Inside, Outside, And All Around the Tank: Asbestos and Access No Match for Chemical-Tank Coatings Crew

VENDOR TEAM CONTRACTOR: Brock Maintenance, Inc. (BMI) PO Box 36 Deer Park, TX  77536-0036 (281) 478-5600 www.brockgroup.com ABATIX Burial bags and low-odor mastic removal 1430 North Post Oak Road Houston, TX 77055 (800) 222-8499 www.abatix.com BINKS Sprayer equipment ITW Industrial Finishing 3600 West Lake Avenue Glenview, IL 60026 (877) 367-3306 www.binks.com GRACO Spray equipment P.O. Box 1441 Minneapolis, MN 55440 (877) 844-7226 www.graco.com JLG LIFTS Bucket lifts 1 JLG Drive McConnellsburg, PA 17233 (877) 554-5438 www.jlg.com SCHMIDT DIVISION INTERNATIONAL SURFACE PREPARATION Abrasive-blast unit 6035 South Loop East Houston, TX 77033 (888) 873-1066 www.surfacepreparation.com SHERWIN-WILLIAMS Coatings www.sherwin-williams.com SPECIALTY SAND COMPANY Abrasive 7500 San Felipe #1001 Houston, TX 77063 (713) 974-5694 TINKER & RASOR Holiday testing equipment 791 Waterman Avenue San Bernardino, CA 92408 (909) 890-0700 www.tinker-rasor.com UNICOAT INTERNATIONAL Coatings 804 Winkler South Houston, TX 77587 (713) 947-254

By  Lloyd Kanter

Being in or around the coatings industry, when most of us hear the word, “styrene,” we associate it with odor. Yet, from the moment we wake up in the morning and turn off the alarm clock, we come in contact with products manufactured from polymerized styrene.

Beside the alarm clock itself, telephones, laptops, CD jewel cases, food containers, video cassettes, and many other items we use in our daily lives are made from this durable petroleum byproduct.

Before styrene finds its way into our homes and offices however, at least some of it is stored in a 60-foot by 48-foot tank at the Texas City, Texas plant of Sterling Chemicals.

Even though in its raw, liquid form styrene is not considered a hazardous material (it occurs naturally in many foods we eat), Sterling Chemicals pays particular attention to the vessel in which it is stored.

The domed-topped unit is constructed of welded steel panels coated inside and out with an epoxy lining material. The outside is further protected with an insulation system and aluminum jacket to help maintain an optimum 60ºF operating temperature, regulated with an internal chiller system.

“As part of an annual inspection program, ultrasonic thickness tests are performed on a regular basis to check the integrity of the steel tank walls, and periodically, tanks are emptied, recoated, and reinsulated,” says Lloyd Johnson, maintenance manager for Sterling Chemicals.

Brock Maintenance, Inc. (BMI), a Deer Park, Texas, contractor, was on-site to complete this styrene tank renovation project. “This project involved two significant challenges for us,” says the manager of business development, Wayne Pruitt. “First, the old mastic material had traces of asbestos, and required special abatement procedures. Second, the only access to the inside of the tank is through a 32-inch entry port on the side of the tank.”

The company is certainly experienced in this type of work. At Sterling Chemicals alone, Brock maintenance employs 45 to 60 people on a daily basis year-round, maintaining pipes and vessels.

“We’ve had a great experience with BMI over the last few years,” added Johnson. “When you have a contractor at your plant and you never notice they are there, you know you’ve got a good contractor. They just knock on your door and tell you they’re done with a project.”

This Jacket Has A Nasty Lining
The first test Brock employees faced was the removal of the aluminum jacket and insulating material on the outside of the tank. JLG Lifts allowed the workers safe access to any location on the outside of the vessel. The old aluminum jacket was installed in horizontal sections held on by steel bands that encircled the tank.

One by one, the aluminum panels were removed to expose the insulating material. The foam glass insulating blocks were adhered to the steel tank walls by a 100-mil thick mastic material containing asbestos.

The five men assigned to this project spent over a week with four-inch scrapers and a low-odor mastic removal product, carefully removing the adhesive. In addition to being tethered to the bucket for safety reasons, they also used respirators to prevent inhalation of the asbestos material.

Corrosion of the tank wall was quite evident as the insulating material was removed. “Being very close to the salt water of the Gulf, and with all the humidity present, corrosion of this type is quite common,” says Pruitt.

Per Environmental Protection Agency regulations, the asbestos-containing scrapings were double-bagged in six-mil “burial bags,” which were then transported to a hazardous waste facility for processing.

Blast (It) Off!
The next step involved abrasive-blast cleaning of the newly cleaned steel tank walls. A 3,400-liter Schmidt Bulk Blast Unit was used to blast the surface with medium-sized, coal slag abrasive material pumped up from ground level through a one-and-a-half-inch hose. BMI laid out ground containment to collect the sand, which was then shoveled up, placed in a bin, and tested prior to disposal.

The crew protected themselves during this process with Bullard 88 Series respirator helmets.

The blasting on the outside of the vessel conformed to NACE No. 3/ SSPC-SP6. These specs control how clean or “white” a surface has to be prior to recoating. Later, when the inside of the vessel was abrasive-blasted, BMI conformed to a NACE No. 2/ SSPC-SP 10 spec, which is a “near white” and more extensive surface preparation.

With the abrasive blasting complete on the tank exterior, it was time to apply the coating.

Using a Binks five-gallon sprayer, the BMI craftsmen applied two coats of Sherwin-Williams’ Phenicon HS, a VOC-compliant epoxy novolac phenolic coating. Brock maintenance field operations manager Mark Schimming said, “Sherwin-Williams has a long history with the Sterling Chemicals facility and this product meets or exceeds all Sterling’s specifications.”

Because the ambient temperatures were fairly warm, the first coat was sufficiently dry by the time workers got around the tank to spray the second coat.

The next step was probably one of the most critical — the installation of the chime coat. The chime coat protects the bottom of the tank from corrosion where it meets the surface it is placed on — in this case, concrete. Without protection, moisture would easily be able to attack the tank from the bottom.

The chime coating, Unicoat’s UI 5800 elastomeric polysulfide caulking product, was installed with a dual-component Graco pump. The flexible material was spread much like a cove base around the bottom four inches of the vessel.

Hi-Tech Insulation
The Tracer Construction Co. of Houston performed the final step to complete the outside of the tank.

“Technology has changed quite a bit in the 50 years since the original insulation was installed on the outside of the vessel,” says Tracer representative Joel Hebert. Tracer’s proprietary Tracloc system incorporates polyisocyanurate insulating sheets that are laminated to 24-inches wide, locking extruded-aluminum panels, pre-cut to the height of the tank prior to delivery. The panels are attached sequentially to each other and locked to ¼-inch galvanized cabling, positioned every three feet behind the panels on the tank’s circumference.

“The Tracloc system will withstand hurricane-force winds in excess of 120 miles per hour,” says Hebert. “As this tank is a below-ambient vessel, we also installed a vapor seal between all the panels to eliminate condensation, which can cause corrosion.”

With the outside of the tank complete, Brock’s crew went to work on the inside of the styrene tank.

No Easy Entry
“In order to complete our work, we had to build a 46-foot-high scaffolding system of casters, which enabled us to access every part of the tank’s interior,” says Pruitt. “The challenge was that every component of this 18-foot by six-foot system had to be brought in through a 32-foot entry port on the side of the tank.”

The client provided lighting for the tank interior. “We had available outside 110-volt power, which we stepped down to 12 volts for safety,” says Sterling’s Lloyd Johnson. “We were able to hand plenty of fluorescent lighting for them to work with.”

Once the scaffolding was assembled, the crew began abrasive-blasting the tank’s interior. Throughout the blasting process, they continually inspected the surface for worn sections or corrosion, marking any problem areas. This blast removed an old, thin-mil phenolic epoxy coating and was performed to NACE No. 2 /SSPC-SP 10 specifications. Ultrasonic-thickness readings and visual inspection did not reveal any areas that warranted special attention. All corrosion was isolated to the tank’s exterior.

The crew then spray-applied the first coat of the Sherwin-Williams epoxy to the interior of the tank, and, after it dried, they performed holiday testing. Brock’s Tinker& Rasor holiday detector measures electrical connectivity and identifies any pinholes in the applied coating. There were none, so the crew proceeded with the second coat.

Then, all the scaffolding that had been brought in through the manhole and painstakingly erected was torn down and brought out the same way.

All that remained was to treat the floor of the vessel. Again, the surface was abrasive-blasted and cleaned. The crew repeated the Sherwin-Williams coating system, with two applications of five to six mils DFT each, performing holiday testing in between coats.

By the time the job was completed, the styrene tank had been off-line for over a month. After signing off on the project, Lloyd Johnson proudly gave Sterling the OK to “fill ‘er up.” The Brock maintenance crew moved on to their next project, knowing this is one vessel that will contain its chemical cargo for years to come.

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