What are the restrictions to repairing longitudinal cracks with the full encirclement or box enclosure method?

What are the restrictions to repairing longitudinal cracks with the full encirclement or box enclosure method?

• A. The repair must be performed only by the original manufacturer.
• B. The crack must be evaluated by a third-party engineer.
• C. The sleeve must be sized to prevent propagation.
• D. The piping engineer must determine the crack will not propagate from under the sleeve.

Answer: (D)

Repairing longitudinal cracks with a full encirclement or box enclosure relies on the sleeve genuinely containing the flaw and not allowing it to grow beneath the sleeve. The essential restriction is that the piping engineer must determine that the crack will not propagate from under the sleeve once it’s installed. This evaluation considers how the sleeve changes the stress state, the remaining wall thickness, material properties, and operating conditions, often using fracture-mechanics methods or approved analyses. Only after this determination is made is the repair deemed acceptable. While other factors like who performs the repair or sizing the sleeve are relevant in practice, they do not replace the need for confirming no under-sleeve propagation.

Repairing longitudinal cracks with a full encirclement or box enclosure relies on the sleeve genuinely containing the flaw and not allowing it to grow beneath the sleeve. The essential restriction is that the piping engineer must determine that the crack will not propagate from under the sleeve once it’s installed. This evaluation considers how the sleeve changes the stress state, the remaining wall thickness, material properties, and operating conditions, often using fracture-mechanics methods or approved analyses. Only after this determination is made is the repair deemed acceptable. While other factors like who performs the repair or sizing the sleeve are relevant in practice, they do not replace the need for confirming no under-sleeve propagation.