Technical article

What’s the material differences of metal pall ring


Pall ring is a new type of packing widely used in packed towers, with different materials and functions. In terms of material, it is mainly divided into metal pall rings, ceramic pall rings, and plastic pall rings. Today, we will introduce the material differences of metal pall rings.
1. What is a metal pall ring?
The metal pall ring packing is made of metal plates, and there are two rows of inner tongue flap window holes on the ring wall. There are five tongue lobes in each row of window openings. Each tongue blade bends in a circular pattern and points towards the center, overlapping at the center. The positions of the upper and lower windows are staggered. In general, the total area of the opening is approximately 35% of the total area of the annular wall. Because the pall ring packing has many window holes on the annulus wall, the gas and liquid in the tower can pass through the annulus wall. The window opens very freely. At present, pall ring is one of the main ring packing used.
Due to its unique material, it is suitable for various separation, absorption, and desorption devices, atmospheric and vacuum distillation units, synthetic ammonia decarbonization and desulfurization systems, ethylene benzene separation, isooctane/methyl benzene separation, etc.
There are various materials available for metal pall rings, such as carbon steel, stainless steel 304, 304L, 310, 410, 316, 316L, etc.
Stainless steel is the abbreviation for stainless steel acid resistant steel. It is resistant to air, steam, water, and other weakly corrosive media or stainless steel. It is called stainless steel. It is resistant to chemical corrosive media (chemical, alkali, salt, etc.). The steel grade is called acid resistant steel. Generally, according to the metallographic structure, ordinary stainless steel can be divided into three types: austenitic stainless steel, ferritic stainless steel and martensite stainless steel. Based on these three basic metallographic structures, dual phase steel, precipitation hardened stainless steel, and high alloy steel with iron content less than 50% are derived for specific needs and purposes.

2. What is the difference between different materials of metal pall ring?
Austenitic stainless steel is used for metal fillers. The matrix is mainly composed of austenite (cy phase) with a face centered cubic crystal structure and is non magnetic. Stainless steel is mainly strengthened through cold working (and may result in a certain degree of magnetism). The American Steel Institute uses serial numbers 200 and 300, such as 304.
1). 304 stainless steel pall ring. 304 material is one of the austenitic stainless steels with a large application volume and a wide range of applications. Suitable for the manufacturing of deep drawn components and acidic pipelines, containers, structural components, various instrument bodies, etc. It can also manufacture non magnetic and low-temperature equipment and components. 304 stainless steel Bauer ring is a common metal filler in stainless steel, with a material density of 7.93g/cm3. High temperature resistance of 800 ℃, with good processing performance and high toughness.
2). 304L stainless steel pall ring. In order to solve the problem of severe intergranular corrosion tendency of 304 stainless steel due to the precipitation of cr23c6, the sensitized intergranular corrosion performance of 304 stainless steel is better than that of 304 stainless steel. Except for slightly lower strength, other properties are similar to 321 stainless steel. It is mainly used for corrosion resistant equipment and components that cannot be treated with solid solution after welding. It can be used to manufacture various instrument bodies.
3). 316 stainless steel pall ring. Adding human molybdenum to 10Cr18Ni12 steel results in good reduction medium and pitting corrosion resistance. In seawater and other media, the corrosion resistance is better than 304 stainless steel, mainly used as a pitting resistant material.
4). 316L stainless steel pall ring, made of 316L material with good plasticity, cold deformation, and welding process. Ultra low carbon steel, with excellent resistance to sensitized intergranular corrosion, is suitable for manufacturing thick section sized welding parts and equipment, such as corrosion-resistant materials in petrochemical equipment.
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Tracy Chen
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