Subsea Hot Taps
08 June, 2011
Subsea Hot Taps
8 June 2011 Aberdeen Branch Evening Meeting
Chairman James Woods, Subsea Execution Team Lead, Shell UK
Sponsored by Subsea 7
Since the start of the modern subsea offshore oil industry the requirement to join, modify and extend pipelines underwater has been an operational requirement. As a consequence ‘Hyperbaric’ habitat welding evolved and once the technique reached an acceptable level of reliability it was extended to enable ‘Hot Taps’ to be performed. Hot tapping is a method of making a connection to a pipeline whilst the pipe remains pressurised and without interruption to the normal flow or operating regime of the pipeline, and has been carried out extensively subsea since the mid to late 70’s.
Hot tapping has traditionally been carried out manually by divers, although some automatic systems have been used in the past. However, now we have entered an era of ever deeper water depths outside the range of divers, and necessity, being the mother of invention, has promoted new remote and innovative systems.
The evening’s speakers covered traditional hot tapping, remote hot tapping and a non- welded system of hot tapping, and aimed to bring the audience up to date with current hot tap developments. In addition, a Tech Byte covered some of the available inspection techniques for the processes.
Subsea Hot Tap Experiences by Technip Norge AS 2007–2010
Geir Leden, Principal Engineer – Technip Norge AS
Technip Norge AS has in the period 2007–2010 completed three projects with subsea hot tap operations. Hot tapping has been carried out by use of both diver operated and remotely operated drilling machines in water depths ranging from 95 to 845 meters. A total of six hot taps have been performed, three hot taps through welded tees and three hot taps through pre-installed flanges. This presentation showed the basic concept of Hot Tapping as well as a description of some of the specific challenges that have occurred during the three projects.
World’s First Deep Water Remote Hot Tap
Keith Evans, MD – Clear Well Subsea Limited
Aberdeen based Clear Well Subsea have provided a unique hot tapping solution to Norwegian state oil company Statoil. As part of the Ormen Lange South Development, located in almost 1000m of water, Statoil required two new connections to the existing 30” gas export pipelines. The two hot taps constitute the first successful use of the remote hot tapping system in deep water and were performed at pressures and temperatures well beyond the capability of existing designs enabling the team to claim a number of world firsts. This presentation explained the evolution and implementation of the unique technology developed by Clear Well Subsea.
Tech Byte – Subsea Automated Ultrasonic NDT Inspection of Hot Tap Welds
Craig Emslie, Integrity Services Manager – Sonomatic Aberdeen
Sonomatic is a specialised inspection company who has been involved in a number of subsea hot tap campaigns. Their involvement has been focused on conducting specialised inspection, from measuring the profile of the pipeline prior to securing the hot tap, to inspection of field welds prior to connecting to the pipeline. This short presentation presented an overview of the inspections that Sonomatic has conducted and recent developments in ROV deployed inspection tools.
Subsea 7 Grouted Tee Hot Tap Technology
Dan Vu, Engineering Manager – Life of Field Services
Grouted Tee technology was developed for hot tapping onto cross country transmission pipelines in the late 1990s. It is now a proven and accepted method for carrying out live intervention on gas and oil pipelines. In 2009, Subsea Grouted Tee™ (SSGT) was successfully developed for subsea pipelines at diver depths. This presentation described the mechanics of Grouted Tee hot tap technology on subsea pipelines and provided high level technical, safety and time comparisons over the traditional welded and mechanical options. It also outlined a further design consideration enabling diverless hot tap operations in deep and ultra deep water environments.