Inspection Plan Development for Mothballed Equipment


A South American operator developed plans to return a sulfur recovery unit to service after an initial ten years of service and a further ten years of mothballing due to changes in field production requirements.

The corrosive nature of molten sulfur, carbon dioxide and hydrogen sulfide in the unit, coupled with the expectation of a less than optimum preservation strategy in a littoral offshore environment, generated a large set of integrity risks that needed to be evaluated to determine the feasibility of repairing and reinstating the system for a further ten years of service.

GATE was engaged to employ our condition assessment, integrity management and field operating experience to develop a fit-for-purpose inspection strategy that would evaluate key risks from the operating and preservation cycles of the life of the unit so as to provide key information to determine the commercial feasibility of reinstating the system versus providing a newbuild replacement.


To pull together a multi-disciplinary team from across the various GATE affiliates to ensure that operational threats and the impact of poor preservation were adequately identified, documented and characterized.

From this, the team was able to use a consistent process to identify inspection requirements, methods and locations for a subsequent field mobilization.

Technical Achievements & Benefits

  • Because of the combined efforts and cross-collaboration between the multiple GATE Energy affiliates, we were able to rapidly conduct a threat assessment and clearly link the various threats and their expected locations with the capabilities of the equipment that would be available during the inspection campaign.

  • Identification of 23 discrete threats to be addressed across 14 corrosion loops containing a total of 37 equipment items and 76 major piping segments, all completed within a two-week deadline.

  • Associated non-destructive testing equipment and best practices were identified and prioritized condition monitoring locations (CMLs) selected for impacted vessels and piping circuits.

  • The overall outcome was an inspection strategy that included required manpower, equipment and cost estimates, in addition to a rigorous threat and operational risk assessment.