Stainless Steel 316
Stainless steel is a type of steel alloy containing a minimum of 10.5% chromium. Chromium imparts corrosion resistance to the metal. Corrosion resistance is achieved by creating a thin film of metal...
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This article will take an in-depth look at stainless steel tubing.
The article will bring more detail on topics such as:
This chapter will discuss what stainless steel tubing is, their manufacturing and how they function.
Stainless steel tubing is a strong and durable material that is used for structural purposes and is corrosion resistant with little need for maintenance. The diameters and variations of stainless tubing differ based on the requirements of an application and how it is to be used.
For most people, piping and tubing are the same, which has led to a certain amount of confusion regarding the use of the two products. Since both products have a circular or round cross section, it is assumed that they perform the same functions. Unlike pipes, tubes come in multiple shapes such as square and rectangular as well as the round shape.
One of the main differences between pipes and tubes is how they are used. Piping is a transport mechanism used for moving gases and liquids and not for structural purposes. It is measured by its inside diameter (ID). Tubing is used for structural purposes and is measured by its outside diameter and its wall thickness.
Stainless steel is a wonderful material for both builders and manufacturers, with properties such as strength, corrosion resistance, and low maintenance. The structural applications of stainless steel tubing necessitate precise sizing based on the outside diameter and wall thickness. The type of tubing is determined based on application. Types of tubing include fractional, hypodermic, square tubing, or metric.
The different techniques of stainless steel tubing include:
This process has operations such as:
With rolling and welding, stainless steel coils are continuously roll formed on a tube mill. The strip edges are welded together using welding techniques such as TIG, high frequency, and laser. Depending on the welding method, the strip edges may have to be prepared to yield a high quality weld. As part of the finishing process, weld beads on the ID and OD of the tube are removed with scarfing, sanding, bead rolling or other means depending on the final application and specification of how the tube is to be made.
The rolled stainless steel tubes produced in this manner are trimmed to the desired lengths based on industry demand. The stainless pipes and tubes are then cleaned to remove the dirt. These rolled tubes are then heat treated to reduce any stress that may have occurred during the welding and forming procedures. The continuously rolling hearth furnace is used for heat treatment. Temperature controllers and recorders are installed in the furnace. Following the heat treatment procedure, the stainless steel tubing and pipes are straightened and pickled to remove surface scales.
In some circumstances, the appropriate size may not be available directly from the mill. The cold operation procedure can then be employed to get the appropriate size. The tubes or pipes are covered with soap and oxalic solution during the cold drawing process. This solution provides lubrication, reducing friction during the cold drawing process. The tube or pipe is dragged over the bench utilizing Die plugs during the cold drawing operation.
Next, the drawn-out tube or stainless steel pipe is cleaned, heat treated, pickled, and straightened. The final pipes or tubes are marked using computerized ink jet marking equipment. Before being sent on to stainless steel pipe exporters, the pipe or tube is labeled with the grade of material, heat number, size, and the stamp of a third party inspection. The resulting stainless tubes or pipes will be subjected to rigorous testing and quality control. This is followed by appropriate packing and shipping. There are several stainless steel pipe applications for which these pipes and tubes are employed.
Extrusion, gun drilling, and piercing are common ways of producing seamless stainless steel tubing. The extrusion method, on the other hand, produces the most consistent exterior diameter and, as a result, the most concentric internal diameter. Furthermore, extrusion is the only procedure that is best suited for long length seamless SS coil tubing. The basic material starts as a hot extruded seamless pipe.
After that, the material is cold. At this point, the raw material is processed in a long straight form by tube reducers known as pilger mills. Because cold pilgering is a longitudinal cold-rolling process that reduces the wall thickness and diameter of steel tubes in one operation. It may retain consistent outside diameters and concentric inside diameters. This method yields cross-section reductions of more than 90% in a single working cycle for selected material types.
When decreasing the tube, lubricants are applied on the outside diameter and inside diameter, which are subsequently degreased in annealing preparations. After reduction, this method typically yields lengths ranging from 40 to 160 feet. When producing long lengths of seamless tubing to be processed in coil form, cold reduction is the most efficient approach.
On specially developed machinery, a straight length of tube is cold drawn in coil shape. Because cold drawing reduces the outside diameter, inside diameter, and wall thickness, the tube lengthens as the product is drawn.
Floating plug drawing is pulling tubing through a conical die and inserting a floating plug into the inside diameter. The final inside diameter and wall thickness are determined by the size of the die and plug. Floating plug drawing produces a more uniform, smoother finish, although it is only suitable for light wall items.
Sink drawing is the process of pulling tubing through a conical die and determining the resulting inside diameter and wall thickness based on the drawing and tubing specifications. Sink drawing is used for high-pressure applications that demand a large relative wall thickness. Compared to floating plug drawing, the inside diameter is often a little rougher.
Lubricants are applied to the outside diameter and inside diameter of tube coils to aid in the drawing process. The lubricant is degreased from the tube for most end-use applications (medicinal, liquid transfer, etc.). In a large solvent degreasing tank, this is achieved in a single process.
After cold reduction, long straight lengths of stainless steel tubing and coils are annealed to reduce internal tensions and restore the material’s crystalline structure, allowing for further cold working. The annealing process's fast cooling turns cold-worked, hard, and brittle material back into soft and ductile material.
This process is repeated until the necessary dimensions (outside diameter, inside diameter, and wall thickness) are obtained.
This sort of tubing should be made in accordance with appropriate ASTM standards and thoroughly checked for potential flaws before being shipped to the client.
The tube is hydrostatically tested to guarantee integrity after it has been entirely formed to the desired specification. Hydrostatic testing is used to assess and confirm that the tubing satisfies the specifications. This verification method might yield a variety of facts. The hydrotest procedure can identify critical inspection data, such as:
Stainless steel coil tubing can be evenly wound on spools for shipping or straightened and cut to customer-specified lengths. For traceability and manufacturer identification, products might be polished and stenciled with relevant information.
A mandrel is a small metal object that is put into a tube to establish a form. It provides additional support to the tube, preventing undesirable wrinkling during drawing. The tube is run through a die with a smaller diameter than the existing tube size. As the tube is drawn, it contracts to meet the diameter of the die. Tight tolerances and requirements are possible using this method.
DOM Tubing begins as CREW (Cold-Rolled ERW tube) or a Hollow. To begin, the bigger ERW tube is "tipped" so that a trolley jaw can grip it. The trolley is a platform that pulls the tube through the die like a conveyor belt. A carbide mandrel is put within the bore of the raw tube after it has been "tipped." The tube is then placed within a carbide die. The surface of the tube is then lubricated with a solvent. The trolley jaws then hold the tube at the pointed end, drawing the pipe through the die through the trolley hook.
The die and mandrel finally decide the outside diameter and inside diameter of the final tube as a newly resized DOM tube. In other words, a high-angle die thins a thick-walled tube, whereas a low-angle die thickens a thin-walled tube. The right diameter-to-thickness (D/t) ratio is determined by optimal die location and angle.
Depending on the DOM process, polish, tube size, and mechanical and metallurgical requirements, multiple passes (iterations) may be required. For example, if the amount of reduction required for the completed tube necessitates multiple incremental reductions. Following that, further surface treatments may be considered necessary.
Now that the tube has finished its initial drawing, the mandrel has to be removed. One approach is to impart pressure to the rotating tube as it passes over a succession of rollers. This movement compresses the tube and causes it to expand enough to allow the mandrel to be extracted. Additional drawing processes may be required until the desired finish is achieved.
Unlike in the past, Computer Aided Design has taken the place of trial and error (CAD). Die design has considerably improved thanks to the use of CAD. As a result, drawing procedures have seen significant advancements. As a result, production has increased, lead times have been lowered, and prices have decreased. For example, calculating the precise die angle for both thick-wall and thin-wall tubes is possible without wasting time or money.
The resulting product is computed using FEM depending on pressure, temperature, material, and other production parameters. Technology such as modeling and simulation has largely replaced trial and error.
MSC SuperForm is one such software that employs FEM. This software, which both designers and engineers use, can model material flow, forming pressures, stresses, and trimming. Engineers and tool designers can use this data to establish accurate die and mandrel shape and angle, lubrication, and other cost-cutting considerations.
The ASTM International standards group has established various standards in the stainless steel tube business. ASTM ensures that appropriate standards are known throughout the world. Stainless steel tubing industry standards include chemical composition (grades), tube wall (in), fractional radii and wall thickness (mm), working pressure (generally in psig), and weight (usually in lbs per ft).
There are numerous varieties of stainless steel tubing and numerous ways in which one stainless steel tube differs from another stainless steel tube. One stainless steel tube, for example, could be of a different quality, be seamless or have seamless, be of a different radius, length, or wall thickness, and be unpolished or polished.
Although the names are sometimes used interchangeably, there is one significant distinction between tube and pipe, notably in how the material is arranged and toleranced. Because tubing is utilized in structural applications, the outer diameter is the most essential dimension. Tubes are frequently used in applications requiring exact outer diameters, such as medical devices. The outside diameter is significant because it indicates how much weight it can hold as a stability element. Pipes, on the other hand, are typically used to carry gasses or liquids, therefore knowing the capacity is critical. Knowing how much water can flow through the pipe is critical. The pipe's round form makes it efficient at bearing pressure from the liquid running through it.
Pipes are classified according to their nominal and schedule diameter. Pipe is normally ordered in accordance with the Nominal Pipe Size (NPS) standard, with a schedule number specified (wall thickness) and nominal diameter (pipe size). The schedule number on different sizes of pipe may be the same, but the true wall thickness will differ.
Tubes are usually ordered by wall thickness and outside diameter, but they can also be ordered by outside diameter & inside diameter or inside diameter and wall thickness. A gauge number specifies the thickness of a tube. The interior diameter (ID) is a theoretical measurement.
Tubes can be square, rectangular, or cylindrical in shape, whereas pipe is always round. The circular form of the pipe distributes the pressure load evenly. Pipes are used for larger purposes and come in sizes ranging from 12 inches to several feet. Tubing is typically utilized in applications that demand smaller sizes.
Although tubing contains three dimensions (outside diameter and inside diameter, and wall thickness), only two of them may be defined with tolerances, while the third is purely theoretical. Tubing is typically ordered and kept to tighter tolerances and requirements than pipe. Pipe is normally ordered in accordance with the Nominal Pipe Size (NPS) standard, with a nominal diameter and schedule number specified. Tubes and pipes can both be cut, bent, flared, and constructed.
A few main characteristics separate tube from pipe:
304 stainless steel tube is a cylindrical, hollow machine and piping component manufactured of a specific steel alloy and commonly used to transfer fluids and gasses. 304 stainless steel is commonly used in industrial, commercial, and even domestic contexts since it has the great tensile durability and strength that almost all steels are recognized for, and good forming and welding qualities.
Originally known as 18/8 stainless steel due to its nominal composition of 18% chromium and 8% nickel, the elemental content of 304 stainless steel is changeable. While carbon and iron are normally found, chromium concentration ranges from 18 to 20% and nickel content ranges from 8 to 18%. Low carbon variations, known as 304L, offer greater weldability, but high 304H, carbon variants, perform better at high temperatures. The desired purpose determines the precise alloy chosen for a certain tube application.
Although the initial cost of this alloyed tubing is more than that of many other choices, the elemental structure considerably boosts tube longevity, lowering long-term expenses such as replacements and maintenance. While 304 stainless steel will inevitably require repair or replacement, it is readily melted down and recycled, cutting costs and waste even more.
316 stainless steel tubes are cylindrical, hollow machine and piping parts constructed of a specific grade of steel alloy and used to transfer fluids and gasses most regularly. 316 stainless steel is commonly used in industrial, commercial, and even domestic contexts since it has a high tensile durability strength and that almost all steels are recognized for, as well as good forming and welding qualities. Because its melting point is between 1,350 and 1,400 degrees Celsius, tubes constructed of this material can be employed in high heat applications.
Grade 316, like all steel alloys, is mostly made of iron. Carbon is a significant metallic addition in steel manufacture, while chromium is required in levels of 10% or more to create steel stainless. However, the molybdenum content in grade 316 permits it to outperform several other alloys in terms of corrosion resistance. 316H, 316L, and 316Ti are popular 316H, 316L, and 316Ti varieties, all of which are available in completed products and tube stock shapes.
Although low carbon versions, grade 316L, have greater weldability, high carbon variants, grade 316H, perform better at high temperatures, as does 316Ti, which contains up to 0.5 percent Titanium.
A corrugated stainless steel tube is a multi-layered hollow cylindrical object that is utilized as an alternative to typical steel piping as a medium for transporting gasses. This type of tubing, frequently abbreviated CSST, is primarily used in gas distribution businesses as well as residential and industrial commercial applications where gas heating, gas transport, and appliances are commonly used.
Corrugated stainless steel tubes are becoming increasingly popular due to the numerous advantages it provides over other gas flow systems. Because stainless steel tubing is very corrosion resistant, it can be utilized for both volatile gasses and under pressure.
The dual-layered tubing enables easy shaping and bending, reducing the requirement for stainless steel pipe fittings and other costly connectors while also lowering the risk of costly and potentially catastrophic gas leaks. CSST's flexibility, lightweight, and smaller size also enable for easier installation, lowering labor expenses in addition to savings from reduced material utilization. The plastic outside coating is available in black or yellow to meet aesthetic requirements, albeit the rest of the tubing is located inside walls and thus is not visible.
There are two layers to this thin-walled metallic tubing. The interior layer is a seamless stainless steel coil made from cold or hot rolling of alloyed steel strips. The element chromium is responsible for the exceptional corrosion resistance of these coils, which are required in many gas supply applications. The corrugated stainless steel tubing's outside layer is made of plastic.
This PVC coating not only adds flexibility to the piping, but it also protects against gas leaks if the stainless steel coils fail. Corrugated stainless steel tubing, like all stainless steel tubing, is available in a range of forms and grades.
Hypodermic tubing is a typical medium for administering medicine or medicines under the skin. Hypodermic tubing, whether used for injection or removal, enables a quick supply of fluids. As a result, this stainless steel tubing is commonly used to make hypodermic needles for medical applications. It is a thin, cylindrical, hollow length of stainless steel, usually 316 or 304 grade, with a puncturing point at one end to form a needle.
In terms of needle uses, different sizes of hypodermic tubing work better for different needs. Large diameter hypodermic tubing, for example, is used for blood donation because the width of the needle permits blood to be removed at a considerably faster rate than a small or average diameter hypodermic tube. A small diameter hypodermic tube, on the other end, must not be used for blood donations since the needle's small size can burst the red blood cells, making the blood unusable by receivers. In addition to needle uses, hypodermic tubes are used in the electrical, mechanical, and chemical fields for spacers, cannulas, hypodermic guide wires, and hypodermic capillary tubes.
A stainless steel pipe is a long stainless steel tube used to transport water, gas, oil, or other materials. Because of stainless steel's strong corrosion resistance, it is employed in applications involving high temperatures, corrosive fluids, and high contaminant levels.
Because of the beneficial features of stainless steel, the most common metal used in the fabrication of piping, its usage in the production of pipes is widespread. Stainless steel resists corrosion well, requires low maintenance, is easy to clean, and is cost-effective in the long run. Although stainless steel has a higher starting cost than other metals, it has reduced maintenance and replacement costs.
Stainless steel pipe fittings are accessories that are used to join or close the ends of pipes and tubing in order to increase offset, in-line, mounting, and multiport possibilities. Because pipe bending is a laborious and sometimes costly secondary process, fittings are frequently used to connect two straight lengths of pipe at an angle as required for various pipe layouts.
Pipe fittings, which are an essential component of flow and plumbing systems, must be capable of properly transporting all fluids, gasses, and even particles that may be introduced into the system. For this and other reasons, stainless steel is a popular material utilized in the manufacture of these fittings because it is exceptionally strong, robust, and resistant to corrosion in a variety of corrosive environments.
These fittings are used in industries including paper and pulp, petrochemical, automotive, water treatment, dentistry, medical, food processing, semiconductor, and aerospace industries. Because high grade metals are sanitary and easily cleaned, stainless steel pipe fittings are the most prevalent choice in food processing and medical facilities. The numerous advantages of stainless steel pipe and fittings frequently exceed the higher initial cost since the elemental structure of stainless steel greatly increases product longevity, lowering long-term expenses like maintenance and replacements. Although fittings may need to be repaired or replaced in the future, this material can simply be melted down and repurposed, lowering costs and waste even further.
Stainless steel square tubing is a hollow pipe-like piece of hardware with four equal-length sides constructed from a number of steel alloys. Although these tubes, like their cylindrical counterparts, can be utilized for gas and fluid transfer, square tubing is most commonly used in structural and support design schemes.
Stainless steel square tubing is used in the construction, architectural, building, material handling, mounting, metal working, and framing sectors for a wide range of goods such as shelving, support beams, racks, grids, stepladders, partitions, and rails. While other materials may be utilized, stainless steel is particularly well suited to these applications.
While other materials may be utilized, stainless steel is particularly well suited to these applications. Although the initial cost of this alloyed tubing is more than that of many other options, the basic structure of stainless steel greatly increases tube longevity, saving long-term expenses such as replacements and maintenance. Though square tubing will inevitably need to be repaired or replaced, it is readily recycled, lowering costs and waste even further.
Stainless steel tubes are cylindrical, hollow items that are utilized as equipment components or as a medium for fluids to travel through. The usage of stainless steel in the construction of tubes is due to the favorable qualities of stainless steel, which is the most commonly used material in tubing production.
304 and 316 are the two most common stainless steel grades used for stainless steel tubes. Other advantages of stainless steel are its superior corrosion resistance, ease of cleaning, low maintenance requirements, and low cost. Although stainless steel may have a greater starting cost than other metals, stainless steel tubes have cheaper maintenance and replacement costs.
This chapter will discuss the applications and benefits of stainless steel tubing. It will also discuss the considerations when selecting stainless tubing.
As previously said, stainless steel tubing is used in various products and infrastructures, from factory machinery to automotive mufflers. Stainless steel tube fulfills the same role in numerous applications. The goal is to convey or regulate the transportation of a gas or a liquid. Because it can reliably sustain hot gasses and corrosive liquids without degrading, stainless steel tubing adapts itself to gasses and liquids. Stainless steel is fantastic since its applications are only limited by one's imagination, innovation, and financial resources.
Stainless steel tubing may be applied anywhere and is only limited by the budget allocated to the tubing portion of the project. Stainless steel tubing can also be left outside for long periods of time without rusting or disintegrating. Many industries and products employ stainless steel tubing due to its ability to resist degradation. Stainless steel tube is utilized in wet industries with concrete floors, various hunting and outdoor equipment like tents and weapons, automobile manufacturing, and kitchenware with stainless steel sanitary tubing.
When compared to typical metal, stainless steel tubes have numerous advantages. The benefits of stainless steel tubing include its durability, ability to transport cold or hot liquids and gasses, resistance to deterioration when exposed to most chemicals, ability to be formed into a variety of grades and tube radii, and ability to be formed at a lower cost for lower pressure systems.
Stainless Steel is expensive to manufacture and the processes used to make the tubing and piping are also costly. Compared with other metals and alloys, stainless steel parts are more expensive. This could be a limiting factor. The assemblage of stainless steel parts may also be problematic. Wear and tear should be avoided when stainless steel nuts and bolts are assembled. When the fine chromium oxide protective coating is scraped away, a grunt is produced.
The base metal connects under pressure in this process. This increased friction, combined with heat, leads the components to adhere at the molecular level. Small portions of basic metal are removed as the assembly progresses. This creates a rough surface that finally binds the two parts together. Anti-jamming compounds are available from stainless steel distributors and suppliers for use in structural pipes to help minimize or decrease wear on installation components. Other types of stainless steel tubing inevitably require repair or replacement.
Considerations when choosing stainless steel tubing include:
Conditions that the final product will experience are analyzed to determine which steel grade will perform best in a specific environment. Absurdly low pH, high stresses and temperatures, as well as crevice corrosion, all have a negative impact on stainless steel performance. Steels in the austenitic T3XX class, like typical kinds 304 and 316 alloys, retain their strength, hardness, and corrosion-resistant qualities throughout a wide temperature range.
Strength: The amount of force that metal can endure before it fractures or deforms.
Ductility: A material's capacity to change shape, such as being drawn into a thread or wire, without losing strength or breaking.
Toughness: Ability of a metal to sustain deformation and absorb energy before fracture.
Austenitic stainless steel is commonly accessible in the forms of bar, wire, tube, pipe, sheet, and plate; however, most products require extra machining or forming before they can be utilized for their intended application.
Many designers like stainless steel because of its aesthetically pleasing look, whether it be a shining, a matte surface polished to a certain RMS, an electro polished "bright" finish, a dull "pickled" finish, or a light-absorbing black oxide coating. Austenitic stainless steel tubing can accept any of these treatments, and the commonly used passivation.
Although high-performance austenitic stainless steel tubing is the most expensive at first, they are well worth the investment. Using a corrosion-resistant material that is well-suited to its application lowers downtime, maintenance, and replacement costs. Life-cycle costing methods can calculate present and future costs and provide a "apples-to-apples" comparison of various materials.
Stainless steel tubing is a multifaceted product that is commonly utilized in structural applications. Stainless steel tubing diameters and variations vary greatly based on the application requirements and are widely employed in a wide range of industrial sectors. It is manufactured by three processes namely seamless, metal spinning, and tube milling. Although the names are sometimes used interchangeably, there is one significant distinction between tube and pipe, notably in how the material is arranged or ordered and the classification.
Stainless steel is a type of steel alloy containing a minimum of 10.5% chromium. Chromium imparts corrosion resistance to the metal. Corrosion resistance is achieved by creating a thin film of metal...
Stainless steel can be fabricated using any of the traditional forming and shaping methods. Austenitic stainless steel can be rolled, spun, deep drawn, cold forged, hot forged, or stippled using force and stress...
Stainless steel grades each consist of carbon, iron, 10.5%-30% chromium, nickel, molybdenum, and other alloying elements. It is a popular metal used in various products, tools, equipment, and structures that serve in many industrial, commercial, and domestic applications...
Stainless steel tanks are widely used in food, beverage, dairy, medicine, cosmetics, and other manufacturing processes where cleanliness and purity are important. These are also used in industrial plants for storing chemicals and gases where strong resistance from chemical degradation is required...