BS ISO 18488:2015 pdf free
BS ISO 18488:2015 pdf free.Polyethylene (PE) materials for piping systems
BS ISO 18488 specifies a method for the determination of the strain hardening modulus which is used as a measure for the resistance to slow crack growth of polyethylene.
The strain hardening modulus is obtained from stress-strain curves on compression moulded samples.
This International Standard describes how such measurement is performed and how the strain hardening modulus shall be determined from such a curve. Details of the required equipment, precision, and sample preparation for the generation of meaningful data are given.
This International Standard provides a method that is valid for all types of polyethylene, independent from the manufacturing technology, comonomer, catalyst type, that are used for pipes and fittings applications.
NOTE This method could be developed for materials for other applications.
The following documents, in whole or in part, are normatively referenced in this document and are indispensable for its application. For dated references, only the edition cited applies. For undated references, the latest edition of the referenced document (including any amendments) applies.
ISO 527-1, Plastics一Determination of tensile properties一Part 1: General principles
ISO 7500-1, Metallic materials 一Verification of static uniaxial testing machines 一Part 1:Tension/compression testing machines一Verification and calibration of the force-measuring system
ISO 9513, Metallic materials一Calibration of extensometer systems used in uniaxial testing
After compression moulding, annealing of the sheets shall be carried out by conditioning the sheet for 1 h in an oven at a temperature of (120±2) °C and slowly cooled down to room temperature by switching off the closed temperature chamber with an average cooling rate of less than 2 °C/min.
During this operation, free movement of the sheets shall be allowed.
NOTE As cooling will take a long time, it is advised to anneal the samples at the end of the day and allow cooling of the samples overnight in the temperature chamber.
Five test pieces shall be punched from the pressed sheets using a die for the specimen geometry specified (see 6.1). The punching procedure shall be carried out in such a way that no deformation, crazes, or other irregularities are present on the test pieces.
The thickness of the samples shall be measured at three points of the parallel area of the specimen. The lowest measured value for thickness of these measurements shall be used for data analysis (see Clause 8).BS ISO 18488 pdf download.
