Detail of GB/T 43117-2023

Introduction of GB/T 43117-2023

GB/T 43117-2023 Glass-reinforced thermosetting plastics (GRP) pipes - Determination of the ring creep properties under wet or dry conditions 1 Scope This document specifies methods for determining the ring creep properties for glass-reinforced thermosetting plastics (GRP) pipes. Properties include the creep factor and the long-term specific creep stiffness. Testing is performed under either wet (total immersion in water) or dry conditions. This document is applicable to the assessment and control of the consistency of raw materials by testing under dry conditions, or to the determination of long-term creep properties under simulated service conditions by testing under wet conditions. 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 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 7685 Glass-reinforced thermosetting plastics (GRP) pipes - Determination of initial ring stiffness ISO 10928 Plastics piping systems - Glass-reinforced thermosetting plastics (GRP) pipes and fittings - Methods for regression analysis and their use 3 Terms and definitions For the purposes of this document, the following terms and definitions apply. 3.1 vertical compressive force F vertical force, applied to a horizontal pipe to cause a vertical deflection 3.2 specific ring stiffness S measure of the resistance of a pipe to ring deflection, per metre of length, under external load as defined by Formula (1): Note: Specific ring stiffness is expressed in newtons per square meter. 3.3 mean diameter dm diameter, of the circle corresponding with the middle of the pipe wall cross-section and given by either Formula (3) or (4) Note: Mean diameter is expressed in metres. 3.4 initial specific ring stiffness S0 value of S determined by testing using constant load in accordance with ISO 7685 Note: Initial specific ring stiffness is expressed in newtons per square metre. 3.5 long-term specific ring creep stiffness at position 1 Sx,1 value of S at a reference position, position 1 (see 10.2), at x hours or x years, obtained by extrapolation of long-term stiffness measurements at a constant force (see 3.2 and 10.2) Note 1: Long-term specific ring creep stiffness at position 1 is expressed in newtons per square metre. Note 2: Position 1 is one of the three pairs of reference lines drawn on the specimen according to 6.3 and is used as the center reference line for the contact between the upper and lower loading devices and the specimen when measuring the initial ring stiffness and creep properties. 3.6 calculated long-term specific ring creep stiffness Sx,creep calculated value of S at x hours or x years obtained using Formula (5): Note: Calculated long-term specific ring creep stiffness is expressed in newtons per square metre. 3.7 creep factor αx,creep ratio of the long-term specific ring creep stiffness to the 0.1h specific ring stiffness, both at a reference position, position 1 (see 10.2), and given by Formula (6): 3.8 vertical deflection y vertical change in diameter of a pipe in a horizontal position, in response to a vertical compressive force (3.1) Note: Vertical deflection is expressed in metres. 3.9 long-term vertical deflection yx,1 value of the vertical deflection y, at the reference position, position 1 (see 10.2), at x hours or x years Note: Long-term vertical deflection is expressed in metres. 3.10 deflection coefficient f dimensionless factor which takes into account general second-order theory as applied to deflection and is given by Formula (7): 3.11 calculated strain εcalc,1 strain on the inner surface at the crown and invert of a pipe at the reference position, position 1, given in percent by Formula (8): 4 Principle A cut length of pipe supported horizontally is loaded throughout its length to compress it diametrically to a prescribed level of strain calculated using Formula (8). The force application surfaces are either bearing plates or beam bars. The pipe is subjected to a force which remains constant and the vertical deflection is measured at intervals. The long-term specific ring creep stiffness is estimated by extrapolation. For wet creep determinations the pipe is immersed in water at a given temperature.The creep factor is then determined from the long-term specific ring creep stiffness and the ring stiffness of the same test piece at 0.1 h. The declared creep factor is the average of the results from two test pieces. It is assumed that values for the following test parameters will be set by the referring standard: a) the time to which the values are to be extrapolated (see 3.6 and 11.1);

Contents of GB/T 43117-2023