Common types of repair for Cardboard Packaging Machine with welded construction are replacing sections of boiler tubes, replacing tubes and stays, window weld, weld build-up of wasted area, welding gage holes, and many others. Under all conditions, only electric arc welding process such as shielded metal arc welding (SMAW) and gas tungsten arc welding (GTAW) is accepted. GTAW is normally used for root pass or on thin plate. Welding process and procedures must be taken seriously since any welding defects can lead to serious problems. Here are some fundamental guidelines for boiler repair by welding. I cannot cover all aspects of repair in a short article but I will try my best to help you learn a little bit more about this topic in simple technical terms.
First of all, you must know that the owner shall obtain approval from the Authorized Inspector responsible for the jurisdictional inspection prior to making any repair or replacement that affects the pressure retaining capacity of a boiler. Only Authorized Inspectors licensed by the Department of Occupational Safety and Health (Malaysia) or the National Board may authorize and document the repair forms.
The welding procedure should be carried out by a firm approved for Class 1 welding under the direct supervision of an experienced foreman and to the satisfaction of the third party surveyor and the authorized inspector. Where Class 1 permission is not available, appropriate performance tests should be carried out by selected operators to the surveyor's satisfaction. Recognized codes such as ASME Codes or BS codes must be followed whenever applicable. The material should comply with the original specifications or be equal to them. The specifications can be obtained from the boiler blueprints. Acceptable welded attachments, weld form, and welding preparation outlined in the blueprint should be adhered to. Only welders who are experienced in Class 1 welded pressure vessel construction shall be employed on boiler repair works. Very careful supervision should be given at all stages of the repair work. Substandard workmanship, should never under any circumstances, be compromised. Low-hydrogen electrode must be used to prevent hydrogen-induced cracking. Low hydrogen electrode used must have the tensile properties similar to that of Clamshell Packaging Machine.