Author: Site Editor Publish Time: 2021-07-23 Origin: Site
Torque, the distance of force applied to a material to produce torsional deformation, in N-m, and lb-ft is the imperial unit of torque.
Any mismatch or improper fastening may result in damage, failure or possible bodily harm to the product. Before installing any hardware, make sure all parts are in near new condition. Neither the bolts nor the threads are in worn or damaged condition. Threads must not have burrs or nicks.
Standard Torque for Constant Torque Hose Clamps | ||
Width of Clamp | Initial InstallationTorque On New Hose | Reassembly orRetightening Torque |
7.9 mm 0.31 inch | 0.9± 0.2 Nm (8 ±2 lb-ft) | 0.7 ±0.2 Nm (6 ±2 lb-ft) |
13.5 mm 0.53 inch | 4.5 ±0.5 Nm (40 ±4 lb-ft) | 3.0± 0.5 Nm (27± 4 lb-ft) |
159 mm 0.63 inch | 7.5 ±0.5 Nm (65± 4 lb-ft) | 4.5± 05 Nm (40± 4 lb-ft) |
The torque indicator assumes conditions such as friction coefficients and shaft design; the actual exact bolt torque is derived from experimental tests.
Constant torque hose clamps can be used in place of any standard hose clamp, but make sure that the constant torque hose clamp is the same type as the standard hose clamp. Due to extreme temperature variations, the hose will heat set. Heat setting will cause the hose clamps to slacken, and slackening of the hose clamps can lead to leaks. There have been reports of component damage due to hose clamp slack, and constant torque hose clamps can prevent such damage.
Correct installation of the constant torque hose clamps with a torque spanner. Correct installation of the constant torque hose clamp requires the following.
The worm tip (1) protrudes 6.35 mm (0.250 in) from the housing (X).
The washer is trapped close to the horizontal position while the screw is held in place with a torque of 11 ± 1 Nm.
The tightening force should first be determined, e.g. for an m20 screw, a tightening force of 20 kg or 20*9.81 = 196.2 Nm is required.
Required torque: 196.2*20/2/1000=1.962 Nm If the length of the spanner is 20cm, the required force is: 1.962/20*100=9.81 Nm i.e. 1kg
Determine the tightening torque according to the length of the spanner. Wrench length: L (m), tightening force: F (Nm) Tightening torque: M (Nm); its calculation formula is as follows: M = LF
The reason why we are concerned about the tightening force of the bolt is that when designing a frictional bolt sub-connection, the tightening force of the bolt sub is the original design data, only when assembling, the tightening force is not good for construction and afterwards detection, generally through tests or empirical values, the construction process is changed to torque. Because 70-90% of the torque is used to overcome various frictional forces and only 10-30% is converted into clamping force, there are more factors affecting the frictional force of the bolt sub, so the relationship between the compression force and torque can only be tested and should try to imitate the actual working conditions of the bolt assembly (including temperature, humidity, lubrication, tightening process).
The rebound after tightening is mainly due to the fast tightening speed and the small friction coefficient of the clamp screw, as well as the slow deformation of the oil and water pipe material causing the torque to decay. It is advisable to tighten the hose in two parts and to add a re-torquing process to overcome the torque decay. Torque standards need to be negotiated with the supplier.
