API 655 Bulk Storage Tank Inspection, NDT Testing and Hydrotest Requirements

摘要

The API and EMMUA standards give guidelines for conducting inspections of Aboveground Storage Tanks (AST's). When conventional NDT inspection methods are augmented with specialist NDT methods such as Acoustic Emission (AE) testing of tank bottoms and over-viewed by an API 653 Inspector, a thorough and comprehensive assessment of the condition of tank can be made. A final test to confirm the integrity of the tank is to hydrotest after major repairs or alterations. As hydrotesting gives an indication of the integrity of a tank and or whether a tank is likely to suffer from 'brittle fracture'. History shows us that tanks are most likely to fail at hydrotesting, either when first filled after construction, re-construction or major repairs. Brittle fracture can cause the tank to have catastrophic failure and is predominantly caused by: 1.The presence of a crack like defect. 2. Low toughness of the material. 3. Inadequate tensile stress.