金沙集团1862cc

Due to the harsh working conditions of petroleum underground, many downhole tools bear the load for a long time and are used in the working conditions of corrosion and wear, resulting in premature failure and failure, and thus shortening their life. For example: oil plunger, large rotor journal, sleeve, bearing bush, oil drill collar, wear plate, wear band, etc., but these parts are often very expensive.

Shipbuilding is a specialized profession that predates recorded history. Ship building and ship repair is a mixed industry of commerce and military, generally referred to as the "maritime industry", in the early primitive society, primitive ancestors lived on fishing, hunting and fishing, and the scope of activity was limited to the area very close to the water.