Principles for determining the minimum thickness of pressure vessels

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Principles for determining the minimum thickness: 1. After the container shell is manufactured, its minimum thickness, excluding the corrosion allowance, shall comply with the following requirements: (1) For containers made of carbon steel and low-alloy steel, the minimum thickness shall be not less than 3 mm. (2) High-alloy steel containers with a minimum thickness of not less than 2 mm. (3) For tower vessels made of carbon steel and low-alloy steel, the minimum thickness shall be 2/1000 of the inner diameter of the vessel, with a minimum value of 3 mm ； For stainless steel tower-type containers, the minimum thickness shall be not less than 2 mm. (4) For containers with multi-layer wrapping (including multi-layer tubular section wrapping and multi-layer integral wrapping), the minimum thickness of each layer (including the inner tube sheet and layer sheets) shall be not less than 3 mm. 2. The minimum thickness of the cylinder of shell-and-tube heat exchangers shall comply with the provisions of the current **standard ‘Heat Exchangers’ GB/T151. 3. For vessels whose nominal shell thickness depends on the minimum thickness and which have a large nominal diameter but a thin thickness, in order to prevent excessive deformation during manufacturing, transportation, or installation, temporary reinforcement measures should be taken according to the specific circumstances (such as installing temporary support elements inside the vessel). 4. The minimum thickness of the composite steel plate coating shall comply with the following requirements: (1) To ensure that the working medium remains clean (free from iron ion contamination), the thickness of the composite steel plate coating shall not be less than 2 mm. (2) To prevent corrosion of the working medium, the thickness of the composite steel plate coating should not be less than 3 mm. 5. The thickness of the stainless steel surfacing layer on the inner surface of the container shell shall not be less than 3 mm. The designer should determine whether to weld a transition layer and a surface layer based on the properties of the working medium, with their thickness being determined according to specific circumstances. 6. The minimum thickness of the stainless steel surfacing layer on components such as flanges, flat covers, and tube sheets, after machining, shall not be less than 3 mm. 7. For containers made of carbon steel or low-alloy steel with corrosion-resistant linings, the minimum thickness of the lined steel shell shall comply with the provisions of the current industry standard \"Technical Specifications for the Design of Lined Steel Shells\" HG/T20678. 8. For shell-and-tube heat exchangers with non-replaceable tubes, the minimum thickness of the baffle plates and support plates shall not be less than twice the corrosion allowance on the shell side. 9. The nominal thickness and minimum formability thickness of the container components shall be indicated on the design drawings, such as the nominal thickness and minimum formability thickness of the head. (Source: HG/T 20580-2020)