What is a high-pressure pipeline?
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What is a high-pressure pipeline? This issue is a bit confusing. In GBJ235-82, high-pressure pipelines were defined as those with a design pressure greater than 10 MPa; however, this classification was removed in the subsequent standard GB50235. Some people refer to manuals and consider pipelines with a nominal pressure greater than 10 MPa as high-pressure pipelines, but such a classification cannot be found in any standards or regulations. Nor is there any mention of the classification of high-pressure pipelines in the current textbooks on pressure pipeline design approval. Pipes are classified only based on the pipe level category. Designers say that pipes with a grade of 900 pounds or higher are generally classified as high-pressure pipes. Some pipes may have a design pressure of less than 10 MPa, but due to considerations related to temperature and the medium involved, their pipe grade is still 900 pounds or 1500 pounds. I’m a bit confused now; could everyone please explain how high-pressure pipelines are defined?
You can refer to the pipeline regulations as well as the classification of pressure vessels
The classification of high-pressure pipelines is unclear; the maximum pressure allowed for domestic production is 32.5 Mpa, while the inspection standards cover up to 500 Mpa. But there is no distinction between levels.
There may be differences during inspection; this is specified in GB50236 and GB50235. Without considering the type of medium, high-pressure pipelines require 100% flaw detection to meet grade 2 standards, medium-pressure pipelines require 20% flaw detection to meet grade 2 standards, and low-pressure pipelines require 5% flaw detection to meet grade 3 standards. Generally, 20 kilograms and 60 kilograms are used as the thresholds
There is currently no strict limit for high-pressure pipelines in China; some say it is 10 MPa, but there is no official documentation to support this. In ANSI B31.3, a design pressure greater than CL.2500 is classified as high pressure