Reception Tests of the Cryogenic Distribution line for the Large Hadron Collider

The paper describes the thermo-mechanical validation of the first sector of cryogenic distribution line (QRL) [1]. The design of the line is recalled and the test methodology presented together with the main results of the reception test at cryogenic temperature

Design, Production and First Commissioning Results of the Electrical Feedboxes of the LHC

A total of 44 CERN designed cryogenic electrical feedboxes are needed to power the LHC superconducting magnets. The feedboxes include more than 1000 superconducting circuits fed by high temperature superconductor and conventional current leads ranging from 120 A to 13 kA. In addition to providing the electrical current to the superconducting circuits, they also ensure specific mechanical and cryogenic functions for the LHC. The paper focuses on the main design aspects and related production operations and gives an overview of specific technologies employed. Results of the commissioning of the feedboxes of the first LHC sectors are presented

Design, production and first commissioning results of the electrical feedboxes of the LHC

A total of 44 CERN designed cryogenic electrical feedboxes are needed to power the LHC superconducting magnets. The feedboxes include more than 1000 superconducting circuits fed by high temperature superconductor and conventional current leads ranging from 120 A to 13 kA. In addition to providing the electrical current to the superconducting circuits, they also ensure specific mechanical and cryogenic functions for the LHC. The paper focuses on the main design aspects and related production operations and gives an overview of specific technologies employed. Results of the commissioning of the feedboxes of the first LHC sectors are presented

Application of risk analysis in maintenance of ship power system elements

Searching for a safe ship, this paper presents operational strategies which are used for ship power system maintenance, conditions for their realization have been shown. The procedure of risk analysis has been decomposed and its stages have been discussed. Methods of risk evaluation and methods of ship power system threat identification have been analyzed. The choice of risk evaluation method has been made for the management of maintenance of elements of the system taking into account good maritime practice, ICM code, regulations of classification societies and international maritime organizations. Studies on possibilities of extending operational time of the engine from the main power system using risk analysis with the Expert Method have been presented. On the basis of the results of studies, applicability of the Expert Method for risk analysis on ships has been shown

The influence of controllable pitch propeller on the correct operation of a ship’s power transmition system

W artykule pokazano znaczenie poprawnej pracy nastawnej śruby napędowej dla bezpieczeństwa żeglugi statku. Dokonano identyfikacji funkcjonowania pneumatycznego układu sterowania śrubą nastawną. Przedstawiono wyniki pomiarów zmian wartości rzeczywistych nastaw skoku śruby napędowej w funkcji wartości ciśnienia powietrza sterującego. Zarejestrowane rozbieżności przypisano eksploatacyjnej degradacji stanu technicznego układu sterowania nastawą skoku śruby. Skonfrontowano je z zależnościami projektowymi i czasem eksploatacji. Pokazano możliwe konsekwencje użytkowania śruby nastawnej z tego typu niesprawnością dla poprawności pracy układu ruchowego statku.This study shows the importance of correct operation of controllable pitch propeller for the safety of navigation. Operation of pneumatic control of controllable pitch propeller in a ship’s power transmission system was identified. The results of the change of the actual setting value measurements of the pitch screw propeller in the function of the value of the control air pressure have been presented. Recorded differences were assigned to operational degradation of the technical state of the pitch propeller control system. They were further confronted with the relationships between the design and time of operation. Possible consequences of operating a controllable pitch propeller with such a defect, and its impact on the correct operation of a ship’s power transmission system have been outlined. Operational requirements were presented

Weldability of high strength steels in wet welding conditions

In this paper are characterized problems of high strength steel weldability in underwater wet welding conditions. Water as a welding environment intensifies action of unfavourable factors which influence susceptibility to cold cracking of welded steel joints. The susceptibility to cold cracking of S355J2G3 steel and S500M steel in wet conditions was experimentally estimated (by using Tekken test). It was concluded that the steels in question are characterized by a high susceptibility to formation of cracks in welds. Usefulness of the proposed Temper Bead Welding technique (TBW) was experimentally verified as a method for improving weldability of the steels in the analyzed conditions

Analysis of thermo-mechanical pipe-strength for the LHC helium relief system and corresponding helium flows following a resistive transition of the magnets.

The LHC cryogenic system will contain of about 100 tons of helium mostly located in underground elements of the machine. The amount of helium stored in the magnet cold masses located in one sector of the LHC machine will be of about 6400 kg. In case of a simultaneous resistive transition (quench) of the magnets of a full sector of the accelerator, the helium will be relieved to a dedicated relief system. The system will comprise header D, quench lines connected to medium pressure tanks, vent line open to environment and accessories. We analyse a dynamic behaviour of the system with respect to its thermo-mechanical properties and overall capacity. Spatial and time distribution of pressure, temperature, velocity, density and flow rates in the system elements are presented. Thermo-mechanical stresses in the critical pipe sections have been calculated