Are welded tanks superior to bolted tanks?
Size: A welded tank can be built in any size and capacity up to 20MG. Bolted tanks generally come in standard sizes, which are dictated by the manufacturer, not the customer.
Durability: For two tanks of equal capacity, the welded tank is made of thicker/heavier steel, adding years to its useful life. It's also the preferred method of building storage tanks in earthquake zones
Safety: Welded tanks can be easily and cost-effectively adapted for cathodic protection systems. This extends the useful life of the tank's steel and its coatings. Because bolted tanks are gasketed, expensive jumper connections must be used to bond together every stave of a bolted tank.
Coatings: Welded steel tanks are easy to recoat. Bolted tanks have many inaccessible areas that are subject to corrosion and must be disassembled, recoated, regasketed, and then reassembled.
Lifespan: With proper maintenance, the useful life of a welded tank is between 75 and 100 years. The lifespan of a bolted tank is between 25 and 30 years. While true that a bolted tank can be less expensive initially, this cost advantage disappears over time.
BOTTOM LINE: The cost benefit per year of useful service is lower for welded tanks.