Detail of GB/T 42952.1-2023

Introduction of GB/T 42952.1-2023

GB/T 42952.1-2023 Thermoplastics pipes for the conveyance of fluids - Dimensions and tolerances - Part 1: Metric series 1 Scope This document specifies tolerance grades for the outside diameter, out-of-roundness and wall thickness of metric thermoplastics pipes for the conveyance of fluids and manufactured with nominal outside diameters and nominal pressures in accordance with ISO 161-1 and nominal wall thicknesses in accordance with ISO 4065. It is applicable to smooth thermoplastics pipes of constant circular cross-section along the whole length of the pipe, whatever the method of manufacture, the pipe material or the intended application. Note: It is intended that the tolerance grades specified in product standards are selected from this document taking into account the material and the intended application. 2 Normative references The following documents are referred to in the text in such a way that some or all of their content constitutes requirements of this document. For dated references, only the edition cited applies. For undated references, the latest edition of the referenced document (including any amendments) applies. ISO 161-1 Thermoplastics pipes for the conveyance of fluids - Nominal outside diameters and nominal pressures - Part 1: Metric series Note: GB/T 4217-2008, Thermoplastics pipes for the conveyance of fluids - Nominal outside diameters and nominal pressures (ISO 161-1:1996,IDT) ISO 3126 Plastics piping systems - Plastics components - Determination of dimensions Note: GB/T 8806-2008, Plastics piping systems - Plastics components - Determination of dimensions (ISO 3126:2005,IDT) ISO 4065 Thermoplastics pipes - Universal wall thickness table Note: GB/T 10798-2001, Table of universal wall thickness of thermoplastics pipe (ISO 4065:1996,IDT) 3 Terms and definitions For the purposes of this document, the following terms and definitions apply. ISO and IEC maintain terminological databases for use in standardization at the following addresses: ——ISO Online browsing platform: available at https://www.iso.org/obp ——IEC Electropedia: available at http://www.electropedia.org/ 3.1 nominal outside diameter dn numerical designation of the size of a component, other than a component designated by thread size, which is approximately equal to the manufacturing dimension Note: For metric pipes conforming to ISO 161-1, the nominal outside diameter, expressed in millimetres, is the minimum mean outside diameter dem.min specified in the applicable pipe standard. 3.2 outside diameter de 3.2.1 mean outside diameter dem measured length of the outer circumference of the pipe divided by π Note: The value of π is taken to be 3,142. 3.2.2 minimum mean outside diameter dem.min minimum value of the mean outside diameter specified in the applicable pipe standard, equal to the nominal outside diameter dn 3.2.3 maximum mean outside diameter dem.max maximum value of the mean outside diameter specified in the applicable pipe standard 3.2.4 outside diameter at any point de measured outside diameter through the cross-section at any point of the pipe 3.2.5 out-of-roundness difference between the measured maximum outside diameter and the measured minimum outside diameter in the same cross-sectional plane of the pipe 3.3 Terms relating to tolerances 3.3.1 tolerance difference between the limit deviation and the nominal value Note 1: The tolerance is always a positive value, which is the difference between the upper and lower deviations. Note 2: For pipes conforming to ISO 161-1, the lower deviation is zero. 3.3.2 limit deviation difference between upper limit of size minus nominal size Note: The difference between the maximum upper limit of size and the nominal size is the upper deviation, and the difference between the minimum lower limit of size and the nominal size is the lower deviation. 3.3.3 tolerance grade group of tolerances for linear sizes characterized by a common identifier Note: A specific tolerance grade is considered as corresponding to the same level of accuracy for all nominal sizes. 3.4 Wall thickness 3.4.1 wall thickness at any point ey measured wall thickness at any point around the circumference of the pipe 3.4.2 minimum wall thickness emin minimum wall thickness for the pipe specified in the applicable pipe standard 3.4.3 maximum wall thickness emax maximum wall thickness for the pipe specified in the applicable pipe standard 3.4.4 mean wall thickness em arithmetic mean of at least four measurements regularly spaced around the same cross-sectional plane of the pipe, including the measured minimum and maximum values obtained, rounded up to the nearest 0,1 mm. Note: The minimum number of measurements will be specified in the applicable pipe standard. 3.4.5 nominal wall thickness en wall thickness, as tabulated in ISO 4065, corresponding to the minimum wall thickness at any point emin. 4 Tolerances on outside diameters 4.1 Mean outside diameter For pipes conforming to ISO 161-1, the values specified therein as nominal outside diameters are minimum mean outside diameters, expressed in millimetres, and the limit deviations from these diameters shall be positive. Hence the tolerances shall be expressed in the form +x/−0 mm, where х is the value of the tolerance from Table 1 appropriate to the tolerance grade. The values in Table 1 are based on the dn specified in the applicable product standard, all dimensions being expressed in millimetres. ——Grade А: For all nominal outside diameters, the tolerance equals 0,009 dn, rounded up to the nearest 0.1 mm, with а minimum value of 0.3 mm. ——Grade В: For all nominal outside diameters, the tolerance equals 0,006 dn, rounded up to the nearest 0.1 mm, with а minimum value of 0.3 mm. ——Grade С: For all nominal outside diameters, the tolerance equals 0,003 dn, rounded up to the nearest 0.1 mm. with а minimum value of 0.3 mm. ——Grade D: For nominal outside diameters from 10 to 1000, the tolerances have been based on practical experience where tighter tolerances than those specified for grade С are required.

Contents of GB/T 42952.1-2023