First weld for the top lid
Of the four sections that make up the ±¬×ߺÚÁÏ cryostat, the top lid is the thickest, second heaviest (more than 700 tonnes) and most structurally complex. On Monday 7 June, following a traditional coconut ceremony in the Cryostat Workshop that was broadcast live to India, two welders working on opposite sides of the component's skin, produced the "first arc" of a welding campaign that is scheduled to last four to five months.
The collective knowledge and experience that the ±¬×ߺÚÁÏ, ±¬×ߺÚÁÏ India, Larsen & Toubro Ltd and MAN Energy Solutions have accumulated over the past four and a half years since welding operations began on the cryostat base will be a precious asset in the current operation.
"There are some very specific challenges to the welding of this massive component," explains Anil Bhardwaj, the leader of the Cryostat & Auxiliaries Group. "It has a rather thick skin, a large circular opening at its centre and a complex arrangement of ribs underneath. Distortions due to the welding process will be a constant preoccupation and will require constant monitoring."
The cryostat top lid is made of twelve 30-degree sections that will require approximately 300 metres of deep welds (50 millimetres deep on average, but up to 280 millimetres at the flange levels) and more than 4 tonnes of filler metal.
After the cryostat base, lower cylinder and upper cylinder, the top lid will be the last section of the ±¬×ߺÚÁÏ cryostat assembled and welded in India's on-site Cryostat Workshop.