scope:

Scope and Applicability

The bonded and composite repairs in this Chapter include using adhesively bonded steel plate or fiber reinforced plastics (FRP laminate) to reinstate the strength of degraded structural members. In general, the degraded structure suitable for bonded or composite repair in accordance with this document includes general corrosion, or local pitting and grooving. The structural repair with bonded or composite material is to be considered only for local repairs of base material. If the hull-girder strength is to be restored, the effective longitudinal continuity of the bonded or composite repair throughout main supporting members and transverse bulkheads is to be provided. Therefore, the overall wastage of the structure caused by corrosion is analyzed to confirm that the required structural intervention can be considered as local.

Bonded or composite repairs are generally not to be used for crack repairs. Repairs for cracks are limited to noncritical structural members and limited to repair products with sufficient bonding layer stiffness. In addition, repairs for cracks may be considered if the repair reinforcement is extended over the span of the stiffeners in the longitudinal direction or the spacing of the web frame in the transverse direction. The procedure to determine if the damage is eligible for repair using the bonded or composite patches method is given in 1-2/2.

Bonded or composite repairs are not to be considered to increase remaining fatigue life.

This document provides an alternative to traditional renewal, where hot work or other factors may have a negative impact on the safety of an offshore unit or a vessel. Instead of using traditional hot welding, an existing degraded steel structure can be repaired to restore the capacity of the structure by utilizing patches of steel plates or FRP laminates that are adhesively bonded to the degraded steel structure. See 1-2/5.

This Chapter provides requirements on adhesively bonded or composite repairs of steel structures. It covers assessment, design, qualification, installation, and inspection of a bonded repair.

This Chapter refers to the ABS Rules for Building and Classing Floating Production Installations (FPI Rules). However, for other vessel/unit types, reference may be made to similar sections of other applicable Rules (i.e., Marine Vessel Rules, MOU Rules, etc.).

1-1/Figure 1 represents the configuration of a bonded patch repair. This repair technique can also be used for modification or reinstatement of existing structures by reinforcing structural elements to provide additional strength or arrest wastage by corrosion. 1-1/Figure 1a represents a repair system including corroded structure, adhesive layer (epoxy) and FRP laminate as reinforcement. 1-1/Figure 1b represents a repair system including corroded structure, perimeter seal/elastomer, adhesive layer (epoxy/polyurethane), and steel plate as reinforcement. 1-1/Figure 1c represents a repair system including corroded structure, perimeter member (bar), bonding layer (elastomer), and steel plate as reinforcement, which is described in AMPP SP21507. Note that there are additional requirements for this the type of repair in the AMPP document.