European network for component integration and optimisation (ENCIO) : final report

The general objective of ENCIO was to test Ni-based components under power plant conditions in order to make 700°C power plant technology ready for deployment. Technical problems with new materials and/or manufacturing methods resulted in a one year delay in the intended operational start of the test facility. The manufacture of further superheater tubes after finding of inner surface cracks and further expected delays during erection, commissioning and operation resulted in a termination of the project before commissioning of the Test Facility. However, the engineering, manufacturing and assembling of the Test Facility led to the following results. The Alloy 617 family (Alloy 617 mod., Alloy 617 B, Alloy 617 occ and HIP Alloy 617 LCC) fulfilled PED 97/23/EC for a Test Loop installation, and they are the candidate materials for a 700°C steam generator. No final conclusions can be drawn for the pipe material Alloy C-263 and the turbine material Alloy 625c regarding leak-before-rupture behaviour under internal pressure. The minimum detectable and critical flaw sizes for volumetric inspection methods like Linac or UT have to be determined. Other components in the test facility, such as monolithic valves, pipes, and superheaters, were manufactured from Alloy 617 B, and manufacturing required highly skilled craftsmen, strict observance of protocols, validation of quality tests and surplus production. There are two possible ways for future application of the Ni-based material. The first way is to continue the development of 700°C technology for deployment. The second route is to replace thick-walled components in power plants operating at temperatures up to 600°C with thinner-walled components in Ni-based materials, to increase the flexibility of power plants.