Connection mode and performance characteristics of spiral steel pipe

　　The allowable deviation of the wall thickness of spiral steel pipe shall not exceed plus or minus 10% of the nominal wall thickness when the wall thickness is not more than 10 mm, and plus or minus 8% of the wall thickness when the wall thickness is more than 10 mm, except for the wall thickness of corner and weld area. Generally, the delivery length of spiral steel pipe ranges from 4000 mm to 12000 mm, with 6000 mm and 12000 mm in the majority. Spiral steel pipe is allowed to consign short length and non fixed length products no less than 2000mm, and it can also be delivered by connecting pipe.

　　But the demander should cut off the interface pipe when using it. The weight of short length and non fixed length products shall not exceed 5% of the total delivery quantity, and the theoretical weight of spiral steel pipe greater than 20kg / m shall not exceed 5% of the total delivery quantity. According to different connection methods, spiral steel pipe can be divided into adhesive socket pipe fittings, elastic sealing diagram socket pipe fittings, threaded joint pipe fittings and flange connection pipe fittings. According to different processing methods, pipe fittings are divided into injection molded pipe fittings and pipe bending molded pipe fittings. The reduction factor of nominal pressure and temperature is due to the sensitivity of plastic products to pressure and temperature.

　　When the water delivery temperature is different, the working pressure should be corrected according to the given reduction coefficient of different temperatures. The technical requirements of various pipe fittings should be smooth inside and outside, and no delamination is allowed. Obvious bubbles, marks, cold spots and uneven color and other defects. For injection molded spiral steel pipe, the wall thickness of the main body outside the socket connection part shall not be less than the wall thickness of the pipe with the same specification and pressure grade: the average outer diameter of the pipe socket shall comply with the provisions on the average outer diameter and deviation of the pipe in.