STATS GROUP COMPLETE CHALLENGING ISOLATION OF 42” SUBSEA PIPELINE Engineers at STATS Group had a hat- trick of challenging issues to overcome when commissioned to isolate a 42” subsea pipeline in the Middle East.

supplies suction to three topside pumps and the main 36” NB feed transfer line. The solution required the provision of a secure isolation which could be deployed subsea via divers into the 42” dead leg through an open flange entry point.

The dead leg pipeline was housed within an oil storage tank and the Middle National Operating Company owner was concerned the integrity of the pipe was suspect after identifying irregular flow characteristics.

Aberdeen-based STATS Group had to overcome three main challenges. firstly, as the pipeline was constructed of thin wall pipe, consideration needed to be given to ensure the weight of the isolation plug would not pose a risk of rupturing the pipeline during the deployment process.

Secondly, the isolation plug is required to provide leak-tight isolation for at least 25 years, so suitability of seal material for long-term deployment was essential.

finally, the storage tank had to remain fully operational throughout the workscope, so STATS had to ensure that the subsea deployment, setting and testing of the isolation plug, could be conducted by divers within a strict 14-day window.

The 42” dead leg is connected to a 96” Pump Plenum, housed within the oil storage tank which

The isolation plug would need to negotiate two mitre joints and travel up a five-degree incline before reaching its final isolation position 38 metres away, directly ahead of the Plenum weld. A triple seal mechanical isolation plug was chosen and provided the option to remove the plug at a later date, if required.

Due to the thin wall pipe of the dead leg, a standard Tecno Plug™ would be too heavy to deploy safely on this occasion, therefore, the plug was re-engineered to reduce the overall weight.

As standard, STATS Tecno Plugs™ feature two elastomeric seals, the dual seal configuration providing an annulus void which is pressure tested to verify both seals are leak-tight. However, as a contingency measure a third seal was incorporated into the design, this additional seal provided a facility to fill the seal annulus with grout if additional sealing was required.

Once the Tecno Plug™ was deployed and set at location, each seal was leak tested at 110% of the


flexitallic, the global leader in static sealing solutions, has expanded its manufacturing capabilities for its innovative Change™ gasket with an investment in new production technology.

The company has invested around £200,000 in state-of-the-art machinery at its facility in Cleckheaton, West Yorkshire, to supplement its existing Change™ gasket manufacturing operation in Texas, United States.

The introduction of the manufacturing equipment will enable Flexitallic to increase production in line with the industry demand for the ChangeTM technology and enable shorter lead-times for Europe and the Eastern Hemisphere.

Change™ has become the most significant development in the gasket and sealing industry

p42 | | March 2017

in the past five years with more than 50,000 sold into sectors such as Steel, Power, Chemical, Refining, and Pulp and Paper, around the world.

Developed by Flexitallic in direct response to customers’ long-term heat exchanger sealing problems, Change™ is a highly-resilient metal- wound gasket, designed to deliver the most dynamic static sealing technology ever.

Manufactured using proprietary equipment, Change™ has a proven track-record showing it outperforms conventional gasket technology in challenging environments, especially in applications with mechanical and thermal cycling conditions.

It has also achieved independent industry accreditation from TALuft for its ability to deliver the tightness of a Kammprofile with the recovery of a Spiral Wound Gasket.

This is achieved through the application of a unique metal spiral profile, which is more advanced than those found in standard gaskets. This profile, combined with a laser welding process, facilitates the construction of a robust and dynamic seal.

for more information on the Change™ Gasket please contact their Applications Engineering Team on: +44 (0)1274 853 463

maximum potential isolation pressure in turn, and once the seal integrity was proved, the annulus was then vented to ambient to create a zero- energy zone, providing effective double block and bleed isolation.

To allow the Tecno Plug™ to reach the desired isolation location, STATS engineered a hydraulically- actuated deployment frame to allow stem bars to be installed in sections, pushing the Tecno Plug™ to location in a controlled manner. Flexible control lines attached to the rear of the Tecno Plug™ provide communication to set the plug, test and monitor the seals.

Prior to the offshore deployment, STATS conducted a client witnessed Factory Acceptance Test at their operational base in Musaffah, Abu Dhabi, which also included two-days of diver familiarisation training on a full-scale replica pipe fixture.

Page 1  |  Page 2  |  Page 3  |  Page 4  |  Page 5  |  Page 6  |  Page 7  |  Page 8  |  Page 9  |  Page 10  |  Page 11  |  Page 12  |  Page 13  |  Page 14  |  Page 15  |  Page 16  |  Page 17  |  Page 18  |  Page 19  |  Page 20  |  Page 21  |  Page 22  |  Page 23  |  Page 24  |  Page 25  |  Page 26  |  Page 27  |  Page 28  |  Page 29  |  Page 30  |  Page 31  |  Page 32  |  Page 33  |  Page 34  |  Page 35  |  Page 36  |  Page 37  |  Page 38  |  Page 39  |  Page 40  |  Page 41  |  Page 42  |  Page 43  |  Page 44  |  Page 45  |  Page 46  |  Page 47  |  Page 48  |  Page 49  |  Page 50  |  Page 51  |  Page 52