Important points discussed in the meeting are listed below:

Pre-prototypes manufacturing:

• 314L: Small flanges under machining. It is expected that the installation starts around the 20th of March;
• S315MC: Flanges welding pending. Radiographic inspection on-going in qualification plate;
• AISI 430: 
  • Welding studies confirmed a significant grain growth and ductility reduction inducing a brittle fracture during tensile testing
  • Phase identification and quantification is on-going
  • Hardness value for AISI430 according to ASTM A240M* should be ≤ 183 HBW 
  • Next test in autogenous mode will be done looking for a weld width reduction
  • Raw material from Notz metal (1 face grinded) is available in the Main Workshop. The purchase included 5 plates of 1x 1000 x 2000 mm: Purchase Requisition (DAI) 9513821 (cern.ch)

Test specimens: 

• The vacuum test is progressing well and the preliminary studies to understand the thickness influence on the outgassing indicate that the rate is thickness independent;
• Nevertheless, additional testing is needed to better understand why machined samples present different behavior (plastic deformation...);
• Analyses on ULC from TataSteel will be presented to the company representatives on March 16th. FIB-SEM to be completed

Corrugated solution. Why? 

Simulations performed indicate that the thin-walled corrugated solution is suitable for steels that can withstand external pressure with a thickness of around 1.3 mm (designed for a pipe diameter around 1.1 ma buckling differential pressure of 3 bars). Corrugation dimensions are for the moment stablished in 35 mm height and 120 mm pitch. (Information from Cedric and Hana).

Main advantages:

• No need of compensation bellows;
• Light structure that can be supported either from the roof or floor;
• Relatively easier to bake out;
• Reduced amount of material and therefore cost

Some of the challenges already highlighted: 

• Circular welding
• Cleaning procedure

Cleaning test campaign. How to prepare representative samples?

• An study is bein prepared by Leonel in collaboration with an external company (Poligrat) to validate a degreasing procedure on pipes up to 15m long and 1.2 m diameter for the pilot sector;
• The goal of the study is to assess the initial surface contamination of the pipes and compare it with the results after degreasing;
• Up to now only the raw material pollution has been taken into account (oil protective layer and handling);
• In order to have a good reference for each material it is needed to understand possible contamination sources during forming and assembly 
• In case it is needed, the extraction of test specimens can be postponed until the welding procedure for the pilot sector is defined. To be discussed
• CERN capabilities allow large diameters but the length is limited (numerous sections of 1 m would be needed). To be discussed. 

Other: 

• Manjunath will share ASAP an Excel table with the material available and samples inventory that everybody can update
• Erichsen test tooling procurement is under discussion in EN-MME-MM

*A240/A240M: 2022 / Standard Specification for Chromium and Chromium-Nickel Stainless Steel Plate, Sheet, and Strip for Pressure Vessels and for General Applications