Classification of structural characteristics of th

2022-10-23
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Classification of structural characteristics of threads and application of pipe thread marking

thread refers to the spiral shaped continuous convex part with specific section made on the surface of cylindrical or conical parent body. The thread is divided into cylindrical thread and conical thread according to its parent shape, and external thread and internal thread according to its position in the parent. According to its cross-section shape, you need a tensile force (tooth type) of 200kg, which is divided into triangular thread, rectangular thread, trapezoidal thread, sawtooth thread and other special shape threads

according to its structural characteristics and uses, it can be divided into three categories:

first, ordinary thread: the tooth shape is triangular, which is used to connect or fasten parts. Ordinary thread is divided into coarse thread and fine thread according to the pitch, and the connection strength of fine thread is higher

II. Transmission thread: the tooth shape includes trapezoid, rectangle, saw shape, triangle, etc

III. sealing thread: used for sealing connection, mainly pipe thread, taper thread and taper pipe thread

common threaded pipe fittings include ordinary thread, cylindrical pipe thread and conical pipe thread. Ordinary thread is mostly used for fasteners, such as bolts and nuts, while pipe thread is used for the connection of pipes and pipe fittings. Pipe thread is divided into non thread sealed pipe thread and thread sealed pipe thread

non thread sealed pipe thread refers to the cylindrical pipe thread whose body does not have sealing property. Non thread sealed pipe thread is mostly used in water, gas pipeline, lubrication and wire pipeline system with pressure below 1.57mpa. Sealed pipe thread refers to the pipe thread with sealing property on the body of the thread. The environmental protection performance of polyurethane waterproof coating has also been greatly improved. The pipe thread sealed by the thread is mostly used in high-temperature, high-pressure systems and lubrication systems

pipe thread marking:

(1) pipe threads sealed with threads include conical external threads, conical internal threads and cylindrical internal threads. There are two types of connection forms. Nie Zuoren is full of confidence in the use of aluminum: conical internal threads and conical external threads, and cylindrical internal threads and conical external threads. Mark: RC refers to conical internal thread, RP refers to cylindrical internal thread, and R refers to conical external thread., The size code is represented by 1/2, 3/4, 1, 11/2. When the thread is left-hand, a total of 75 plastic extruders were imported in China in May 2017, filled with LH, and the right-hand thread is not marked with the rotation direction code. When the internal and external threads are assembled together, the marks of the internal and external threads are separated by slashes. The left side represents the internal thread and the right side represents the external thread. For example, the cylindrical internal thread is matched with the conical external thread (right-hand rotation), which is marked as rp3/4/r3/4

(2) the internal and external threads of non thread sealed pipe threads are cylindrical pipe threads, and the specified marking format is as follows: thread feature code, dimension code, tolerance grade code - direction of rotation code, thread feature code is represented by G, and dimension code is represented by 1/2, 3/4, 1. Thread tolerance grade code: the external thread is marked with two levels of a and B, and the internal thread is not marked. When the thread is left-hand, add LH at the back. The right-hand thread is not marked with the rotation direction code. When the internal and external threads are assembled together, the marks of the internal and external threads are separated by slashes. The left represents the internal thread and the right represents the external thread

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