【Chemical Engineering】Reference table for various pipe sizes

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1The meanings of De, DN, d, and φ: Generally speaking, the diameter of a pipe can be divided into outer diameter (De), inner diameter (D), and nominal diameter (DN). 1. DN refers to the nominal diameter of a pipe, which is the average of the outer diameter and the inner diameter. The value of DN = the value of De = 0.5 * wall thickness. Note: This is neither the outer diameter nor the inner diameter. Pipes such as water and gas transmission pipes (galvanized or ungalvanized steel pipes), cast iron pipes, steel-plastic composite pipes, and polyvinyl chloride (PVC) pipes should be labeled with the nominal diameter “DN” (such as DN15, DN50). 2. De refers mainly to the outer diameter of the pipe; for PPR, PE, and polypropylene pipes, the outer diameter is indicated using De. It should always be specified in the form of outer diameter x wall thickness, for example, De25 x 3. 3. D generally refers to the inner diameter of the pipe. 4. Inner diameter of the d concrete pipe. For pipes such as reinforced concrete (or concrete) pipes, clay pipes, acid-resistant ceramic pipes, and cylinder tile pipes, the pipe diameter should be indicated by the inner diameter d (e.g., d230, d380, etc.). 5. φ represents the diameter of a regular circle ； It can also indicate the outer diameter of the pipe, but in that case the wall thickness should be multiplied by it. For example, φ25 x 3 indicates a pipe with an outer diameter of 25 mm and a wall thickness of 3 mm. For seamless steel pipes or non-ferrous metal pipes, “outer diameter x wall thickness” should be indicated. For example, φ108 x 4; the φ can be omitted. Some steel pipe standards in China, ISO, and Japan use wall thickness dimensions to denote the steel pipe wall thickness series. The specification for this type of steel pipe is expressed as outer diameter x wall thickness. For example, φ60.5 x 3.8. 6. DN stands for Nominal diameter, which means the nominal size. 7. De stands for external diameter, which means the outer diameter. 1. Method of indicating pipe diameter: For pipes such as steel pipes for water and gas transmission (galvanized or ungalvanized), cast iron pipes, and plastic pipes, the nominal diameter “DN” should be indicated (e.g., DN15, DN50) ； De can also be used for indicating wall thickness ； Taking galvanized welded steel pipes as an example, the two notation methods are as follows: DN, De – DN20 De25 x 2.5mm, DN25 De32 x 3mm, DN32 De40 x 4mm, DN40 De50 x 4mm, and so on... 2. For pipes such as seamless steel pipes, welded steel pipes (with straight or spiral seams), copper pipes, and stainless steel pipes, the diameter is preferably indicated as outer diameter x wall thickness (e.g., De108 x 4, De159 x 4.5, etc.) ； For seamless steel pipes or non-ferrous metal pipes, “outer diameter x wall thickness” should be indicated. For example, φ108 x 4; the φ can be omitted. 3. For pipes such as reinforced concrete (or concrete) pipes, clay pipes, acid-resistant ceramic pipes, and cylinder tile pipes, the pipe diameter should be indicated by the inner diameter d (e.g., d230, d380, etc.). 4. For plastic pipes, the pipe diameter should be indicated in accordance with the methods specified in the product standards ； Plastic pipes are usually specified by their outer diameter. The terms 20, 25, 32, etc., which we use informally in actual construction work, refer to De rather than DN; there is thus a difference in specification here. Failing to clarify this can easily lead to losses during the procurement and construction processes. 5. When the pipe diameter is specified using the nominal diameter DN in the design, there should be a table correlating the nominal diameter DN with the corresponding product specifications. The respective range of values for 3De, DN, d, and φ: 1. De–PPR, PE pipes, outer diameter of polypropylene pipes. 2. DN--Nominal diameter of PVC pipes, cast iron pipes, steel-plastic composite pipes, and galvanized steel pipes. 3. φ--For seamless steel pipes or non-ferrous metal pipes, “outer diameter x wall thickness” should be indicated, e.g., φ108X4. 4 units of measurement: imperial and metric. Inch is a unit of length. 1 inch = 2.539999918 centimeters. Inches is a unit of length used in the United Kingdom (UK), that is, Britain (the Commonwealth), and its former colonies. The United States and others **also use it. In **and**, “inch” is usually written as “ inch”. The common abbreviation for inch is “inch”; “ inch” is a term created in modern times. It is pronounced as “inch” and belongs to those Chinese characters that have two pronunciations. Other examples include “ “li”, which is pronounced as “nautical mile”. These terms are derived from traditional Chinese length units like “cinch”, with an additional radical added to distinguish them. 1. Dimensions: DN15 (4-inch pipe), DN20 (6-inch pipe), DN25 (1-inch pipe), DN32 (1.5-inch pipe), DN40 (1.5-inch half pipe), DN50 (2-inch pipe), DN65 (2.5-inch pipe), DN80 (3-inch pipe), DN100 (4-inch pipe), DN125 (5-inch pipe), DN150 (6-inch pipe), DN200 (8-inch pipe), DN250 (10-inch pipe), etc. 2. Divide 1 inch into 8 equal parts: 1/8, 1/4, 3/8, 1/2, 5/8, 3/4, 7/8 inches. (1) This corresponds to what is commonly referred to as 1/8 inch to 7/8 inch; smaller sizes are expressed using 1/16, 1/32, and 1/64, with inches still being the unit of measurement. If the denominator and numerator can be simplified (such as when the numerator is 2, 4, 8, 16, 32), they should be simplified. (2) The inch designation is indicated by two dashes in the upper right corner, such as 1/2". (3) For example, a pipe with a diameter of DN25 (25 mm, the same below) is equivalent to an English 1\" pipe, which was also known as an 8⁄8 pipe in the past. (4) A DN15 pipe is equivalent to a British 1/2\" pipe, which was also the former 4-inch pipe. (5) A DN20 pipe is equivalent to a British 3/4\" pipe, which was also known as a 6-inch pipe in the past. (6) The relationship between the outer diameter and DN, NB is as follows: (better readability on a computer). 5 Pipe specifications and related data: International pipe size chart, DN nominal diameter chart for stainless steel seamless pipes. For pipes that are seamless steel tubes, the outer diameter is denoted by the letter D, followed by the value of the outer diameter and the wall thickness; for example, a seamless steel tube with an outer diameter of 108 mm and a wall thickness of 5 MM is indicated as D108*5. Plastic pipes are also specified by their outer diameter, such as De63. Others such as reinforced concrete pipes, cast iron pipes, and galvanized steel pipes are denoted by DN. In design drawings, the nominal diameter is generally used to represent it. The nominal diameter is a standard arbitrarily established for the convenience of design, manufacturing, and maintenance; it is also referred to as the nominal bore, and serves as the specification name for pipes (or pipe fittings). The nominal diameter of a pipe is not equal to its inner or outer diameter. For example, for a seamless steel pipe with a nominal diameter of 100 MM, there are several variants such as 102*5 and 108*5; here, 108 represents the outer diameter of the pipe, while 5 indicates the wall thickness. Thus, the inner diameter of this pipe is (108 – 5 – 5) = 98 MM. It is not exactly equal to the outer diameter minus twice the wall thickness. In other words, the nominal diameter is a specification name for the pipe diameter that is close to, but not exactly equal to, the inner diameter. Nominal diameters are used in design drawings so that the structural and connection dimensions of pipes, fittings, valves, flanges, gaskets, etc., can be determined based on them. The nominal diameter is denoted by the symbol DN. If the outer diameter is used in the design drawings, a table showing the specifications of the pipes, including their nominal diameter and wall thickness, should also be provided.