Vortex-Induced Vibrations (VIV) on Subsea Pipeline

In fluid dynamics, vortex-induced vibrations (VIV) are motions induced on bodies interacting with an external fluid flow, produced by – or the motion producing – periodical irregularities on this flow. They occur in many engineering situations, such as bridges, stacks, transmission lines, aircraft control surfaces, offshore structures, thermowells, engines, heat exchangers, marine cables, towed cables,...

Read More

Lateral Buckling Analysis of Offshore Pipelines Using SIMLA

Offshore pipelines are required to operate at ever highertemperatures and pressures. The resulting high axialstress in the pipe-wall may lead to unexpected buckling, which may have serious consequences for the integrity of the pipeline if this is not taken into account during the design phase. Unexpected lateral buckling has been observed in several operating pipeline systems. The offshore industry lacks a complete understanding of lateral buckling, and efficient tools for simulating buckling behaviour early in the design phase would...

Read More

How to Weld Underwater

Underwater welding is a process whereby metals are melted together underwater to either repair a structure or create a new structure. Used on oil wells, ships, and other underwater structures, underwater welding is done by one of two methods. The first is hyperbaric welding, in which a structure is created around the weld and a pressurized environment created. The second is arc welding, in which the welding electrode contains a flux coating that releases gases to preserve the integrity of the weld. Because of the dangers of shock, explosion and...

Read More

Offshore Cathodic Protection

Richard Baxter and Jim Britton How does steel corrode in water? To understand cathodic protection, you must first understand how corrosion is caused. For corrosion to occur, three things must be present: 1. Two dissimilar metals 2. An electrolyte (water with any type of salt or salts dissolved in it) 3. A metal (conducting) path between the dissimilar metals The two dissimilar metals may be totally different alloys – such as steel and aluminum...

Read More

New Installation Methods May Facilitate Ultra Deep Water Pipelay

Since the 1970s, offshore oil and gas development has gradually proceeded from shallow-water installations up to around 400 m (1,312 ft) to the ultra-deep waters around 3,000 m (9,842 ft) that represent the maximum today. The question is whether the curve will flatten at 3,000 m, or if this is just a temporary pause on the way to even greater depths. There have been plans for a gas trunkline from Oman to India at 3,500 m (11,483 ft) depth, but...

Read More