Tender For Supply Of Gas Gap Switch., delhi-Delhi

Tender For Supply Of Gas Gap Switch. 1 Fabrication Of Gas Gap Switch As Per The Attached Drawing Scope Of Work For The Supply Of Gas Gap Switch. A Gas Gap Switch Is A Device Having Two Cylindrical Copper ( Etp Quality With Certificate ) Surfaces Positioned With An Annular Gap Of 100 Micron Without Any Physical Touch. These Copper Cylindrical Posts Are Positioned Inside A Thin Walled Ss-304 Tube Which Helps To Minimise Conduction Heat Load At Low Temperature. The Switch Has A Small Charcoal Chamber At The Top Which Is Used To Activate The Switch With A Small Heater. At The Bottom A 1 / 8” Copper Tube Is To Be Kept For Filling Of Activation Gas Inside The Switch. All The Copper Surfaces Need To Be Gold Plated To Avoid Oxidation Of The Surface Before The Final Welding Is Done. The Most Important Feature Of This Assembly Is Its Low Clearance Between Two Annular Concentric Cylindrical Parts. Its Annular Clearance Is 0.1 Mm After Gold Plating Of The Copper Posts And Also Between The Outer Copper Post And The Id Of The Thin Ss Tube. Important Fabrication Requirements Are Listed As Follows. 1. The Thin Wall Cylinders Are To Be Made Concentric Without Ovality Throughout Its Length. 2. Surface Finish All Over To Be Maintained At Super Finish. 3. Outer Ss Tube ( 0.3-0.4Mm Wall Thickness ) May Be Preferably Seamless Tube With Little Distortion And High Cylindricity. If Specified Thin Walled Ss Tube Is Not Available Then It Can Be Machined From A Higher Thickness Seamless Tube Leading To Desired Size. 4. Brazing And Welding To Be Done With Extra Caution ( Use Of Temporary Fixture If Necessary ) For Safeguarding Against Dimensional Deviation. 5. Welding To Be Carried Out After Brazing, Should Done Cautiously To Avoid Excessive Heating, Leading To Leaks From The Brazing Joint. 6. Allowance To Be Kept For Gold Plating So That The Final Clearance Can Be Obtained. 7. Final Assembly To Be Checked By Helium Leak Testing Using Msld And To Be Leak Proof At A Leak Rate Of ~1E-9 Mbar Lit Per Sec At Normal Condition As Well As After Cold Shocking In Liquid Nitrogen For 3 Times. Temporary Testing Fixtures May Need To Be Made For The Leak Testing. 8. Material Shall Be Made Of Stainless Steel ( Ss-304 / Ss-316 With Certificates ) And Etp Copper Suitable For Low Temperature Application. 9. Final Acceptance Is Subjected To Satisfactory Results Obtained From The Leak Test And Conductance Test For Maintaining The Annular Clearances. Conductance Test To Be Carried Out In Two Stages Such That First One For Copper To Copper Clearance And Second For Copper To Stainless Steel Cylinder Clearance. These Ensures Final Assembly Is Retained Its 100-Micron Clearance Without Any Contact All Along The Annular Path. The Test Results Have To Be Submitted With Video Clips Showing Mustimeter Connected At Appropriate Points With Live Reading Zero Continuity In Support Of Their Proof For The Final Acceptance Of The Product.

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INR 1.20 Lakhs /-