As one of the important products of the scientific development of modern materials, thin-walled stainless steel pipes and pipe fittings have great advantages due to their exquisite appearance, corrosion resistance and durability. They are energy-saving and environmentally friendly products and have been widely used in construction projects at home and abroad. At present, there are many types of thin-walled stainless steel pipe connections such as compressional pipe fittings, and they are more convenient, safer and more reliable when it comes to installation, which significantly reduces the cost of wall thickness and has a wider application prospect in the future.
 
1. Features of stainless steel pipes and pipe fittings
Even after long-term use, stainless steel pipes still have excellent anti-scaling performance, and the transported water's quality can meet the requirements of current sanitary standards. After the solution treatment of the stainless steel pipe, its surface is acid pickled and passivated, which can effectively improve its corrosion resistance. Its durability will also be greatly improved. In addition, related tests have proved that the bonding strength of stainless steel pipes and pipe fittings is twice that of galvanized pipes and three times that of copper pipes, but their weights are only 1/3 those of galvanized pipes. For this reason, stainless steel pipes and pipe fittings are very suitable for pipeline construction in high-rise buildings. The stainless steel pipe has a great advantage in thermal conductivity. Its thermal conductivity is only 1/25 that of copper pipes. It is relatively less affected by thermal expansion and contraction caused by cold. Using stainless steel pipes in the process of engineering construction does not produce any pollutants, which can minimize the impact of construction on the environment. Other types of pipes do not have these advantages. There is a thin but strong oxide film on the surface of stainless steel, which can make stainless steel have good corrosion resistance in any water quality. Even if it is buried underground, it can also have relatively good corrosion resistance. It is because stainless steel pipes and pipe fittings have the above excellent characteristics, the thick wall, installation and transportation costs can be greatly reduced. When stainless steel pipes and pipe fittings are used in the tap water industry, they are suitable for various water quality and will not cause corrosion and leakages. In addition, stainless steel pipes can be subjected to high-speed water scouring at speeds up to 30m/s. Even in the diversion stainless steel pipes for high-speed hydropower stations, the water flow at the end of the stainless steel pipes can be as high as 60m/s, and the service life can still be maintained at about 100 years. A secondary coating is not required.
 
2. Matters needing attention for selecting thin-walled stainless steel pipes and pipe fittings
2.1 Diameters and connections of pipes 
Stainless steel pipes are currently the main pipes for water supply pipelines. In indoor buildings, especially high-rise buildings, most water leakage occurs at the connection part of the water supply pipeline. Although the continuous development of current material technology has given birth to many new types of pipes, whether some connecting methods of some pipes and pipe fittings can be used is still debatable. Part of the connection is good for pipes with small diameters, but problems can occur in pipes of large diameters. For example, the most suitable connection method for pipes with a diameter of more than 70 mm is the welding or flange connection, while the best connecting method for pipes with a diameter of less than 70 mm is reaming. At the same time, the selection of materials will have a direct impact on the service life and cost of pipes and pipe fittings.
 
2.2 The flexibility of the pipeline
Everything is in a state of non-stop movement. When pipelines are used in water supply and drainage projects, they are often affected by vibrations of construction engineering, water impacts and other factors, and there will be a certain degree of expansion and deformation. Therefore, when selecting thin-walled stainless steel pipes and pipe fittings, it is necessary to fully consider the flexibility of the pipes and pipe fittings. From the relevant research results, plastic pipes have relatively good flexibility, so there is no problem with flexibility. The copper tube is sealed by rigid sealing, and it does not have flexibility. Although the connection method of thin-walled stainless steel pipes and pipe fittings is also rigid, they can be equipped with matched flexible joints, which have good flexibility, and the possibility of loosening and leakage of connection parts is also greatly reduced.
 
2.3 Impact resistance and pulling force of the pipe
The current high-rise buildings show a large-scale development trend. For example, a 30-storey building can reach a height of about 100 m, and when water is filled in the whole pipe, its pressure will reach 10MPa. However, most of the current construction projects use frequency conversion speed regulation, and the water pressure value cannot be guaranteed at all times. For this reason, when selecting thin-walled stainless steel pipes and pipe fittings, it is necessary to consider the value of the impact pressure at the connecting position of the two. According to the current experimental and research data, the impact resistance of thin-walled stainless steel pipes and pipe fittings is the best. Other pipes such as stainless steel composite pipes and aluminum alloy composite pipes have suffered serious leakages under the same water pressure impact value. As long as manufacturing pipes and pipe fittings fully comply with the requirements of the production process, the strength and damage tests carried out separately on the two will be fine. However, when the two are connected together, the connection between the two is the weakest place.
 
For this reason, when selecting stainless steel pipes and pipe fittings, it is necessary to conduct a pulling force test on the connection position of the two. Ensure that the connection method at the connecting part can meet the actual needs of the project.
 
2.4 Distortion of the pipeline
In the construction process of the project, construction workers often take advantage of the pipe's plasticity and ignore construction code requirements due to the influence of various factors such as construction sites and space. In this case, the torsion of the connecting position of thin-walled stainless steel pipes and pipe fittings needs to be considered when selecting them. For this reason, when selecting thin-walled stainless steel pipes and pipe fittings, torsion tests should be performed under the condition of constant pressure for the pipe joint and pipe to ensure that the torsion of thin-walled stainless steel pipes and pipe fittings meets the requirements of engineering construction.