Development and testing of fixture to automate the welding process for hydro end cover plates

Abstract

A simple mechanical fixture is developed to overcome the difficulties encountered in welding of hydro end cover plates with pipes using shielded metal arc welding (SMAW) process. This paper relates to semi automation of hydro end cover plate with pipe welding in submerged arc welding (SAW) machine for which the fixture is designed to avoid manual welding to eliminate cracks. Hydro end cover consists of a pipe of SA335 P12 grade material and a plate of carbon steel of higher thickness and it is welded manually. Presently, the pipes of hydro end covers are heated by Liquefied Petroleum Gas (LPG) burner to obtain necessary pre-heat and the inter pass temperature. Due to higher thickness and faster cooling rate crack occurs at weldment. Manual welding of the Hydro end cover plate results in more LPG consumption, more electrode wastage, cracks, laborious and unsafe way of crack removal, and poor surface finish. Hence, the need was felt to develop an apparatus to complete the welding of hydro end covers pipes with plate in automated mode in SAW machine. Welding of hydro end covers pipes with a plate in SAW machine using the developed fixture eliminated welding cracks. In addition, cycle time is reduced by 76%, and saving of 480 kg of LPG per job is obtained.