| 摘要 |
<p>A method of welding tubes includes forming a layer of foam(S) inside a first tube, filling shield gas in a space defined by the layer of foam and welding the tubes (1,1). A foaming agent including keratin protein is used to form the layer of foam (S) for containing shield gas. A spray (2) containing the foaming agent for containing shield gas sprays the foaming agent into the tube (1) through a nozzle (22).</p> |
