Manufacture and test of seismic bellows for ITER magnet feeder

Highlights: • The design of the double bellows was iterated with the results of analysis based on the Expansion Joint Manufacturers Association (EJMA) standard. • The seismic bellows was tested with cyclic pressurization of the interlayer space to 2 bars absolute pressure for 5 cycles. • 200 cycles of tensile fatigue test with 90 mm of stretching from the nominal design length. • A full tensile test with 315 mm of stretching from its nominal length was conducted. • The prototype bellows was qualified for its leak tightness (less than 1 × 10⁻⁹ Pam³/s of helium) at all time during the qualification test. - Abstract: This paper presents the key manufacturing and testing processes of the prototype ITER feeder seismic bellows. The design of the double bellows was iterated with the results of analysis based on the Expansion Joint Manufacturers Association (EJMA) standard. Each inner and outer bellows was supported in dedicated molds and formed by a hydraulic pressure machine rated at 800 tons. The double bellows were constructed by welding individual collars to the end flanges. The seismic bellows was tested with cyclic pressurization of the interlayer space to 2 bars absolute pressure for 5 cycles. This was followed by 200 cycles of tensile fatigue test with 90 mm of stretching from the nominal design length. After the mechanical fatigue test, a full tensile test with 315 mm of stretching from its nominal length was conducted. Helium leak tests, with the sensitivity of the helium leak detector set to 1 × 10⁻⁹ Pa m³/s of helium, were performed at different stages of pressure and mechanical tests. The prototype bellows was qualified for its leak tightness at all time during the qualification test.