Tag Archives: Steel

Manufacturing, Steel

Steelmaking In The 21st Century: An Ancient Art, A Complex Modern Science, A Danger At Every Stage

Metal briefcase

Product liability lawyers should be familiar with both the dangers and the science of steel manufacturing.  Steel is one of the most indispensable products in the modern world.  Its uses, forms, and composition are limitless.  Like any other product, steel in its final form and use is a “product” subject to the same consumer expectation test in Oregon that applies to household appliances.  However, unlike most other product manufacturing, steel production, which creates the base material for pipe, rails, aviation, and innumerable transportation, mining, oil and gas, and other products, is incredibly dangerous.  Although serious burns might be the most obvious risk, there are also crush, amputation, and a host of other potential injuries which justify the most careful training, exacting safety processes, and best PPE.  This is especially true given the danger posed by the typical 24-hour-a-day production schedules and the undisputed fact that nighttime workers are in more danger than day workers.

Steelmaking Is An Ancient Art

In the ancient world, steelmaking was considered an art, and as the centuries passed, the process became more and more complex.  Steel was known in antiquity and may have been produced by managing bloomeries, or iron-smelting facilities, in which the bloom contained carbon.  Blooms are steel formed into large blocks to which further tempering or chemical procedures can be applied.  The use of blooms persists into the steelmaking of today.

The earliest known example of steel production, thought to be about 4000 years old, is a piece of ironware excavated from an archaeological site in Anatolia (the Asian part of Turkey).  “Ironware piece unearthed from Turkey found to be oldest steel.”  The Hindu (Chennai, India).  The Haya people of East Africa invented a type of furnace that they used to make carbon steel at 3,276 degrees Fahrenheit nearly 2000 years ago.  Africa’s Ancient Steelmakers (http://www.time.com/time/magazine/article/0,9171,912179,00.html?promoid=googlep).  Time Magazine September 25, 1978.

What Is Steel?

Steel is an alloy of iron and carbon.  Steelmaking is the process of producing steel from iron and ferrous scrap.  In steelmaking today, impurities such as silicon, phosphorus, and excess carbon are removed from the raw iron, and alloying elements such as manganese, nickel, chromium, and vanadium are added to produce different grades of steel.  Limiting dissolved gasses such as nitrogen and oxygen, and entrained impurities or “inclusions,” in the steel is also important to ensure the quality of the products cast from the liquid steel.  B. Deo and R. Boom, Fundamentals of Steelmaking Metallurgy, Prentice and Hall (1993).

Carbon is the primary alloying element, and its content in steel is between 0.002% and 2.1% by weight.  Additional elements are also present in steel, including manganese, phosphorous, sulfur, silicon, and traces of oxygen, nitrogen, and aluminum.  Carbon and other elements act as hardening agents, preventing dislocations in the iron atom crystal lattice from sliding past one another.

Varying the amount of alloying elements and the form of their presence in the steel (solute elements precipitated phase) controls qualities such as the hardness, ductility, and tensile strength of the resulting steel.  Steel with increased carbon content can be made harder and stronger than iron, but such steel is also less ductile than iron.  Ashby, Michael F. and Jones, David R.H.  Engineering Materials 2 (with corrections ed.) Oxford:  Pergamom Press.  ISBN 0-08-032532-7 (1992 [1986]).

Alloys with a higher than 2.1% carbon content are categorized as cast iron.  Because cast iron is not malleable even when hot, it can be worked only by casting, where it has a lower melting point.  Steel is also distinguishable from wrought iron, which may contain a small amount of carbon.

Even in the narrow range of concentrations that make up steel, mixtures of carbon and iron can form a number of different structures with very different properties.  One of the most important polymorphic forms of steel is martensite, a metastable phase that is significantly stronger than other steel phases.  When the steel is in an austenitic phase and then quenched rapidly, it forms into martensite, as the atoms “freeze” in place when the cell structure changes from FCC to BCC.  Depending on the carbon content, the martensitic phase takes different forms.  Below approximately 2% carbon, it takes a ferrite BCC crystal form, but at a higher carbon content, it takes a body-centered tetragonal (BCT) structure.  There is no thermal activation energy for the transformation from austenite to martensite.  Moreover, there is no compositional change to the atoms, which generally retain their same neighbors.  Smith, William F., Hashemi, Jared, Foundations of Materials Science and Engineering (4th ed 2006) McGraw Hill ISBN 0-07-295358-6.

Special Modern High Performance Alloys

There are a number of extremely complex super-alloys and other metals available today for high performance aviation and other uses, including Transformation Induced Plasticity (TRIP) steel and Twinning Induced Plasticity (TWIP) steel.  A complete discussion of these super-alloys merits a separate article, and one will be forthcoming shortly.

Introduction To The Modern Process

In the modern era, there are two major processes for making steel.  The first is basic oxygen steelmaking, which uses liquid pig iron from the blast furnace and scrap steel for the main feed materials.  Alternatively, iron ore is reduced or smelted with coke and limestone in the blast furnace, producing molten iron that is either cast into pic iron or carried to the next stage as molten iron.  In the second stage, impurities such as sulfur, phosphorus, and excess carbon are removed, and the alloying elements such as manganese, nickel, chromium, and vanadium are added to produce the steel required.  The vast majority of steel in the world is produced using the basic oxygen furnace.  In 2011, approximately 70% of the world’s steel was produced in this way.  R. Fruehan, The Making, Shaping and Treating of Steel (11th ed. AIST 1999).

The second major modern process is electric arc furnace (EAF) steelmaking, which either uses scrap steel or direct reduced iron (DRI) as the main feed material.  Oxygen steelmaking is fuelled predominantly by the exothermic nature of the reactions inside the vessel, whereas in EAF steelmaking, electrical energy is used to melt the solid scrap and/or DRI materials.

In recent times, EAF steelmaking technology has moved closer to Oxygen steelmaking as more chemical energy is introduced into the process.  E.T. Turkdogan, Fundamentals of Steelmaking, IOM (1996).  EAF steelmaking is predominantly used for producing steel from scrap and involves melting scrap, and combining it with iron ore.

Alternatively, the oxygen method can involve melting DRI using electric arcs (either AC or DC).  It is common to start the melt with a “hot heel” (molten steel from a previous heat) and use gas burners to assist with the meltdown of the pile of scrap.  EAF furnaces typically have capacities of around 100 tons every 40 to 50 minutes.

Regardless of the process used, through casting, hot rolling and cold rolling, the steel mill then turns the molten steel into blooms, ingots, slabs, and sheet.

At the typical steel mill, the raw materials are batched into a blast furnace where the iron compounds in the ore give up excess oxygen and become liquid iron.  At intervals of a few hours, the accumulated liquid iron is tapped from the blast furnace and either cast into pig iron or directed to other vessels for further steelmaking operations.  During the casting process, various methods are used, such as the addition of aluminum so that impurities in the steel float to the surface where they can be cut off the finished bloom.

Conclusion

The steelmaking process involves exposure to hundreds of tons of molten metals, often poured manually into ceramic, wax, or other casting forms or hot rolled into shapes.  The potential for catastrophic injury or death is everywhere in the steelmaking process, and it is essential that workers be trained and supervised to avoid lapses in safety that could result in such unfortunate occurrences.  Although automation continuously decreases the exposure of workers to significant injury or death as a result of virtually every phase of the process, the utmost care should still be exercised by all who enter a steel mill.

Manufacturing, Negligence, Steel, Uncategorized

“Secondary Processes” Don’t Translate to Secondary Risks

Steel manufacturers know that the global demand for steel is almost always increasing, and customers require greater engineering performance.  Customers also require variations in the performance characteristics of specialized, costly alloys, which warrant investment in safe, efficient QC testing equipment.  Specialized components, such as those used in aviation, require precision machining.  Aircraft turbine engine compressor blades, for example, may require precision casting to tolerances of seven microns or less.

The urgency to increase production and focus on key production values can sometimes lead to risk of serious workplace injury, often due to under-recognized dangers in secondary processes.  QC testing operations – where injuries often involve equipment that lacks necessary retrofitting with safety devices, or compliance with published ANSI, ASTM, ISO, or other industry standards – is a case in point.

Additionally, secondary processes like QC testing are what might be called “first assignment” areas for new, contract, or temporary workers who all too often are under-trained and unaware of the potential dangers of metal production.

The “class” of worker is noteworthy because the differing ways in which injury compensation is handled have financial implications for the employer.  Basically, employees are limited to the exclusive remedy provision of worker’s compensation law, which does not provide for non-economic damages.  Other classes of workers may be able to sue for non-economic damages, resulting in verdicts or settlements that can cripple a company.

Our firm was involved in a real-world example as counsel for a large steel mill that burns roughly 30,000 quality-control test samples a year.  In that case, eight-foot-long, 500-pound tail samples were cut from sheet steel in the main roller room and were channeled onto a customized metal roller conveyor system that diverted samples to the sample burning room.  A series of gates restrained and managed each sample’s movement along the conveyor until a final gate clamped down on the tail sample so a laser could cut the sample into smaller segments for QC testing.

In this case, however, with the final gate on the conveyor shut, the penultimate gate opened, freeing an uncut tail sample to continue down the conveyor and collide with the slab in the clutch of the final gate.  The uncut slab careened into the air, striking an employee in the head.  The injured employee was hired through a service, and it was his first day on the job.

It was a tragedy in personal terms, and the steel company lived up to its responsibilities to the injured worker.  Additionally, by following a number of prudent practices, both before and after the accident, the company was protected from legal action that might have created a serious financial threat to the business.  Here are some operations and legal steps every metal manufacturer should consider to reduce personal injury on the job and damaging financial liability in secondary process areas:

  • Immediately examine older equipment and put requisite safeguards into place.  It is natural to be focused on mainline production safety and operations.  However, a safety audit may reveal necessary retrofitting in areas such as QC sampling.  In this case, a post-accident engineering study resulted in the installation of horizontal spacers spanning the conveyor track to prevent tail samples from jumping the conveyor.  The spacers were not required by written standard, but they provided extra safety.
  • Ensure compliance with published industry standards.  The litany of ASTM, ANSI, OSHA, ISO, and other standards for production of metal and component parts and machine safety is beyond the scope of this article.  Consider retaining an occupational safety engineer to conduct an audit that closely assesses older QC test equipment.
  • Ensure that contracts with any temporary worker service providers expressly state that the provider will provide worker’s compensation coverage.  For your employees, worker’s compensation is the “sole remedy” for claims in the event of workplace injury.   However, temporary, contract and other classes of workers – again, often placed in secondary process positions – may be able to sue under Employer Liability Law (“ELL”) that can include non-economic damages such as pain and suffering.

To maintain consistent standards of coverage and liability across a mixed workforce, your worker-service contracts need to delineate that your contractor’s worker’s compensation coverage is the sole remedy for temporary workers.  Although plaintiffs may challenge contractual provisions in court, manufacturers should put in place contractual indemnity provisions that result in consistent protection across all worker classes and forms of claims.

  • Ensure that contracts contain an indemnity provision providing that the service provider will fully indemnify the metal manufacturer for injuries of any kind to the temporary worker.  Clauses that provide an exception for the “sole negligence of the manufacturer” can often lead to expensive litigation and leave the door open for exposure.  Protect your company by resisting the inclusion of such language in your service contracts.

To close, as important as it is for metal manufacturers to meet growing demand and concentrate on the principal staffing, processes, and equipment of main-line production, experience indicates that the dynamics and risks associated with secondary production processes also deserve increased attention.

Catastrophic Injury, Head Injuries, Heavy Equipment Manufacturing, Heavy Machinery, OSHA, Personal Injury, Quality control testing, Steel, Temporary Workers, Workplace Injuries

Assess Steel Quality Control Testing For Potential of Personal Injury

Despite the recent domestic economic downturn, global demand for steel, other metals and heavy equipment continues to increase in emerging markets and elsewhere.  With the increasing demand for production, a potential source of personal injury that is often overlooked is quality control testing.  Manufacturers face pressures to produce, poor communication with and between workers, and what can sometimes be decades-old equipment.  This equipment has usually been continuously retrofitted and appears to function perfectly well, but that is not always the case and serious injury can occur during secondary procedures.

For example, Scott Brooksby defended a steel mill against the claim of a temporary worker who was subject to injury when he was struck in the head by a tail sample cut during sample burning operations.  During steel production, tail samples are typically cut from sheet steel.  At temperatures approaching 1300 degrees, the tails, which vary in size, are routed on a conveyor system into a sample burning room so that samples can be taken for routing to the laboratory to conduct tensile, radiographic and other quality control tests.  The conveyor system is a series of metal rollers controlled by a series of steel gates that regulate the tail samples so that they do not collide and cartwheel into the air or fall from the conveyor, posing a danger to workers.

In Scott Brooksby’s case, a steel tail approximately 8 feet long and 1.5 inches thick was cut from a sheet in the main production roller room.  At approximately 1350 degrees Fahrenheit, the sample, which approached 500 pounds, was routed into the sample burner room.  Sample burning and many other quality control processes may take place in smaller rooms adjacent to the main production halls.  The sample tail is diverted from the main hall after being cut from sheet steel via a steel roller conveyor system where it would pass through a series of gates controlled either electronically or by a set of foot or hand pedals.  By the time the eight foot sample reaches the penultimate steel gate it has cooled to approximately 1,000 degrees.  Theoretically, after passage through the final gate, the section is cut into smaller lengths, approximately 18-21 inches long, which can be used to stretch and test tensile strength or other quality control issues.

On this particular day, the final gate, at the sample burner itself (which is a laser torch used to cut the 18-21 inch tails), jammed shut just as the penultimate gate opened, allowing the eight-foot section to roll down the conveyor.  The section collided with the sample still clutched by the final sample burner gate and cartwheeled into the air, striking one of the two operators in the head and causing injury before falling and smashing the electronic control system.  The injured worker’s co-worker was able to deactivate further sample conveyance through use of a retrofitted electronic emergency estop.  The steel mill processed approximately 30,000 samples per year and the age of the conveyor system was unknown, but believed to be in excess of 40 years old.

Such cases can be important reminders that the original testing equipment may function perfectly well, but may be retrofitted with any number of safety devices.  It is critical that the documentation, if available on older machinery, be preserved and that any maintenance records, including the addition of such safety features as light curtains (which did not exist at the time older, but still functional equipment was manufactured).  If a steel or metal mill, foundry, or component manufacturer is operating older equipment, it may be prudent to do a safety engineering study on machinery such as sample burners that exist in virtually every steel mill to determine whether retrofitting available safety devices is an option.  For example, with the conventional sample burning conveyor system, it may be that the equipment is custom designed and custom safety add-ons such as horizontal spacers can be welded or bolted across the top of the conveyor at sufficient intervals so that the potential for a sample tail to cart wheel off the conveyor becomes impossible because any vertical force is arrested inches above the conveyor rollers.

If manufacturers have questions about the adequacy of the retrofitting of safety devices on older equipment, they should consider contacting the workplace safety regulatory agency in their state.  In some states, OSHA will work with companies and may even provide free safety audits during which the party requesting the audit is granted a period of immunity to correct safety violations that are discovered.  Manufacturers should check with their state safety agencies to determine whether such programs are available and should be sure to determine whether immunity from citation is provided in exchange for the voluntary request for inspection.

The additional safety precautions are particularly important in quality control test facilities such as the sample burning room where often less-experienced workers, or temporary workers who may not be sufficiently trained or conscious of the dangers, begin work.

Recall also that any such serious injury must generally be reported to OSHA immediately and certainly within 24 hours.  In such cases OSHA investigators may also appear at the premises unannounced and, in most states, there is no right to have counsel present when OSHA is conducting its initial interviews with employees, so management should consider a plan for unplanned requests for interviews from safety investigators and ensure that employees are instructed in advance to focus on only what they actually saw, heard, or said during such interviews.