High frequency weld steel pipe weld cracking common defects, cracks, lack of fusion, cold welding, internal and external burrs, inclusion and so on. For weld cracking and crack, the actual detection of defects are strong echo, very easy to detect and determine the crack echo height is generally larger (large crack wave width, small cracks narrow range), and sometimes there will be more peak (instructions are hot cracks). Probe pan, the reflected waves appear continuously, volatility changes, the probe is rotated, the crest will be the upper and lower dislocation phenomenon. Lack of fusion defects is generally small, the defects are the main characteristics of the reflected wave probe pan, the waveform is stable, both sides of the probe, the reflection amplitude is basically the same. HF no metal pipe weld filler material, slag rarely, but because the board edge burrs, rust, pitting, coils itself ingredients and other issues will appear mixed. Mixed surface irregularities, divided into point-like inclusions and strip inclusions. Point-like inclusions echo signal with punctate stomata similar; strip inclusions mostly jagged echo signal, low reflectance, the general volatility is not high, it is a short wave, often dendritic, the main peak of the edge of a small peak. Probe panning volatility of changes detected from all directions, reflecting volatility are not the same.
High-frequency welded steel pipe weld molten metal is extruded outside scraper scraping, but very easy to weld residual internal and external metal, namely internal and external burrs. Glitch in the outer surface of the outer pipe is easy to see, to help identify good, but within a burr in the pipe wall, inspectors can not see, and its echo is often mistaken for weld defects echo, causing false test results. Typically, the inner burr is relatively long, which is continuous and stable echo, after moving the probe, moves with the echo. Within the inner burr usually unilateral burr burr and trapezoidal form. For unilateral inner burr, detection can only be detected in the side seam echo, echo other side of the non-reflective. The trapezoidal burrs from both sides of the weld could be detected echo. Identified within the burr echo method using the following multiples. The sensitivity of the test piece through holes on the vertical adjustment of the probe, the secondary and tertiary echo echo location marked on the testing instrument's display. Unilateral trapezoidal waveform within the burr burr similar waveform detection, and the inner side of the burr from different sides of their detected. The first wave over within the burr hole in the vertical secondary waves, three waves burr wave lags vertical vias three waves, from the horizontal scale of the display can be distinguished glitch waves. Unilateral inner burr echo detected only from the side seam, trapezoidal glitch detection situation is the same from both sides. If the weld defect echo, its echo is generally between two waves and three waves, so you can distinguish between the weld zone and the inner burr flaw echo echo.
