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.

材料的硬度值可以換算成抗拉強度值，這一點具有很大的實用意義。由于拉伸試驗不便于測試，并且由硬度換算到強度很方便，因此人們越來越多地只測試材料硬度而較少測試其強度。一旦該套管由于某種原因被持續破壞，空氣或液體中的氧原子將持續滲透，或者金屬中的鐵原子將持續析出，形成松散的氧化鐵，金屬表面將被持續腐蝕。

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.

氣壓、水壓試驗對耐壓用管逐支進么水壓試驗,在規定壓力值不保持不小于5秒,不泄露,常規供貨水壓壓力試驗為2.45MPa。氣壓壓力試驗為P=0.5MPAa。通風管道防水套管表面粘有酸、堿和鹽類物質(如濺在裝飾墻上的堿水和石灰水)，導致機器局部腐蝕。在受污染的空氣中(如含有大量硫化物、碳氧化物和氧化炎癥的空氣)，冷凝水會形成硫酸、硝酸和醋酸液斑，造成化學腐蝕。

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.

上述所有情況都可能導致通風管道防水套管表面保護套管的破壞，從而導致腐蝕。爐體密封性好。光亮退火爐是封閉的，并且與外部空氣隔絕;如果使用氫氣作為維護氣體，則只需要一個排氣口。 為避免微泄漏的出現，爐內的維護氣體應堅持一定的正壓。

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.

如果是氫氣維持氣體，通常需要超過20kBar。 在焊接過程中熔池上沒有形成小孔。焊縫成形過程類似于鎢氬弧焊，只考慮穿透深度和火焰寬度。 預埋等離子體弧焊工藝參數：預埋等離子體弧焊不是銹鋼焊管該過程類似于預埋焊接。每個預埋電流在通風管道防水套管管的表面上形成焊點，并且每個焊點彼此重疊以形成焊縫。

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.

與普通等離子焊接相比，預埋等離子焊接的優點是:焊接通風管道防水套管管工藝更加穩定，焊接線能量易于控制，熔池可以更好地控制，保證良好的焊縫形成;焊接量小熱影響區，焊接變形小。

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.

通風管道防水套管具有攪拌效果，這有利于細化晶粒，降低裂縫的靈敏度并進行全位置焊接。 通風管道防水套管焊管預埋等離子體弧焊工藝參數為：預埋電流，基電流，預埋頻率，預埋寬度比等。通風管道防水套管組成的這種均勻性只能說是其宏觀統計均勻性，因為不存在均勻的事物。

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.