The drill pipe joint is a component of the drill pipe, divided into male joints and female joints, connected at both ends of the drill pipe body. The connector is provided with a thread screw thread (thick screw thread) to connect each single drill pipe. In the drilling process, the joint is often disassembled, and the joint surface is subjected to a considerable bite force, so the drill pipe joint wall thickness is larger, the joint outer diameter is larger than the pipe body outer diameter, and the alloy steel with higher strength is used. Domestic drill pipe joints are generally made of 35CrMo alloy steel.
The connection of the screw thread must be content with three conditions, that is, the size is equal, the type of the screw thread is the same, and the male and female screw thread are matched. The joint sizes of different drill pipe are different. The thread type of drill pipe of the same size is also different. The joint type used by each drill pipe manufacturer is also difficult to be completely consistent. Therefore, in order to facilitate the distinction between drill pipe joints and engineering applications, API has made uniform provisions on the type of drill pipe joints, forming the API drill pipe joints commonly used in the petroleum industry.
API pipe fittings are available in both old and new standards. The old API drill pipe joint is proposed for the early use of fine drill pipe, which is divided into three types: internal flat (IF), perforated (FH) and regular (REG).
The inner flat joint is mainly used for the outer thickening of the drill pipe, which is characterized by the inner diameter of the drill pipe and the inner diameter of the joint at the thickening of the pipe body, and the drilling fluid flow resistance is small, which is conducive to improving the water power of the drill bit, but the outer diameter of the joint is large and easy to wear.
The perforated joint is suitable for the internal thickening of the drill pipe, which is characterized by two internal diamediamets of the drill pipe, and the internal diameter of the joint is equal to the internal diameter of the thickening of the pipe body, but less than the internal diameter of the pipe body part. The resistance of drilling fluid flowing through the joint is greater than that of the inner flat joint, but its outer diameter is smaller than that of the inner flat joint.
The regular joint is suitable for internal thickening of the drill pipe. The inside diameter of this joint is relatively small, less than the inside diameter of the drill pipe thickening. Therefore, there are three different bore diameters of drill pipe connected with normal joints. Drilling fluid flows through this joint with the greatest resistance, but it has the smallest outside diameter and greater strength. Regular joints are often used for small diameter drill pipe and reverse drill pipe, as well as drills, fishing tools, etc. The three types of joints all use "V" shape threads, but the screw thread type (expressed by the width of the top cut), the screw thread distance, taper and size are very different.
Joint identification
1.hole FH, XH, not common in the tool shop, not commonly used.
2.commonly used IF and normal REG, the difference is as follows:
IF 4 buttons per inch, the relative screw thread is thicker, and the taper is smaller, REG 5 buttons per inch, the relative screw thread is smaller, and the taper is larger. The size of the IF screw thread ranges from 2-3/8 "to 4-1/2", and those greater than 4-1/2 "have no IF, usually REG, where 7-5/8" and above have no REG.
3. Common expression method:
It is represented by three numbers, such as 310,410,411, etc.
The first number indicates size (2 ~ 7) commonly: 2-2 -, 3-3-7/8 ", 1/2 ", 4-4-1/2 ", 5 1/2 "- 5 -, 6-6-5/8", July 7-5/8 ";
The second number indicates the screw thread type (there are 1, 2, 3), 1-- IF; 2---FH; 3-- REG;
The third number represents male and female (represented by 0 and 1)
0--Box( female); 1--Pin (male);
4.other common drill pipe screw thread types are BTC, MT, AMT, HT55 and so on.
5.in addition, the common screw thread type of the motor 7-5/8 "REG, 6-5/8" REG, 4-1/2 "REG, also has 4-1/2" IF. The common screw thread type of pipe scraper and hydraulic cutter is REG.
|
数字型接头 |
旧API标准接头 |
油田叫法 |
|
NC26 |
2 3/8IF（内平） |
2A11/210 |
|
NC31 |
2 7/8 IF（内平） |
211/210 |
|
NC38 |
3 1/2 IF（内平） |
311/310 |
|
NC40 |
4FH（贯眼） |
4A21/4A20 |
|
NC46 |
4IF （内平） |
4A11/4A10 |
|
NC50 |
4 1/2 IF（内平） |
411/410 |
Common API standard connector identification methods
Post time: Aug-18-2023
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