Critical joint integrity service managed

Edited by the Engineeringtalk editorial team Feb 27, 2006

Recently completed Brent Delta shutdown for Sigma 3 involved work on some 906 flanges, ranging in size from 1.27 to 92cm and from 68 to 1130kg ratings, with stud sizes of 1.27 to 7.62cm.

A joint integrity programme on nearly 1000 critical joints has been managed under the Pressurised Systems Integrity Management (PSIM) service from Furmanite as part of the recently completed Brent Delta shutdown for Sigma 3.

Some 906 flanges, ranging in size from 1.27 to 92cm and from 68 to 1130kg ratings, with stud sizes of 1.27 to 7.62cm, have been worked on by Furmanite under the PSIM programme, on the gas coolers, compressor (low pressure option plus), manifold valves, gas export valve, test separation, high pressure separation, high pressure flare knock out drum, all main vessel isolations and fuel gas tie-ins.

The service covers every stage from joint inspection and engineering analysis, unbolting and machining as required, gasket installation and controlled bolting, to eliminate joint failure and ensure leak-free joints on start-up.

Furmanite technicians undertook initial work in advance of the shutdown to identify the joints requiring work and marked these on the process and instrument diagrams at Shell's offices.

Weekly meetings helped compile the plan for Furmanite's activities during the shutdown and gather information on the activities being added to the shutdown activity register.

This stage saves time and reduces workscope pressures, avoiding delays during the shutdown.

Two visits were made to the platform before the shutdown to tag the relevant joints using the PSIM colour coded system.

These are then updated as work proceeds, providing immediate status recognition.

The information relating to each joint, including all mechanical and work data, is also logged on the bespoke PSIM system, held and managed by Furmanite.

A detailed history of each joint is thus built up to create a comprehensive, easily accessed record for full traceability and assistance in future maintenance planning.

The PSIM system was introduced last year and addresses all factors known to cause leaks (typically flange distortion, sealing surface damage, incorrect bolt loads and uncontrolled tightening methods) for an on-schedule, zero-leak start-up.

Among the key benefits of the service are avoidance of costly delays, reduced equipment and testing costs and need for rework, and earlier demobilisation of labour, all of which contribute to driving down cost and reducing risk.

In addition to the flanged joints, Furmanite also worked on the 147 and 200cm diameter coolers.

With the cooler cover and dome end removed, the seal faces were surveyed for flatness, found to be within tolerance so no machining was required, and then closed and the 7.6 and 7cm studs tensioned, to ensure a reliable seal.

The technicians were also able to undertake additional services while mobilised to the platform.

As well as general maintenance work, this included hot tapping and drilling a 15.2cm hole into an 45.7cm stainless steel line to tie in a new branch welded on to the line, as well as remachining on-site two 20cm flanges that had been damaged in transportation.

"This project has highlighted both the benefits of our new PSIM service for a leak-free, on-time start-up, and the ability of our technicians to multi-task for optimum efficiency that's particularly valuable within tightly scheduled shutdowns offshore," Furmanite Business Manager Graham McKay said.

"This is representative of our approach to offer technologies and services to help minimise downtime".