Repair Procedure for Roof Leakage in LHB AC coaches.
ANNEXURE - 1
Procedure for FRP trough Roof Leakage in LHB AC coaches-testing & repair
1) Drain outlet of FRP trough to be cleaned from (outside) end wall side to clear any blockage due to dry leaves, dirt, garbage and sediments.
2) Visual inspection of RMPU bellows of return air & conditioned air, RMPU bellow gaskets, tightness of bolts, if any defects observed it has to be attended. If the duct bellows are found to be damaged, replace the damaged duct bellows.
3) Non-AC area ceiling below RMPU trough and Lavatory ceiling have to be removed and kept in open condition to check and locate the water leakage during leak testing.
5) Water has to be poured over the condition air duct bellows, return air duct bellows, Fresh air duct bellows & their joints with car body, harting connector gland, cable entry through flexible conduit end-fitting on coach inside, RMPU trough drain area and entire circumference of FRP trough seating area over the car body. During leak test, two persons shall be available inside the coach along with proper hand lamp and permanent marker pen. Leakage area has to be marked with permanent marker Pen.
6) lf there is no leakage in the FRP trough, ensure there is no crack/ damage/ peel off in sealant.
7) lf damages / crack found in sealant, procedure given in Annexure-A has to be followed.
8) lf there is leakage observed from the surface of FRP trough, surface cracks has to be attended following procedure mentioned in Annexure-B.
9) Suitable packing (Compreg/ Rubber) to be provided between transition return air duct and FRP trough, to avoid bending of transition return air duct.
10) Drain pipe arrangement to be modified as per Drg No.593-6-3-001 ALT 'L'.
11) The above activity shall be carried out prior to monsoon seasons / whenever necessary, to achieve leak free trains '.
ANNEXURE.A
Repair of damaged sealant
1) Peeled Off/ cracked/ loose sealant has to be removed using knife. Removal of old sealant and surface preparation by grinding the entire surface of the RIVIPU area by using 36 grit sanding sheet to make it free from old adhesive, dust, dirt, oil, grease, fungus and rust etc.
2) Fresh Sealant of approved brand with more than 6 months left over shelf life shall be applied on the affected area.
3) Sealant shall be applied at RMPU drain area in such way that sloping shall be towards the end wall in order to ensure free flow of rain water.
4) Curing time shall be ensured for proper curing of sealant applied.
5) After complete drying of sealant, fire barrier water tight tape covering the entire sealed joints to be pasted all over the joints between RMPU tray and coach shell uniformly to provide additional support and protection to prevent water entry. After application of fire barrier water tight tape of correct size,. water test to be done to check water leakage.
ANNEXURE.B
Repair of FRP RMPU
a. RMPU air bellow duct cover, that covers the RMPU and roof sheet has to be removed. (if available)
b. Harting connectors, Earthing cables, return air duct bellows, fresh Air duct bellows and conditioned air duct bellows have to be detached from the RMPU unit.
c. RMPU has to be dismantled from RMPU mounting bracket lifted from the coach by using overhead crane or mobile crane.
d. Entire trough area has to be cleaned and foreign materials like, tree leaves, cotton waste and other muck has to be removed. Blockage /choke at RMPU drain has to be cleared.
e. FRP trough shall be cleaned thoroughly with water and shall be free from dirt.
f. Defective area and nearby surrounding area, top surface layer to be chipped off by using grinding machine.
g. Then the area has to be cleaned thoroughly by -using brush/ compressed air / cotton waste.
h. One coat of putty (FRR 2645 resin + chalk powder) shall be applied over the chipped off area. immediately, one coat of FRR 2645 resin shall be applied over that area. Then CSM 450 / 300 glass mat shall be laid over the resin and again resin shall be applied over the mat.
i. This process shall be repeated, till the required depth is covered by the FRP material. Finally smooth mat shall be laid as a top layer and to be levelled.
j During the course of FRP trough work, no other parallel work shall be permitted in order to ensure proper bonding. After completion of above work, FRP trough should not be loaded and disturbed for 2 hours.
k. If damages / crack found in sealant, procedure given in Annexure-A has to be followed.
l. Leak test to be carried out.
m. After attending the leak points, RMPU to be re-loaded and all air duct bellows connections, mounting bolts and Harting cables to connected, RMPU covers to be re-fitted also to be ensure
