The pressure vessel design, fabrication and certification will be done to ASME pressure vessel Code, section VIII division 2, as much as is possible. Any exceptions must be fully reviewed and approved by an appropriate technical committee.

The vessel design,contracting and fabrication process (individual responsibilities) is defined in ASME code and is as follows:

1. We write a User's Design Specification for the Vessel which includes all ( user required) dimensions, media, conditions, loads, load history, etc. that the vessel will be subject to. ASME PV code sec VIII div. 2, par. 2.2.2 is a specification for what needs to be included, and allows for additional requirements. We will add additional conditions that allow us to assure quality in particular, for radiopurity, from material purchase, through all cleaning, joint preparation, welding, pressure testing step. Normally the Manufacturer performs (or contracts) the calculations to determine wall, flange and nozzle thicknesses, however I understand from Sara that, by agreement we can perform these. However, the Manufacturer is responsible for the pressure retaining integrity of the Vessel (par. 2.3.1.1), and may well want to to do their own. Here I suggest we let the manufacturer choose whether or not to accept our calcs and submit their own, if they prefer.  

2. The User's Design Specification must then be certified by an independent Certification Authority to assure that the vessel is fully specified. Sara has found a group in Madrid that can do this for us. The individual(s) in charge of certifying the Users Design Specification must be licenced professional Engineers (I'm not one, by the way)

3. The Manufacturer must provide a Manufacturer's Design Report, which includes final as-built drawings, design calculations and analyses. This Manufacturer's Design Report must be certified by a Certifying Authority. So, even if the manufacturer, by agreement accepts our calculations, they must be Certified. 

3. A Certified Inspector must be hired to inspect all stages of the fabrication, and certify the vessel is being built in accordance with Specification; we will also perform our own inspections of the fabrication process. I believe the same Certification firm can provide the Inspector.

4. The Manufacturer must be certified to perform all the operations specified in the Specification. They must have a certified Quality Assurance Program in place that can track progress and demonstrate compliance with the requirements for fabrication.

Due to the nature of the vessel, we are taking a much stronger hand in the design and fabrication than is usually done (this will be made clear in the user's Design Specification), however this does not absolve Manufacturer of their responsibilities, so they may well elect to do all their own calcs.













VESSEL DESCRIPTION:

POSSIBLE EXPERIMENTAL CONFIGURATIONS:
  Asymmetric:  
    Energy plane at cathode:
	1. 36-60 encapsulated 3" DIA PMT's -4 pins each, max
	2. 240 (max) hardened 1" cube PMT's - 4 pins each, max
    Tracking plane, at anode:
	1. 180-200 SiPM DB's (64/DB) - 1 coax (2 pins), 1 optical fiber each
	2. 240 (max) hardened 1" cube PMT's - 4 pins each max
  Symmetric:
    Energy/tracking both ends:
	1. 240 (max) hardened 1" cube PMT's both ends, ~70 kV central HV mesh with feedthrough port


	

	
	
CURRENT ENGINEERING ISSUES WITH THE PRESSURE VESSEL DESIGN:

1. Lack of suitable bolting material- ASME code is particularly stringent here -no high strength radiopure material allowed; no Ti bolts - we a need material exception; preliminary calcs show that simply designing for huge copper (or Si bronze?) bolts results in huge flanges (25 cm thk, 1.9m OD). Any hope for radiopure Inconel 718? (50% Ni,20% Fe,20%Cr, with several percent Mo, Nb, 1% Co), high strength steel? should we test? (I'll check Al's database)- A better suggestion, from Sara, is to use a two-piece clamped joint. These are more efficient, allow radiopure materials for the clamps, will have a smaller OD (except at clamp ends, which can be located in the corners of a lead castle) and greatly ease assembly/dissassembly. Win-win-win-win! A Ti anodize process will need to be aplied to the clamps to avoid galling.
2. Flanges and clamps may not be machined from plate using div. 2 rules. This is likely due to planar imperfections in the rolling direction being cross wise to the high stress direction. We will need (roll or other) forgings made, or roll and weld very thick plate