1, the cracks. 2, the length and diameter size does not meet the design requirements. 3, Duanliang only regulation by thread trails. 4, only the end of the threaded plug screwed into more than 3P (P is the pitch). 5, through the end of the threaded plug screwed into the connection can not be successfully and achieve the ends screwed sleeve length. Not only to the construction of these five phenomena has brought a lot of trouble, but also makes the quality of the project without any protection. For this straight threaded sleeve technical staff summary reasons, mainly due to the following two points: First, the sleeve material does not comply, cracks appeared after processing; Second, poor maintenance and processing machinery, appear large tolerances. I hope this construction, quality control unit in accordance with the following prevention measures: the approach must have certificate sleeve, the sleeve in the transport and storage should be properly protected from rain and stains, suffered mechanical damage. www.chinataotong.com