直縫焊（hàn）管是（shì）通過（guò）高頻焊接機組或者是通過（guò）埋（mái）弧焊機（jī）組焊接而成。高頻焊接直縫焊管國內目前（qián）可生產範圍：口徑（jìng）10-711mm厚度3-25mm。埋弧焊（hàn）直（zhí）縫焊管可生產範圍，口徑：325-1420mm厚度8-25mm。直縫焊（hàn）管工藝簡單，生產速度快（kuài）所以它在城市建設，鋼構工程，輸氣工（gōng）程和供排水工（gōng）程建設方（fāng）麵起著不（bú）可替代的作用。所以選（xuǎn）擇好優質（zhì）的直縫焊管是保證工程安全順利進行的必（bì）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第一我們要注意材（cái）質，一般直縫焊管（guǎn）的材質有Q235,16Mn，和L245等等（děng），在我們（men）驗貨（huò）的時候首先要確定材質是（shì）否合格。第二要看（kàn）看直縫焊管的壁厚，是否達到要求（qiú）的壁厚（hòu）。公差是否在國家要求範圍（wéi）之內。第三要看焊管表麵情況，是否有鏽，鏽的程度，一般黃鏽（xiù）沒有問（wèn）題（tí），一般黃鏽都是一層浮鏽，紅鏽稍微嚴重一點。
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（yǐ）在（zài）一些不（bú）是很嚴格的項目上使用，但是如果是黑（hēi）鏽（xiù），說明這管子就隻能賣廢鐵了。還有我（wǒ）們要看一下焊管表麵是否有（yǒu）由，因為直縫焊管在生產過程中在機（jī）組上有可能會沾染油漬，最後我們要看管子兩（liǎng）頭的斷麵情況是否是圓麵還是有擠壓不規整。還要看下是（shì）否有毛刺。經（jīng）過以（yǐ）上幾種（zhǒng）嚴格的檢（jiǎn）測手段如果焊管都通過（guò），那麽說明管子是合（hé）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.
