The karfe bututu abu ne wadanda ba gami low carbon karfe.Hanyar fasaha ta samar da bututu an yi ta ERW wanda aka yi masa walda tare da kabu mai tsayi.Ka'idodin samfuri suna iya yin aiki da ASTM A500, ASTM A53, ASTM A795, BS1387, BS EN10255, EN 10219, BS 1139, BS 39.