Collapse of Paper Pulp Tank

Abstract

The paper pulp tank in Valkeakoski, Finland, collapsed on 27 March 1996. The volume and height of the steel tank was 6000 m3 and 35.5 m, respectively. The collapse occurred during test filling with water. During the test filling it was noticed that the tank was tilting. The time from first observation to final collapse was around 12 min. The tank collapsed onto a building next to it, causing the death of one person. During the collapse there was approximately 5000 m3 of water inside the paper pulp tank. The ambient temperature was −20°C during the collapse. The Safety Investigation Authority started an investigation because the incident was a major accident and there was loss of human life. Several reasons for the collapse were discovered. In addition, several recommendations were made for construction in general. This article presents a case study and details based on material that has already been published, but it also includes a structural analysis made in the study. The goal was to clarify the main reasons and form them into a timeline of the collapse. Also, lessons learnt are presented.