Quality control of the coatings consists of the following:
- visual control
- coating thickness check
- determination of coating porosity
- test of coating adherence with the base metal
- determination of mechanical coating properties
The Paint Quality is evaluated on the following parameters: absence of cracks and sinks, uniform of color and density pasting, no stains, streaks, mounds, wrinkles and so on.
Demagnetization is the process of magnetization reducing by alternating magnetic field influence with decreasing amplitude to facilitate welding. Welding of pipes and steel constructions with direct current is often accompanied by the effect of “magnetic blow”, which is caused by residual magnetization. Wherein the stability of the process getting worse, there is a sprinkling of metal, forming the weld defects such as pore formation, poor fusion, incomplete penetration, slag inclusions and sometimes welding becomes just impossible because of the disruption the arc and the electrode sticking. Due to the pipe magnetization does not allow to get a good quality of weld, its demagnetization is a necessary process step before welding.
- – the simplicity and ease of operation;
- – demagnetization done before welding, and demagnetized can stacked as welding pipe and as loose ends
- – small demagnetization time (no more than 20 minutes with the installation and dismantling of cables)
- – demagnetized condition is kept long time
- – in case of repeated additional connections pipes demagnetization is not required.