Big, Heavy, and Automated: Trends in Machining for Seafloor Recovery
Extracting oil and gas in the deep ocean requires heavy-duty expertise. But the tight skilled labor market is forcing more efficient use of capital equipment through single setup and automation
By Bruce Morey
The sea is beckoning to energy providers, with oil and gas drilling platforms moving into ever-deeper waters. The US is seeing a rebound in offshore drilling after recovering from the BP Gulf of Mexico spill in 2010. Dana Scott of Mazak Corp. said 105 drilling permits were issued through August 2012, compared to 79 in all of 2011. What’s more, Scott said the equipment is getting elderly, which means it will need to be replaced soon—a potential boon to manufacturers. "Of the 474 jack-up rigs used in the worldwide fleet, 317 are 25 years and older—approaching the end of their useful life," Scott said. "There is going to be a tremendous amount of deep-water drilling."
Contract manufacturer Dan Cotrino, COO of Rockwell Precision (Houston, TX), said that his company is delivering more components for use in offshore drilling, such as tooling, motion compensation equipment, spherical blowout preventers (BOP) and valve bodies. However, they mix that work with directional drilling components and blocks used in hydraulic fracturing for land-based rigs because the machining equipment he needs to produce oil and gas components does not differ greatly whether it is land or sea-based equipment.
There are some differences though. "On the offshore side, the parts are larger," Cotrino said. Harder materials that are more durable are another difference between sea and land, mainly in duplex materials. These include stainless steel with an Inconel inlay for grooves in piping and couplings, requiring high cutting forces.
Bruce Cates, regional manager for Absolute Machine Tools (Lorain, OH), the supplier of the YouJi machine tools used by Rockwell Precision, agreed that a key difference "between land-based extraction and offshore is exotic materials." Equipment on the seafloor, he explained, has to withstand higher pressures.
"To cut exotic materials, what you are looking for in a machine is one with a heavy, rigid box-way machine able to take difficult cuts," Cates said. He believes a stable machine needs to deliver high torque. "For example, our 2000-mm vertical turret lathe [VTL] delivers 41,133 ft-lbs of torque [55,550 N•m]." Absolute specializes in both two-axis and three-axis VTLs—live tooling provides the third axis. He also noted that the bulk of what Absolute Machine Tools sells are three-axis machines, primarily for combined turning and drilling.
Rockwell Precision uses YouJi vertical turret lathes supplied by Absolute Machine Tools. These are equipped with live tooling, needed for most offshore components, such as their YV1600 ATC+C, boasting a 1600-mm diameter table. "Live tooling means we can do the whole thing in one setup and not bottleneck a [separate] boring mill, to do the mill work," Cotrino said. "We do a lot of our spherical BOPs with that machine, as well as pistons, adapter rings, locking rings, and valve bodies—all for offshore." He also owns a smaller YV1200ATC+C with live tooling and YV1600ATC without live tooling.
A key difference that Cotrino has observed since the 2010 spill is the increasing amount of nondestructive testing of subsea components and the witnessing of those tests. They use primarily ultrasonic testing, magnetic particle testing, and liquid penetrant testing at different manufacturing phases. He reported that a third party must witness tests for practically every phase of the process.
Richard Estes, corporate account manager, oil and gas for Okuma America Corp. (Charlotte, NC), deals with both major oil field equipment suppliers and small contract manufacturing shops. "Since the 2010 Gulf of Mexico spill, all of the BOPs in the deep sea are going to be changed out," Estes said. "They are all going to be redesigned."
Although each company will have its own, unique design for BOPs, some of the new elements are common to all. These include much larger physical size, newer, more exotic materials, and more stringent machining accuracies. "Tolerances that once were measured in millimeters are going to microns," he said. Surface finishes were largely ignored in the past. Today certain features have finishes that are found in the aerospace industry.
He noted that tricky devices like BOPs and downhole instruments are future challenges to machining as they become larger and use ever more exotic materials. "Downhole instruments are now made of titanium with very complicated structures, such as holes with angles that intersect other holes," Estes said. "Some take up to 300 hours to machine and the initial material cost is $60,000–$100,000. This requires a rigid machine to meet tighter tolerances and challenges us to make larger machines." An example of a larger, multitasking machine that Okuma sees as a future mainstay in oil and gas is its MULTUS B750 capable of delivering 37 kW of power and 5000 N•m of torque with a maximum turning diameter of 1050 mm.
Reducing Demand for Labor
Not all contract manufacturing shops know whether their products are used on land or in sea. "The technical requirements for these parts are about the same," said Marc Breaux, manufacturing manager of Taylor Oilfield Mfg. (Broussard, LA). "Ninety percent of the components we make are for mud motors. ... We do a lot of shaft work, components, long parts, and other parts with long splines on them."
Since his start in machining for oil and gas, he has seen equipment transition from shops filled primarily with manual equipment to advanced four and five-axis CNC machines. "We do a lot of three-axis and four-axis work," he said, mostly with combined machining and turning centers. They have a Mazak Integrex e-650H-II and two Integrex e-500H-II multitasking machine models. These provide turning, milling, drilling and optional long boring bar capabilities. They also feature
B-axis high-torque milling spindles, heavy-duty C-axis turning spindles, long bed lengths and rethreading functions.
The move to done-in-one setup is not isolated to Taylor Oilfield. "One-setup machining has grown in importance," agreed Scott of Mazak, who noted that labor costs have increased for manufacturers of oil and gas equipment as skilled labor continues to be difficult to find. "A single-setup operation minimizes labor and thereby reduces cost because one person does the work of what used to take three or four," he said. He also emphasized that done-in-one is no more difficult for a machine operator to handle, especially if they are already familiar with operating milling centers.
Recent additions to Mazak’s line of machining centers targeting oil and gas include the newer Integrex e-670. "It is the anchor machine for the oil service group, because it allows them to machine parts for either subsea or land service, with more sophisticated features, on heavier parts," he said. For example, the e-670HS-II cuts parts to 42" (1067 mm) in diameter, and a maximum machining length of 160" (4064 mm). For smaller components, such as PCD drill bits, Mazak introduced their I- and J-Series Integrex multitasking milling/turning centers.
Stakes are High
The 2010 Gulf of Mexico spill highlighted the inherent dangers in the business and the need for top-of-the-line engineering and manufacturing. "Quality is paramount now in this business. If we make a mistake, we can kill somebody," said Luke Brader, president and CEO of BHI Corp. (Houston, TX). His shop primarily supplies a single OEM oil services supplier, Schlumberger (Houston, TX), which has demanding standards. He compared the measurement, inspection, and documentation requirements as comparable to those for nuclear-powered submarines. "We maintain and digitally archive a record on all physical dimensions on everything that goes out of our door," Brader said. "Everything that leaves BHI Corp. is 100% inspected, each dimension of each part, and archived."
Safety isn’t the only driver in quality, though. Offshore drilling platforms cost more than $200,000 per hour to operate, so a failure of a critical part at the bottom of the well, such as the components for perforating guns BHI produces, can make a rig useless for days at a time.
Brader also confirmed two trends—bigger parts and the need to automate. Competitive pressures from overseas, coupled with an apparent shortage of skilled machinists, is pushing him to automate. "Machines with toolchangers, multiple spindles, multiple axes—you put the part in and push the button, and it comes out complete with lathe and mill work all at once, that is becoming attractive," Brader explains. "It needs to run 24/7."
BHI Corp. received equipment that meets these goals from Methods Machine Tools Inc. (Sudbury, MA) via their distributor Koch Machine Tool Co. Inc. (Houston, TX), including two Matsuura MAM63Vs five-axis in a 34-pallet cell, a Nakamura NTJX nine-axis turning cell, and two four-axis Fanuc RoboDrills. The Matsuuras are equipped with BigPlus 40 taper 12,000-rpm spindles both in one cell, sharing 34 pallets with a cell controller, and two setup stations. Both machines have spindle and tool probes and tailstocks.
Automation can be tricky in this business, noted for small lot sizes. Brader noted that lot sizes vary from 10 to 30, with some orders up to a 100. This is a far cry from either aerospace or automotive. "We are not a manual shop, we are a CNC/automated shop with two 12-hour shifts," he said. "The trade-off is that you cannot run one piece on a CNC, like you can on a manual machine."
Drill bits are as important in sea drilling as land drilling, according to David Lucius, vice president of sales for North and Central America, Methods Machine Tools. "Failure is not an option for drillheads that might need to go down two to three miles," he said. "Even though machining is rigorous, part tolerances can be as tight as less than a thousandth of an inch." Machines should be versatile to facilitate processes such as complex contouring, required on many oil field components.
MAG IAS (Fond du Lac, WI) provides a full range of large horizontal boring mills (HBM), vertical lathes, and horizontal machining centers (HMC) for the oil and gas industry. "The parts for oil and gas have heavy cutting requirements because of the size and materials involved," said Peter Beyer, director of product strategy and product development for MAG IAS. "In addition to milled, bored, and tapped features, there are turned features, such as threads and interior/exterior profiles, or grooves that require turning." Contouring is required for a number of parts used at the wellhead: valve bodies, piping, connectors, or motor parts.
To help manufacturers get the most out of their equipment while easing labor requirements, MAG is introducing an integrated contouring head for its boring mills and large HMCs. "The key word is integrated," Beyer said, citing advantages such as fully automatic tool change into the contouring head, use of standard tools, and part probing with main spindle or an auxiliary probe.The head handles a diameter range of 50 to 540 mm, and derives power from the machine’s main spindle motor. "This is mechanically simpler, saves operator time, tooling cost and cycle time, and means a single setup to machine an entire part," Beyer said.
In his 30 years of dealing with oil and gas customers, one thing he is certain of—parts are getting bigger and heavier. Said Beyer: "We’re seeing parts now greater than 60" [1524 mm] in diameter and over 80,000 lbs [36.3 t] with cutting at the extremes of machine travel." ME
This article was first published in the February 2013 edition of Manufacturing Engineering magazine. Click here for PDF.