The technical solution adopted for directly buried maintenance free sleeve compensators to improve the performance of pipeline operation and further reduce engineering costs is a direct buried maintenance free sleeve compensator, which adopts a triple sealing structure. The double combination sealing structure is located between the outer sleeve and the end pipe, and the other double sealing structure is located between the outer casing end ring and the sealing guide sleeve on the end pipe; The reseal is composed of a combination sealing ring, a middle cover, and a floating pressure ring; During operation, as the pressure of the medium inside the pipeline increases, the two lips of the combined sealing ring tightly adhere to the stopper of the outer sleeve and the convenient surface of the end pipe under the combined action of the intermediate pressure cover and the floating pressure ring, achieving a tight seal; The reseal is composed of a packing disc root, a pressure cover, and a compression bolt with a combined disc spring; During operation, the gland compresses the packing root, and the gland is connected to the flange of the outer sleeve through a compression bolt with a combined disc spring. The combined disc spring keeps the gland tightly pressed against the packing, compensating for the wear of the packing caused by the sliding of the end pipe and preventing the leakage of the medium inside the pipeline; The third sealing structure consists of a sealing guide sleeve, an outer cover, a packing, and an end ring protective cover component; The sealing guide sleeve is located on the outer end pipe of the heavy seal, and the outer cover and packing are located on the sealing guide sleeve. The outer cover presses the packing tightly, and the upper surface of the packing is tightly attached to the inside of the end ring of the end ring protective cover assembly. The protective cover of the end ring protective cover assembly is connected to the flange of the outer sleeve to form a third sealing combination structure. During operation, the third sealing structure isolates the penetration of external media, achieving the purpose of protecting the sliding working surface of the end pipe. At the same time, the sealing guide sleeve also plays a guiding role in the displacement of the end pipe. The outer part of the end ring protective cover component and the outer sleeve have an outer sleeve, and an insulation layer is provided between the outer sleeve and the outer sleeve. The insulation layer is made of polyurethane foam. The surface of the end pipe is sprayed with a corrosion-resistant and anti friction coating to reduce the wear of the combination sealing ring, packing packing packing, and the surface of the end pipe.

There are also many things to pay attention to in the construction of direct buried sleeve compensators. Firstly, the sliding sleeve of the one-way compensator should be installed at the inlet end of the medium, and the pipe section welded to both ends of the compensator should be chamfered. After welding, a water pressure test should be conducted according to the acceptance specifications, with a pressure of 1.5 times the working pressure. If the sealing device leaks during pressure testing, the bolts should be evenly tightened until there is no leakage.