Large-scale development Nuclear Projects
CRADLE TO GRAVE SERVICES
COMPREHENSIVE FLANGE & GASKET DESIGN
(TAKING INTO ACCOUNT THE ENTIRE BEAM LINE)
FORCE TESTING
MOCK UP TESTING
(LAB CONDITIONS, CLEAN ROOM, UHV)
MANUFACTURING
FLANGES, CHAMBERS & TUBES, METAL GASKETS
ON-SITE ASSEMBLY, INSPECTION
SPARES & LONG-TERM INVENTORY
1. PRELIMINARY DESIGN
2. DEVELOP FORCE TESTING HARDWARE
Force-test flanges and gaskets for each junction.
3. MOCK VESSELS / TUBES
Build and assemble mock components with RGAs, vacuum pumps, turbos, other connections and junctions that represent full scale. Assemble in Bostec lab for testing and validation.
4. USABILITY TESTING
Study ease of installation, spacing conflicts, thermal cycling, bake to 240º C, seismic, repeated thermal cycles, shock tests, clown mallet.
5. PARTIAL PRESSURE TESTING
Measurement of partial pressures to calibrated UHV standards. Multiple points across vessels and tubes. ‣ Surface area & finish ‣ Gaskets & Flanges ‣ Junctions & Welds ‣ RGAs, Baratrons ‣ Vacuum Pumps, Turbos, etc
6. MANUFACTURE PRODUCTION LEVEL FLANGES & GASKETS
7. ASSEMBLE COMPONENTS AT PRODUCTION SITE
Repeat Partial pressure Testing of Mock Tube
Measurement of partial pressures to calibrated UHV standards. Multiple points across vessels and tubes. ‣ Surface area & finish ‣ Gaskets & Flanges ‣ Junctions & Welds ‣ RGAs, Baratrons ‣ Vacuum Pumps, Turbos, etc
PRODUCE FINAL DESIGNS
MODIFY DESIGNS
BASED ON TESTING
Accelerators
Fermilab’s Tevatron was a landmark particle accelerator; until the startup in 2008 of the Large Hadron Collider (LHC) near Geneva, Switzerland. It was the most powerful particle accelerator in the world, accelerating antiprotons to energies of 500 GeV, and producing proton-proton collisions with energies of up to 1.6 TeV, the first accelerator to reach one “tera-electron-volt” energy.
Bostec engineers worked with FermiLab to solve persistent leakage problems with their aluminum seals that were the principle seal in the 3.9 mile particle accelerator. Failures were principally attributed to seals that had insufficient crush zones to conform to existing flanges, wrong material substrates, and poor tolerances. The existing design also had no mechanism to protect the critical knife edge during replacement; the knife was often unknowingly damaged by technicians who were rushing to complete the work quickly to avoid radiation exposure. The initial design was flawed and plagued FermiLab technicians for many years. Long repair and replacement times resulted in radiation overexposure for many technicians.
Bostec took a holistic approach to the project and redesigned all aluminum seals throughout the ring to one common configuration. Protective shoulders were included with each gasket to shield critical surfaces from damage and aid technicians in installation. Care was taken to ensure the new gaskets were backward compatible with existing flanges.
Before and after results have been significant. Repair times are now reduced considerably, in the range of 50%. Technicians are now more confident seals will not be damaged during installation and consequently are comfortable moving much faster. Gasket failures with the old design were in the neighborhood of 50%; thus 1 out of 2 failed. Using Bostec’s new designs, yields have so far been 100%, no failures have yet been recorded.
BOSTEC’S ROLE: FACILITY-WIDE RESIGN
In 2017, Bostec was named the sole supplier of metallic gaskets to CERN.
CERN operates the worlds largest proton accelerator which covers 26 km of tunnels under the city of Geneva. CERN had been experiencing significant leakage problems with its copper and aluminum seals. Over 10% of their junctions were failing, causing the main beam line to be shut down and costing millions of Euros in lost revenue due to delayed projects.
Bostec undertook a facility wide redesign of all metallic gasket seals in 2016. Time was short and Bostec’s work was conducted on an emergency basis. An American engineering team was assembled and dispatched to CERN. The team lived in Divonne, France, nearby to CERN, to work out new designs and fix the problems. There was considerable travel back and forth to the US to coordinate with manufacturing. Prototypes were built in America and rushed back to CERN for installation and UHV testing. In all, 39 gasket profiles were re-designed ranging in size from 100mm to over 3000mm. All the new designs proved to be successful and Bostec commenced manufacturing of production gaskets to replace the leaking seals. The complete redesign effort took over 1 year and the costs were in time, travel and overhead were high but small in comparison to the lost revenue CERN was experiencing. Full replacement of all gaskets at CERN took over 2 years and consumed over 30,000 metallic seals ranging from 2” to over 40” in diameter.
Assembly yields now are near 100%. In addition, Bostec tackled high failure rates with CERN’s energized seals. That obsolete design required high tensile strength metallic bolts that became nuclear activated over time.
Fusion
The majority of components in a Tokamak system operate at some level of UHV. Most junctions are metal sealed due to radiation. Elastomers are forbidden. The challenge with Fusion systems is the large size and off-round shapes of the flange assemblies. The flanges themselves are heavy and difficult to handle. And the metal seals are equally as large and often difficult to seal. Once in production, radioactivity added to the problems.
Mock-up Testing
IN-HOUSE MOCK UP TESTING
Mock-up testing consists of constructing a full size representation of the finished product. This includes simulation of external conditions, internal loads, RGAs, turbo pumps and other devices.
The principle element tested for in the mock up is total achievable pressure, which is an aggregate of all partial pressures in the system.
Out gassing and permeation is often biggest sources of UHV contamination. The general rule is to use only metal seals, eliminate all elastomers and polymers and anything other than stainless steel. As that is not always possible, the goal is to eliminate as many elements as possible that contribute to contamination.
On-Site Engineering Engagement, Tracking, Training
On-Site Engineering Engagement
Bostec designs, develops and manufactures flanges and precision metals seals for UHV applications, particle accelerators and beam lines.
When working on-site, our method is to study the situation on-site, determine an appropriate solution based on environmental conditions, temperature cycling, mating materials, comparative CTEs and so forth.
We develop prototype designs, mock up and force test plans which are conducted in-house to verify designs. That generally leads to production of a small number of prototypes which are then laboratory and field tested for final iterations. Production volumes are then manufactured.
While on-site, we keep track of structural components, electrical systems, vacuum components, and mechanical systems as well as the design, construction, installation, and testing of the beam line.
Project Tracking & Auditing
While all project deadlines are initially set by our customers, Bostec’s holistic, overall project design focus combined with our real-world manufacturing experience allows us to impose realistic project goals. Because we design major project systems or subsystems and then also manufacture those components, our schedule tracking is realistic and actual.
We first identify major milestones and then utilize Gantt chart systems to track progress. Float times are estimated and critical path points identified.
Frequent and regular meetings with customers are held to keep both parties coordinated.
In some very complex and long term projects, we develop specialized database driven software for tracking. Software tracking through online systems provides real-time visibility to all parties involved.
Repair Training
Bostec specializes in developing service and repair training programs dealing with gasket change-out for use by all technicians. Untrained technicians are the largest single source of postlaunch leaks and failures. The training courses are online and have exams and certificates.
