The Loose Steel Pipe Flange with Weld-On Collar is a two-component connection system consisting of a stub end (weld-on collar) and a freely rotating loose flange. This innovative design allows the flange to spin freely for fast and precise bolt hole alignment, significantly simplifying installation and maintenance. The stub end is butt-welded to the pipe for a permanent, leak-proof seal, while the loose flange remains easily removable. Ideal for systems requiring frequent disassembly, thermal expansion compensation, or constructed from corrosion-resistant stainless steel, it offers a more flexible and economical alternative to a fixed weld neck flange in non-critical service applications.