Internal suckback or concavity is one of the most frustrating—and costly—defects in orbital pipe welding. Everything looks perfect during the weld, only to discover internal concavity right at the tie-in. In high-purity, code, or critical service applications, that’s a failed weld. ASME B31.3 states that there should be no excessive internal concavity for process piping. So if we see we must make some adjustments to get rid of it! The good news: internal suck back is easily