直縫焊管是通過高頻焊接機組或者是通過埋弧（hú）焊（hàn）機組焊接而（ér）成。高（gāo）頻焊接直縫焊（hàn）管國內目前可生產範圍：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。直縫焊管工藝簡單，生產速度快所以它在城市（shì）建（jiàn）設，鋼（gāng）構工程（chéng），輸氣工程和供排水工（gōng）程建設方麵起著不（bú）可替代的作用。所以選（xuǎn）擇好優質的（de）直（zhí）縫焊管是保證工程（chéng）安（ān）全順利（lì）進行的必要因素。
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（féng）焊管的時候第（dì）一我們要注意材質，一般直（zhí）縫焊管的材質有Q235,16Mn，和L245等等，在我們驗貨的時候首先要確定（dìng）材質是（shì）否合格。第二要看看直縫焊管的壁厚，是否達到（dào）要求的壁厚。公差（chà）是否在國（guó）家（jiā）要（yào）求（qiú）範圍之內（nèi）。第三（sān）要看焊管表麵情況，是否有鏽，鏽的程度，一般黃鏽沒有問題，一般黃鏽都是一層浮鏽，紅鏽稍微嚴重一（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不是很嚴格（gé）的項目上使用，但是如果是黑鏽，說明這管子就隻能（néng）賣（mài）廢鐵了。還有我們要看一（yī）下焊管表麵是否有由，因為直縫焊管在生產過程（chéng）中在機（jī）組上有可能會沾染油漬，最後我們要看管子兩頭的（de）斷麵情況是否是圓麵還是有擠壓不規（guī）整（zhěng）。還要看下（xià）是否有毛刺。經過以上幾（jǐ）種嚴格（gé）的檢測手段如果焊管都通過，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.
