Standard precision seamless steel tubes
Standards and steel grades.
Tube sizes acc. to European Standards EN,
Tube sizes acc. to American Standards ASTM
Tube sizes acc. to Japanese Standards JIS.
Standard precision tubes are produced using the cold drawn process. As the semi-finished product we use rolled seamless steel tubes. Standard precision tubes are practically used in all areas of the machine production. Tubes are manufactured from carbon and alloyed steel. Overview of dimensional standards and technical-deliver conditions for standard precision tubes are presented in separate overview.
summary table. Steels are produced in electric arc furnace and are fully killed. Other types of steel can be supplied by agreement.
Delivery condition and thermal processing of standard precision tubesPrecision tubes are supplied in condition that is presented in the table below. It is marking for thermal processing according to EN 10305-1.
|+C||Cold drawn / hard. |
After the last cold forming no heat treatment.
|+LC||Cold drawn / soft. After the last heat treatment follows the cold drawing there is a light finishing pass.|
|+SR||Cold drawn and stress relieved annealed. After the final cold drawing process the tubes are stress relieved annealed in a controlled atmosphere.|
|+A||Annealed. After the last cold drawing process the tubes are annealed in a controlled atmosphere.|
After the last cold drawing process the tubes are annealed in a controlled atmosphere.
Marking for material condition according to STN 42 0002 and STN 42 0004, ČSN 42 0002 and ČSN 42 0004, DIN 2391-2 and ASTM 519 may be found here.
Length of standard precision tubes
- random length precision tubes in the range of 3 – 7 (9) m
- fixed length with tolerance +/- 500 mm
- exact length with tolerance – 0 / +x mm (x upon agreement)
- maximum length, upon agreement - 18 m
Tolerances for standard precision tubesTolerances of the precision tubes are in accordance with the appropriate dimensional tables of standards. Usual value for the outside diameter (OD) is less than 0.5% (OD) in no heat treatment process used (+C and +LC according to the European Standards). For the heat treated tubes tolerance values are depended upon the relation of the wall thickness and the tube diameter (WT/OD) larger (up to a single or twofold). In tolerances of the outside diameter (OD) the allowed deviation of circularity is included. When ordering based on the wall thickness, the tolerance is 10% from the wall thickness. Eccentricity of precision tube is included in the wall thickness tolerance.
Zeleziarne Podbrezova a.s. offers standard precision tubes with reduced tolerances, i.e. tolerances that are reduced compared to standard values. Reduced tolerances are presented in a separate table.
Wall thickness of standard precision tubes, according to the ASTM A450 Standard is presented in the BWG table and is converted to inches and millimeters. Usually the tubes are supplied with the wall thickness tolerance of –0 +20% (calculated from the minimal wall thickness). Upon agreement the precision tubes are supplied with the wall thickness tolerance of 10% (calculated from the medium wall thickness).
Straightness of standard precision tubesStraightness of the tubes is influenced by the mechanical properties of the tubes. For material having the yield point ReH <= 500 MPa is straightness 0,0015 x L (L – tube length) maximum, allowed straightness for one meter length is 1.5 : 1000. For material with the yield point ReH > 500 MPa the allowable straightness for the whole length of the tube is 0.0020 Xx L, allowed straightness of one meter is 2 : 1000.
Surface condition of standard precision tubesSurface condition of a tube meets the appropriate standards and depends upon the process of manufacturing the tube and its thermal processing. Precision tubes must have smooth outer and inner surface. The roughness value (Ra) is less or equals to 4 micrometers (0.004 mm) for the outer surface in the tubes in the +SR, +A and +N condition and is less or equals to 4 micrometers (0.004 mm) for the outer and inner surface of the tubes in the +C and +LC condition.
Ends of standard precision tubesEnds of the tubes are square to the longitudinal axis of the tubes and are free of burrs. Upon agreement the tubes may be supplied with mechanically machined ends. Likewise the ends of the tubes may be capped with plastic caps.
Marking of precision tubes and bundles of tubesMarking of standard precision tubes is done according to standards or upon agreement by the InkJet system either in one spot or along the whole length of a tube. Bundle marking is done either by one or multiple labels with required data.
Surface protection of standard precision tubesTubes are supplied with anticorrosion application. The type of protection is subject to agreement.
Tubes are tied with steel band. Packaging into a plastic foil or wooden crated is possible upon agreement.
Testing of standard precision tubesTesting is performed according to the appropriate standards. Test selection is according to standards or as per agreement with customer. The mandatory tests for standard precision tubes are chemical analysis, tensile test, dimensional inspection and visual inspection.
Specific testing – acceptance testing certificate 3.1.B (3.1.A, 3.1.C).
Elective testing: flattening test or drift expanding test, roughness measurement and NDT to find longitudinal defects: eddy current (STN 01 5054, ČSN 01 5054, PRP 02-74, SEP 1925, ASTM E 309, EN 10246-3 Grade E3 for OD > 6 mm, WT > 0,5 mm), stray flux (STN 01 5047, ČSN 01 5047, SEP 1913, ASTM E 570, EN 10246-5 Grade F3 for OD > 32 mm, WT > 2 mm), and ultrasound (STN 01 5028, ČSN 01 5028, SEP 1915, ASTM E 213, EN 10246-7 Grade U3 for OD >10 mm, WT > 2 mm), NDT as a proof of tightness or leakage test by eddy current EN 10246-1.
Certificates for standard precision tubesCertificates are issued according to standards, as an example we are showing: EN 10 204 (non-specified testing – 2.2, specified testing 3.1.B or 3.1.A, 3.1.C).