Abstract: Abstract: In the process of maritime transportation, self-heating substances are one of the most common causes of maritime accidents. The standard test method N.4, United Nations “Recommendations on the transport of dangerous goods” manual of tests and criteria, is used to identify whether the goods belong to self-heating substances. The standard test method N.4 is developed based on the "heat basket" model and studies based on the self-heating characteristics of carbon substances.The applicability of standard test method N.4 to azo-dye powder lacks relevant verification data. By exploring the self heating characteristics of azo-dyes, it is found that the "heat basket" model is suitable to describe the self-heating process of azo-dyes. The activation energy of self-heating reaction of azo-dyes is 129.6 J / mol and the standard test method N.4 is not fully suitable to judge azo-dyes, which may lead to the misjudgment of "false positive". It is suggested that the relevant standard test methods or management regulations should give more detailed management to the chemical goods whose self-heating characteristics have been fully studied, so as to reduce the waste of resources and economic losses.

Key words: Key words: azo-dye powder, self-heating substance, heat basket model