How Long After the Brass Compression Fitting is Installed does It Need to be Checked for Looseness?

Brass compression fitting is a mechanical component that realizes the sealing connection of pipes through metal plastic deformation. Its core structure includes a conical compression ring, an olive-shaped sealing ring and a threaded locking device. The lead brass substrate with a zinc content of about 60% gives the joint moderate cold deformation ability and corrosion resistance, and the geometric constraint of the conical surface fit forms an initial seal through the assembly preload.

The risk of loosening during the use of brass compression ftting comes from the interaction between material stress relaxation and external loads. The creep characteristics of brass cause the initial assembly stress to decay at a rate of about 3-5% per year. Especially in an environment with a temperature fluctuation greater than 50°C, the alternating stress caused by the difference in thermal expansion coefficient will accelerate this process.

If the mechanical vibration frequency caused by fluid pressure pulsation is close to the natural frequency of the joint, it will stimulate the dynamic stress superposition effect. When the system pressure fluctuation amplitude exceeds 30% of the design pressure, the uniformity of the contact pressure distribution of the sealing surface will gradually deteriorate.

The preventive maintenance cycle of brass compression fitting requires a comprehensive evaluation of the pipeline vibration spectrum, medium temperature gradient, and pressure fluctuation amplitude. Under steady-state conditions, it is recommended to perform basic stress testing after the first 2000 hours of operation, and perform torque verification every 8000 hours thereafter. For systems with high-frequency vibration or impact loads, the inspection interval should be shortened to within 3000 hours. In wide temperature range usage scenarios, it is recommended to perform sealing surface morphology testing twice a year.