直（zhí）縫焊管是通過高頻焊接機組或者是通過埋弧（hú）焊機組焊接而成。高（gāo）頻焊接直縫焊管國內目（mù）前可生產範圍：口徑10-711mm厚度3-25mm。埋弧焊直縫焊管可生產範圍，口徑：325-1420mm厚度8-25mm。直縫焊管工（gōng）藝簡（jiǎn）單，生產速度快所以它在城市建設，鋼構工程，輸氣工程和供排水（shuǐ）工程建設方麵起著不可替代（dài）的（de）作用（yòng）。所以選擇好優質的直縫焊管是（shì）保證工程安全順利進行的（de）必要因素。
Longitudinal welded pipe is welded by high frequency welding machine or submerged arc welding machine. At present, the domestic production range of high frequency welded straight seam welded pipe is 10-711mm in diameter and 3-25mm in thickness. Submerged arc welding straight seam welded pipe can be produced in a range of sizes: 325-1420 mm thick 8-25 mm. Longitudinal welded pipe has simple technology and fast production speed, so it plays an irreplaceable role in urban construction, steel structure engineering, gas transmission engineering and water supply and drainage engineering construction. Therefore, the selection of high quality straight seam welded pipe is a necessary factor to ensure the safe and smooth operation of the project. 在選擇直縫焊管的時候（hòu）第一我們要（yào）注意材質，一（yī）般直縫焊管的材（cái）質有（yǒu）Q235,16Mn，和（hé）L245等等，在我們驗（yàn）貨的（de）時候首（shǒu）先要確（què）定材質是否合格。第二要看看（kàn）直縫焊管的壁厚，是否達到要求的（de）壁厚。公差是否在國（guó）家要求範圍之（zhī）內。第三要看焊管表麵情況（kuàng），是（shì）否有鏽（xiù），鏽（xiù）的程度（dù），一般黃鏽沒有問題，一般黃鏽都是一層浮鏽，紅（hóng）鏽稍微嚴重（chóng）一（yī）點。
When choosing straight seam welded pipe, we should first pay attention to the material quality. Generally, the material of straight seam welded pipe is Q235, 16Mn, L245 and so on. When we inspect the goods, we should first determine whether the material is qualified. The second is to see whether the wall thickness of the longitudinal welded pipe meets the required wall thickness. Is tolerance within the scope of national requirements? Third, it depends on the surface condition of welded pipe, whether there is rust or not, the degree of rust, general yellow rust is no problem, general yellow rust is a layer of floating rust, red rust slightly more serious.
但是退火過後也可以在一些（xiē）不（bú）是很嚴（yán）格的項目上使用（yòng），但是如果是（shì）黑鏽，說明這管子就隻能賣廢鐵了。還有我們要看一下焊管表麵是否有由，因為直（zhí）縫焊管在生產過程中在機組上有可能會沾染油漬，最後我們（men）要看管子兩頭的斷麵情（qíng）況是否是圓麵還是有（yǒu）擠壓不規整。還要看下是否有毛刺。經過以上幾種嚴格的檢測手段（duàn）如果焊管都通過，那麽說明管子是合格的。
But after annealing, it can also be used in some less stringent projects, but if it is black rust, it means that the pipe can only sell scrap iron. Also, we need to see if there is any reason for the surface of the welded pipe, because the longitudinal welded pipe may be contaminated with oil stains on the unit during the production process. Finally, we need to see whether the cross-section of both ends of the pipe is round or irregular extrusion. It also depends on whether there are burrs. After the above several strict testing methods, if the welded pipe passes, then the pipe is qualified.
