The issue of valve structural length in GB12221

Same question, please answer if you know.

It depends on how you design the pipeline~ Some can use short series, while others can only use long series. Actually, this problem isn’t serious at all. As long as it meets the standards, that’s fine~ unless specified by the customer. But generally, they are made in longer series~

Several series of structural lengths are actually derived by combining previous standards and pound-class standards; they represent structural lengths with Chinese characteristics. China’s valve standards were initially based on those of the Soviet Union, later the Ministry of Machinery developed its own set of standards, followed by alignment with ISO standards, and finally the structural lengths according to American standards were introduced. As a result, there are series of structural lengths ranging from long to short, with the black-colored ones representing the preferred series. There is no particular difference in the usefulness of the products.

In 1965, China carried out joint design work for valves, using Soviet technology primarily at that time. To this day, most of our design calculations still rely on the formulas developed in the former Soviet Union; other calculation systems seem to have not yet been established. In the valve industry, we are currently facing a situation of knowledge gap, as there is a significant difference between the knowledge structure of the older generation and that of the younger generation. For example, the wall thickness of valves according to national standards used to be relatively thick, owing to the limitations in casting and forging techniques. With the current higher standards, still applying the old criteria is actually unscientific. When the Ministry of Machinery still existed, Hefei General Research Institute would also organize some technical activities. Now, the Ministry of Machinery no longer exists, and the Hefei Institute is also left unattended; everyone now focuses on economic development. Perhaps you place a lot of emphasis on **standards, but it’s not that complicated. If you’re willing to pay 20,000 yuan, you can also include your name alongside the standard. These standards are basically copied from abroad. There was a dispute back during the valve standards committee meeting two years ago; originally, it was the companies responsible for developing the standards that were supposed to get paid. But now, once the standards are drafted, it’s possible to submit bids, and the company that offers the most money will be the one to develop the standards. As for what’s written inside, it doesn’t really matter if everyone copies it. I work in technology too; the standards these days can be really confusing. Currently, design work is primarily based on foreign standards; it’s no longer possible to follow domestic standards, as many of them are contradictory to each other.

For pipelines with low pressure and temperature, a short type is sufficient; if the process medium involves higher conditions, it is better to choose a medium or long type. The bold black text inside represents the recommended size.

There are various series available with different lengths for valve structures

There’s no watering going on. I’m also confused by the length of the valve’s structure – where is the water being supplied?