Analysis Qualitative of the Influence of Flow Thermal on Both Sides of the Joint Welded in Welding Orbital

Abstract

This work presents a qualitative analysis of the decrease or increase of the difference temperature in the pipeline through graphics in order to verify if the mass difference and unknown parameters (density etc.) existing on both sides of the installation contributes to the emergence of discontinuities (highlighted the lack of lateral fusion). To determine if these characteristics affect, were carried welds in pipe, observing the thermal flow with use of a thermographic camera in order to analyze the variation of temperature in symmetrical points. The welds were carried out in downhill progression by using orbital displacement device (mechanized welding), ER70S-6 wire with 1.2 mm diameter and Ar+25%CO2, as shielding gas (15 l/min). The material was deposited on butt V joint with 15º bevel, 1 mm of root face and 3 mm root opening, without backing. For the proposed joint, GMAW processes with short-circuit metal transfer was assessed the derivative mode by using commercial power source namely STT (Surface Tension Transfer). In this context, decrease and increase temperature was investigated for root pass and filling pass. Were carried out a total of 12 welds (6 root pass and 6 filling passes) in two test pipe (with 3 tubes and 2 tubes). After, the recording files ceded by the thermographic camera were decoded and analyzed with of Matlab and OriginPRO® software. The results showed that the rate decrease of temperature the in both sides of the pipe doesn't affect the welding generally because the temperature difference in both sides for symmetrical points in the worst case it's 4 °C.

Key-words:
Pipe welding; GMAW; Rate temperature; Thermographic camera; Discontinuity; Controlled Metal Transfer