... introduce ourseleves as professional manufacturer of ERW square tube and rectangular tube. Owning to high quality, competitive price and good services ... A500 API 5L Gr.B/DIN, BS1382, DIN2440 and so on...Yearly capacity: 600,000ton/yearUsage: Our products are widely used ... on structure, liquid, boiler, petroleum, natrual oil and so on. If you are interested in our ...