Steel pipe suppliers, please help. Which type of pipe is the most common in the market?
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Pipes come in different outer diameters: those with a large outer diameter (imperial pipes), those with a small outer diameter (metric pipes), and those whose outer diameter has been rounded off. In HGT20553, these are classified asⅠa for large outer diameter, Ⅱ for small outer diameter, and Ⅰb for outer diameter after rounding. Over the years of purchasing from various companies, I’ve found that pipes with a rounded outer diameter are easy to obtain, as are those with a small outer diameter. However, imperial pipes, whose outer diameter values include decimals, are more difficult to find. In design documents, companies, especially those of a certain scale, tend to use pipes with a large outer diameter. This indicates a mismatch between design requirements and market realities; there must be some misunderstanding on my part, which is why I’m quite puzzled. I would like to ask steel pipe suppliers, as well as those with extensive experience in this field, which outer diameter is more common in the market
@Liu Jiajia: Could Teacher Liu answer this?
You had better consult the people at the design institute to find out whether the design project follows American standards or European standards
Whether a circle is round or not depends on the standards; for British standard pipes, namely those with a large outer diameter, the standards are primarily based on ASME B36.10 and ASME B36.10. Previously, domestic standards used rounded values; now, in order to align with international standards, the trend is to make them completely consistent with ASME B36.10. For example, SH/T 3405-2017 has been revised to be fully in line with ASME B36.10. Additionally, it is also related to the design institutes; for example, chemical engineering design institutes* typically use HG/T 20553, petrochemical design institutes* typically use SH/T 3405, and long-distance pipeline design institutes* typically use ISO 4200. Apart from rounding and slight differences in certain pipe diameters (such as DN65), the differences are not significant, so there’s no need to worry too much about them. Additionally, you mentioned procurement issues. As far as I know, it is available for purchase under current standards. We usually use SH/T 3405; the purchasing department reported no difficulties in acquiring it.