直縫焊管是用鋼板或鋼帶經過彎曲成型，然後經焊接製成。按焊縫形式分為直縫焊管和螺旋焊管。按用途又分為一般焊管、鍍鋅（xīn）焊管、吹氧焊管、電線套管（guǎn）、公製焊（hàn）管、托輥管、深井泵管、汽車用管、變壓器管、電（diàn）焊薄（báo）壁管、電焊異型管和螺旋（xuán）焊管。大口徑直縫焊管主要生產流程說明：
Longitudinal welded pipe is made of steel plate or strip after bending and welding. According to the weld form, it can be divided into straight welded pipe and spiral welded pipe. According to its use, it can be divided into general welded pipe, galvanized welded pipe, oxygen-blowing welded pipe, wire sleeve, metric welded pipe, idler pipe, deep well pump pipe, automobiles pipe, transformer pipe, welded thin-walled pipe, welded special-shaped pipe and spiral welded pipe. Description of main production process of large diameter straight seam welded pipe:
1.板（bǎn）探：用來製造大口徑埋弧焊（hàn）直縫鋼管的（de）鋼（gāng）板進入生產線後，首先進行全板超聲波檢驗;
1. Plate prospecting: After the steel plate used to manufacture large diameter submerged arc welded straight seam steel pipe enters the production line, the whole plate ultrasonic inspection is carried out first.
2.銑邊：通過（guò）銑（xǐ）邊機對鋼板兩邊緣進行（háng）雙麵（miàn）銑削，使之達到要（yào）求的板寬、板邊平（píng）行度和坡（pō）口形狀;
2. Milling: Double-sided milling of steel plate edges by milling machine to achieve the required width, parallelism and groove shape;
3.預彎邊（biān）：利用預彎機進行板邊預彎，使板邊（biān）具（jù）有符（fú）合要求的曲率;
3. Pre-bending edge: Pre-bending edge with pre-bending machine, so that the edge of the plate has the required curvature;
4.成型：在JCO成型（xíng）機上首（shǒu）先將（jiāng）預彎後（hòu）的鋼板的一半經過多（duō）次步進衝（chōng）壓，壓成（chéng）"J"形，再將鋼板的另一半同（tóng）樣彎曲，壓成"C"形，最後形成開口的"O"形
4. Forming: On JCO forming machine, first half of the pre-bended steel plate is stamped into "J" shape by several steps, then the other half of the steel plate is also bent into "C" shape, and finally the "O" shape of the opening is formed.
5.預焊：使成型後的直（zhí）縫焊鋼管合縫並采（cǎi）用氣體保護焊(MAG)進行（háng）連續焊接;
5. Pre-welding: to make the formed straight seam welded steel pipe seam and use gas shielded welding (MAG) for continuous welding;
6.內焊：采用縱列多絲埋弧焊(最多可為四（sì）絲)在（zài）直縫（féng）鋼管內側進行焊接;
6. Internal welding: Longitudinal multi-wire submerged arc welding (up to four wires) is used to weld the inside of the straight seam steel pipe.
7.外焊：采（cǎi）用縱列多絲埋弧焊在直縫埋弧（hú）焊鋼管外側進行焊接;
7. External welding: Longitudinal multi-wire submerged arc welding is used to weld the outer side of longitudinal submerged arc welded steel pipe.
8.超聲波檢驗Ⅰ：對直縫焊鋼管（guǎn）內外焊（hàn）縫及焊（hàn）縫兩側母材進行（háng）100%的檢查;
8. Ultrasound Inspection I: 100% Inspection of the inside and outside welds and the base metal on both sides of the weld of the longitudinal welded steel pipe;
9.X射（shè）線檢查Ⅰ：對內外焊縫進行100%的X射線工業電視檢查，采用圖象處理係統以保證探傷的（de）靈敏度;
9. X-ray inspection I: 100% X-ray industrial television inspection of internal and external welds, image processing system to ensure the sensitivity of flaw detection;
10.擴徑：對埋弧（hú）焊直縫鋼管全長進行（háng）擴徑以提高鋼管的尺寸精度，並改善鋼管內應力的分布狀態;
10. Diameter enlargement: The whole length of submerged arc welded straight seam steel pipe is enlarged to improve the dimensional accuracy of steel pipe and the distribution of internal stress of steel pipe.
11.水壓試驗：在水壓試驗機上對擴（kuò）徑後的鋼管（guǎn）進行逐根檢驗以保證（zhèng）鋼管達到標準要求的試驗壓力，該機具有自動記錄和（hé）儲存功（gōng）能;
11. Hydraulic test: The expanded steel pipe is inspected one by one on the hydraulic test machine to ensure that the test pressure meets the standard requirements. The machine has the function of automatic recording and storage.
12.倒棱：將檢驗合格（gé）後（hòu）的鋼管進行管端加工，達到要求的管端坡口尺寸;
12. Chamfering: The qualified steel pipe will be processed to meet the required pipe end groove size;
13.超聲波檢驗Ⅱ：再次逐根進行超聲（shēng）波檢（jiǎn）驗以檢查直縫焊鋼管在擴徑、水壓後可能產生的缺陷;
13. Ultrasound Inspection II: Ultrasound Inspection is carried out one by one again to inspect the possible defects of longitudinal welded steel pipe after diameter enlargement and hydraulic pressure.
14.X射線（xiàn）檢查Ⅱ：對（duì）擴（kuò）徑和水壓試驗後（hòu）的鋼管進行X射線工業電視檢查和管端焊縫拍片;
14. X-ray inspection II: X-ray industrial television inspection and photography of weld seam of pipe end after diameter enlargement and hydraulic test;
15.管端磁粉檢驗（yàn）：進行此項檢查（chá）以發現（xiàn）管端（duān）缺陷（xiàn）;
15. Tube end magnetic particle inspection: this inspection is carried out to find the defect of the tube end;
16.防腐和塗（tú）層：合格（gé）後的鋼管（guǎn）根據用戶要求進行防腐和塗層。
16. Anti-corrosion and coating: qualified steel pipes are anticorrosive and coated according to user's requirements.
