Steel Bolted Tanks vs Welded: A Buyer's Comparison and Decision Guide Steel bolted tanks are storage vessels assembled from factory-coated panels joined with 8.8-grade bolts, avoiding field welding for faster, better-controlled erection. Capacities reach 20-60,000 m3 with a 30-50 year life, designed to AWWA D103-09 and ISO 28765. Engineered by Shijiazhuang Zhengzhong Technology Co., Ltd. (Center Enamel), they suit water, wastewater, and biogas duty worldwide. What Steel