Hydrostatic Test And Heat Treatment Of Galvanized Pipe

Galvanized pipes are now mainly used to transport gas and heating. Galvanized pipes are used as water pipes. After several years of use, a large amount of rust and scale will be generated in the pipes. The yellow water flowing out will not only pollute the sanitary ware but also be mixed with bacteria that grow on the rough inner wall. The rust will cause excessive heavy metal content in the water, which will seriously endanger human health.

The uniformity of the galvanized layer of the galvanized pipe The galvanized steel pipe should be tested for the uniformity of the galvanized layer. The steel pipe sample shall not turn red (copper-plated color) after being continuously dipped in the copper sulfate solution 5 times. Cold bending test The galvanized steel pipe with a nominal diameter not greater than 50mm should be subjected to a cold bending test. The bending angle is 90°, and the bending radius is 8 times the outer diameter. No filler is used during the test, and the weld of the sample should be placed on the outside or upper part of the bending direction. After the test, there should be no cracks and peeling off of the zinc layer on the sample.

The water pressure test of galvanized pipe is carried out on the clarinet pipe, and the eddy current flaw detection can also be used instead of the water pressure test during operation. The mechanical properties of steel are important indicators to ensure the performance (mechanical properties) of steel, which depends on the chemical composition and heat treatment system of steel. In steel pipe standards, tensile properties (tensile strength, yield strength or yield point, elongation), hardness, toughness, and high and low-temperature properties required by users are specified according to different use requirements.

During the stretching process, the greater force (Fb) that the sample bears when it breaks, the stress (σ) obtained by the original cross-sectional area (So) of the sample is called the tensile strength (σb), and the unit is N/mm2 (MPa). It represents the maximum ability of metal materials to resist damage under tension. The calculation formula is: In the formula: Fb--the maximum force that the sample bears when it is broken, N (Newton); So--the original cross-sectional area of the sample, mm2. For metal materials with yield phenomenon, the stress at which the sample can continue to elongate without increasing the force (keep constant) during the stretching process is called the yield point. If the force drops, the upper and lower yield points should be distinguished. The unit of yield point is N/mm2 (MPa).