STEEL TUBE AND PIPE HANDBOOK - February 2012

8 Steel Specific weight Coefficient Carbon 7,85 kg.dm –3 1 Austenitic stainless 7,97 kg.dm –3 1,015 Ferritic and martensitic 7,73 kg.dm –3 0,985 Review of basic characteristics of steel tubes Element Mass rate in % 1 2 Al aluminium 0,30 B boron 0,0008 Bi bismuth 0,10 Co cobalt 0,30 Cr chrome 0,30 0,50 Cu copper 0,40 0,50 La lantanides (each) 0,10 Mn manganese 1,65 1,80 Mo molybdenum 0,08 0,10 Nb niobium 0,06 0,08 Ni nickel 0,30 0,50 Pb lead 0,40 Se selenium 0,10 Si silicium 0,60 Te tellurium 0,10 Ti titanium 0,05 0,12 V vanadium 0,10 0,12 W wolfram 0,30 Zr zircon 0,05 0,12 Other elements (except: carbon, phosphorus, sulphur, nitrogen), (each) 0,10 The following formula is used for calculation of referenceweight (mass): M = (D – T) × T × 0,0246615 (kg/m), or x10,69 [in(lb/ft)]. Formula is applicable for carbon steel. For other steel the value is multiplied by the following coefficient: Steels for tubes Steel definition and division according to EN 10020 – steel is defined like: • material with iron mass rate upper then rate of any other ele- ments • content of carbon (C) is less than 2%, what is current limit between steel and cast iron (except some Cr-steel with al- lowed content of carbon more than 2%) • steel contains also more elements, shown in following table: Limit value of elements for non alloyed and alloyed steel – col- umn Nr.1 Weldable fine grain structural alloyed steel. Limit value of chem- ical composition of qualitative and high-grade steel – column Nr. 2 The basic characteristics classification is detailed in the previ- ous section. In this chapter there is a general description of these characteristics with the aim to serve as basis for description of individual particular types and groups of steel tubes. They are: • tube sizes • steel for tubes – steel classifications and definitions – steel marking system for tubes according to EN • technical delivery conditions (TDC) of tubes (excludes testing) • tube testing – test types – types of document control – individual tests Tube dimensions The tube dimensions belong among the basic characteristics of tubes. For industry needs and general use, tubes are manufac- tured in diameters ranging from tenths of milimeters to those hav- ing diameter of a few meters. It is mandatory that the tube sizes be set out in such a way that they define the tube completely from this point of view. In the tubes with circular cross section, there are, except for the length, three main dimensions: outside diameter, inside diameter and wall thickness. In circular tubes two values out of those mentioned are given. According to tube types we can also assign to dimensions the appropriate dimensional tolerances. Dimensions of individual tubes are not created by chance, but they are arranged into the dimensional sequels under the specific system. The tube sizes are in mm; in the USA and some other countries they use inches (“Zoll” in German). In this case tubes are also classified into two groups – “Tubes” are those used in mechanical applications and in energy facilities, while inches are used for the actual outside diameter. “Pipes” are those used in pipelines for different matters. Pipe size is denoted as the nominal pipe size, and up to 12 inches the denotation is given as an ap- proximate value (clearance) of the inside pipe diameter (more details can be found in the particular pipe types). After converting the pipe dimensions to milimetres used in the SI system there is a first and preferred sequel of outside diameters of steel pipes created (the first series in EN 10220, DIN 2448, etc.). However, this doesn’t mean that the pipes within Series 2 and 3 are not used at all. The sizes in Series 2 and 3 (for use in Europe, and supplemented by rounded off dimensions in mm) constitute the standards for Tubes, used in energy facilities design, and in tubes intended for mechanical usage. Sequel of pipe wall thicknesses has its origin in the inch Unit sys- tem, where in order to express a size uses fractions. The series “Schedule” forms pipe wall thickness (40, 60, 80, 120, etc.), and in some dimensions is interconnected with the mass class (STD, XS, XXS). These values, converted to milimeters, form a part of pipe wall thickness series. (Note: size – value Schedule, e.g. 40, is not constant, bud dependant upon the outside diameter of a pipe). In the Tube category the wall thickness values are de- rived either from “scales” BWG, SWG, or other ones. After con- version to milimetres, these values become a part of sequel in steel tube wall thicknesses. For precision tubes used in Europe and in countries using SI units are established the dimensional series with rounded off measures of outside diameters and wall thicknesses. Element Index Cr, Co, Mn, Ni, Si, W 4 Al, Be, Cu, Mo, Nb, Pb, Ta, Ti, V, Zr 10 Ce, N, P, S 100 B 1000 Note – Alloy steel: 1. Steel is also given in EN. 2. Cast analysis is valid. 3. Minimum element content – see table. 4. In the case when maximum element content is given, 70% of that value (except Mn) is used for qualification. Index of defining of alloying elements content characteristic number