IPEC can perform basic and detailed engineering works and carry out the conceptual studies of offshore pipelines and loading and offloading terminals. Some of the major activities of pipeline engineering in offshore and onshore sections include:
Pipeline Route Selection
As the first and most critical task in pipeline design, the pipeline route selection includes a technical and economic evaluation of alternative routes during the conceptual design phase.
Material Grade Selection
The steels applied in the offshore oil and gas industry vary from carbon steels (taken from API standards, Grade B to Grade X70 and higher) to exotic steels (i.e. duplex).
Wall Thickness Analysis
The offshore pipelines and risers wall thickness is assessed against the following possible modes of failure based on subsea pipeline design code:
- Hoop stress (pressure containment)
- Collapse due to external pressure
- Buckle initiation/ propagation
The riser analysis covers Vortex Induced Vibration (VIV), fatigue and in-place stress analysis. The purpose of VIV and fatigue analysis is to determine the maximum allowable span and verify distances between riser clamps.
Flow assurance is the ability to identify and prevent potential fluid related problems from impacting production to ensuring successful and economical hydrocarbon flow for up-stream facilities throughout the asset life time which is consist of:
- Hydraulic analysis, Transient Analysis, Network Modeling, Corrosion Study, Wax deposition & Hydrate formation Study
- Shore Approach Design
In more case of marine pipeline, the pipeline needs to cross the coastal lines. Near the shoreline the morphology may change over time, having an additional effect on the wave, current, and sediment transport patterns in the area. Therefore the near shore area is one of the most important sections in pipeline design process.
Due to the operating conditions (mainly high temperature) the pipelines may be subject to lateral buckling and all kind of consequential issues such as pipeline walking, potential buckling at crossing location, upheaval and then lateral buckling. This may have an impact on the selected pipeline routing and pipeline design, and needs consequently to be checked at an early stage of the project.
Pipeline Crossing Design
Crossing of the existing pipelines is achieved by creating a ramp by means of number of proper supports to allow for installation of the new line over the existing facility. The supports spacing shall not exceed the maximum allowable free span length previously defined in PIPELINE FREE SPAN analysis.
Cathodic Protection Design
A corrosion resistance coating is applied to prevent corrosion, but a cathodic protection (CP) system using anode is used as a supplemental corrosion protection system. This is because the corrosion coating can be damaged during pipe transportation and installation.
Pipelines are cathodically protected using two methods; impressed current system and sacrificial anode system. The selection between the two methods is made on economics and feasibility.