Technical requirements of spiral tube

1. manufacturing method
(1) using hot rolled strip as billet, high temperature spiral forming is often adopted, automatic submerged arc welding is used for spiral seam, and internal and external submerged arc welding seam is not less than 1.
(2) the allowable weld head on the steel pipe should not be less than 300mm from the pipe end. The buyer agrees with the manufacturer to allow the head to be welded to the tube end, but the circumference between the head and the corresponding tube end spiral candle should be at least 150mm.
(3) the length of each short steel pipe shall not be less than 2m for each section of the pipe which allows two short sections of the same size and the same model. The two sides of the annular weld should be interlaced and the distance of the ring is less than 150mm.


Type of 2. steel
In the welding of Q195, Q215 and Q235 steel, the range of standard steel pipe should be GB / T700-1988. Note: Q refers to the yield strength of the letter and the back value of the yield strength value.


3. static water pressure test
The static water pressure test should be carried out in each tube, without leakage, the test pressure is tested P = 2ST / D, of which the stress of the S hydraulic test test is Mpa, and the stress of the static water pressure test test is carried out according to the corresponding steel strip standard. The minimum yield (Q235 235Mpa) of selected 60%. Regulator time: D <508; test pressure holding time not less than 5 seconds; D > 508 test pressure holding time not less than 10 seconds.


4. nondestructive testing
Spiral tube weld, steel strip weld and girth should be inspected by X ray or ultrasonic. For the spiral weld of flammable ordinary fluid conveying steel, 100%SX ray or ultrasonic testing should be carried out. The spiral weld of general purpose fluid conveying pipe, such as water, sewage, air and heating steam, should be examined by X ray or ultrasonic examination (20%).




5. defect treatment
(1) the grinding wheel may wear defects, but the remaining wall thickness must be within the permitted range.
(2) minimum weld length 50mm; after grinding, the parent material shall not exceed 1.5mm after welding.
(3) remove defective pipes in the allowed length range.
(4) it was rated as unqualified.