Exhaust Systems WG

The aim of ETN in producing this Recommended Practice is to create a document that can be submitted to the industry and eventually be recognised as an ISO Standard.


To optimise the design of the Waste Heat Recovery Units and address exhaust system issues.



The Exhaust Systems Project was initiated in 2009, and initially chaired by Statoil, as they experienced problems with their exhaust systems. The goal was to bring together operators facing similar problems with their exhaust systems, as well as exhaust system designers and external expertise and support, who could address the problems by developing a common standard for the design of gas turbine (GT) exhaust systems.


In the first phase of the project, the group carried out a gap analysis, uploaded an index to facilitate the creation of the standard, and collected valuable material. Both Shell and Statoil shared their internal standard. In the autumn of 2010 Total took over the lead of the project group. The shared standards were then merged as well as supplemented by additional internal documents, which had been provided by exhaust system designers, such as Mjørud and BIHL.


During various meetings it was decided to focus on the creation of the Waste Heat Recovery Unit (WHRU) standard and later amend the existing API standard on Heat Steam Recovery Generators (HRSG). The different organisations have reviewed their section of the standard which will be rewritten to fit ISO standard regulations.


Moreover, it has been decided that the standard should highlight the possibilities and importance of Computational fluid dynamics (CFD) simulation. The group agreed that the best way to validate the CFD code is to use a benchmark case which can be included in the appendix of the standard. ETN, Total and Frazer-Nash have writteb the Description of Work (DoW) for the benchmark test, explaining the benefits of the study and including a clear timeline and financial overview.


Utilities are encouraged to join the Exhaust Systems Project which provides a forum to present and discuss problems experienced in the design of WHRU and HRSG systems, as well as to exchange best practices with the other project group members.


The ETN standard has been issued in 2015. In February 2016 the ISO TC 192 initiated a New Work Item aiming at drafting an ISO standard on the WHRU based on the ETN standard. As liaison member of the ISO TC192, ETN is following the development of the ISO standard.



Ole Torp (Mjorud)
Paul Setchfield (Mjourd)
Ugo Simeoni (ETN)


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