Hydraulic bolt stretchers, as a tool in electric power, shipbuilding, metallurgical coal mine, petrochemical industry, heavy machinery and other fields, is very popular with the majority of users. So, how to choose a hydraulic bolt stretcher suitable for our working conditions?

The bolt tension method is to apply external force directly to the end of the bolt by hydraulic cylinder, stretch the bolt to the required length, and then tighten the nut gently by hand to maintain the applied load. Because the influence of bolt smoothness and thread conflict is not affected, the tension method can obtain more accurate bolt load. In addition, the bolt stretcher can also stretch multiple bolts at the same time. Usually two synchronizers, four synchronizers, eight synchronizers or more are selected to make the whole ring bolt bear uniform force and load balance. The stretching method is especially suitable for connection of key flanges and other tightening accuracy requirements. The flange force can be evenly connected to prevent leakage.

The hydraulic bolt stretchers are mainly composed of cylinder, tie rod and support sleeve. It is described by the pressure of 150 MPa. The disc spring is in the active position and the cylinder is on the axis of the bolt. It is used for the axial tension of bolts to complete the tension required for bolts. It is the elongation or tension of the bolt that produces the clamping force required for bolt fastening. When the bolt is stretched, the nut will be separated from the flange contact surface. The lower end of the support sleeve has an opening for the operator to manually replace the nut (usually, the pull sleeve is pulled out of the nut by the pull rod to replace the nut, and the pull sleeve is pulled by the metal pull rod). After unloading the oil pressure in the stretcher, the nut is reconstructed to be close to the joint surface, and then the axial deformation of the bolt is locked, that is, the remaining bolt load is locked in the bolt. The load applied on the bolt is proportional to the oil pressure in the hydraulic cylinder, so that the payload can be accurately maintained. Since the load is applied directly to the bolt and all the influence is exerted on the bolt’s elongation, the space required for the load to occur can be minimized. The description of the common distributor enables multiple stretchers to be easily connected through fast joints and pipes, and then complete the balancing of bolt loads. The same pump station distributes the same pressure to each cylinder through a distributor. The high precision of the hydraulic cylinder ensures the consistency of the bolt force near the flange. The residual load/payload of bolts fastened by tension method is larger than that of moment method. It can be said that tension method is a more effective and accurate fastening method.

Hydraulic Bolt Stretchers

Hydraulic Bolt Tensioning Tools

High Tension Hydraulic Bolt Tensioners,Hydraulic Nut Tensioner,Jack Bolt Tensioner BTS Series, Hydraulic Bolt Tensioning Tools Bolt Range:3/4″- 4″ M20-M100 Load Capacity:18-312 tons Stroke:0.6inch Max. Operating Pressure:21,750psi Light weight and compact structure suits operations in small space. Special steel body and advanced surface treatment with perfect rust and corrosion resistance. Strong versatility and high adaptability. Synchronous […]View More