(1) to determine their prestressed spiral steel
pipe pile production process, according to foreign related record is extensive, and the use of LSAW pipe expansion process, turn off any part of the yield limit, residual stresses are close to zero.
Heating the outer surface of the tube is wrong surface can show cracks, creases and for migraine and other wastes reasons.
(2) the spiral weld line tracking difficulty and ultrasonic detection and tracking compared to, so the probability of welding defects exceeds the submerged arc welding straight seam steel pipe will be higher.
This behavior is heated uniformly heated to a key blank suitable for processing temperature. Although significant impact drilling, i.e., the quality, the process temperature in the elbow is an important condition affecting quality, which is generally operated drilling the billet temperature.
The amount of the thickness of the wall thickness of the case spiral pipe LSAW pipe and (3) less than 10% under, for example: on the wrong side of the small, difficult to meet the requirement is negative, so the problem is not according to the international practice there will be a lot of wrong side of the 1.1 ~ 1.2 mm unit welding.
Since the key process is at a high temperature, spiral, because during manufacture welded steel pipes, heating operation, product quality resolution is a very important process.
Furnace heating, according to these results, the reheating furnace is divided into two, the former, the processing temperature for the slab is heated from room temperature, which is then heated to the desired treatment temperature has been used in the machining of the blank.
(4) compared to LSAW pipe, spiral weld illiquid, severe stress concentration
What to do or bad, to control the quality spiral welded pipe? Blank Aki temperature will depend on the odd strange material varies. Thermal expansion of the pipe, almost 1200 ℃, carbon and other alloying elements is a multiple of slightly lower temperature.
The second key is to try to reduce the amount of heating operation scale. In particular, starting from the hot elbows rubbing, kneading tube life expectancy and, more seriously, those guilty inch thermal expansion pipe surface quality
(5) spiral submerged arc welded pipe, large specific heat affected zone and LSAW HAZ heat affected zone of weakness in the quality of the pipe.
Stove, there are many ways but mainly tube furnace. It has a circular hearth furnace, which can be retrieved from the entrance slowly, inverted and heated to the rules at the bottom outlet of the soaking temperature with a load change in the diameter direction of the blank it will be able to sample the stove.
(6) the construction site to bring some difficulties (such as partners welding), spiral welded steel pipe geometric accuracy.
Compared to some shortcomings and LSAW quality spiral steel pipe pile cofferdam, as well as a summary of the following for your reference 7.
(7), it can be much less than the same diameter spiral welded steel pipe seam thickness LSAW.