Spiral Pipe Manufacturer: How Should the Quality of Spiral Pipes Be Tested?

　　 Spiral pipe manufacturer : How should the quality of spiral tubes be tested?

　　1. Physical‑method testing: Physical testing methods involve using certain physical changes to perform measurements or conduct verification.

　　2. Strength Testing of Pressurized Vessels: In addition to leak‑tightness tests, pressurized vessels must also undergo pressure testing. The two most common methods are hydrostatic testing and pneumatic testing. Both can assess the weld integrity of vessels and piping under pressure. Pneumatic testing is more convenient and faster than hydrostatic testing, and after the test, small‑diameter spiral‑welded pipes do not require drainage; this makes it particularly suitable for products where drainage is difficult. However, pneumatic testing carries a higher risk than hydrostatic testing. During such tests, appropriate safety measures must be strictly observed to prevent accidents.

　　3. Water‑tightness test: Each small‑diameter spiral pipe shall undergo a hydrostatic pressure test with no leakage. The rated test pressure is calculated according to the formula P = 2ST/D, where S represents the test stress in MPa. For the water‑tightness test, the test stress shall be set at 60% of the corresponding yield strength specified in the relevant steel‑grade standard.

　　4. According to spiral pipe manufacturers, visual inspection—conducted through straightforward procedures and widely applicable—is an essential component of quality control, primarily used to identify surface defects in welds and dimensional deviations. Typically, this involves manual visual examination, supplemented by standard reference templates, gauges, and high‑magnification magnifying glasses. If surface defects are detected, there is a strong likelihood that the weld’s internal structure also exhibits deviations.

　　Analysis of the Causes of Weld Beads in Spiral Pipes:

　　1. In overhead welds, such as fillet welds in the overhead position, lap welds in the overhead position, or lap joints of reinforcing bars welded in the overhead position, unstable welding current, incorrect wire‑to‑workpiece angle, or improper welding technique can easily lead to this type of defect.

　　2. If the molten pool temperature is too high, solidification proceeds slowly, and under the influence of the molten steel’s own weight, it tends to sag downward, resulting in weld bumps.

　　How can we prevent weld bumps from forming on spiral pipes?

　　According to spiral pipe manufacturers, a weld bead—also known as a weld lump—is excess weld metal that forms outside the intended weld. Such defects can lead to dimensional inaccuracies in the finished product and create stress concentrations at the joint. When the molten pool is overheated and solidifies slowly, the weight of the molten steel may cause it to sag downward, resulting in a weld bead. In overhead welding—whether it’s fillet welding, backing strip welding, or lap‑joint welding—unstable welding current, improper wire angle, or improper operator technique can easily give rise to this type of defect.

　　In the production of spiral tubes, the following preventive measures can be implemented:

　　1. When a “small bulge” occurs at the bottom of the weld pool, it can be controlled by oscillating the welding wire from side to side and using an arc‑striking technique.

　　2. When performing overhead welding on rebar lap splices or sleeve‑type connections, the welding current should be appropriately reduced compared to vertical welding; the welding wire should be oscillated slightly toward the center at a faster speed, with slightly slower movement on the sides.

　　3. When performing uphill welding on groove‑type vertical weld joints, a 3.2 mm diameter electrode should be used, and the welding current should be kept as low as possible.