ISO 899-1规定了在预处理、温度和湿度等规定条件下，以标准试样形式测定塑料拉伸蠕变的方法。 该方法适用于以哑铃形试样形式直接模制或由板材或模制制品加工而成的刚性和半刚性非增强、填充和纤维增强塑料材料。 该方法旨在为工程设计和研发目的提供数据。用于工程设计目的的数据要求使用伸长计测量试样的标距长度。 用于研究或质量控制目的的数据可以使用夹点之间距离的变化（标称延伸）。 拉伸蠕变可能因试样制备和尺寸以及试验环境的不同而显著不同。试样的热历史也会对其蠕变行为产生深远影响（见附录A）。因此，当需要精确的比较结果时，应仔细控制这些因素。 如果拉伸蠕变性能用于工程设计目的，则塑料材料应在广泛的应力、时间和环境条件下进行测试。

ISO 899-1 specifies a method for determining the tensile creep of plastics in the form of standard test specimens under specified conditions such as those of pretreatment, temperature and humidity. The method is suitable for use with rigid and semi-rigid non-reinforced, filled and fibre-reinforced plastics materials in the form of dumb-bell-shaped test specimens moulded directly or machined from sheets or moulded articles. The method is intended to provide data for engineering-design and research and development purposes. Data for engineering-design purposes requires the use of extensometers to measure the gauge length of the specimen. Data for research or quality-control purposes may use the change in distance between the grips (nominal extension). Tensile creep can vary significantly with differences in specimen preparation and dimensions and in the test environment. The thermal history of the test specimen can also have profound effects on its creep behaviour (see Annex A). Consequently, when precise comparative results are required, these factors are intended to be carefully controlled. If tensile-creep properties are used for engineering-design purposes, the plastics materials are intended to be tested over a broad range of stresses, times and environmental conditions.