When should flanges for heat exchanger equipment be chosen as necked butt-welded or type A flat-welded flanges? How to choose?
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I don’t understand when to choose a flanged weld neck fitting for equipment, and when to choose type A butt weld flanges or type B butt weld flanges What is the basis?
Refer to the operating conditions specified in the equipment flange standards.
First, consider the operating conditions of the equipment flanges; second, refer to clause 3.2.5 of the Solid Content Regulations regarding the use of pipe flanges.
It is mainly based on the applicable tables in the flange standards, as well as the provisions of product standards and regulations; for example, the device flanges of low-temperature vessels must use a butt joint structure, and in such cases only long-neck flanges can be used
Generally, the materials used in pipe systems are mild, non-toxic, and not flammable or explosive; materials such as water and water vapor can be used, and type A or type B flanges can be selected when the temperature and pressure are not high. Conversely, choose a long neck. However, from personal experience, aside from encountering type A a few times occasionally, they are mostly long-necked, while type B is not very common.
The NB/T47020-2012 standard specifies the applicable conditions!