When is an On-stream Inspection NOT allowed to substitute an Internal Inspection without an RBI assessment?

When is an On-stream Inspection NOT allowed to substitute an Internal Inspection without an RBI assessment?

• A. Vessel was previously repaired with strip lining
• B. Vessel has a remaining life less than 15 years
• C. Vessel general corrosion rate is 0.003 ipy
• D. Vessel operates in the CUI temperature range

Answer: (A)

An On-stream Inspection is typically a method used to assess the condition of a pressure vessel while it remains in operation. However, it cannot substitute for an Internal Inspection without an RBI (Risk-Based Inspection) assessment under certain conditions to ensure safety and reliability. In the case where a vessel was previously repaired with strip lining, it is crucial to conduct a thorough Internal Inspection rather than rely solely on an On-stream Inspection. Strip lining is often used to extend the life of a vessel, but it may also mask underlying defects or issues such as corrosion or cracks that could compromise the vessel's integrity. Since there may be critical areas concealed under the lining, an Internal Inspection is necessary to verify that the lining has not failed and that the base metal remains intact. A proper assessment of the underlying material condition can only be achieved through Internal Inspection, making it impossible to substitute with an On-stream Inspection in this scenario without an RBI assessment. For the other situations described, while they represent varying degrees of risk and condition for the vessel, they do not present the same critical need for a direct visual and tactile inspection of the internal surfaces as does the presence of a strip lining. Thus, those scenarios may allow for an On-stream Inspection depending on the circumstances but would still require an

An On-stream Inspection is typically a method used to assess the condition of a pressure vessel while it remains in operation. However, it cannot substitute for an Internal Inspection without an RBI (Risk-Based Inspection) assessment under certain conditions to ensure safety and reliability.

In the case where a vessel was previously repaired with strip lining, it is crucial to conduct a thorough Internal Inspection rather than rely solely on an On-stream Inspection. Strip lining is often used to extend the life of a vessel, but it may also mask underlying defects or issues such as corrosion or cracks that could compromise the vessel's integrity. Since there may be critical areas concealed under the lining, an Internal Inspection is necessary to verify that the lining has not failed and that the base metal remains intact. A proper assessment of the underlying material condition can only be achieved through Internal Inspection, making it impossible to substitute with an On-stream Inspection in this scenario without an RBI assessment.

For the other situations described, while they represent varying degrees of risk and condition for the vessel, they do not present the same critical need for a direct visual and tactile inspection of the internal surfaces as does the presence of a strip lining. Thus, those scenarios may allow for an On-stream Inspection depending on the circumstances but would still require an