Ammonia Reservoir is used as an intermediate storage for liquid ammonia and is a single unit in the plant. The equipment is critical and falls under hazardous service conditions. In fertilizer & chemical industries health survey of static equipment is carried out by conventional NDT technique in which only welded areas are covered in general. In addition to that hydraulic test is mandatory either to meet statutory requirements of the country or to determine the strength of the equipment. A hydrotest alone may not assure the soundness of material/welds and new flaws may get introduced because of the proof load. So, a hydrotest alongwith AE can provide additional information particularly structural integrity which can give confidence to industry for safe operation of pressurized components.

The paper discusses the results of the off-line acoustic monitoring during proof loading in addition to internal NDT inspection and on-line Acoustic monitoring surfacing out the vital information required to establish structural integrity with "Reliability Approach".