Roundness: mainly for the circular cross-section rolled products, such as the cross section round and round steel pipe, unequal diameters in all directions.

Because of the pre-weld own characteristics, in the back of the welding operations, there often produce tumors, burn, wrong side, solder partial, broken weld (broken arc), weld reinforcement is too low or too high, porosity and slag and other defects. Among them burn, broken weld (broken arc) more likely to be found to take timely repair welding, generally does not have a significant impact on the internal and external welding quality.

As there are numerous types of steel pipe, the pipe damage will inevitably occur during loading and unloading, for these cases, are summarized as follows series of ssaw steel pipe related issues.

High-precision cold drawn seamless carbon steel pipe abroad is generally increased in the metal alloy approach to improve material performance in the cold drawn seamless steel pipe, after all need to stress annealing, to eliminate residual stress of materials, to improve the organization of materials,improve the plastic material, thus preventing the purpose of seamless steel pipe fracture failure occurs.

Frequency welded pipe production process, affecting the quality of the pipe element has multiple aspects, mainly for raw materials, welding technology and roll operator which is beginning to adjust. Key to look at the raw geometric dimensions.

NONDESTRUCTIVE TESTING METHODS An NDT method is classified according to its underlying physical principle.

Metallographic Metallographic method (or etching method) is polished bead cross-section, showing the inside and outside weld bead after welding performed partial measurement method, as shown in FIG.

Mild steel consists of iron alloyed with less than 0.3 percent carbon, most commonly between 0.1 to 0.25 percent. The building industry frequently uses mild steel pipe in construction because of its ductility and malleability.

Welding residual stress refers to weldments in the welding process, the thermal stress, transformation stress, machining stress exceeds the yield limit (Yield strength), so that after cooling left weldment fails to eliminate the stress.

Thick-walled spiral pipe wall thickness of steel pipe means with respect to ordinary spiral steel pipe spiral pipe slightly thicker. With respect to the advantages of ordinary spiral pipe wall thickness are: high strength, high impact strength, high safety performance, longer life

Tube and clamp scaffold (commonly called tube and coupler scaffold) is a versatile type of scaffold consisting of steel tubes and clamps. Vertical tubes are connected to horizontal tubes via right angle clamps. Diagonal tubes are periodically connected to the scaffold via swivel clamps in order to stabilize the scaffold.

Deformation by a principle known thermal processing, when thermal processing, high temperature produced compression deformation due to the heating temperature is uneven, the parts of the contract is also by other parts of the (low-temperature cooling zone or the first part) blocking when cooling, resulting in a variety of residual stresses and distortion.