A. Fabrication Procedure:
1. Prepare leveled horizontal bed before starting any activity. 2. Prepare marking of items as per approved cutting plan & check the marking before gas cutting. 3. All the items have to be cut by automatic gas cutting process as far as possible. 4. The items which need to be joined by welding to be prepared as per following process a. Cut the items as per suitable length.
b. Prepare bevel as per drawing & that has to be checked by L&T, QAQC Dept. The bevel surface to be ground smoothly before joining/fit up. & shall be checked 100%by 100% check byPT MT for FULL PENETRATION BUTT JOINTS & shall be recorded as per ITP format.. c. Join the two parts to be welded by maintaining root angle, root gap, root face etc. as per approved drawing/WPS/PQR(WPAR)/WPAR. d. Welding clearance has to be taken from QAQC dept & that has to be recorded accordingly. e. Run off/on plates to be fixed as per groove configuration at the both ends for any groove joints. f. Put ‘C’ or ‘U’ clamp of higher thickness (32mm min.) with all round welding at a suitable spacing at the top surface (for double ‘V’ joints) of the plate joints. g. Turn the plate at the opposite direction with proper care. h. Lock the plates with the bed by putting angles at a suitable spacing & check the flatness of the plate. The flatness should be within tolerance. i. Engage two nos qualified arc welders for root welding by SMAW process. j. Preheat the plate first by engaging two pre heating persons from middle of the joints & they will move opposite in direction for uniform heating. Check the preheating temperature by Thermo chalk before starting welding. Preheating to be done as per below mentioned table and indicated on the approved WPS/ WPAR. |Material Specification|Recommended Electrodes |Carbon |Plate thickness |Preheating |Interpass Temperature(0C) | | | |Equivalent |(mm) |temperature (0C) | | |SAILMA 350HI |AWS E7018 -1 for SMAW,EL-8 |0.37-0.43 as per|12–140 mm as per |Asper approved WPS |As per approved WPS | | |for SAW & ER70S-6 for GMAW |MTC |drawing | | |
|Material Specification |Plate thickness (mm) |Preheating temperature (0C) | |Recommended Electrodes | | | |Carbon Equivalent | | | |Plate thickness (mm) | | | |Preheating temperature (0C) | | | |Interpass Temperature(0C) | | | | | | | |SAILMA 350HI | | | |AWS E7018 -1 for SMAW,EL-8 for SAW & | | | |ER70S-6 for GMAW | | | |0.37-0.43 as per MTC | | | |12–140 mm as per drawing | |...