Stupp Coatings Protects Oil and Gas Piping With FBE

According to the Pipeline and Hazardous Materials Safety Administration (PHMSA), the U.S. utilizes more than 2.6 million miles of pipeline infrastructure to deliver trillions of cubic feet of natural gas and hundreds of billions of ton-miles of liquid petroleum products each year at a pace that other forms of commercial transportation could never rival.

Approximately 70 percent of the transport of oil and gas in the U.S. is by pipeline, and much of it is underground. PHMSA, federally funded in four-year cycles through the PIPES (Protecting our Infrastructure of Pipelines and Enhancing Safety) Act, asserts that pipeline transportation is significantly safer than any other transportation means. A key component of keeping our nation’s pipelines safe starts with the manufacturing and coatings process.

Stupp Bros., Inc. was established 163 years ago in St. Louis, producing ornamental iron and small machine parts. Over time, Stupp Bros., Inc. has maintained family lineage at the ownership level while establishing several successful subsidiary companies. One of those subsidiaries, Stupp Corporation, was established in 1952 as Cal-Metal Pipe to produce Korean War “invasion pipe,” which supported Allied amphibious operations on the Korean peninsula. Today, Stupp Corporation is a major producer of custom steel line pipe and related products and services used by the oil and natural gas industry. The company recently announced a $22 million initiative to upgrade their two Baton Rouge, LA, steel pipe manufacturing plants, which will result in 128 new jobs for the region.

Stupp Corporation mills high frequency welded (HFW) and helical submerged arc welded (HSAW) pipe. HFW, also known as radio frequency (RF) or dielectric welding, is the process of fusing materials together by applying radio frequency energy to the areas to be joined. The process involves subjecting the materials to be fused to a high frequency electromagnetic field along a longitudinal seam, and the resulting weld can be as strong as the original materials. HSAW is an arc welding process that joins metals by heating them with an arc between a metal electrode and the substrate. The arc burns beneath a layer of flux, which is supplied to the welding head. The arc melts the flux, which forms slag on the surface of the weld. This protects the molten metal from reacting with oxygen and nitrogen in the air. Steel coils (strips) are welded spirally, like a helix or paper towel roll, so that the coil assumes the shape of a pipe.

Conveniently located adjacent to Stupp Corporation’s headquarters and pipe manufacturing plants is the aptly named Stupp Coatings. This on-site finishing operation was added in 1994 so high-quality line pipe could be seamlessly manufactured and coated on the same campus, which has direct access via rail and truck to Baton Rouge’s deep-water port. Stupp Coatings’ Director of Commercial, Quentin Wiltz, PMP, EMBA, who has been in the industry for over 13 years and is active in NACE, jokes he is considered a relative newcomer to the industry. He says the facility has liquid and powder coating capabilities, primarily coating onshore piping for the oil and gas industry. While they have the capability to coat a wide range of pipe diameters and lengths, Quentin says they coat pipe as large as 48 inches in diameter; the majority of pipe coated by Stupp Coatings is 24-inch diameter HFW pipe, between 40 to 80 feet in length.

A key component of keeping our nation’s pipelines safe starts with the manufacturing and coatings process.

The first stage of the coating process is to shot blast the pipe surface to remove contamination and create an anchor pattern for the coatings. “The blast profile and surface preparation process are just as vital as the coating process to ensure a high-performance coating,” Quentin underscores. The carbon steel pipe, weighing anywhere from 60 pounds per foot to 400 pounds per foot, is moved as much as nine inches per second on a pitch via a customized conveyance system. The pipes move through the facility on rubber tires, which minimizes the impact to the surface of the coating and is one of many safeguards in place to ensure a defect-free coating. For application, Quentin points out the pipe is heated to 450-480 degrees Fahrenheit, so when the single layer fusion bonded epoxy (FBE) electrostatic powder is applied with Nordson guns, it adheres in a gelatinous state. An epoxy powder coating specially formulated to be applied over FBE as an Abrasion Resistant Overcoating (ARO) is then sprayed in the next booth to form a durable outer layer resistant to gouge, impact, abrasion and other forms of penetration. Quentin says the powder coating color is based on the powder supplier, and most have conformed to green as the standard single-layer coating, while black or brown generally designates a dual-layer FBE+ARO coating. He adds the coating thickness is determined based on the project specifications. Historically, an average 10 to 12 mils coating thickness was standard, but now a minimum of 18 mils is often specified by clients. Quentin feels this is understandable from the standpoint of wanting optimal corrosion protection but maintains there are tradeoffs. “With that thickness, there are additional manufacturing costs and inefficiencies involved, and it also limits the ability of the pipe to be bent on the job site.” He explains that pipe is often bent during installation to meet topographical requirements, so a greater coating thickness can limit performance characteristics after the pipe is reshaped, particularly for dual-layer coatings that exceed 45 to 55 mils. “Luckily,” reports Quentin, “newer ARO formulations allow for greater bending flexibility.”

Once the coatings cool past the powder manufacturer’s recommended first-touch temperature, the pipe is cooled with water and sent along the line for inspection. Inspection consists of a visual, manual and automated inspection in which a conductive probe contacts the coated surface to determine porous defects or if inconsistencies, called holidays, are present in the coating. The electric current is applied at an average rate of 125 volts per mil. After passing inspection, several polypropylene braided ropes are fastened around the circumference and the pipes are carefully loaded for transportation. Any damage done during transport harms the structural integrity of these critical components for our nation’s energy infrastructure, so great care must also be taken at this juncture. As the pipes are carefully loaded onto flatbed trucks or railcars for transport, wood spacers are used to secure the pipes and prevent damage to the finish, and nylon straps wrap around the entire load to securely anchor the pipes into place. Once the pipes arrive at their destination, minor scrapes and scratches can be managed by administering field repairs. Abrading and heating the surface around the defects allows the coating to reflow over the affected areas and adhere to the substrate.

The pipe is heated to 450-480 degrees Fahrenheit, so the single layer FBE adheres in a gelatinous state.

Quentin posits that since Stupp Coatings was founded, they have applied enough powder coating (12,900 tons worth) to coat a 24-inch pipe from the U.S. to China. Over the decades, regulations related to inspections, data collection, application standards and reporting requirements have increased significantly. At the same time, Quentin points out, advancements in application gun technology, improvements in coating mechanical performance, and refined formulations that allow greater flexibility in ARO’s have allowed them to meet those challenges head-on.

Troy Newport is publisher for Powder Coated Tough.