The hardness test is to slowly press a waterproof sleeve of a ventilation pipe into the surface of the sample according to the specified conditions, and then test the depth or size of the indentation to determine the hardness of the material. Hardness test is a simple, rapid and easy to implement method in material mechanical property test. The hardness test is non-destructive, and there is an approximate conversion relationship between the material hardness value and the tensile strength value.
The hardness value of the material can be converted into the tensile strength value, which is of great practical significance. Because tensile test is not easy to test, and it is convenient to convert hardness to strength, more and more people only test the hardness of materials and less test their strength. Once the casing is continuously damaged for some reason, the oxygen atom in the air or liquid will continue to penetrate, or the iron atom in the metal will continue to precipitate, forming loose iron oxide, and the metal surface will be continuously corroded.
Air pressure and water pressure test: conduct water pressure test one by one for pressure resistant pipes, and keep the specified pressure value for no less than 5 seconds without leakage. The conventional supply water pressure test is 2.45 MPa. The air pressure test is P=0.5MPAa. There are acid, alkali and salt substances (such as alkali water and lime water splashed on the decorative wall) on the surface of the waterproof sleeve of the ventilation pipe, causing local corrosion of the machine. In polluted air (such as air containing a lot of sulfide, carbon oxide and oxidation inflammation), condensate will form sulfuric acid, nitric acid and acetic acid spots, causing chemical corrosion.
All of the above conditions may lead to the destruction of the surface protective sleeve of the waterproof sleeve of the ventilation pipe, thus leading to corrosion. The furnace body is well sealed. The bright annealing furnace is closed and isolated from the outside air; If hydrogen is used as a maintenance gas, only one vent is required. In order to avoid micro leakage, the maintenance gas in the furnace should adhere to a certain positive pressure.
如果是氢气维持气体，通常需要超过20kBar。 在焊接过程中熔池上没有形成小孔。焊缝成形过程类似于钨氩弧焊，只考虑穿透深度和火焰宽度。 预埋等离子体弧焊工艺参数：预埋等离子体弧焊不是锈钢焊管该过程类似于预埋焊接。每个预埋电流在通风管道防水套管管的表面上形成焊点，并且每个焊点彼此重叠以形成焊缝。
If it is hydrogen maintenance gas, it usually needs to exceed 20kBar. No small holes were formed in the molten pool during welding. The weld forming process is similar to tungsten argon arc welding, and only the penetration depth and flame width are considered. Process parameters of embedded plasma arc welding: embedded plasma arc welding is not stainless steel pipe welding. The process is similar to embedded welding. Each embedded current forms a welding spot on the surface of the waterproof casing pipe of the ventilation pipe, and each welding spot overlaps with each other to form a weld.
Compared with ordinary plasma welding, the advantages of embedded plasma welding are: the process of welding waterproof casing pipe of ventilation pipe is more stable, the welding line energy is easy to control, and the molten pool can be better controlled to ensure good weld formation; Small welding amount, heat affected zone, small welding deformation.
The waterproof sleeve of the ventilation pipe has a stirring effect, which is conducive to refining the grains, reducing the sensitivity of cracks and conducting all position welding. The process parameters of pre buried plasma arc welding of waterproof casing welded pipe of ventilation pipe are: embedded current, base current, embedded frequency, embedded width ratio, etc. The uniformity of waterproof casing of ventilation pipe can only be said to be its macroscopic statistical uniformity, because there is no uniformity.