The material selection of external pressure expansion joint outer protective cylinder needs to consider a variety of factors, the following are some common materials:
Carbon steel
Carbon steel is a more commonly used material, such as Q235 carbon steel. It has high strength and toughness, and the cost is relatively low. It can provide sufficient mechanical protection for the expansion joint and withstand certain external pressure. In general industrial piping systems, if the medium is not corrosive and the temperature and pressure conditions are relatively moderate, carbon steel outer casing is an economical choice.
Stainless steel
304 stainless steel: Similar to the bellows material, 304 stainless steel contains 18% chromium and 8% nickel, and has good corrosion resistance. When the pipeline system is in a certain corrosive environment, or when the appearance of the equipment has certain corrosion resistance and neatness requirements, the 304 stainless steel outer casing can effectively prevent rust and extend the service life of the outer casing.
-316 stainless steel: contains molybdenum element, corrosion resistance is better than 304 stainless steel. In some pipeline systems close to the sea and with heavy chemical corrosion environment, 316 stainless steel outer protection drum can better resist the corrosion of seawater and chemical media.
Glass reinforced plastic
Glass reinforced plastic (FRP) is a fiber reinforced plastic. It has the characteristics of light weight, high strength and corrosion resistance. For some pipeline systems with special chemical corrosion environments, such as pipelines conveying strong acid and alkali media, FRP outer casing can provide good chemical protection to avoid corrosion damage to the outer casing.
