choke clearing of tubes in w5 heat exchanger and leak testing of w5 and w2 heat exchanger tubes in sa plant fact - cd , during ata 2020 . , choke clearing of tubes in w5 heat exchanger and leak testing of w5 and w2 heat exchanger tubes in sa plant fact - cd , during ata 2020 . , arrangements for w5 tube choke clearing: collect required materials / tools 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 choke clearing 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 . , cleaning of acid sludge between the tubes and tube sheets of w5:- thorough cleaning of deposited acid sludge between the tubes and tube sheets using necessary tools to facilitate improvement of efficiency of heat exchange process . , choke clearing of w5 heat exchanger tubes:- make necessary site arrangements including scaffolding for the work . each blocked tube shall be cleared using suitable equipment . , arrangements for leak testing of w5 and w2 tubes . :- 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 . closing of w2 outlet vent dummy , 800 nb , with proper gasket in order to 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 and w2 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 . , plugging the leaky tubes of w5 and w2 on both sides with suitable plugs and full welding as per instructions of engineer-in-charge . 1 no= 2 plugs . , full welding of cone and boxing up w5 and w2:- removal of blinds from 1800 nb duct for w5 , and other dummies closed for w2 , 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 work is over and shall be under the scope of the contractors work . any structural supports for ducts shall be provided . clear the site after work and transport the scrap to scrapyard .