What is the difference between a double ferrule fitting and a single ferrule fitting?

Ferrule joint is a commonly used pipe connector, mainly composed of three parts: joint body, ferrule and nut. When the ferrule and nut are inserted into the fitting body and the nut is tightened, the outer side of the front end of the ferrule fits with the tapered surface of the fitting body, and the inner edge bites into the seamless steel pipe uniformly to form an effective seal. The ferrule fittings can be divided into two kinds: double ferrule and single ferrule, so what is the difference between double ferrule fittings and single ferrule fittings? Take a look.

Simply put, the number of ferrules inside the ferrule joint is distinguished, two ferrules is double ferrule, a ferrule is a single ferrule.

Single ferrule fittings are suitable for hydraulic and pneumatic pipelines below 45MPa. Because the ferrule has a certain degree of elasticity, when the temperature changes, the ferrule through its own compression or expansion of self-adjustment, not only to prevent the edge of the stress concentration, but also to increase the vibration resistance.

Although there are many advantages of single ferrule pipe fitting, but a large number of use has proved that it still has shortcomings: sealing performance in the environment of large temperature difference declines, because the ferrule and the steel pipe, the fitting body is made of different materials, different coefficients of thermal expansion, in the temperature difference is large, the fitting body and the ferrule, the ferrule and the steel pipe may produce a gap between the gap, resulting in leakage. Poor performance of multiple disassembly, according to experience, after multiple disassembly of domestic single ferrule fittings, there will be more damage to the taper surface in the fitting body, the fitting body or the nut off the wire, which is easy to produce leaks. The consistency of assembly is poor, the hardness of the fitting body is low, in order to avoid damage to the taper surface of the fitting body during assembly, it is necessary to carry out ferrule pre-assembly first. Most of the single ferrule fittings are pre-assembled by hand, which requires high assembly skills, and the technical level and working attitude of the workers directly affect the assembly quality.

Double ferrule fittings are characterized by reliable connection, high pressure resistance, temperature resistance, good sealing and repeatability, easy installation and maintenance, safe and reliable work. Thus it is a more advanced connector in the pipeline of self-control device of oil refining, chemical industry, petroleum, natural gas, food, pharmacy, instrumentation and other systems, applicable to oil, gas, water and other pipeline connections. The sealing performance of double ferrule pipe fitting has high pressure-bearing capacity and anti-vibration and anti-vibration performance, the pipe can be sealed normally even if there are scratches, and the double ferrule pipe fitting is corrosion-resistant and can still be used normally under high-pressure vibration.