Did you know that iron is rarely found in its pure form in nature, except in meteorites? As for the iron that humans have worked and forged for millennia, it’s an amalgamation known as iron oxides.
The process of recovering iron from iron ores starts with mining processes, stripping the earth’s outer layers that contain this metal. Iron ore then gets converted into various versions of what we call “iron” today.
Before this happens, however, it must be processed in a blast furnace, producing pig iron. Pig iron itself has few uses because of its brittleness. That said, when alloyed with other metals, it transforms from a useless substance into a sought-after and valuable commodity.
Ready to learn more about steel manufacturing, ductile iron manufacturing, and cast iron manufacturing? Keep reading for our ultimate guide to these top materials’ manufacturing process.
Cast Iron Manufacturing
How does pig iron gets transformed into cast iron? Through a process that involves remelting and combining it with large quantities of scrap iron or steel.
We use “cast iron” to denote gray cast iron. But the term can also be applied to a whole group of alloys that we often identify by their color.
Besides combining pig iron with scrap iron or steel during the remelting process, contaminants get removed. Then, the iron is cast.
What does the casting process involve? At the most basic level, iron gets poured into a mold, giving it a shape. But the process can be divided depending on the pouring methods and molds used.
Molds include non-expendable molds (metal) and expendable molds (sand). Pouring methods range from gravity to vacuum or low-pressure. The more intricate the mold, the more controlled the pouring process must be.
What happens after casting? The iron must solidify correctly, or solidification could result in a ruined effort. When this occurs, the scrap metal gets recycled into pig iron for another attempt at casting.
The demand for steel continues to grow worldwide. As a result, manufacturing remains a non-stop enterprise, relying on a steady supply of raw materials. There are two methods for producing steel:
- Blast furnace
- Electric arc furnace
Let’s take a closer look at the similarities and differences between these two modes of production.
Blast Furnace Steel Manufacturing
Blast furnaces first appeared in the 14th century. Today, blast furnaces produce one ton of steel every day. Over the centuries, the equipment used for this steel production method has greatly evolved, leading to higher production rates.
Nevertheless, the processes that occur within the furnace have remained the same as the ingredients. Iron ore, coke, and limestone are all utilized to produce pig iron. As a result, coal remains a vital part of the coke-making process.
How does the process work? Coal gets crushed, ground into a powder, and then heated in an oven in the absence of oxygen at a temperature of 1800 degrees Fahrenheit. Heated to this extreme, the coal begins to melt, removing the most volatile materials within:
This purification process results in coke. The coke gets removed from the oven between 18 to 24 hours after reaction time. After being cooled and screened into one to four-inch pieces, it’s much stronger than average coal even though it still contains some sulfur and ash.
A porous, hard black rock, coke produces high energy value. It provides heat, gases, and permeability. These characteristics are vital to the reduction and melting of iron ore, sinter, and pellets.
A concentrated energy source, coke contains 90 to 93 percent carbon.
Electric Arc Furnaces
Electric arc furnaces (EAFs) came on the scene much later than their blast furnace counterparts towards the end of the 19th century. Electric arc furnaces quickly expanded to dominate the steel manufacturing industry.
Today, this process accounts for nearly two-thirds of all American steel production. What’s different between electric arc furnace steel production and blast furnace steel production? EAFs rely on an electrical current to direct reduced iron or to melt scrap steel.
The combination of steel and electricity result in molten steel. Now that you understand the basics when it comes to cast iron and steel manufacturing let’s explore stainless steel manufacturing.
Stainless Steel Manufacturing
Stainless steel is manufactured much in the same way as steel. But this iron-containing alloy proves extra resistant to rust and stains because of its chromium content. Usually, chromium comprises 12 to 20 percent of this alloy.
More than 57 stainless steels have been identified as standard alloys. There are also many proprietary alloys produced by various stainless steel producers. They boast countless applications:
- Automobile components (e.g., trim/decorative, exhaust, engine, chassis, tubing for fuel lines, chassis)
- Bulk materials handling equipment
- Building exteriors and roofing
- Chemical processing plants (e.g., heat exchangers, scrubbers)
- Pulp and paper manufacturing
- Petroleum refining
- Consumer products
- Water supply piping
- Marine and shipbuilding
- Sporting goods (e.g., snow skis)
- Transportation (e.g., rail cars)
- Pollution control
- And more
Each year, nearly 200,000 tons of nickel-containing stainless steel gets manufactured for the food processing industry. This metal also gets utilized in food storage, handling, cooking, and serving equipment. But the uses for this metal don’t end with food manufacturing and services.
Stainless Steel Microstructures and Variations
Stainless steels can have different microstructures. These microstructures include:
- Austenitic stainless steels
- Ferritic stainless steels
- Martensitic stainless steels
- Duplex stainless steels
Austenitic stainless steels must contain a minimum of six percent nickel and austenite. Austenite is a carbon-containing iron with a face-centered cubic structure. It boasts good corrosion resistance and high ductility.
As for ferritic stainless steels, they contain ferrite, a body-centered cubic structure. As a result, they have better resistance to stress corrosion when compared to austenitic stainless steel. But they prove difficult to weld.
Martensitic stainless steels are comprised of a needle-like structure of iron. Finally, duplex stainless steels contain both ferrite and austenite in equal parts. Duplex stainless steels are more resistant to cracking from chloride stress corrosion.
What’s more, duplex stainless steels provide better overall resistance to crevice corrosion and pitting in most environments. They’re also twice as strong as common austenitics. No wonder so many industries, from chemical refineries to seawater piping, rely on it.
Find out more about high-performance stainless steels.
What to Know About Ductile Iron
In essence, ductile iron marks an essential step in the evolution of plumbing. This evolution can be traced through the manufacture of iron pipes in the UK. Over time, there have been three significant changes.
The term “ductile” refers to a metal’s ability to be stretched into wires or undergo deformation before failure. Used heavily in the world today, ductile pipes remain vital to water supply infrastructure.
In other words, these are the pipes that transport municipal drinking water. These are also the pipes that facilitate the removal of sewage from residential dwellings along with other household liquid waste.
The Far-Ranging Properties of Ductile Iron
Ductile iron consists of various materials manufactured to have many far-ranging properties. The addition of a small amount of cerium or magnesium to gray iron prior to casting results in a unique microstructure and set of mechanical properties.
Rather than forming flakes, the graphite creates sphere-like nodules or particles. The resulting alloy is known as ductile or nodular iron.
Why do we use ductile iron for these infrastructures? Because it’s more flexible than ordinary gray iron, which means it can withstand the pressure these types of utility pipes must endure. In other words, these pipes will bend before they break or leak.
Besides the need to withstand the pressure associated with water flow, these pipes must also withstand corrosion since most are fitted underground. To ensure longevity, they’re manufactured with an adherence to the highest quality stands.
These pipes must also endure a comprehensive series of product tests before introduction to the market.
Benefits and Uses of Ductile Iron
In the 1920s, the UK relied on pipes made from gray iron vertically cast. Around this time, gray cast iron that was spun also came into use, and the utilization of these pipes would continue through the 1960s. By the 1960s, another transition occurred to ductile cast iron.
Why has ductile cast iron come to dominate the industry? For many different reasons. Ductile iron demonstrates excellent mechanical properties under the influence of forces. It’s also characterized by great resistance to high impacts and tensile stresses.
As a result, ductile cast iron boasts many above and below-ground applications. It’s also associated with energy conservation and low pumping costs.
Ductile iron comes in a variety of sizes with different pressure capabilities. It can also withstand ground movement and is resistant to corrosion. As a result, it comes with assured long-term reliability based on a single-rated system.
Installation proves a cinch, and testing the final system is also intuitive and straightforward. When it comes to hydraulic flow, it offers consistent performance and also proves surge resistant.
Ductile Iron Manufacturing
To manufacture ductile iron requires a variety of materials. You’ll recognize some of these from the manufacture of cast iron. They include:
- Recycles iron
- Cement (mortar)
- Zinc and aluminum alloy and blue epoxy (for coatings)
Various machines are also used during the manufacturing process of ductile iron, which is then utilized to manufacture pipes.
Ductile iron pipes generally come in a length of six meters and range from 60 mm to 2m or 3m in width. That said, these values vary by the factory and the country of origin.
What does the ductile iron manufacturing process look like? Let’s take a closer look.
The Equipment Required to Manufacture Ductile Iron
Which machines are necessary to manufacture ductile iron? They include the:
- Blast furnace
- Centrifugal casting machine
- Annealing furnace
Here’s what you need to know about the role of each of these pieces of machinery in the production of ductile iron.
The Blast Furnace
The first machine we want to highlight in the ductile iron manufacturing process is the blast furnace. When you walk into a ductile iron manufacturing plant, you can recognize the blast furnaces by their tower-like appearance.
Blast furnaces are used in the steel making process, too, because they’re ideal for mixing iron ore and charcoals together. The furnace facilitates extreme heat, making it easy for both of the substances to transform into a melted and integrated liquid metal.
When heat gets generated in the furnace, it creates the ideal environment for iron to produce iron oxide. How does the furnace sustain such soaring temperatures? The blast of air the furnace emits intensifies the heat produced.
At the base of the furnace, you’ll typically find a drawer facilitating the collection of slag. Secure doors are mounted o the front of the furnace, too. These doors make the introduction of raw materials to the furnace by a trough or conveyor belt easier.
The Centrifugal Casting Machine
Of course, the ductile iron manufacturing process’s whole point is the cast metal into usable parts and components. After solid materials get rendered molten in a blast furnace, the molten metal is poured into a mold cavity containing the desired shape.
After cooling down for a period of time, the molten substance cools and solidifies until it can be removed from the casting machine. How does a centrifugal casting machine fit into this mix?
It relies on inertia forces caused by spinning or rotation to distribute the molten metal equally throughout the model cavity. These machines come in three types:
- Centrifugal casting
- Semi-centrifugal casting
- True centrifugal casting
We rely on a horizontal true centrifugal casting machine for the intents and purposes of casting ductile iron.
What are the benefits associated with using this machine in the manufacturing process? The many advantages of this type of casting include:
- Any material may be cast
- Very large parts may be produced
- Complex geometries, both internally and externally, may be manufactured with ease
- Material waste decreases
- Casted parts prove consistent in all directions
The next step in the process is a visit to the annealing furnace.
The Annealing Furnace
Think of the annealing furnace as a heat-treatment process. These furnaces permit the change of internal structures of metals. For example, they remove the grain coarseness of pipes, making them both more flexible and harder at the same time.
The Ductile Iron Designing Process
Iron pipe designs were drawn up by engineers until very recently, and all of the calculations were done manually. As you can imagine, this represented a time-consuming and tedious process.
Fortunately, new industry advances have paved the way for a more efficient process. New technologies and software like AutoCAD have rendered the design process easy for engineers and designers.
Now pipes can be easily designed and given specs, saving plenty of time and money in the pursuit of meeting consumer needs. Because of these impressive and far-reaching technological breakthroughs, custom made fittings and pipes are possible.
These custom pieces can be designed and manufactured rapidly. What do the designing tools used in the manufacture of ductile iron include? Two primary versions predominate, Pipespec software and PAMCAD design software.
Engineers rely on Pipespc software to design and create specifications about various pipeline schemes. Five analytical tools in the software permit engineers to remain grounded in the planning and design of piping through all stages of the project.
These steps include:
- Full pipe hydraulics
- Part-full pipe hydraulics
- Installation cost
Besides the many advantages of using Pipespec software, you also need to understand PAMCAD design software’s benefits.
PAMCAD Design Software
PAMCAD design software facilitates the creation and modification of pipework designs by giving engineers a complete water pipeline product database. The software permits the creation of accurate drawings rapidly and easily by calling up pipeline components.
These components can then be arranged on the screen, allowing engineers to craft new schema without having to “reinvent the wheel.” Compatible with the latest version of AutoCAD, PAMCAD offers engineers the following benefits:
- Facilitates the ease and speed with which pipe runs get drawn up
- Aids the creation of pipe facilities
- Relies on standard products to decreases cost and lead time
- Provides a clear list of products used with its bill of materials function
What’s more, PAMCAD features a floating menu that makes pipework design as streamlined as it gets.
How Is Ductile Iron Manufactured?
We’ve gone over the materials, machines, and software used in the ductile iron manufacturing process. Now, it’s time to go step-by-step through the process.
Ductile iron manufacture begins with the 90 percent of recycled iron found in the backyards of pipe factories. Old cars are also chewed to bits and pieces for utilization in the process.
Next, this “shredded” metal is analyzed by chemical composition and sorted accordingly. Plastics, aluminum, and copper get discarded. But steel and iron are reserved for the manufacturing process.
Other sources of scrap steel include material taken from demolished buildings and other sources. Using an industrial magnet, a crane operator will gather precise amounts of this iron and steel.
From here, the chewed up metal goes into the blast furnace along with coke. As these substances liquefy in the furnace, impurities get burned away. After refining, workers introduce magnesium to the low-sulfur base iron under closely-monitored conditions.
Creating a Stronger, Tougher Substance
What occurs with the introduction of magnesium? As alluded to earlier, the molten iron forms graphite spheres or nodes rather than flakes, as is the case with gray iron.
Once the free graphite has formed in a spheroidal or nodular form, the metal matrix’s continuity is at a maximum. This ductile material exceeds gray iron both in terms of strength and toughness as ductile iron.
At this point, the molten iron is directed into a trough where the spinning or rotating mold of the centrifugal casting machine takes over. Through centripetal force, the iron spreads against the mold walls.
Next, a cooling system kicks in. Within seconds, the iron solidifies, and the extractor pulls out an iron pipe mold to the standard industry length of 6 m.
Casting Ductile Iron
Workers insert a round core form in one end of the pipe mold before each casting. The molten iron fills the void between the core and the mold. In the process, it forms a flared edge called a “bell.”
To prevent molten iron from flying out during casting, the core then seals off that end of the mold.
What happens when it’s time to connect the pipe? Installers fit the bell of one pipe over the other.
From there, a rubber gas seals the links together. In this way, the casting machine manufactures pipes of various diameters by changing the mold inside the centrifugal casting machine.
Once the pipe gets extracted, inspectors weigh it and measure its wall thickness. Once they’ve ensured the pipe meets all specifications, the core is removed from the bell end. The core, comprised of sand and plastic resin, will disintegrate.
No matter the diameter requested for the pipe, the casting process remains the same for all sizes. Bear in mind, however, that smaller types harden more rapidly due to smaller surface area.
Ensuring the Strongest and Least Corrosive Structure Possible
Freshly cast pipes register piping hot temperatures of 850 degrees Fahrenheit, but they cool rapidly after leaving the mold. This rapid cooling renders the iron brittle. For this reason, the pipes next go into a gas-filled annealing furnace.
This furnace reheats the pipes to about 950 degrees Fahrenheit. Reheating the pipes to this temperature alters their internal structure, making them flexible and strong.
After this reheating occurs, the pipe heads into a cooling chamber where it gets showered with cold water.
While ductile iron proves somewhat resistant to corrosion, linings are available to ensure the longevity of these structures. These internal linings include polyurethane (PUR) and cement mortar. Cement mortar remains more common in ductile iron pipe manufacturing.
Cement is sprayed inside the pipe, creating a 1/8 inch thick lining. Then, the pipe gets spun for a few seconds to smooth out the cement and ensure thickness consistency. This process seals the surface. Then, the cement cures for 24 hours.
After the pipe’s internal surfaces have been treated, then the outside of the pipe gets painted with an external coating such as zinc, polyethylene, or a bituminous coating. After this, a robot paints a stripe around the straight end of each pipe.
That way, the installation crew has a depth guide when it t’s time to insert the straight end of one pipe as far as it can go into the bell end of another pipe.
Ductile Iron Quality Control
The quality of the final product is vital to plumbing that stands the test of time. That’s why quality control gets factored into various steps in the manufacturing process. These quality control measures include:
- Validation of suppliers and their materials
- Continuous assessment of quality systems
- Ongoing monitoring of product quality
- Technical support before and after sales
- Punctual delivery of products and supporting information
What processes are in place for ongoing monitoring of product quality? Here’s what you need to know about how quality gets ensured during the manufacturing process.
Ongoing Monitoring of Product Quality
Ongoing monitoring of product quality includes detailed metallurgical analysis of the molten metal. They also involve tight control of coating and lining applications.
During the manufacturing process, workers will also monitor for the following potential defects:
- Impurities left in the molten that proceeds o the centrifugal casting machine when carrying away impurities
- During the mold spinning process, the release of molten iron outside the machine although the sore is attached to the bell end of the pipe due to cracks and holes
- Systematic errors related to measuring the length and diameters of the pipes
- The presence of missed spots or scratches on the surface that can oxidize following the spraying of anti-corrosive fluids
- Defects in blast furnaces and centrifugal cast iron machines (e.g., cracks, holes, etc.)
What happens in the case of systematic errors when measuring the length and diameters of the pipes and when the pipes are detected by inspection? They get sent back for remanufacturing, increasing their costs.
These pipes are also created to meet two new European standards. These standards cover ductile iron pipes, accessories, fittings, and their joints for water pipelines. Sewage pipelines also fall under these standards, both of which superseded the British standard.
Trench Drain Systems
Now that you have a thorough understanding of how cast iron, steel, and ductile iron get manufactured, it’s time to explore some of ductile iron’s many uses. For example, ductile iron is cast to create trench drain systems.
These trench drain systems come in a variety of sizes and materials. How do you know which system is right for you? Let’s take a closer look at some of the important decisions you must make when choosing a trench drain system and the factors you must consider.
These factors include:
- Flow rate
- Load capacity
- Chemical resistance
- Heat resistance
- Ease of maintenance
These factors are all vital to securing the best trench drain system for your needs. Here’s what you need to know about sustainable drainage systems.
The first factor we must consider when choosing a ductile iron trench drain system is the flow rate. After all, a drainage system’s main objective is to remove liquids quickly. So, you’ll need to ask questions like how much a drain can remove and how rapidly.
Depending on the trench drain system you choose, complicated formulas will determine the flow rate. But for the purposes of this article, we’ll focus on the easiest trench drain system to calculate flow rate, slot drains.
To calculate the flow rate for slot drains, it’s as simple as looking at the system’s width. The slot opening determines the trench drain system’s capacity. For example, a 1/2 inch slot opening permits 11 gallons per minute per foot of slot to escape.
A one-inch slot opening permits 18 gallons per minute per foot of slot to flow out, and one and a quarter inch slot opening lets 27 gallons per minute per foot of slot out.
You can also work with a trench drain system company to meet specific flow rate requirements. For example, the depth of the trough can be customized to increase the flow rate.
What does it mean when we refer to load capacity? That’s the weight your drainage system needs to be able to handle. In low-traffic areas, your load capacity requirements could prove low.
If you’ve got a system placed in an area of heavy equipment traffic or high automobile traffic throughout the day, then you’ll need a different load capacity.
Traditional drain systems must be assessed in terms of the grate’s material to ensure your load capacity needs get met. Otherwise, you could find your grate degrading over time under the weight of heavy loads.
The optimal trench drain system should integrate seamlessly into the floor. It should also stand up to heavy loads without breaking or wearing down. Make sure high-traffic environments are heavy load classes to ensure your system can stand daily pressures.
Learn more about load ratings for your facility.
When you see the term “chemical resistance,” you might immediately assume it doesn’t apply to your facility. Especially if your trench drain system will be primarily handling water. But this is a huge misnomer that could lead to short longevity for your trenches.
No matter the situation, you need a trench drain system that’s chemical resistant. Why? Because you want to be able to clean the drains thoroughly and repeatedly.
Don’t get stuck with a system that corrodes due to the introduction of cleaning chemicals. For example, consider stainless steel to handle chemicals without corroding.
You must also take into account the temperature of the liquids that will be passing through your system. For example, if you own a food processing plant, brewery, or industrial plant, you may need to facilitate the removal of liquids at elevated temperatures.
If you don’t consider this when installing your trench drain system, it could lead to premature damage. For traditional drains, bear in mind the heat resistance of both the grate and trench materials.
For systems without grates, it’s easier to choose the right material. Again, stainless steel systems do well when it comes to extreme temperatures. They provide the flexibility you desire from a trench system.
Ease of Maintenance
Another vital consideration when choosing a trench drain system remains how easy it is to maintain. Maintenance refers to everything from how you’ll clean it to which parts will require replacement over time.
As you’re considering various systems, inquire about special tools to make cleaning easier. For example, if you need to flush your drains regularly, there are tools to facilitate this. Some even allow you to choose between cleaning drains manually and setting a flushing timer.
You might also wish to consider designs such as slot drains, which eliminate the need for grates. Without grates, you have fewer replacement costs over the life of your system. What’s more, slot drains are built for durability and little ongoing maintenance.
Remember that installing a trench drain system represents a major construction project. It’s not something that you want to turn and have to repeat prematurely due to a system’s poor choice.
Over time, drain systems can degrade. They can develop leaks and gaps. You don’t want this to happen prematurely to your system. To avoid these issues, know up front that you’ll need to make a more substantial investment.
By refusing to go the cheapest route or cut corners, you’ll guarantee the installation of a system that stands the test of time. That means more money in your pocket over the long-term. Check out these FAQs about drainage systems.
Last but not least, you must ensure that your trench drain system is safe. For example, if you have hazards such as standing water or lose or broken grates, you are liable for them.
In other words, you need to select a system that adequately drains the area and can stand up to the rigors of traffic, chemicals, and other potentially damaging elements.
What’s the takeaway? Make an investment in safety from the get-go.
That way, you’ll avoid the chance of liquids pooling on your property. You’ll also prevent injuries associated with damage to drain systems such as gaps, leaks, damaged or broken grates, and open trenches.
Learn more about the best trench drain systems on the market and discover which one’s right for your facility.
Manhole Frame and Cover
Like trench drain systems, you’ll also want to consider a variety of factors before selecting a manhole frame and cover. Manufactured from cast iron, manhole covers come in different strengths and decorative options.
For example, in a residential area, you might be able to get away with a medium-duty strength manhole cover. That’s because heavy vehicles don’t generally pass over it.
Of course, you’ll want to go the heavy-duty route when it comes to areas of increased traffic.
You’ll also want to choose a manhole that’s airtight. That way, you can mitigate the smell from sewers or septic tanks (in the case of residential manhole covers).
An airtight seal gets attached to the manhole frame hole and the cover to facilitate an airtight design. This also makes the manhole watertight, which is vital for septic systems.
When it comes to shopping for manhole frames and covers, other considerations include anti-slip motifs. Anti-slip motifs come in square and diamond motifs, and they ensure that customers and employees don’t slip on wet covers.
You’ll also want to decide on whether you want a manhole cover with or without a hinge. If you’re concerned about manhole covers getting stolen in your area, then opt for the hinge. However, if your facility is secure, there’s no need for this additional feature.
From Trench Drain Systems to Manhole Covers
As you can see, the process of creating trench drain systems and manhole frames and covers begins with cast iron manufacturing and ductile iron manufacturing. Over the decades, ductile iron manufacturing has revolutionized plumbing.
Its unique mixture of durability, flexibility, and longevity is an obvious choice for trench drain systems. On the other hand, cast iron manhole frames and covers can often handle the situation in other areas of your property.
That said, there are also situations where steel or stainless steel comes with added benefits. For example, stainless steel proves highly non-corrosive in situations where elevated fluid temperatures or the presence of chemicals exist.
Besides the materials from which your trench drain system is manufactured, you’ll want to bear in mind other vital features such as water flow, durability, general corrosion resistance, safety, load capacity, and ease of maintenance.
In areas that see a high traffic volume, you must choose a trench system manufactured from materials that can stand large load capacities on a daily basis. The same holds true for manhole frames and covers.
We Sell Manufacturing of Drainage Products
Now, you’ve got a more thorough understanding of what goes into the manufacture of cast iron, steel, stainless steel, and ductile iron. You also understand why ductile iron remains the optimal choice for plumbing and draining systems.
Nevertheless, applying this information to the construction and installation of the best drainage and plumbing systems for your facility is another thing. You need to rely on experts to help you with these complex systems.
If you’re feeling overwhelmed by all of the factors that go into selecting the best trench drain system and manhole covers for your facility, it’s time to speak to the experts. Contact us for all of your drainage needs. We carry a variety of trench drain systems, grates, and more.