ABSTRACT
Bolts of certain materials when subjected to loads within their elastic limit do not return immediately to their original condition after release of load. One popular material in particular, ASTM A193 B7, is prone to this phenomenon [4]. The problem was initially identified during the preparation of tension control indicators for offshore fasteners. When the indicator bolts were checked 2 days after production prior to an independent Lloyd's load test witness, the indicators were found to be inaccurate, despite 100% quality load tests on the finished product. Further investigation showed that the fastener load setting had actually increased.
