What regions are there currently in China's stainless steel pipe threaded fittings manufacturers?

If the main origin is Foshan, Wenzhou, Hangzhou, Chengdu and other Guangdong provinces, the production quality and price are generally higher than other regions.
Wenzhou mainly sells more at low prices and is known as the city of stainless steel valves. And the connection methods are also different. It depends on the needs of each company and customer.
List the more famous stainless steel water pipe manufacturers in various regions as below
Guangdong Province: Yaolong Pipe Industry, Guan Yisheng, Meiya, Minle, Artron, etc.
Zhejiang: Zhengkang, Flante, Wenzhou luwei valves and fittings Co.Ltd

Sichuan: Common