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Exhaust canals: Need for a common standard

There is a widespread desire in the industry to develop a common standard for the design and construction of exhaust canal systems. This became clear during the Petroleum Safety Authority Norway's seminar on exhaust canals.

15 October 2005, a fire occurred in the waste heat recovery units (WHRU) of one of the generators on Åsgard B. Three months later, a shower of sparks was observed coming out of the turbine hood seal of one of the export compressors on Åsgard B. Both events resulted from vibrations and cracks growing in the exhaust canals above the turbine hood.

Known problem
On Wednesday 7 February the PSA held an industry seminar on exhaust canal systems. The purpose was, inter alia, to contribute to more players effectively being able to exchange their experiences. It appeared from all presentations that vibrations and crack growth were known problems. The PSA's investigations of the two events showed the same.

Important commitment
"Operators, contractors and equipment suppliers all participated in the discussion, and expressed a desire to develop a common standard for design, operation and maintenance," says Chief Engineer Øystein Sævik. He adds that the Petroleum Safety Authority Norway is pleased with the wide support, and that the commitment is of great importance to the work ahead. "We have faith in this resulting in a common standard," says Sævik.

The speeches included Statoil's experiences from the events at Åsgard, and Hydro's views on the challenges the present canal systems may entail. Several equipment suppliers accounted for the design and maintenance assumptions.

Trial and error?
"At present, the adaptations are implemented individually on each facility with no common standard. There is reason to ask whether the design basis could improved, if the exchange of information between users and suppliers is good enough and if there is too much use of "trial and error" methods in connection with maintenance," says Sævik. He pointed out that a lack of control with the connection between the package solutions (turbine-exhaust canal -WHRU) is among the main challenges.

Approx. 70 people participated in the industrial seminar. All presentations can be found in the link box.

Contact in the Petroleum Safety Authority Norway:
Chief Engineer Øystein Sævik