Continue of Part 5 - Inert Gas Purging
6. Sub-sea Piping and Vessels Preparations
The Piping and Vessels Preparations detailed in this document are also applicable to sub-sea installations, however due to the nature of the equipment they are not carried out as sequentially as those for traditional topsides systems. Each project should require different Piping and Vessels Preparations dependent on the sub-sea configuration, type of produced product (oil or gas) and the operating conditions such as water depth and temperature.
6.1 Leak test
Leak tests for sub-sea piping and tubing are carried out during the commissioning phase.
The leak tests for sub-sea production lines are normally carried out using inhibited water with dyes visible by ROV. These tests are carried out after the line pigging and gauging operations.
The leak tests for the tubing within the control umbilicals are normally carried out using fresh water within the chemical lines and always the operating fluid within the hydraulic control lines.
The leak tests should be carried out in accordance with the procedures prepared by the commissioning group.
6.2 Drying out
See part 3, dry out, of Piping and Vessels Commission article.
6.3 Chemical loading of vessels
Not applicable to sub-sea. Any loading of glycol or methanol should be carried out in accordance with section 4 of this document, by the topsides commissioning group.
6.4 Inert gas purging
See part 5, inert gas purging, of Piping and Vessels Commission article.