drilling mud losses. Walnut shell is an easy and efficient solution to lost circulation problems. Walnut shell does not significantly change mud properties and can be removed and perhaps recycled with ease. Walnut shell is available in coarse, medium and fin grit sizes.

 

Walnut shell is biodegradable, non-toxic, environmentally safe and cost effective for blasting. Walnut shell does not cause silicosis.

The cosmetic industry uses walnut shell media as an exfoliate in facial, body and foot scrubs. Walnut shell is used by many, from the novice soap maker to the commercially distributed cosmetic lines. Eco-Shell will aid in formulating the custom grit sizes desired.

Walnut shell is used in many applications as a filler or extender. Paint and coating materials, resins, pigments, plywood, adhesives, ceramics, dynamite, tile and livestock feed just to name a few. Media sizes vary from coarse walnut shell to walnut shell flour.

Safety/Environmentally Sound
◊ Non-toxic and biodegradable
◊ Requires no flammable solvents
◊ Dust free
◊ Natural product
◊ Use required on most U.S. Government contracts
◊ Found not to cause Silicosis (can occur from use of sand or silica products)

Cost Effective
◊ Cleans without leaving scratches or pitting
◊ Cleaned parts require no additional machining or fitting
◊ Cleans precision parts without a change in dimensions
◊ Non-corrosive
◊ Lightweight
◊ Pollution prevention

Fast
◊ Surface areas require no drying time
◊ Easy to use
◊ Fast clean up after use
◊ Easy disposal process

Elasticity and Durability
◊ Resistant to rupture and deformation
◊ Limited breakdown
◊ Can be re-used in various applications

 

Inventoried Media Sizes
4/6 12/20 20/40 60/100 -100 6/10 14/30 35/60 60/200 -200 8/12 18/40 40/60 60/200-10.5 -325 4/20 20/30 40/100 70/200
Custom sizes available upon request. Please contact our sales staff at info@ecoshell.com.
Eco-Shell, Inc.

MASON WITH GREAT QUATERNARY COMPOUNDS GOES TO PILOT

CINCINNATI, Jan. 9, 2013 /PRNewswire/ -- Pilot Chemical Company announced today that it has acquired Mason Chemical Company, based in Arlington Heights, Illinois. Together the companies represent more than 100 years of successful family-based ownership and leadership as privately held businesses in the United States.

(Logo: http://photos.prnewswire.com/prnh/20130109/CL39379LOGO)

"Both Pilot, established in 1952, and Mason, founded in 1968, are successful companies built by their respective founders' families over many decades," said Paul Morrisroe , chairman and CEO of Pilot Chemical Company. "The Pilot and Mason product lines are complementary and will allow us to build on synergies between the two companies. Customers of both companies will be better served through a more complete and expanded global product offering from Pilot."

Mason Chemical Company is a leader in the development, registration and sale of quaternary ammonium compounds and related chemistries. The acquisition enhances Pilot Chemical's household, industrial and institutional, personal care and oil and gas product portfolios, strengthening its offering by adding registered and non-registered biocidal quats and tertiary amine derivatives.

"Mason and Pilot share a strong history of innovation in the chemical industry," said Gregg Mason , owner of Mason Chemical Company. "Having both of our product lines available from one source makes strategic sense. Together we can leverage our combined technologies, offering new solutions to our combined global customer base."

"Our goal is to be a leading provider of chemistry based solutions," said Pam Butcher , president and COO of Pilot Chemical Company. "Acquiring Mason Chemical illustrates our commitment to providing a broader product portfolio, new technology and applications expertise to better serve our customers."

Financial terms of the agreement were not disclosed.

About Pilot Chemical CompanyPilot Chemical is a privately owned and independent global specialty chemical company providing high quality products and services to the household and industrial detergent, personal care, lubricant, oilfield, emulsion polymerization, textile and agriculture industries. Proprietary core technologies involve alkylation, sulfonation, sulfation and a number of other specialty operations. Pilot, an industry leader in chemical innovation and safety, owns the most state-of-the-art continuous sulfation process in North America and is the world's largest manufacturer of disulfonates. Pilot Chemical Company is headquartered in Cincinnati, Ohio. To learn more, visit www.pilotchemical.com.

About Mason Chemical CompanyMason Chemical Company is a leading supplier of specialty chemistry to a broad range of industries. In business since 1968, Mason is known around the world as a market leader in the supply of EPA-registered actives and prototype formulations. Mason, a privately owned specialty chemical solution provider, serves the personal care, HI&I cleaners, textile, oilfield and other markets. For more information, visit www.masonsurfactants.com.

SOURCE Pilot Chemical Company

ONE FACT ABOUT SUGARS

As you can understand, not all sugars are the same, and obviously some are better than others.

Following is a link to a presentation by a known scientist that makes emphasis on what is not advisable for consumption and what can contribute to obesity.

 It is a long presentation but is very worthwhile.

http://www.youtube.com/watch?v=dBnniua6-oM&feature=youtu.be

 

 

 

STORING AND HANDLING ACIDS

Processing & Handling :: Process Chemicals

October 1, 2012

Acids Handling

General guidelines on materials, storage, pumping and other concerns for the proper and safe handling of acids

Alberto Baumeister Sebastiano Giardinella Mayhell Coronado Ecotek

Inorganic acids play a major role in the chemical process industries (CPI). They are used as raw materials, catalysts or finishing and pH control agents in the manufacture of a wide range of chemical products, from fertilizers to detergents, and even foods. Given their widespread use, a major issue in the CPI is the proper and safe handling of the acids, the adequate materials selection for the pieces of equipment, piping and fittings used in the process, and the correct storage and even disposal of these materials.

These are important factors that need to be taken into account from the design phase throughout the operating life of a facility, in order to ensure there will not be integrity problems that may negatively impact project economical turnover, personnel safety or the environment.
This article covers the most important inorganic acids: sulfuric acid (H₂SO₄), nitric acid (HNO₃), phosphoric acid (H₃PO₄), hydrogen chloride (HCl) and hydrochloric acid, and hydrogen fluoride (HF) and hydrofluoric acid; providing general guidelines on their physical properties, safety data, appropriate materials, storage, pumping and other common issues encountered when handling such fluids in the CPI.

Physical properties

Some acids are naturally present as liquids (H₂SO₄), some are solids at ambient conditions (anhydrous H₃PO₄), and others are gases (HCl, HF). Acids are very soluble in water and thus also widely available as aqueous solutions at different concentrations. Some of these solutions are also enhanced by dissolving additional compounds (for example, fuming sulfuric acid is made by dissolving SO₃ in sulfuric acid).
Given that there are several available grades, the knowledge of physical properties for each one is important in order to avoid freezing, the formation of hazardous fumes, or other problems when storing and handling these materials. The physical properties of the acids covered in this article are briefly presented here. These properties for common available grades are presented in Table 1. Figure 1 plots their vapor pressures at different temperatures.

Table 1. Physical and Chemical Properties of Acids [1–5]

Units

H2SO4

H3PO4

HNO3

HF

HCl

CAS Number

7664-93-9

7664-38-7

7697-37-2

7664-39-3

7647-01-0

Molecular weight

g/gmol

98.079

97.994

63.01

20.01

36.46

Grade

Concen- trated

Fertilizer

Tower

Fuming, 65% oleum

Pure

WFNA

Strong

Common

Gas (anhy- drous)

Aque- ous

Aque- ous

Gas (anhy- drous)

Aque- ous

Aqueous. Technical Grade 22°Be

Concen- tration

wt.%

98

78–80

62–70

35 H2SO4, 65 SO3

75–85

100

90

68

100

48–51

40

100

50

33

Physical state

Liquid

Liquid

Liquid

Liquid

Solid

Liquid

Liquid

Liquid

Gas

Liquid

Liquid

Gas

Liquid

Liquid

Color

Color- less

Color- less

Color- less

Color- less

Color- less

Color- less

Color- less

Color- less

Color- less

Color- less

Color- less

Color- less

Color- less

Color- less

Odor

Odor- less

Odor- less

Odor- less

Odor- less

Odor- less

Pun- gent odor

Pun- gent odor

Disagree- able (can cause choking)

Pun- gent odor

Acrid Odor

Acrid odor

Pun- gent odor

Pun- gent odor

Pun- gent odor

Boiling point (760 mmHg)

°C

340

200

155.85

151.1

212.8

86

120.5

121

20

108

112.2F

–85

100

83

Vapor density (air = 1)

3.4

3.4

2.2

2.5D

0.7

1.97

1.3

0.62

1.267

Specific gravity (H2O=1)

1.83

1.72

1.57

1.56

1.87

1.50

1.50

1.50

1.17

1.14

1.03

1.16

Liquid density (at 20ºC)

g/mL

1.8361

1.7272B

1.6105C

1.5533

1.579A

1.5129

1.4826

1.4048

1.202

1.159

1.251

1.164

Melting point

°C

10.5

–4.29

–36.55

–36.98

42.2

–42

–41.6

–83

–40

–62

–114

–46.2

Dynamic viscosity (at 20ºC)

cP

20.5

6.5

3.52

2.68E

2

Notes: A Liquid Density of phosphoric acid at 75% B Liquid density of sulfuric acid at 80% C Liquid density of sulfuric acid at 70% D Vapor density of nitric acid at 65% E Dynamic viscosity obtained after extrapolation F Boiling point at 38.2%

Figure 1. The vapor pressure as a function of temperature for the acids covered in this article

Sulfuric acid. Sulfuric acid is the single most important inorganic chemical in tonnage produced and in use. H₂SO₄, can be described as a colorless, oily, hygroscopic liquid with no odor; it is the largest inorganic chemical manufactured and one of the most widely used inorganic chemical in the manufacture of many other products. By the year 2004, North America and Asia were the biggest producers of sulfuric acid, recording almost 60% of world total production. Sulfuric acid is manufactured by the combustion of sulfur with dry air to form sulfur dioxide (SO₂), then sulfur trioxide (SO₃) is produced through a catalytic conversion. Finally, sulfuric acid is obtained after absorption of SO₃ in water.
Sulfuric acid is a strong acid and a strong oxidizing agent; therefore it reacts violently with bases, combustible, reducing materials, water and organic compounds with the evolution of heat. It is highly corrosive to most common metals and forms a flammable/explosive gas.
Sulfuric acid is mostly used in the manufacturing of fertilizers, organic pigments, explosives and more. As a strong electrolyte it is used in electroplating baths for pickling, and for operations in the production of iron and steel. Moreover, it is extensively used as a solvent for ores and as a catalyst in the petroleum industry.
Nitric acid. HNO₃ is a solution of nitrogen dioxide (NO₂) in water; it is a colorless to light-brown fuming liquid with an acrid suffocating odor. Nitric acid is the second most important industrial acid; it is a highly oxidizing agent, used in the manufacture of chemicals, explosives, fertilizers, steel pickling and metal cleaning. However, the largest use for nitric acid is for the production of fertilizers.
Nitric acid is a strong acid that reacts violently in the presence of strong bases, reducing agents and combustible fluids, such as turpentine, charcoal and alcohol. It is corrosive to metals, forming flammable or explosive gas. Nitric acid also reacts violently with organic compounds.
Phosphoric acid. H₃PO₄ or orthophosphoric acid is a white solid with a melting point of 42°C, which is highly soluble in water, non-toxic and a relatively weak acid.
H₃PO₄ is the third most important acid in industry. It is used mostly in the production of phosphate fertilizers; but also in the manufacturing of agricultural feeds, soaps, detergents, waxes; and in the food industry as preservative, acidifier, clarifier or flavor enhancer; among other uses.
H₃PO₄ has two main methods of production: the wet process and electric furnace. It is commercially available at concentrations of 75, 80, 85 and 87 wt.% of PO₃. Higher concentrations, such as 105 wt.% (superphosphoric) and 115 to 118 wt.% (polyphosphoric) are also available. “Pure” or “technical grade” phosphoric acid is usually found at 85 wt.%.
Hydrogen chloride and hydrochloric acid. Hydrochloric acid is a solution of the gas hydrogen chloride; it is a poisonous, highly corrosive, hazardous liquid that reacts with most metals to form explosive hydrogen gas. Its appearance varies from pale yellow to colorless, according to purity.
Hydrochloric acid has many applications in the production of organic and inorganic compounds such as fertilizers, chlorides, dyes and more. HCl plays an important role in pickling of steel, acid treatment of oil wells, chemical cleaning and processing, and ore reduction among others.
When boiling all aqueous solutions, HCl forms an azeotropic constant-boiling mixture that contains 20.24% HCl and boils at 110°C (230°F).
Hydrogen fluoride and hydrofluric acid. Anhydrous hydrogen fluoride (AHF) is a clear, colorless, corrosive fuming liquid with an extremely sharp odor. It easily dissolves in water to form hydrofluoric acid.
HF forms dense white vapor clouds if released. Both liquid and vapor can cause severe burns to all parts of the body. Specialized medical treatment is required for all exposures.
HF occurs naturally in volcanic gases and may result from industrial activities, such as coal-burning, and the manufacture or production of aluminum, phosphate fertilizer, steel and other chemical derivatives.
Commercially, HF is used to manufacture fluoropolymers, pharmaceuticals, aluminum, stainless steel, high-octane gasoline, electronics (microchips and printed circuit board cleaning) and uranium isotopes. It is also used to etch glass or metal.

Safety and emergency response

Because acids are mostly hazardous chemicals, their toxicity levels and incompatibilities need to be taken into account when storing and transporting them, as well as how to respond in the event of a spillage.
Permissible exposure limits (PEL) for hazardous materials are given by the U.S. Occupational Safety and Health Administration (OSHA) regulations: 29 CFR 1910.1000, 29 CFR 1926.55 and 29 CFR 1915.1000 for the general, construction and maritime industries, respectively. Other toxicity levels, such as the Recommended Exposure Limit (REL) and Immediately Dangerous to Life and Health Concentrations (IDLH) are published in the U.S. National Institute of Occupational Safety and Health (NIOSH) Pocket Guide to Chemical Hazards. The chemical incompatibilities, health effects and other concerns when handling or storing hazardous chemicals are also given in the NIOSH Pocket Guide.
In the U.S., transportation of these acids or other hazardous materials is subject to the U.S. Department of Transportation Pipeline and Hazardous Materials Safety Transportation regulations. Transportation of hazardous materials in various forms (bulk, pipeline or tank cars) is subject to Title 49 of the Code of Federal Regulations (49 CFR).
In the event of spills of these acids or other hazardous materials, only properly trained personnel such as firemen and policemen (or properly trained plant personnel) should be involved in the emergency response and containment of the product.
The Emergency Response Guidebook 2008 (ERG2008) provides guidelines for managing emergencies when hazardous chemicals are involved. This guidebook is available in printed form, and can also be downloaded in convenient electronic form, including applications for smart phone that allow for quick searches of the chemicals and their associated guides. A new version of the Emergency Response Guidebook is scheduled for release this year (2012).
The chemical safety data for the acids covered in this article, including toxicity levels, incompatibilities and emergency response guides are summarized in Table 2.

Table 2. Toxicity and Emergency Response Data
	H2SO4		H3PO4	HNO3	HF		HCl
PEL (OSHA) [6–8]	1 mg/m3		1 mg/m3 TWA	2 ppm, 5 mg/m3 TWA	3 ppm, 2 mg/m3 TWA		5 ppm, 7 mg/m3 ceiling
REL (NIOSH) [9]	1 mg/m3 TWA		1 mg/m3 TWA; 3 mg/m3 STEL	2 ppm, 5 mg/m3 TWA; 4 ppm, 10 mg/m3 STEL	3 ppm, 2.5 mg/m3 TWA; 6 ppm, 5 mg/m3 (15 min) ceiling		5 ppm, 7 mg/m3 ceiling
IDLH (NIOSH) [9]	15 mg/m3		1,000 mg/m3	25 ppm	30 ppm		50 ppm
Incompatibilities & Reactivities	Organic materials, chlorates, carbides, fulminates, water, powdered metals. Reacts with water to produce heat. Corrosive to metals		Strong caustics, most metals, Reacts with metals to form H2 gas. Do not mix with solutions containing bleach or ammonia	Combustible materials, metallic powders, hydrogen sulfide, carbides, alcohol. Reacts with water to produce heat. Corrosive to metals	Metals, water or steam. Corrosive to metals. Attacks glass and concrete		Hydroxides, amines, alkalis, copper, brass, zinc. Hydrochloric acid is highly corrosive to most metals
UN Listing Number	1830: sulfuric acid; sulfuric acid, with more than 51% acid 1831: sulfuric acid, fuming; sulfuric acid, fuming, with less than 30% free sulfur trioxide; sulfuric acid, fuming, with not less than 30% free sulfur trioxide 1832: sulfuric acid, spent	2796: sulfuric acid, with not more than 51% acid	1805: phosphoric acid; phosphoric acid, liquid; phosphoric acid, solid; phosphoric acid, solution 3453: phosphoric acid, solid	2031: nitric acid, other than red fuming 2032: nitric acid, fuming; nitric acid, red fuming	1052: hydrogen fluoride, anhydrous	1790: hydrofluoric acid	1050: hydrogen chloride, anhydrous 2186: hydrogen chloride, refrigerated liquid	1789: hydrochloric acid; hydrochloric acid, solution
Emergency Response [10]	Guide 137	Guide 157	Guide 154	Guide 157	Guide 125	Guide 157	Guide 125	Guide 157
Notes: PEL: Permissible exposure limit REL: Recommended exposure limit IDLH: Immediately dangerous to life or health concentration TWA: Total weighted average STEL: Short time exposure limit ERG: Emergency Response Guidebook

Materials selection

The materials of construction, as well as any lining or internal coating requirements should be determined by a materials expert based on the acid, its concentration and storage conditions.
Aqueous acid solutions are very corrosive, and usually require special materials depending on the temperature or phase.
Some recommendations are given regarding the correct material selection depending on acid, such as in the following reference for H₂SO₄: NACE RP0391 — Materials for the Handling and Storage of Concentrated (90 to 100%) Sulfuric Acid at Ambient Temperatures; HF: NACE 5A171 — Materials for Storing and Handling Commercial Grades of Aqueous Hydrofluoric Acid and Anhydrous Hydrogen Fluoride.
Depending on the acid and storage, transport or process conditions, interior coatings or linings could also be considered. For instance, rail tank cars transporting concentrated sulfuric acid should be internally coated according to NACE SP0592 — Application of a Coating System to Interior Surfaces of New and Used Rail Tank Cars in Concentrated (90 to 98%) Sulfuric Acid Service.
Tables 3–8 list some common metal alloys used in the CPI, along with their general acceptable use ranges (concentrations and temperatures) for each of the acids covered in this article.

Table 3. Materials of Construction, Cladding & Lining [12]
Materials of construction	H2SO4
Aluminum	Aluminum alloys may be used to handle dilute (concentration below 10%) and concentrated acid (above 98%). It suffers corrosion for handling sulfuric acid in a range of concentration of 40–95 %
Carbon steel	It can be used to handle concentrated sulfuric acid at ambient temperatures under static and low-velocity condition. Corrosion resistance depends on temperature, acid concentration, iron content and flowrates
Cast Iron	Alloys with 14.5% content of silicon have shown best resistance to corrosion for sulfuric acid handling in all concentrations at temperatures up to the boiling point
Copper	Copper and copper alloys are not suitable for sulfuric acid handling
Lead	It has shown high resistance to corrosion in sulfuric acid handling up to 70% concentration. Although, this material is not recommended for pumps or valves
Nickel	Nickel 200 demonstrates good tolerance to sulfuric acid when it is handled at low or moderate temperatures
Niobium	It can be used for handling sulfuric acid at concentrations below 95% under oxidizing conditions
Gold	Exhibits excellent resistance to sulfuric acid up to 250°C (480°F) and is used when no corrosion can be tolerated
Platinum	Resists sulfuric acid in all concentrations and temperatures
Palladium	It is attacked by sulfuric acid in the presence of air
Rhodium	In wrought or cast form rhodium is not recommended for handling sulfuric acid
Stainless steel	Concentrated sulfuric acid turns extremely corrosive in presence of 316 and 304 stainless steels. The conventional austenitic grades show good resistance in dilute or highly concentrated acid at moderate temperatures
Zinc	It is slowly dissolved by dilute sulfuric acid; corrosion resistance depends on the concentration of the acid and the purity of the metal

Table 4. Materials of Construction, Cladding & Lining [12]
Materials of construction	H3PO4
Aluminum	Aqueous solutions of phosphoric acid with concentration of 5 to 85% are highly corrosive for alloys 1100. Consequently this material is not recommended for phosphoric acid handling
Cast Iron	All cast irons can be considered to handle phosphoric acid; although the presence of contaminants must be previously evaluated since it can provoke severe cases of corrosion. High-silicon cast irons are ideal to manage phosphoric acid in all concentrations at any temperature, no presences of fluoride ions (F-) are allowed
Copper	Copper and copper alloys can be used to manage pure phosphoric acid solutions in heat-exchanger tubes, pipes and fittings. System impurities can accelerate the rate of corrosion more than acid concentration
Lead	It is extensively used in the manufacture of phosphoric acid. It is highly resistant to corrosion
Nickel	Nickel alloys are appropriate for handling phosphoric acid. For dilute acid alloys 20Cb-3 and 825 are recommended; for concentrated acid at high temperatures alloy B-2 offers the highest corrosion resistance
Niobium	Resistant to corrosion for handling acid at temperatures below 100°C in all concentrations
Silver	Resistant to corrosion for handling acid at temperatures between 160 and 200°C in all concentrations
Tantalum	Resistant to corrosion for handling acid at temperatures up to the boiling point in all concentrations in absence of fluoride ions (F)
Stainless Steel	Conventional austenitic stainless steel has shown elevated corrosion resistance for all concentrations of phosphoric acid up to 65°C (150°F)

Table 5. Materials of Construction, Cladding & Lining [12]
Materials of construction	HNO3
Aluminum	Aluminum alloys commonly used for nitric acid services are 1100 and 3003. Corrosion depends on temperature and concentration of the acid. Aluminum alloys are compatible with nitric acid at temperatures up to at least 71°C (160°F) when it is inhibited by hydrofluoric acid
Cast iron	Cast iron can be used for handling concentrated nitric acid under control conditions such as low temperature and low velocity. Corrosion attacks when handling dilute nitric acid
Stainless steel	For concentrations of 0 to 65%, most AISI 300-Series stainless steel has shown great corrosion resistance for temperatures up to the boiling point
Copper	Not suitable for use in nitric acid
Lead	It can be used for concentration between 52 and 70%
Molybdenum	Not suitable for use in nitric acid
Nickel	Nickel alloys are widely used in the production of nitric acid. Alloy 617 offers an excellent performance and corrosion resistance for handling nitric acid at high temperatures in the catalyst-support grids in high pressure plants
Niobium	It is completely resistant to nitric acid in all concentration at temperatures below 100°C
Gold	It is resistant to nitric acid in concentrations up to 50% above that it is attack by corrosion
Palladium	It is vulnerable to attack from corrosion when nitric acid is in presence of air
Rhodium	In wrought or cast form rhodium is resistant to corrosion produced by concentrated nitric acid at 100°C
Silver	Not suitable for use in nitric acid
Tin	Not suitable for use in nitric acid. Complex reaction occurs
Titanium	Appropriate for handling nitric acid at any concentration in temperatures below the boiling point. As temperatures exceed 80°C (175°F), corrosion becomes stronger depending on nitric acid purity. Titanium alloys can’t be used for red fuming nitric acid due to a violent reaction that can take place in the system

Table 6. Materials of Construction, Cladding & Lining [12]
Materials of construction	HF
Aluminum	Unsuitable for handling hydrofluoric acid
Stainless steel	Stainless-steel type 304 has a good performance for handling anhydrous hydrogen fluoride up to 200°C (390°F), it has poor resistance to dilute or concentrated hydrofluoric acid. On the other hand stainless-steel type 316 can be used for handling dilute acid at low temperatures
Copper	The use of copper alloys is affected by aeration and velocity, its corrosion resistance depends on the concentration and temperature
Lead	Fair corrosion resistance in a wide range of concentration and temperatures for handling hydrofluoric acid. Not recommended for handling dilute acid
Molybdenum	It offers great corrosion resistance to aqueous and anhydrous hydrofluoric acid with concentrations up to 50%, below 100°C (212°F)
Nickel	Nickel 200 is ideal for handling hot anhydrous hydrogen fluoride vapor, but it is not recommended for handling hydrofluoric acid in aqueous solutions
Niobium	Unsuitable for handling hydrofluoric acid
Tin	Unsuitable for handling hydrofluoric acid
Titanium	Unsuitable for handling hydrofluoric acid
Zirconium	Unsuitable for handling hydrofluoric acid

Table 7. Materials of Construction, Cladding & Lining
Materials of construction	HCl
Aluminum	It is not appropriate for handling HCl; it has no resistance to corrosion
Cast Iron	Unalloyed cast iron systems are unsuitable for handling HCl, especially if high velocities are involve. A high-silicon iron alloyed with small amounts of molybdenum, chromium and copper can be used to handle hydrochloric acid up to 95° C (200°F) at all concentrations
Stainless steel	Corrosion attacks stainless steel (316) and stainless steel (304) when handling HCl at any concentration or temperature
Copper	Copper can be used to handle dilute hydrochloric acid only, due to its sensitivity to velocity, aeration and oxidizing impurities
Lead	It exhibits tolerance to corrosion at 24°C (75°F) and concentrations up to 15%. It is unsuitable for concentrated acid at higher temperatures
Nickel	Pure nickel and nickel-copper alloys can be used for handling hydrochloric acid below 10% concentration, without air presence, at low temperatures. The lower the concentration the higher can be the temperature of the system; for example, HCl at 0.5% can stand temperatures up to 200°C before corrosion attacks the alloy
Niobium	It has shown excellent corrosion resistance to handle HCl at any concentrations and temperatures up to 100°C (212°F)
Gold	It can be used for handling hydrochloric acid at any concentrations and atmospheric pressure up to the boiling point
Palladium	Unsuitable for handling hydrochloric acid
Rhodium	In cast or wrought form, rhodium has excellent corrosion resistance to handle concentrated hydrochloric acid in temperatures up to 100°C (212°F)
Silver	It is very susceptible to aeration when concentration and temperature are high
Tantalum	It has shown excellent corrosion resistance to handle HCl at any concentrations under atmospheric pressure and temperatures up to 90°C (195°F). It can be used to handle acid with concentrations below 25% up 190°C (375°F)
Titanium	Unsuitable for handling hydrochloric acid

Table 8. Materials of Construction, Cladding & Lining
ACIDS	COMMON ALLOYS
H2SO4	For dilute and intermediate sulfuric acid (between 40 and 80% concentration) Incoloy alloys 25-6MO, 825, 020 and Inconel alloy G-3 have shown excellent corrosion resistance for temperatures up to 50 °C (120°F). When handling aggressive acid, Inconel alloys 625, 622, C-276 and 686 are suitable. For reducing conditions, Monel alloy 400 is appropriate in the absence of air for temperatures up to boiling point for concentrations below 15%. For storage of H2SO4, Monel alloy 400 can be used at room temperatures up to 80% concentration. Hastelloy B3, C-2000 and G-30 are also suitable for handling sulfuric acid
HNO3	Chromium enhances corrosion resistance in alloys while handling nitric acid, due to this fact, Incoloy alloy 800 and 825 are adequate for nitric acid at all concentrations for temperatures up to the boiling point. Inconel alloy 600 and C-276 also offer good corrosion resistance to nitric acid for concentration over 20% at room temperature; alloy 690 has shown better corrosion resistant because its chromium content is higher. Hastelloy G-30 alloy and G-35 offer excellent corrosion resistance for this same reason
H3PO4	When handling phosphoric acid, Incoloy alloys 825, 020 and 25-6MO, as well as Inconel alloy G-3 are suitable and regularly used. For extreme conditions such as high temperature and high amount of impurities or halides contaminants, Inconel alloys 625, 622, C-276 and 686 are recommended. Hastelloy alloys B-3 and G-30 stand phosphoric acid in all concentrations and temperatures. Hastelloy alloy G-35 was especially designed for phosphoric acid wet processing in fertilizers manufacture
HCl	Incoloy alloys 25-6MO, 825 and 020, and Inconel alloy G-3 are used for dilute hydrochloric acid handling. Another alloy that offers good corrosion resistant in concentrations below 10% with aerated conditions at room temperature is Monel alloy 400. Nickel alloy 200 can be used at room temperature for concentrations up to 30% as well. For environments that contemplate the presence of oxidizing contaminants and hot hydrochloric acid, Inconel alloys 625, 622, C-276 and 686 are recommended. Hastelloy alloys B-3, C-2000 and G-30 are also suitable for handling hydrochloric acid, at all concentrations and temperatures
HF	The formation of fluoride films is key on engineering materials in order to offer good corrosion-resistance rates while handling hydrofluoric acid. Monel alloy 400 is widely used for this purpose, due to the fact that it has shown excellent corrosion resistance for all hydrofluoric acid services in all concentrations and temperatures up to (and even above) the boiling point. For anhydrous hydrogen fluoride up to 82°C (180°F), Nickel alloy 200 is commonly used. For dilute HF and temperatures up to 70°C (158°F) Inconel alloy 600 can also be used. Other alloys like Hastelloy C-2000 and Hastelloy G-30 are also recommended for handling hydrofluoric acid

Storage tanks

Usually aboveground storage tanks (ASTs) are used to store acid as they facilitate accessibility to tanks and ancillary equipment for inspection and maintenance. The storage tank should be sized for at least 50% more volume than required.
Tanks for acid storage are usually built of either metal (lined or non-lined), or fiber reinforced plastic (FRP). Metal tanks offer a higher durability, and can also resist higher stresses or impacts; whereas FRP tanks are economical, usually chemically inert, and can be a good alternative for low-volume, short storage times.
The mechanical design of tanks for acid storage usually follows either of the following codes:
• API STD 650 — Welded Steel Tanks for Oil Storage: for vertical tanks with flat bottoms and operating pressures less than 0.14 barg (2.5 psig)
• API STD 620 — Recommended Rules of Construction of Large, Welded, Low Pressure Storage Tanks: for vertical tanks with flat bottoms and operating pressures between 0.14 barg and 1.03 barg (2.5 psig and 15 psig)
• ASME BPV Code, Sect VIII, Div 1: for other operating pressures
Special design criteria, such as particular corrosion allowances or nozzle design, are also considered in acid storage tanks — either by special company or supplier criteria, or from professional associations. For instance, concentrated sulfuric acid tanks design should follow NACE SP0294 — Design, Fabrication, and Inspection of Storage Tank Systems for Concentrated Fresh and Process Sulfuric Acid and Oleum at Ambient Temperatures.
Tanks should allow access to the top nozzles and the vent system, and offer an appropriate facility for sampling. Periodically, it is necessary to homogenize the contents of the tank, because the acid that remains on the surface establishes a vapor-liquid equilibrium in which toxic and corrosive gases are released, so a recirculation system is recommended.
Special attention should be given to the acid physical properties in storage to prevent freezing, high corrosion rates or vaporization.
In general, corrosion rates increase at higher temperatures, so acids should be stored at the lowest possible temperature without freezing the acid. Higher corrosion rates could also result from heating of the metal surfaces due to sun radiation, so the tank exterior should be painted with a radiation reflecting color, such as white. Another regular measure to maintain acids at an appropriate temperature is coating the tank with an adequate material such as vinyl-based materials.
In places where the storage temperature could be below the acid freezing point, storage tanks and vessels should be provided with heating facilities, such as plate coils mounted on the outside of the tank wall, or external heat exchangers connected to the tank. Internal heating coils are not recommended, because excess temperature in the coil walls accelerates corrosion and could cause leaks. Also, high-pressure steam is not recommended as a heating medium since heat exchange surfaces could exceed 100°C, causing severe corrosion.
Pressurized storage is required when the vapor pressure exceeds the atmospheric pressure at the storage temperature.
Common guidelines for acid storage tank design are summarized in Chem. Eng. May 2008, Facts at your Fingertips: Acid Storage.
When storing acids above ground, containment is also an issue. Tanks should be properly diked, or double walled, to contain spills. In general, containment should be at least for one tank volume (if not properly drained), or less provided there is adequate drainage to an acid neutralization pit, with blockage valves accessible to operators. Local code requirements should also be addressed when designing acid-tank containment; for instance, the U.S. State of Florida has specific requirements as given by Rule 62-762.891 — Mineral Acid Storage Tank Requirements.

Pumps

The design basis should be set before selecting a pump, that is, the operating conditions such as temperature, suction pressure, acid concentration, and so on.
A primary issue that must be taken into account while pumping acids is safety, so, the selected pump for the system cannot leave place for leakage; this is an advantage regularly offered by vertical submerged pumps over horizontal pumps. Also, material selection guidelines shall be followed to avoid casing, impeller or other internals damage.

Piping and fittings

Selecting pipe material and designing the pipe system is a very important issue in a plant, especially while handling acids. The system must ensure the acid is transported safely and efficiently. Piping should have as few flanges as possible, so the chance of having leaks becomes negligible.
In order to select the piping material, the following aspects have to be defined: acid concentration, transport temperature, phase, fluid velocity, type of flow, impurities in the acid and solids presence.
Corrosion is often related to an acid’s velocity. In order to maintain a low velocity of the fluid, a bigger pipe diameter is suggested.

Valves

Valves are used for various functions, including the following:
For blocking, gate valves or plug valves are regularly used. However, plug valves are preferred for this service, to ensure proper valve operation.
For control, globe or butterfly valves are suitable; they can be manually operated or be fitted with actuators.
Materials for different parts of the valves (disk, stem and seat) should be selected according to the acid concentration and operating conditions, by consulting the valve manufacturer.
Some common materials according to the acid to be handled are presented in Tables 9–13.

Table 9. Specific Equipment, Piping, Valves and Protective Clothing Guidelines
Equipment	H2SO4
Tanks	Iron sulfate is produced in storage tanks of sulfuric acid; it is a consequence of interaction between the tank’s surface and the acid. Usually iron sulfate precipitates, therefore the pump suction pipe should be placed above the tank bottom to avoid pumping solid residues that can compromise pump well-functioning. Under the same line, storage tanks must provide a facility to clean the tank bottom. The tank’s maintenance should be performed periodically according to the laws of the state and the company policies
Pumps	According to the plant requirements, pumps used for sulfuric acid handling are usually horizontal centrifugal pumps or heavy duty vertical, submerged type For handling sulfuric acid at 93.19% (66 °Bè) usually horizontal centrifugal pumps with mechanical seals are used Common materials of construction are: cast iron or Alloy 20 wetted ends, Alloy 20 plunger, tetrafluoroethylene plastic chevron packings
Piping and fittings	For sulfuric acid service, welded pipe lines with schedule 80 are commonly used, these pipes should be kept full of acid to minimize corrosion attacks. Sulfuric acid also promotes hydrogen gas formation; for this reason it is necessary to avoid pressure buildup by venting the line In case of draining the pipe, the use of air is not recommended, because it can accelerate corrosion. Nitrogen can be used for such purposes
Valves	Butterfly Valves: Lead is an adequate stem and disk material for sulfuric acid at all concentrations; for concentrations lower than 75% at low temperatures Alloy 20 and Hastelloy have also been used. The seat should be made of PVF, with Viton and Hypalon also been used
Protective clothing	Properly fitted chemical safety goggles, face shield (8-in. high minimum) and protective clothing should be worn. Acid-proof clothing should be fitted snugly at neck and wrists, in a manner preventing drainage of acid to gloves or boots. Impervious rubber or polyvinyl chloride gloves with gauntlets covering forearms should be used. Boots made of the same material should be worn, with tops being covered by the trousers. Head protection via hard hat or full cover acid hood should be worn, as well as a respirator for protection against fumes

Table 10. Specific Equipment, Piping, Valves and Protective Clothing Guidelines
Equipment	H3PO4
Tanks	Heating coils should be provided in order to maintain the phosphoric acid above its freezing point, depending on ambient conditions and acid concentration. For instance, 85% H3PO4 freezes at 21.1°C
Pumps	All fittings should have wetted parts of 316 L stainless steel, with mechanical seals rather than packing. Centrifugal pumps are also used for phosphoric acid handling
Piping and Fittings	Stainless steel 316 is regularly used for piping because it has shown excellent results in corrosion resistance for all concentrations of phosphoric acid, even though the piping material can be the same used for storage When using stainless steel, the fittings and valves should be welded or flanged; screwed fittings are not recommended because they may allow leakage
Valves	Butterfly valves: 316 SS, Alloy 20 and Hastelloy C are good stem and disk materials for phosphoric acid at various concentrations, with Monel also showing fair results. Common seat materials include: PVF, Neoprene, Hypalon, Viton or EPT
Protective Clothing	Properly fitted chemical goggles and protective clothing should be worn. Impervious gloves and aprons are recommended. No special respiratory protection is required under ordinary conditions of use, provided that adequate ventilation is maintained. When vapor or mist concentrations exceed applicable standards, approved respiratory protective equipment must be used

Table 11. Specific Equipment, Piping, Valves and Protective Clothing Guidelines
Equipment	HNO3
Tanks	For acid grades lower than 95 wt.%, tanks should be designed for slight pressure and vacuum, with fumes collected at a disposal system and sent to a scrubber. Vent piping should be designed taking into consideration possible corrosion from contact with moisture
Pumps	Wetted parts should be made of 304L stainless steel for concentrations lower than 95 wt.%; for higher concentrations, they should be made of titanium (with a water content higher than 1.34% to prevent spontaneous combustion), silicon iron or 3003 aluminum alloy [11]
Piping and Fittings	Piping made of 304L stainless steel is frequently used for HNO3 up to 95 wt.%, and of aluminum for higher concentrations. Carbon steel (CS) piping with TFE, FEP or glass linings (up to certain temperatures) can also be used for all grades. [11]
Valves	Butterfly valves: 316 SS, Alloy 20 and Hastelloy C are good stem and disk materials for nitric acid at various concentrations. Seats made of Viton can handle various concentrations up to 70%; for low concentrations at low temperatures, Neoprene, Hypalon and EPT have also been used
Protective Clothing	Neoprene or natural rubber latex gloves are acceptable for handling nitric acid.

Table 12. Specific Equipment, Piping, Valves and Protective Clothing Guidelines
Equipment	HF
Tanks	Anhydrous and 70 wt.% HF up to 66°C, or HF between 60 to 70 wt.% up to 38°C, can be stored in carbon steel (CS) tanks, since the metal is passivated with an iron fluoride film when the fluid is in contact with the metal. Hydrogen corrosion may occur in steel tanks. Other grades of HF can be stored in tanks made of CS with natural rubber lining, polyethylene or unplasticized PVC [11]
Pumps	Diaphragm pumps with TFE or polychlorotrifluoroethylene (CTFE) diaphragms can handle anhydrous, 70 wt.% and electronic-grade HF. Centrifugal pump materials depend on grade: Ni-Cu alloy of Alloy 20 is used for anhydrous HF, Vinylidene chloride (VC)-lined steel for 70 wt.% and electronic-grade HF, and Penton-lined steel or solid Penton for electronic grade HF [11]
Piping and fittings	Anhydrous and 70% wt HF can be transported in seamless CS piping. The rating and schedule should be selected according to the operating pressure and corrosion allowance, with Sch 80 and Sch 160 commonly used for both grades, respectively. CS with VC, TFE and FEP lining is also used, depending on fluid temperature. Electronic-grade HF can be transported in unplasticized PVC pipe
Valves	Butterfly valves: Hastelloy C is the best material for the stem and disk, with Alloy 20 also exhibiting fair results. Common seat materials include: PVF, Hypalon and Viton; for pure (100%) HF, only PVF or Viton should be considered
Protective Clothing	Neoprene and natural rubber gloves are excellent for handling hydrofluoric acid in all concentrations, glove change is necessary before 8 hours

Table 13. Specific Equipment, Piping, Valves and Protective Clothing Guidelines
Equipment	HCl
Tanks	Outdoor tanks are preferred for storing hydrochloric acid; some common measures of protection when tank is placed indoors are coating the floor with asphalt or another corrosion resistant material to prevent several damages in case of leaks or spills. The tank must be provided with a vent so acid fumes do not accumulate in the tank and a drainage system so maintenance can be performed periodically. Vents should be routed to a scrubber
Pumps	Pumps similar to those used for H2SO4 and H3PO4 can be used. Centrifugal pumps lined with, or constructed of TFE, PVDF of Derakane are commonly used. Mechanical seals of carbon and ceramic faces with TFE or fluoroelastomer secondary seals, and Hastelloy C metal parts, are also recommended [11]
Piping and fittings	CS piping with TFE, PVDF, Derakane or polypropylene lining is frequently used for HCl. PVC or FRP piping have also been used, depending on fluid pressure
Valves	Butterfly Valves: common stem and disc materials include: lead or Hastelloy C. Common seat materials include: PVF, Neoprene, Hypalon and Viton
Protective clothing	For concentrations up to 40% neoprene and fluoroelastomer gloves are recommended for handling hydrochloric acid. For concentrated acid, butyl gloves are suitable

Acid handling

Sulfuric acid. Sulfuric acid must be stored separately from combustible and reducing substances in a well-ventilated environment at temperatures below 23°C (73.4°F). Concentrated acid needs to be isolated from water, as it may react violently, releasing heat. If sulfuric acid needs to be diluted or combined with water, then it has to be added to water carefully.
To manipulate sulfuric acid, proper personal protective equipment, such as gloves, a vapor respirator when ventilation is inadequate, face shield and full suit shall be used.
Nitric acid. Nitric acid must be stored separately in a corrosion resistant location, avoiding contact with powders, carbides, hydrogen, sulfide, turpentine and strong bases. Along the same lines it is important to mention that nitric acid’s storage requires special conditions, such as adequate ventilation and especially low temperatures to ensure a cool environment for the solution, because heat may cause containers to burst and result in escape of poisonous gases; so it should not be stored above 23°C (73.4°F), and the container must remain dry and locked up.
Nitric acid and its vapors can cause severe damage during its handling to persons who have contact with it; the severity of the damage is related to the time of contact or exposure and the acid concentration.
Every process that involves nitric acid handling or storage must contemplate an adequate ventilation system that ensures airborne levels below the safety exposure limits allowed, not only this measure needs to be taken into account but also workers should be aware of the risks arising from management of nitric acid.
Phosphoric acid. Phosphoric acid can be described as a stable chemical, because it is not subject to thermal decomposition. However, the design criteria for its handling should be based on the acid concentrations and operating temperatures. The most important issue about this acid is the variation of its freezing point according to its concentration; the freezing point of standard concentrations are –17.5°C (0.5°F) at 75%, 4.6°C (40.2°F) at 80% and 21.1°C (70.01°F) at 85%, therefore it becomes necessary to heat phosphoric acid at high concentrations in order to maintain the acid as a liquid solution.
Unlike other acids, phosphoric acid does not react violently with metals; reaction occurs slowly and progressively with hydrogen as a product, so, caution should be exercised because the vapors formed are flammable.
Hydrofluoric acid. HF acid is a very hazardous material, both in liquid and vapor phase. It can cause severe burns, which may not be immediately painful or visible. HF is a strong irritant to the skin, eyes and respiratory tract. The fluoride ion easily penetrates the skin and generates destruction of tissue and severe bone damage.
Package sizes range from 500–1,000 mL for analytical products, to 10,000-L ISO containers. HF is delivered commercially in concentrations of 98 wt.%, 48–51 wt.% and 40 wt.%.
Due to HFs nature, strict measures shall be taken when handling the acid in industrial facilities. Such measures include administrative controls (for example, work permits); engineering controls (instrumentation: detectors, relief valves, emergency dump systems); and personal protection equipment (appropriate clothing).
When boiling all aqueous solutions, HF forms an azeotropic constant boiling mixture that contains 35.6% (by weight) HF and boils at 111.35°C (231.8 °F).
Hydrochloric acid.HCl must be stored in a corrosion resistant location. Even though the acid is non-flammable, when it is heated hydrochloric acid fumes are released, which can compromise the safety and toxicity levels allowed, therefore storage tanks need proper venting that shall be directed to a safe location and treatment facility.
Operators handling hydrochloric acid must wear protective equipment and it is advisable for them to take a shower and gargle with sodium bicarbonate after manipulating the acid in order to avoid teeth corrosion in other activities performed by the operator.
Undesirable reactions can take place between hydrochloric acid and the following compounds: chromate, permanganate and sulfate. Such reactions generate chlorine gas as a result. A subsequent reaction occurs with metal peroxide forming its corresponding chloride.
When storing hydrochloric acid, proper ventilation has to be ensured in order to maintain the acid concentration in air below the permitted limit of exposure.
Edited by Gerald Ondrey

References

1. Perry, R., Green, D. W., & Maloney, J. O. Perrys Chemical Engineers Handbook, McGraw-Hill, N.Y., 2008.

2. Davenport, W. G., and King, M. J., Sulfuric Acid Properties, In Sulfuric Acid Manufacture: Analysis, Control and Optimization, Elsevier, pp. 287–291, 2006.

3. DKL Engineering, Inc.,. Technical Manual, April 12, 2003. Retrieved July 6, 2012, from Sulfuric Acid Properties: www.sulphuric-acid.com/techmanual/Properties/proper ties_acid_properties.htm

4. Material Safety Data Sheet, Nitric acid, 65% MSDS.

5. Potash Corp., Purified Phosphoric Acid, Technical information bulletin, PCS Sale — Industrial Products, 2005.

6. U.S. Dept. of Labor, Occupational Safety and Health Administration (OSHA). Retrieved May 14, 2012, from Regulations: 29 CFR 1910.1000 (General Industry): www.osha.gov/pls/oshaweb/owadisp.show_document?p_table=Standards&p_id=9991

7. U.S. Dept. of Labor, Occupational Safety and Health Administration (OSHA), Retrieved May 16, 2012, from Regulation: 29 CFR 1926.55 (Construction Industry): www.osha.gov/pls/oshaweb/owadisp.show_document?p_table=Standards&p_id=10628

8. U.S. Dept. of Labor, Occupational Safety and Health Administration (OSHA), Retrieved May 16, 2012, from Regulation: 29 CFR 1915.1000 (Maritime): www.osha.gov/pls/oshaweb/owadisp.show_document

9. National Institute of Occupational Safety and Health, NIOSH Pocket Guide to Chemical Hazards, NIOSH Publications, 2007.

10. U.S. Dept. of Transportation, Emergency Response Guidebook 2008 (ERG2008), 2008.

11. Grossel, Stanley S., Safe, Efficient Handling of Acids, Chem. Eng., July 1998, pp. 88–98.

12. ASM International, (2002). Handbook of Corrosion Data, 2002.13. API Std. 620.

14. API Std. 650.

15. ASME Boiler and Pressure Vessel Code Sec. VIII Div 1.

16. DKL Engineering, Inc., Technical Manual, December 20, 2005, Retrieved July 6, 2012, from Strong Acid System — Piping, www.sulphuric-acid.com/techmanual/strong%20acid/sa_piping.htm

17. International Program on Chemical Safety, Chemical Safety Information from Intergovernmental Organizations, April 2000, Retrieved May 12, 2012, from Hydrogen Chloride: www.inchem.org/documents/icsc/icsc/eics0163.htm

18. Pohanish, R. P., Sittigs Handbook of Toxic and Hazardous Chemicals and Carcinogens”, Elsevier, 2012.

19. Southerm States Chemical A Dulany Industries Co., Chemical Safety Handbook, 2002.

20. The Dow Chemical Company, June 2008, 2008, Retrieved July 9, 2012, from Product Safety Assessment: Nitric Acid: http//msdssearch.dow.com/publishedliteratureDOWCOM/dh_0131/0901b80380131028.pdf?filepath=productsafety/pdfs/noreg/233-00312.pdf&fromPage=GetDoc

21. U.S. Dept. Transportation, Electronic Code of Federal Regulation. Retrieved May 14, 2012, from Chapter I Pipeline and Hazardous Materials Safety Transportation regulation: ecfr.gpoaccess.gov/cgi/t/text/text-idx?c=ecfr&tpl=/ecfrbrowse/Title49/49cfrv2_02.tpl

Authors

Alberto Baumeister is the CEO and co-owner of the Ecotek group of companies, which is located in the City of Knowledge, Panama (Calle 60, PH Obarrio 60, Piso 15, Ofc. 15-A, Obarrio, Panamá, Rep. De. Panamá; Phone: +507-203-8490; Fax: +507-203-8491; Email: abaumeister@ecotekgrp.com). He has experience as coordinator and senior process consultant in engineering projects for the chemical, petrochemical, refining, oil and gas industries. He has a Master’s Diploma in water treatment management from Universidad de León (Spain, 2011), a specialization in management for engineers at Instituto de Estudios Superiores de Administración (Venezuela, 1990), and a degree in chemical engineering from Universidad Metropolitana (1987), graduating first of his class. He has been a professor of the Chemical Engineering School at Universidad Metropolitana between 1995 and 2007 and has written several technical publications for international associations.

Sebastiano Giardinella is the vice president and co-owner of the Ecotek group of companies (same address as above; Email: sgiardeinella@ecotekgrp.com). He has experience as process leader, and in project planning and control, in engineering projects for the chemical, petrochemical, refining, oil and gas industries. He is a certified project management professional (PMP), has Master’s Degree in project management from Universidad Latina de Panamá (Panama, 2009), and a degree in chemical engineering from Universidad Simón Bolívar (Venezuela, 2006), graduating summa cum laude; and is currently a student of the M.Sc. in renewable energy development at Heriot-Watt University (Scotland). He is also professor of project management at Universidad Latina de Panamá, and has written technical publications for Chemical Engineering magazine, international associations and academic institutions.

Mayhell Coronado is a process engineer of the Ecotek group of companies (same address as above; email: mcoronado@ecotekgrp.com). She has experience in the development of conceptual and basic engineering projects for the oil and gas, and chemical industries, as well as in support to company management. She has a degree in chemical engineering from Universidad Metropolitana (Venezuela), where she taught thermodynamics, transport phenomena and general chemistry as professor assistant, and has published a work on the effects of microbial contamination in diesel fuel used for thermal power generation.

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