Abstract: A bulk bag or a liner for a bulk container is formed from a plurality of tubular blanks of flexible material so that each wall of the bag or liner has at least two layers of material. Desirably, many woven or plastic sheet materials suitable to make such bags or liners are available in elongate and circumferentially continuous tubular webs such that a plurality of liners or bags may be formed connected in end to end relation on an elongate web. In one form, a pair of gusseted tubular blanks are disposed between and sealed to a pair of overlying flat tubular blanks to define a liner or bag having two layers of material in each wall. In another form, a pair of tubular blanks are folded so that each tubular blank defines one flat panel and one gusseted panel and the tubular blanks are heat sealed along a pair of side edges of the liner or bag to also define a liner or bag having two layers of material in each wall.