Stainless steel pipe and carbon steel pipe are the most common type of standard pipe used today. They are part of tubular goods, which are manufactured to different specifications and standards. Pipes are sold by "nominal pipe size" in sizes from 1/8" to 72". The two most common types of pipes are welded pipe and seamless pipe. Both are available in carbon steel and stainless steel. Welded pipe is also called ERW (Electric Resistance Welded) pipe. Most common specification for welded carbon steel pipe is A53. Seamless pipe is made by a process that requires no welding. Most common specification for seamless carbon steel pipe is A106B. Stainless Steel pipe is made to spec A312. Stainless steel pipe is also available in both seamless and welded configuration. Most common stainless material is 316 and 304.
Pipe is generally identified by "Nominal Pipe Size" (NPS), with the wall thickness defined by "Schedule" (SCH). NPS is dimensionless designator and is an indication of a size but not an actual size. This is confusing for many people new to the piping industry. NPS 1/8 through NPS 12 has an outside diameter that is defined by the ansi pipe sizes. Generally speaking, a schedule 40 pipe dimension for up to 12 NPS is roughly equal to the ID of the pipe. Pipe sizes 14 and above are less confusing as a 14 NPS is equal to 14" OD (outer diameter).
ASME B 36.10 has more details of pipe sizes. The industry norm for pipe size also varies between different types of pipe. For a standard pipe, a 4.5" OD pipe will be referred to as 4" NPS however for line pipe and OCTG, it will be referred to as 4.5" only. Wall thickness is also mentioned differently. For standard pipe, pipe schedule is used to designate wall thickness. However line pipe is almost always referred by wall thickness whereas OCTG is referred by weight per foot.
Weight of pipe is measured in pounds per foot or kilograms per meter. One should remember that weight of pipe in the ansi pipe size chart is "theoretical" weight and not an actual weight. Actual weight will vary based on the tolerance of pipe size.
Formula to calculate weight of steel pipe is;
W = Weight per lineal foot
OD = Outer Diameter
WT = Wall Thickness
Steel pipe is grouped in two main categories;
There are four main methods of producing metal pipe:
ERW Pipe is produced in sizes from 1/8 to 24 in NPS. ERW welded pipe is produced from flat sheet metals. ERW pipe is first cold formed into a cylindrical shape and then welded longitudinally. both continuous welded and elctric resistance welded pipe are made by shaping rolls of coiled steel into cylindrical forms and welding along the longitudinal seams. Picture below shows the first step of forming strips into cylindrical shape and then fusing it together in 2nd step.
There are many ways for the electric current to be used for welding the rolled strip. This includes revolving copper disc, fixed alloy Cu contacts and induction coils. These methods raise the temperature of the steel edge to deg F for effective welding. The rolling process exerts so much pressure that it creates a metal welded seam on the outside and inside. These weld seams are then removed during the finishing process. The welded pipe is heat treated, inspected and hydro tested.
ERW pipe is available in following common specs;
ASTM A53, A135, A252, A500, A795, API 5L and API 5CT.
Most common spec for welded pipe is A53 and API 5L.
What is seamless definition? or seamless meaning? we get this question a lot. Seamless pipe is produced in sizes from 1/8 to 36" nominal. Seamless pipe has no longitudinal seam or weld when compared to ERW pipe. In simple terms the seamless pipe is produced by piercing a solid round billet leaving behind a hollow seamless pipe. There are two main methods of producing seamless pipe;
In Extrusion Process, hot billets of metal are formed into seamless pipe by forcing the billets through extrusion dies and over a forming mandrel. See picture below;
Hot rotary piercing method is the most common process of producing seamless pipe. In this process hot billets are forced through rotating heavy rollers over a mandrel or piercing plug. The piercing plug creates the hole through the seamless cylindrical billets. Picture below illustrates the hot rotary process.
Seamless pipe goes through various finishing operations such as straightening, inspection, hydro testing and imaging. Seamless pipe is widely used in pressure piping, construction, petrochemical and oil refineries. Seamless pipe is available in the following specifications;
ASTM A53, A106, A252, A333, A335, A501, A523, A589, API 5L and API 5CT. Most common seamless pipe is A106B.
End finish of seam less pipe includes plain ends either beveled or square cut. Seamless carbon steel pipe is available in black, bare, galvanized or with epoxy coating.
Generally steel pipe is supplied in 21 ft lengths. It is also available in Single Random Length (SRL) which could be anywhere from 17 ft to 24 ft. Double Random Length (DRL) refers to pipes that is at least 37 ft long and up to 44 ft.
There are five common type of metal pipe end finishes;
Picture below shows different steel pipe end finishes;
Coupling for extra strong and double extra strong pipe are taper threaded and recessed for all sizes. Picture above shows straight tapped coupling and straight tapped coupling with recess.
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Steel pipe is available in different classification, grade, weight, schedule number etc. Hence it is important to identify steel pipe markings. Steel pipe is identified by paint stencil or stamped marking on the pipe itself or by a tag attached to it.
Pipe identification as per ASTM
Picture below shows marking requirements as per ASTM specifications
Pipe identification as per API
Picture below shows marking required as per API specification.
Most common finish on the metal pipe is lacquer coating that prevents corrosion and protects the pipe from weather. This is also called Black Iron Pipe. Other than lacquer, there are four types of metal pipe finishes;
Galvanizing involves using zinc coating as a sacrificial element to prevent corrosion. Zinc is usually applied by a hot dipping process where pipe is submerged in a molten bath of zinc solution. Standard weight of zinc is 1.8 oz per sq ft. Galvanized pipes provide good protection to the pipe inside and out.
Pipe's corrosion resistance can also be enhanced with corrosion resistant pipe coating. Such coatings are usually long lasting compared to lacquer or galvanized finishes. There are three main types of Corrosion Protective Coating for Steel Pipe
Metal Pipes are available in following material grades;
Stainless steel is iron based alloy containing a minimum of 16% chromium. Nickel is another important alloying element in stainless steel pipe. Stainless Steel pipes are highly resistant to corrosive media and to oxidation at almost any temperature.
Stainless steel welded and seamless pipes are used for variety of reason such as to resist corrosion, preform at high temperature, for clean look and low maintenance cost. The most important aspect for stainless steel pipe is its inherent material characteristics that allows much thinner walls to be created such as sch 5, sch 10 without compromising the structural integrity of the pipe. The use of fusion welding to join pipe also eliminates the need for threading.
Type 304 stainless steel pipe is mostly used for general corrosive resistant application. it is used in chemical plants, refineries, paper mills and food industries. 304SS pipe has maximum carbon content of 0.08%. It is not recommended for use in the temperature range between 800 deg F and deg F due to carbide precipitation at the grain boundaries. Type 304L is the same as 304 except that it has a 0.035% maximum carbon content.
Type 316SS pipe is much more resistant to pitting than other chromium nickel alloys due to the addition of 2-3% molybdenum. It is useful in applications with acids, brines, sulphur water, sea water and with hologen salts. 316L stainless steel pipe, like 304L, has a max carbon content of 0.035%.
Welded Stainless Steel Pipe is made to specification ASTM A312 and A358. A312 is the most common spec for stainless steel pipe. Welded stainless pipe is made from 1/8" to 24" NPS.
Seamless Stainless Steel Pipe is made to specification ASTM A312 and A376. A312 is also the most common spec for seamless stainless steel pipe. Seamless stainless pipe is made from size 1/8 to 14" nominal
Steel pipe is made by mills all around the world and traded in different countries. Some of the big names in the pipe industry are US Steel, ArcelorMittal, Nippon Steel, Nucor Corp, Hyundai Steel, ThyssenKrup, Vallourec, Hebei Iron and Steel Group, Posco, Jiangsu Shagang, Ulma Piping, Shultz USA and Webco etc.
Trupply sells a large variety of welded and seamless pipe. Based on our years of experience, the following are main questions or key points customers inquire about;
Stainless steel pipes are one of the most popular types of pipes used in modern construction. These pipes are known for their durability, strength, and resistance to corrosion. When it comes to selecting the best stainless steel pipe for your project, you’ll need to consider a few factors. Among the most essential is the type of stainless steel material used in the pipes. In this guide, we’re going to explore the top factors you need to consider when choosing the best 304 stainless steel seamless pipe for your project.
Stainless Steel 304 Seamless Pipe is a type of stainless steel pipe made from an alloy of iron, chromium and nickel. It has excellent corrosion resistance and a high strength-to-weight ratio. The seamless design gives it superior flexibility compared to welded pipes, making it ideal for applications such as plumbing systems and industrial piping. It also has low permeability which makes it resistant to rusting, staining and temperature extremes.
The first factor you must consider when choosing the best 304 stainless steel seamless pipe is the material quality. Quality is, indeed, critical when it comes to choosing the right stainless steel pipes for your project. High-grade stainless steel materials typically offer a higher level of durability, corrosion resistance, and strength. So, always choose materials that are made of high-grade material, so you get quality products that can withstand pressure and last for a long time.
Another crucial factor to consider is the pipe’s size. When selecting the right stainless steel pipe size, you will need to determine the application’s design and how it will be installed. So, it’s essential to measure the correct pipe size to ensure the pipe can efficiently carry fluids. Plus, always ensure the pipe size is compatible with other pipe fittings, components, and assemblies you plan to use in your project.
What is the project’s application, and how can stainless steel seamlessly blend with it? These are some of the questions you must consider. Always consider the application of the stainless steel pipe before purchasing to avoid making errors. Different applications require different types of pipes, and 304 stainless steel seamless pipe is best suited for commercial, industrial, and heavy-high-temperature applications.
The pressure handling capacity refers to the maximum pressure that the stainless steel seamless pipe can withstand without causing severe damage or even breaking altogether. Note that high-pressure environments require a thicker-walled and more robust pipe to handle the pressure optimally. If you’re going to be working in high-pressure environments, always choose a stainless steel pipe that can withstand pressure and is designed accordingly.
Finally, always compare the different products and material costs from multiple vendors before making a purchase. The cost of 304 stainless steel seamless pipes varies from vendor to vendor; thus, it’s not always guaranteed that the cheapest options will offer the best value. Be sure to research your vendors first before purchasing to guarantee quality service, delivery, and after-sales support.
In conclusion, choosing the right stainless steel seamless pipe for your project may seem like a daunting task, but armed with this guide, you can make an informed decision. Consider the factors we’ve outlined here – material quality, pipe size, product application, pressure handling capacity, and cost, and you’ll be sure to make a wise selection. Remember to always work with trusted manufacturers and vendors that can provide you with the highest quality materials and services.
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