Procedure for Disassembly and Removal of Top Portion of Central Baffle Stack from 4m Mayall Telescope

Transcription

1 Doc #: 2100-AD Revision: - Procedure for Disassembly and Removal of Top Portion of Central Baffle Stack from 4m Mayall Author(s): Matthew Evatt

2 Contents Revision History Purpose Applicable To Scope Definitions Training Safety Personnel, Equipment and Material Required Procedure Procedure Review Records AD Docx Page 2 of 13

3 Revision History Rev Date Approved Sections Affected Reason for Change Remarks and/or Change Details Name Initiated M. Evatt - 1/30/2018 Initial Release M.Evatt Approved by: Matt Evatt Name, ME Title SigEM Name, EL Maint SigSci Name, SciOps Tammie Lavoie 31 January 2018 Tammie Lavoie, Safety Manager Date 2100-AD Docx Page 3 of 13

4 1.0 Purpose The purpose of this procedure is to describe how to disassemble and remove the top portion of the 4m Mayall s center baffle assembly from under the telescope after the whole baffle has been removed from its operational position in the telescope (see Figure 1). The part being removed will not be reused during DESI. Figure 1. Baffle and Cart 2.0 Applicable To 4m Mayall telescope center baffle made up of part numbers E002 Coudé #3 Lower Support and Primary Defining Unit Assembly, E002 Coudé #3 and Baffle Assembly, and E702 Coudé #3 Replacement Counterweight). 3.0 Scope It is assumed that the telescope will be in the following condition prior to starting this procedure: 3.1 positioned at Zenith 3.2 Declination and RA Zenith stay bars installed 3.3 The telescope drives locked and tagged out 3.4 Primary mirror removed from telescope 3.5 The Cassegrain Ramp rotated all the way east (passed the limit switch) and tied into place as described in 2100-AD Mayall Primary Mirror Removal Procedure AD Docx Page 4 of 13

5 3.6 The Baffle Assembly sitting on the Baffle Stack Cart (2140-E9) in its standard storage location (Figure 2) near the south west corner of the telescope mount assembly. Figure 2. Center Baffle on Cart in Storage Location 4.0 Definitions N/A 5.0 Training Training required for personnel using this procedure is: 5.1 Crane Operator training (one person) 5.2 Qualified Rigger training (at least one person) 6.0 Safety 6.1 JHA Form 6.2 Daily Briefing Form 7.0 Personnel, Equipment and Material Required 7.1 Personnel Required 2100-AD Docx Page 5 of 13

6 Crane Operator Qualified Rigger Mechanics 7.2 Equipment Required Ton Dome Crane Foot (minimum) Extension Ladder Ratchet Strap (or a rope) to lash the ladder to the stack at least 15 feet long Container or bag to catch drill chips preventing them from falling into the mirror cover mechanism inside the Coudé stack ½ Electric Drill with 17/32 Drill Bit (clearance for ½ screw) Ratchet Drive with ¼ Hex Bit ¾ Wrench ½ Drive with ¾ Socket, 1-1/8 Socket EA Coudé Stack Lifting Fixtures (Figure 4) EA 20 ft x 4000 lb minimum capacity lifting slings EA 2500 lb capacity Hoist Rings with ½-13UNC x 1 inch long thread (e.g. McMaster Carr 2994T65) 7.3 Material Required N/A 2100-AD Docx Page 6 of 13

7 8.0 Procedure 8.1 Ensure the baffle stack is tied off to the telescope mount so it cannot move when a ladder is placed against it (JHA-1). 8.2 Set up an extension ladder (20 ft minimum) to drill three holes near the top of the baffle stack as shown in Figure 3 (JHA-2). Figure 3. Hole Drilling Instructions 2100-AD Docx Page 7 of 13

8 8.3 Attach one Baffle Lifting Fixture to each hole as shown in Figure 4 (JHA-3). Figure 4. Lifting Fixture Assembly 8.4 Move the baffle stack on its cart to a position where the 5 ton crane can be moved directly over it so the crane can lift it straight up without hitting anything (Figure 5) (JHA-4). Figure 5. Baffle in Removal Position 2100-AD Docx Page 8 of 13

9 8.5 Rig the baffle stack with three 20 ft straps going from the 5 ton crane hook down to each of the shackles on the Coudé Stack Lifting Fixtures (JHA-5). 8.6 When rigging has been completed, take the slack out of the slings with the crane (JHA-6). 8.7 With the weight of the stack supported by the crane, remove the 40EA ½-13 screws and lock washers (Figure 6) (JHA-7). Figure 6 Starting Disassembly of Stack 8.8 When all screws have been removed, use the crane to lift the stack up (Figure 7) (JHA-8). Note that the weight of this load should be around 1210 lbs AD Docx Page 9 of 13

10 Figure 7. Lifting Top Portion of Coude Stack 8.9 When being moved with the crane, make sure someone is assisting the crane operator by watching the load. Do not let it contact the telescope or anything else as it is moved. Set it on the Main Floor to the east of the floor hatch (JHA-9) AD Docx Page 10 of 13

11 8.10 The remaining parts of the stack look like this (Figure 8): Figure 8. Defining Unit and Coude #3 Counterweight 8.11 The Coudé #3 Counterweight must be removed next. Attach four lifting rings to the ½-13UNC holes on the top rim of the counterweight (JHA-10). The counterweight should weigh about 2100 lbs. Figure 9. Lifting Rings on Counterweight 8.12 Bring the 5 ton crane hook back over the counterweight, and attach four 2500 lbs capacity lifting straps between the hook and the four lifting rings on the counterweight (JHA-11) With load rigged up to the crane, remove 12 EA ½-13UNC cap screws and washers that hold the counterweight onto its mounting flange using a ¼ Allen Wrench (JHA-12) AD Docx Page 11 of 13

12 Figure 10. Remove 1/2-13 Cap Screws 8.14 When all the screws have been removed, lift the counterweight up and place it on the main floor to the east of the hatch (JHA-13) Move the cart containing the Defining Unit to its storage location near the SW corner under the telescope mount (JHA-14) Lower the two portions of the stack that were placed to the east of the hatch down to the ground floor for removal from the 4m (JHA-15). This procedure is now complete. 9.0 Procedure Review This procedure is meant to be used once during the DESI installation. If it is to be used after the DESI installation has been completed, it is to be reviewed prior to use Records Regular paragraph here Number paragraph References Call out procedures by number & title DOCUMENT NUMBER DOCUMENT TITLE 2100-AD Docx Page 12 of 13

13 NA KPNO Emergency Manual 2100-AD Docx Page 13 of 13