Walk into almost any steel warehouse, fabricator, or OEM and you will see a variety of different steel products. One of the most common items is pipe and tube. Steel pipe and tube are great in a multitude of different applications \u2013 from a sprinkler overhead protecting you from harm, to wonderful architecturally exposed structures waiting to be explored. Wait\u2026did you catch something there?! Those are two very different applications that are oftentimes lumped into the same category. But why? It is time to take a journey down the tubes\u2026err, across the pipeline to find out what exactly are the differences between pipes and tubes. In this three-part series, we will first take a deep dive into each product, and then, see how the two products stack up against each other.<\/p>\n
Steel pipes can be found everywhere you look and everyone (even those not in the steel industry) know what a pipe is. Round in shape, pipes are used as a vessel to transfer liquids and gases safely across long areas. Furthermore, pipes are used both above ground and underground in a wide variety of applications. Some of the common applications that use steel pipe include:<\/p>\n
Steel pipe is ordered, or called out in their \u201cNPS\u201d size, or \u201cNominal Pipe Size\u201d and \u201cSchedule.\u201d The nominal pipe size was established in 1927 by the American Standards Association to replace \u201cIron Pipe Size.\u201d This system designates wall thicknesses based on smaller steps between sizes and the \u201cSchedule\u201d to specify the nominal wall thickness. On pipe sizes, 12\u201d and under, the size loosely refers to the inside diameter (ID) of the pipe itself. So, while you may think a 1\u201d pipe is actually a 1\u201d outside diameter (OD), that 1\u201d is closer to the ID of the pipe. In fact, schedule sizes designate wall thicknesses, so a schedule 5 will have a thinner wall thickness than a schedule 40.<\/p>\n
Things get a little \u201cgray\u201d when you get into the larger pipe sizes such as 10\u201d and above. As an example, for the larger sizes (anything above 12\u201d), the NPS \u2013 which was closer to the inside diameter of the pipe before as we just learned \u2013 is now equal to the outside diameter of the pipe. Why is this? When the standard was created, the NPS was tied to the same inside diameter based on the standard wall thicknesses at the time. As those have evolved, based on processes and applications, the inside diameters developed to a point where the ID and OD were only indirectly related.<\/p>\n
Depending on size you are looking for, steel pipe is called out with schedules. Also, it can be called out as a standard wall (STD), extra strong or extra heavy (XS or XH), and double extra strong or double extra heavy (XXS or XXH). These terms, that were in the original Iron Pipe Sizes (IPS), are still a part of the steel pipe language that is used today.<\/p>\n
Frankly, the schedule designations were introduced in the hopes of phasing out that terminology. Because they are still in use today, some of the schedules do not always align with the former \u201cstandard\u201d and \u201cXS\u201d. As an example, Nominal Pipe Size 12\u201d sch 40 is a 12.75\u201d OD round pipe with a .406\u201d wall thickness. But, a standard (STD) schedule, or 40s, has a wall thickness of .375\u201d. When in doubt, it is always best to refer to a pipe size chart to ensure you are ordering and receiving the size you need.<\/p>\n
Some of the most common pipe sizes you can order are:<\/p>\n