主要工艺形式有: % f1 g R3 s E3 k: K! r. I$ _: J1. All continuously welded or brazed. 3 Z0 w. F$ f, u% H2. Tack or spot weld (and sealed or unsealed) R4 E2 N! ?/ `6 |- t3 g8 \9 X) A
3. Seam locked (and sealed or unsealed)5 H z4 T& e! z ?# U) R
4. Rivet, screw, or punched-die-stamp locked (and sealed or unsealed)