See the color of the head can see its quality

The head is a part of the vessel which is connected in a welding type cylinder, can be divided into spherical, oval, dish shaped, spherical, conical shell and cover several types. The utility model is mainly used for various container equipment, such as storage tank, heat exchanger, tower, reaction kettle, boiler and separation equipment, etc..
1, purple: poor, unqualified;
2, gray or dark gray: poor, unqualified;
3, gray white: very poor, unqualified;
4, silver white: good, qualified;
5, golden yellow (compact): still good, qualified;
6, blue: slightly worse, not qualified