By Bill Neighbors, Tank Connection
In today’s market, information technology on storage applications has collided with advanced steel tank designs, advanced coating systems, and field construction processes. The outcome includes some of the most cost efficient, high-quality storage containment products ever developed for industrial and municipal applications. Under review, high-quality storage products offer significant benefits to the client in the form of extended service life, low maintenance, and cost savings generated over its service life.
|Table 2: XL storage tank construction under review|
The problem in comparing alternative types of storage construction is separating high-quality “Tier A” (Table 1) storage products from marginal and poor performance “Tier D” storage products. It may surprise you to know that in today’s market, premier quality dry bulk storage products can be purchased and installed for about the same price as low-quality storage products. Of course, the real kicker is when you add the life cycle costs to the equation. In many cases, the life cycle costs of “Tier D” products will calculate at more than twice the cost of “Tier A” products. Needless to say, it becomes an expensive lesson for the client when marginal and poor-quality tank construction is specified and procured for a project.
The construction of a storage tank/system should always be reviewed as a major infrastructure project. Never assume that a vendor will provide you with the right type of storage tank construction for your application. Always cover the specifications on tank construction, coating systems, and field construction processes in detail. Then you can specify and procure a premier quality storage system with confidence.
Today’s Storage Industry
It is interesting to note that on a global basis, storage products are being introduced in the marketplace today that will not “stand the test of time”. As typical with new product offerings by manufacturers, it is all about profit margins. Many suppliers of storage systems fall into the same “ant line” procession as other suppliers of capital equipment. They equate “cheapening” their storage products to “making them less expensive”. This has always been a bad model to follow. Relative to the storage tank industry, it is a total misread on today’s storage tank requirements.
|API 620 field-weld construction dry bulk storage application|
As previously noted, the best storage containment tanks and products are designed, manufactured, and installed as major infrastructure projects. As a reference point, the minimum service life of a storage tank used to be considered 40 years. In today’s storage industry, there are tank and containment products that are being introduced into the market that will provide less than a 10- to 20-year service life and other products that will provide service in excess of 60 to 80 years. All of these products have a comparable initial installed cost by construction type, but when the life cycle costs are added, “Tier D” products will cost over twice as much as “Tier A” products.
Today, in industrial and municipal applications, there are steel storage tanks throughout North America that are over 100 years old. Based on proper maintenance of a storage tank and its coatings, a steel storage tank can be maintained for an indefinite service life.
Bolted Tank Construction
In bolted construction, the bolted RTP (rolled, tapered panel) design is the top performance product offered in the industry today worldwide. It is the premier product and it is outdating other types of bolted tank construction. API 12B (flanged panel tank) is an older bolted tank design that has incurred too many field leak issues in dry bulk applications and is being replaced by the RTP design.
|Table 1: Quality and field performance classifications of storage tank construction|
A newly introduced storage product is the vertical FP (flat panel) design that is being promoted as another replacement for API 12B construction. The vertical FP design is a poorly conceived design. There is no merit in a vertical panel design, except that it allows the use of older, existing API 12B field construction equipment (i.e., air tugger and gin pole), which is also considered outdated by today’s field construction technology. In precision-bolted fabrication, the RTP panel design must be rolled horizontally, the same as API 650 and API 620 fabrication.
Field-Weld (FW) Tank Construction
In field-weld construction, API 650 and API 620 fabrication has changed little, with the exception that state-of-the-art shop fabrication equipment is now utilized. In the field, new field-weld construction technology has allowed for advances in welding processes. API 650 and 620 construction remains the premier storage products in welded-tank construction. All panels (~8–10 ft high × ~25–35 ft long) are rolled horizontally and leading fabricators will minimize the large piece count in the shop. A variety of other field-weld construction types have also surfaced in the industry by smaller fabrication shops, without governing code requirements. Field-weld construction that does not minimize the large piece count in the shop or is not subject to radiograph examination (both in the shop and the field) per API 650 should be considered no better than “Tier D” quality.
Hybrid Tank Construction
Any tank component combination of bolted, field-weld, or concrete construction will produce a storage product classified as a hybrid. As noted, tiers range from A–D in quality and performance.
Concrete Tank Construction
Slip-form concrete construction is the premier concrete storage tank design for dry bulk storage applications. Jump-form concrete is routinely utilized in biomass storage, grain applications and elevated water tank pedestals.
Always Specify Wisely
When you specify or request a quotation on a storage system, always cover the bases by following the storage checklist:
|RTP (rolled, tapered panel) construction (left) API 12B flanged panel construction (right)|
• Always request the tank vendor specification and make sure every detail is specific. Tailor the specification for your application.
• Always request the tank design plate thickness broken down separately (i.e., sidewall, hopper/bottom, and deck) at the quotation stage, not after order placement. This will allow for a side-by-side design comparison of vendor storage products.
• Always review the tank vendor performance guarantee in writing at the quotation stage–again not after order placement. In dry bulk storage applications, make sure that the tank vendor will guarantee material flow from the tank. If the tank vendor does not guarantee that the product is going to discharge properly from the tank, then move on to a different vendor.
• Always request safety information (i.e., EMR) on any subcontractors that will be utilized for field construction services, if the company does not have its own field erection crews. Although some storage tank manufacturers represent that they have their own field construction services, the reality is that most tank manufacturers subcontract their field construction labor.
• Always request coatings information and DFTs (dry film thicknesses) applicable for the tank interior and exterior coating systems. This has become a major issue in today’s market. Some tank vendors are applying coatings at less than the recommended minimum mil thickness to save costs. We have even measured coatings in the field that were applied at less than 2–3 mils. There is absolutely no reason for tank coatings to be applied at readings less than 2–3 mils. As the right coating selection is critical to the success of a project, the proper mil thickness is equally as important to protect the stored product internally and the tank exterior from the exposed environment.
• Always request from your supply vendor the name of the tank manufacturer. There are a number of tank suppliers and vendors today that represent themselves as tank manufacturers, which could not be further from the truth. Don’t be fooled by tank suppliers that have fabrication shops or field construction crews, as they are not the storage tank manufacturer, but rather independent dealers representing themselves as tank manufacturers. In other words, always know who you are dealing with or you will be surprised, typically at the wrong time.
• Always conduct prequalification to verify a vendor’s shop and field capabilities, financial stability, bonding capacity, safety record, etc. Again, don’t assume. Today’s market is not yesterday’s market.
• Always request whether or not your tank quote is subject to price escalation after order placement. Unless steel pricing becomes volatile as it did in late 2008, the pricing you receive should be firm through the agreed to “scheduled date” for shipment or field installation.
• Always set a firm schedule with the tank manufacturer and hold their “feet to the fire” to ship the tanks on time and on schedule.
In summary, if you follow the checklist of items noted, then product specification and procurement will be made as an informed buyer. Don’t assume that an old vendor name in the marketplace should go unquestioned. Most importantly, the biggest problem witnessed in today’s market is vendors that do not assume any responsibility for the tank in the storage application. In all cases, cover your bases and specify a premier quality storage system that will stand the test of time as a major infrastructure investment.
Bill Neighbors is president, Tank Connection LLC (Parsons, KS). Tank Connection is a leading designer, manufacturer, and installer of storage containment products and field construction services. Tank Connection offers all types of steel tank construction, with more than 100 different types of storage containment products tailored specifically for the application. For more information, visit www.tankconnection.com.