Page 371 - Pipelines and Risers

342 Chapter 18

18.4 Pipeline Repair Methods

18.4.1 Conventional Repair Methods
Damage to a submarine pipeline can be repaired in different ways depending on the water
depth and on the type and extent of the damage. This section describes the various types of
conventional repair methods currently available for repairing a damaged subsea pipeline in
water depths of less than 300 m. This maximum depth limitation is one that is realistically
imposed as a result of diver constraints. Non-conventional pipeline repairs are considered to
be those carried out diverless and in water depths exceeding 300 meters, as discussed in Table
18.1 summarizes the various repair methods and their applicable water depths. The various
types of conventional repair methods can be summarized as follows:

Non-critical repair work;
0 Minor repair requiring the installation of a pin hole type repair clamp;
Medium repair requiring the installation of a split sleeve type repair clamp;
0 Major repair requiring the installation of a replacement spool.

Repair Method Water Depth
I 0-5om 50m-300m I >3m

Surface Welding J (note 3) NIA NIA

1. Technology exists for the diverless installation (by ROV) and the diverless installable hardware such as
repair clamps and mechanical connectors.
2. Hyperbaric welding in water depths less than 20 rn is not practical and other repair solutions are required.
3. Water depth limitation for surface welding is governed by size of pipeline, weight of pipeline and vessel
lifting capabilities.