Sizes of tubes and pipes
|Sizes and weights of seamless steel tubes|
|Sizes and weigths of cold drawn tubes|
|Sizes and weigths of precision tubes|
|Size tolerances of precision tubes|
|Sizes and tolerances of tubes for hydraulics and pneumatics|
|Sizes and weigth of butt welding fitting|
Dimensional series of steel tubes
Dimensions of the individual tubes are not randomly produced, but are arranged according to dimensional series based on certain systems. Tube dimensions are in mm. In the USA and some other countries dimensions are given in inches (German "Zoll"). In this case, the tubes are divided into two groups so called TUBE. These tubes are used for mechanical usage and energy facilities and in inches are given dimensions of the outside diameter. PIPE are tubes for pipelines for different types of media. The PIPE sizes are given as the nominal tube size. For sizes up to 12 inches the approximate size (clearance) of the inside pipe diameter is given. From the PIPE dimensions after their conversion to millimeters, is created the first preferred line of the outer diameter of steel tube (1st line is in EN 10220, DIN 2448, etc.). This does not mean that the tube dimensions in the 2nd and 3rd series are not used. Dimensions in series 2 and 3 (for use in Europe are modified by the rounded off dimensions in mm) are standards for TUBE used in the construction of energy facilities and for tubes for mechanical application.
Series of wall thicknesses of steel tubes
Series of wall thicknesses have its origin in the Imperial Unit system (inch), which for expression of sizes uses fractions. Wall thicknesses in PIPE are created by "Schedule" (40, 60, 80, 120 ....), connected in some dimensions to the weight class (STD, XS, XXS). These values, converted to millimeters form a part of series of wall thicknesses. (Note: size - the value of Schedule for example 40 is not constant, but depends on the outside diameter of tube).
(out of roundness), is the difference between max. and min. diameters readings taken in the same given section. Ovality shall be within OD tolerance.
Eccentricity of steel tubes
(mean deviation), is a measure of the distance between centres of the outside and inside diameters. Eccentricity shall be within WT tolerances and is calculated from the WT in one cross section using formula:
Tube straightness deviation (e)
indicates the maximum deviation of the tube from a line joining its two ends, where L is the length of the tube. It is given in percentages per unit length. Usually required straightness is 3 mm for 1 meter.