Name of Work: Replacement of Damaged Tubes of W5 Heat Exchanger in SA Plant during ATA 2021
Sl.No.
Item Description
Service Code
Quantity
Units
1
1
Replacement of Damaged Tubes of W5 Heat Exchanger in SA Plant during ATA 2021
2
1.01
Work arrangement and replacement of tubes:-Collect required materials for the work from store and transport to work site. Make necessary site arrangements for the work. Open all manholes of W5 heat exchanger. Arrange required scaffolding. Cut open and remove the top cone of W5 HE along with associated outlet and bypass ducts(if necessary) to facilitate the removal of tubes . After removing the cone the outlet duct and bypass duct shall be given temporary supports. The side (suitable side may be chosen depending upon the site conditions) of the shell along with baffle plate, any other ducts, valves etc. may be dismantled with the concurrence of Site engineer for ease of work for removing/cutting damaged tubes. Thorough cleaning of deposited acid sludge between the tubes and tube sheets using necessary tools to facilitate smooth cutting of old tubes and insertion of new ones. Make necessary site arrangements including scaffolding for the work. Cut and dismantle the damaged tubes. The already plugged tubes, including the plugs shall also be cut and removed. Clean the tube sheet area and prepare the tube sheet hole area by proper grinding. Edge preparation if required shall be done on the new tubes. Erect/insert new tubes in position, full weld top and bottom of the tube with tube sheet. All plugged tubes shall compulsorily be replaced with new tubes. Any additional tubes to be replaced other than damaged/plugged tubes shall be done as per instructions from competent authority. After completion of the replacement works and leak testing remove the blinds from 1800 NB Duct, removal of hose connection / testing arrangements and full weld the duct joint after edge preparation / grinding etc. in order to have leak free joint, removal of scaffolding arrangements, scrap removal etc. Prepare the edges of W5 shell at cone area, cone, outlet duct and bypass ducts. Erect back the cone along with removed outlet duct and bypass duct. Full weld the cone, outlet duct and bypass duct after proper fit up. The ducts shall be erected back without any strain. Pad plates shall be provided at joints with full welding if required as per instructions from competent authority. After welding the cone and ducts erect back the dummies and man hole covers. Any other ducts, valves etc. that were removed from the site, shall be welded back once the retubing work is over and shall be under the scope of the contractor's work. Any structural supports for ducts shall be provided. Clear the site after work and transport the scrap to scrapyard. After completing the work, damaged/removed tubes shall be transported to scrap yard. Usable tubes shall be neatly stacked in area earmarked. [1 no indicates cutting and removing of existing tube including plugs, edge preparation, inserting new tube and full welding on both sides of tube sheets].
CDM-S-W5-01
800
NO
3
1.02
Choke clearing:-All choked tubes which are not damaged shall be cleared manually .Full length of the tubes shall be cleared for free passage of gas
CDM-S-W5-02
1000
NO
4
1.03
Transporting the required MS plates from stores /near by plant area, collection of scaffolding material etc. and providing the required scaffolding at site / site arrangements. Marking / cutting the new MS pates [8mm thick, approximate OD 2000 mm ] for providing slip plates (1800 mm dia) and grinding the inside / outside plate edges properly. Cutting and blinding the W5 inlet and outlet duct, 1800 mm dia and full welding in order have a leak free joint. Fabrication and erection/hooking up of air lines with necessary accessories like hose connection/valves etc. at desired point for leak testing of W5 tubes. Provide required assistance for leak testing. Leak test the replaced tubes as per standards and instructions from competent authority. Any leaks detected shall be corrected as per site instructions.
CDM-S-W5-03
1
LS
5
1.04
Plugging the leaky tubes of W5 on both sides with suitable plugs and full welding as per instructions of Engineer-in-Charge .1 No= 2 plugs
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