Science Behind It: Below-Grade Polyurea


By Art Weiss, Technical Supervisor, VersaFlex Incorporated

Below-grade containment isn’t just a concern for the water industry; it touches a plethora of fields including oil and gas. In turn, the oil and gas industry encompasses every possible niche requirement for properly installed coatings and liners. The major components of its needs are: secondary containment of stored product; primary containment within concrete and steel tanks for holding oil field products and production material; primary and secondary containment on refinery facilities that convert the raw oil field liquids and gases; and storage of finished product including transport and transmission of the fuels and other distillates they produce.

At the well head, itself, each and every component is now required by government regulation to have a secondary containment enclosure capable of protecting the environment from accidental spills and other operating conditions.  This requirement moves right down the line, through the refineries, to the transmission and transport side of the industry, and to the storage sites scattered around the country, many of which are located in major urban areas.

There are some conflicting aspects to the implementation of these regulations. The producers, the largest companies in the world, have been accused of price gouging and excessive profits. These same producers are now required to quickly adhere to regulations, and this necessitates a huge outlay of money to accommodate the mandates. They must do this under scrutiny of their pricing, especially relating to the price of gasoline at the pump, the cost of heating fuel, and the consumption of increasing amounts of natural gas and bio produced fuels. Coupled with increasing demand for these products that will only be satisfied by expenditures of billions of dollars to bring new sources from the fields to the consumers and whole new types of plants to convert biological produce into energy sources, the producers must simultaneously retrofit their current plants to accommodate regulations. Many of these facilities are older operating units, having already exceeded their expected life cycle.

All of this must be done with sensitivity regarding consumer angst about higher prices and stockholders’ concern about return on investment.

With these considerations in mind, oil and gas producers are seeking new technologies to fulfill their needs.  Polyurea has proven to be that material of choice up and down this very complex and diversified line of need. Often that solution is at the well sites themselves. Containment systems are being erected around the wells themselves, plus around individual storage tanks containing raw crude and production water, as well as the piping and valve systems.



Technology To The Rescue

Companies in both the United States and Canada are meeting these new challenges presented by modern technology demands.  For example, Falcon Technologies of Grapevine, Texas, a major supplier of field service for the oil and gas industry, has taken full advantage of the resurgence of oil drilling activities. In their shop yard, oil field condensate and oil tanks are abrasively blasted to a minimum two mil (0.05 mm) profile. Polyurea is then applied at a minimum 60 mils (1.5 mm) to the interior of the tanks and man-way doors. In addition, in the field, the secondary containment area around these tanks is lined with the polyurea over geo-textile, as opposed to the traditional sheet liner systems that have seams and leaks.

Additionally, similar processes are underway at refineries. The variety of containments at refining facilities is much more numerous than at the production well head. Here, light and heavy distillates have to be accounted for. Further, many of the distillates are solvents or root raw materials for organic coating materials. The current emergence of flex fuels vehicles, ethanol and methanol fuel blends, and the emerging biofuels industry facilities are causing the production of fuels that are much more aggressive to concrete and steel tanks. These facilities must convert their existing tanks for use with these new products, which requires a whole new approach to interior coatings.

New generations of lining coating materials are being introduced to accept these aggressive containments. For example, sprayable blends of Teflon (PTFE) have been used by one manufacturer to accommodate these innovative chemicals.

As expected, the requirements are very exacting for this type of tank lining. Access ways are generally required to allow heavy equipment into the interior of the tank. The pictured conversion, provided by Carolina Service Group, a diversified provider of services, shows the scope of work required for lining large steel tanks. The tank required abrasive blasting to bare metal to remove an existing coating unsuitable for the future use of the tank. Huge quantities of blasting sand were required, and all the expended blasting sand had to be removed and properly disposed of in accordance with local contamination standards.

Concrete tanks and storage containments are undergoing extensive rehabilitation to meet new industry regulations. The pictured tank is being rehabilitated to hold process water with high concentrations of acid. The tank was parged to fill out the pitted substrate and then blasted. Next, 60mils (1.52mm) of polyurea were installed to the wall and floor surfaces. Then a Viton-Teflon coating, a patented elastomer with very good chemical resistance especially to acid attack, was rolled into place. The white aromatic polyurea was used to give wear indication against a black Viton-Teflon coat.
   
Secondary Containment Solutions
 

This method does take skill. Pipe racks in plant applications are very difficult to contain with any assurance. One method has been developed by FSI Incorporated of Fort Meyers, Florida, that uses patented pre-sprayed panels for these difficult applications.

This is a very labor-intensive operation at the site, even if most of the required square footage is completed prior to arrival for installation. The sprayed seaming requires great attention to detail in order to assure complete protection. The seams must be as strong as the sprayed panel itself. This requirement is widespread throughout most jurisdictions. However, it can be accomplished. 

A tank farm in New York State installed over 600,000 square feet (55,741.82m2) of secondary containment using pre-sprayed panels. Wide open large scale containment projects, such as the New York tank farm installed over two months by FSI Incorporated, are relatively easy to complete since there is little or no impediment to proper layout and seaming operations. 

Canadian standards developed several years ago have been adopted by the United States government, and local jurisdictions are mandated to oversee their installations where required, which is just about everywhere.

For Petro-Canada’s GOT Project, two new chemical storage tanks were being constructed with a clay liner system for secondary containment. Petro Canada and Stantec Consulting proposed a clay liner upgrade to a synthetic geo-membrane / polyurea based on the aromatic polyurea sprayed elastomer system, as opposed to a sheet liner system based upon a thermoplastic material. Environmental issues related to leaks and spills of chemicals, required a seamless system. This project sprawled over many acres and the actual containment covered over 450,000 square feet (41,806.37m2). Follow-on projects will cover an additional 10 acres (40,468.56m2) on this large Petro Canada facility. Dudley Primeaux II, named patent holder on many aspects of polyurea, supplied on-site supervision for the project, working closely with the Owner and Contractor to resolve issues as they arose on a day to day basis.

This was a complex project with a variety of elevations as well as pipe racks, roadways, and other traffic areas had to be accounted for along with backfill considerations. Advance Coating Solutions, Edmonton, Alberta installed the project over a three-month period.

Older containment systems are being upgraded. Concrete, asphalt and other types of containment substrates are being made fluid-tight by application of polyurea directly over the existing substrates. Seamless membranes such as polyurea are able to quickly convert such areas.

Not all oil and gas containments require the high pressure spray rigs commonly associated with polyurea. Low-pressure polyurea spray material can be used for this relatively small project. Many smaller contractors are taking advantage of opportunities opened up by government regulations such as now exist in this industry.

Since regulatory requirements call for quick application of secondary containment on such a broad scale, the use of polyurea is ideal since installation temperature restrictions are not onerous. So long as a workman can work, the polyurea containment system may be installed.

Once recognized as a suitable coating material for the oil and gas industry, polyurea has found an enormous variety of installation applications that fit its physical properties. Development of new products has occurred to provide protection not previously contemplated. With the advent of skilled and knowledgeable installing contractors having a base in the industry, this enormous market is being fully explored.  These installers, using innovation to patent systems, bridge the relationship between their industrial owners and the manufacturers, each attempting to discover new methods to serve this vital industry.