Crown Oilfield Services slashes brush replacement cost and avoids machine breakdowns in corrosive air.

Welding is an art, but when it comes to selecting and maintaining welding machines, Crown Oilfield Services is all business.

When General Manager Randy Aulds saw that his old DC generator-type welding machines were spending too much time in the maintenance shop, he knew the smart business decision meant trying new equipment. This included the new Big Blue® 302 welding generator and Mark series of multiple-arc power sources from Miller Electric. These welding machines provide reliable service in rugged environments, improve economics and have an arc quality that satisfies even finicky pipe welding professionals.

Based in Bayou Vista, Louisiana, Crown provides the oilfield industry with onshore and offshore fabrication and maintenance services. Typical shop work for its 35 operators includes welding spool pipe, interconnect piping for separators, heat exchangers and compressor packages, small caisson decks, boat bumpers, heliports and crane bases. From its dockside loading on Tech Bayou, which connects to the Intercoastal Waterway, the company transports these components to the Gulf of Mexico. At any given time, 100 to 200 Crown operators are welding tie-ins for compressors, fabricating items like framework for safety capsules or performing maintenance welding on mobile drilling rigs.

Until recently, Crown exclusively used traditional DC generator engine drives for all its offshore work. However, in the highly corrosive and humid Gulf environment, Aulds says “we'd often run into problems with older DC generators that would shut the machines down. They'd work great in our yard after maintenance, but it seemed like three days offshore in the salt air would cause something else to go wrong. The brushes or armature would be worn or the wiring brittle. The customer has a hard time understanding these problems. He's paying for a man and a machine. And when we have a broken machine on a platform, we're at the mercy of the crew boat's schedule or hiring a workboat to make a special run. The customers want something that's going to give them better service.”

Lowering Maintenance Costs

Throughout their years of service, Crown performed routine maintenance on all its DC generators. In fact, maintaining welding machines is a full-time job for two mechanics and a helper. Preventive maintenance activities performed every time a unit comes off a platform include steam cleaning to remove salt, changing fuel and oil filters, changing the oil and swabbing the fuel tank. To improve uptime, Crown frequently replaced the brushes and had the armatures rewound several times. Replacing a DC generator's brushes takes about 2 1/2 hours and costs $120 (10 brushes @ $12 each). Rewinding can take 10 to 14 days and cost $1,400 to $1,600.

Frustrated with the cost of maintaining old equipment and recognizing the need to upgrade to more reliable equipment, Aulds welcomed the opportunity to participate in a field test for the Big Blue 302. He initially thought that some operators might hesitate to use the Big Blue 302 because of their historical preference for the arc produced by a DC generator. However, Miller improved the Big Blue 302's arc characteristics by adding more iron and copper to the generator.

“Our maintenance crew has been welding pipe with the Big Blue 302 on an oil production platform in the Gulf of Mexico, and they are very impressed with how smoothly it places a bead,” states Aulds. “In fact, they do not want to go back to the old machines after experiencing the new Big Blue 302.”

Shop Foreman Jack Martin also believes that Miller has come a long way and now makes a welding generator that can stand up to every day pipe welding.

“Just to see if I could bog down the machine,” says Martin, “I ran a bead completely around a pipe, dragging the rod in the open root. The Big Blue never bogged down, which means that it has good voltage control. I was pretty impressed because not many machines can do that. Also, the new Millers don't throw a lot of buckshot (spatter), so the sides of the weld stay clean.”

After getting such positive feedback from Martin and the welding operators, Aulds immediately purchased a Big Blue 302 and plans to buy a new one every quarter this year. He jokes that the mechanics are nervous about Crown going to Miller machines “because they have such a great warranty. Three years parts and labor is hard to beat. I hope it's going to be a tremendous maintenance savings.”

The Big Blue 302 will lower maintenance costs because it only has three brushes that cost $5.34 each and take five minutes to replace. Also, these brushes receive much less stress than those in a DC generator because they carry a small amount of current, not the entire welding load.

“Another thing operators really like is the machine's quietness,” adds Aulds. “The Big Blue isn't noisy; you don't get that rumbling in your ears, so you can hear yourself think.” To put this in perspective, consider that a single 300 amp competitive unit creates more noise than the combined sound of three Big Blue 302s.

Standing Up to Salt Water

While single arc units such as the Big Blue work well for Crown's numerous maintenance contracts — the company provides services to Texaco, Vastar, Burlington Resources, El Paso Energy, Amerada Hess and others — multiple-arc welding machines make more sense for large jobs.

“We just completed three compressor hook-ups, which is a major coup for us,” says Aulds. “We had 25- to 40-man shifts working day and night to Stick and TIG weld all the tie-ins. On larger jobs like this, we've had great luck with Miller's six- and eight-arc welders, the Mark VI™ and Mark VIII®-2. And by luck, I mean that we don't have breakdowns.”

Multiple-arc welders create independently controlled welding arcs through a single primary power cable. Aulds uses a 50 kW generator to power the Mark VI and an 80 kW generator to power the Mark VIII-2. While initially acquired for the irreliability, multiple-arc machines also save Crown money. First, it takes much less time to load a single machine and a generator on a workboat than six or eight separate engine drives. Second, multiple-arc machines dramatically lower the cost per welding arc. A Mark VI and a 50 kW generator set together cost about $24,000, or a per-arc cost of $4,000. Engine drives with a 300 amp output cost $8,000 to $11,000 each. Third, engine drives cost more to maintain because they have more parts that wear.

“On larger jobs, we've had very good success using multiple-arc machines instead of engine drives,” states Aulds. “With fewer moving parts, we don't have the problems that we ran into with our old diesel machines. And if one arc should go out on a Mark VIII-2, the other seven arcs keep working. After three years, the electric machines from Miller have held up really well in the salt water environment."