Oil field equipment & machinery. (Casting Market Focus).

"The allure of the fledgling oil industry, like that of gold, tapped one of mankind's greatest emotions, the thrill of discovery. For some, the quest for oil led to great riches. There were sudden jobs, excitement, new towns, new places, incredible inventions and ponderous machinery... The same thrill is there and new territory and deeper pools await the drill."

These words, from Samuel T. Pees, oil historian and author, capture the impact that the oil industry has had on our nation and way of life. While the Chinese drilled 800 ft deep using bits attached to bamboo poles in the earliest of times (300 A.D.), metal castings have been right in the thick of things virtually ever since, including when the U.S.' first oil well was drilled in 1859 in Titusville, Pennsylvania.

Castings have been, and remain, the most economical route to manufacture for many components in oilfield equipment and machinery (NAICS 333132). In some cases, the casting process is the only option due to complex geometries, internal passageways, size and property requirements.

Striking 'Black Gold' with Casting

According to the most recent Casting Source Directory database, 455 foundries in the U.S. and Canada are serving customers in the oil field machinery and equipment sectors, which represents $259 million in casting sales.

There are numerous castings used in the production of oil, from the drilling rig to the "christmas tree" sitting on top of a producing well, and finally the pipeline and refinery. David Nelson, Southwest Steel Casting Co., Longview, Texas, said a tremendous variety of castings exists on each drilling rig. Numerous valves and other components make up the "christmas tree" and many more valves go in the pipelines and refineries.

According to Ron Taylor, KO Steel, San Antonio, Texas, some of the most common uses for castings are in manual and power tong components (levers, jaws, latches, covers and safety clamps) elevator components, (bodies, doors, latches, link blocks, bails and slip segments) rig components (swivel bodies, gear boxes, kelly bushings and brake levers), blowout preventers (bodies and rams), valves (high-pressure bodies for wellheads) and pumps (bodies, covers and impellers).

A Vital Industry

While environmentalists often view oil as a "black-eye" industry, the petroleum industry actually saved the whale from extinction, as oil was rapidly "harvested" from the ocean mammals for lighting and machine lubrication. Had petroleum products not appeared in the 1850s as an alternative, the San Joaquin Geological Society predicts that many species of whales would have disappeared long ago.

The U.S. consumes an average of 19 million barrels of oil per day, with 44% going to motor gasoline, 24% other oils, 20% distillate fuel oil, 8% jet fuel and 4% residual fuel oil. Further, shampoo, cosmetics, detergents, paint, ink and plastics would not be possible without the key ingredients derived from refined oil.

The U.S. ranks 12th worldwide in reserves of oil with 22 billion barrels of proved oil reserves. Reserves are concentrated in four states: Texas, Alaska, California and Louisiana.

The ability to produce oil efficiently, cost-effectively and timely is critical to our nation's needs, which packages 8.1 million barrels of oil every day.

Even so, nearly 60% of the total gross oil demand must be imported ($97 billion), with 47% coming from the OPEC nations, and Persian Gulf countries accounting for 23%. As a result, the nation's reliance on oil, and the health of its domestic supply is constantly monitored, particularly with the uncertainty of the Middle East.

Two specific casting applications are described in the following sections.

Swing Check Valve

A record casting application was set this year with the world's largest sub-sea swing check valve produced by Atchison Casting Corp., Atchison, Kansas, for Stream-Flo Industries, Ltd., Edmonton, Alberta, Canada.

This 48-in, diameter, 9500-lb swing-check valve (Fig. 1) is the fail-safe shutoff device between the platform out in the ocean and the pipeline headed for land. It is a safety-critical, high-liability component that would save the platform in the event of a fire. It is used near Trinidad Island off the coast of Venezuela.

Discussing the manufacturing method, Martin Ishkanian, Stream-Flo's Corporate Quality Manager and Metallurgist, said, "Castings are often the best choice because of the requirements on materials, CTOD, fracture mechanics, etc. With casting you get the same directionality (isotropic) properties throughout the part; that's the beauty of the process. You can't get that on a forging.

"If produced and heat-treated properly, casting is better than forging because there are no weaknesses in orientation. If you need a certain yield strength by design, you can't afford to have variations."

Because of the high values in fracture mechanics, a high-alloy steel with a tightly controlled steel alloy chemistry was selected. The part, which has thickness varying from 6-10 in., required two ladles to pour, and spent seven days in the mold.

He added: "On this particular part, there was simply no other way to do it. You could not forge a component of this size, and it would be ridiculous to hog-out (machine) such material."

Blowout Preventer Bodies for Rotary Oil Well Rigs

Another critical casting application is the blowout preventer (BOP) (Fig. 2), which is the safeguard standing between hole gas and the disaster of full-scale blowout. If gas emerging from the hole reaches atmospheric pressure at the top and starts to vent, a blowout could result in death and destruction, not to mention irreparable environmental damage.

Needless to say, the BOP must work reliably as intended. According to an article in Casteel magazine, Hydril Co. counts on the strength of cast steel for nearly all of its BOP pressure-containing parts.

A huge valve, the BOP closes off the space between the pipe and the casing and keeps the gas from reaching the surface. Hydril's designs are about 90% cast steel, and employ the firm's own specially formulated alloy.

Casting was chosen because many of the extremely complicated shapes can only be cost-effectively produced via casting, and again, for its isotropic and corrosion-resistant properties. Pressure ratings as high as 20,000 psi are common, and weights run from 3000 to 30,000 lb. Castings typically have minimum property values of 80 ksi, 17% elongation and 30% reduction of area.

Figure 3 shows cast packer components for an annular BOP.

Offshore Applications

Castings serve critical purposes on offshore oil rigs as well. According to Geoff J. Marston of the U.K.'s River Don Castings (writing in a series of technical papers), steel casting applications for offshore oil drilling rigs have become fully accepted by structural engineers. "Steel castings are now commonly specified for complex, high-stress structural members such as heavy lift padears, spreader bar ends and increasingly, nodal applications," he said.

He maintains that creative design of castings often enables steel sections to be tailored to meet specific engineering loads, thus improving engineering efficiency (resulting in design benefits and weight reduction in the surrounding steelwork). Citing casting advantages in enhanced fatigue life, isotropic material properties, guaranteed mechanical properties in thick sections and weldability issues, he said many offshore applications simply could not be achieved through conventional fabrication technology.

Industry Outlook

According to the Baker Hughes Rig Count, the number of rotary drilling rigs (847 as of August) is down about 32% from 2001, which was the most robust year in as many as 15. In 1981, 4530 active rigs existed--an all-time high.

Usually, said Nelson, a price of $21/ barrel spurs additional drilling. Despite the fact that the price has been well above this threshold in 2002 (and nearly $30 at press time), the uncertainty of the economy didn't spur much additional drilling.

According to Nelson, natural gas production remains down about 4% from last year. He added, however, that "wells are being depleted faster. Because today's fields are smaller and harder to produce, wells are becoming marginal and drilling is taking place at a faster rate."

Stratecasts, Inc., which tracks trends in application and supply/demand for castings, predicts a 2% annual growth rate in petroleum equipment over the next 10 years. Ductile iron (currently at 67,000 tons) and carbon steel (currently at 42,000 tons), are expected to see 2% growth, followed by gray iron (55,000 tons) to a lesser extent.

"Peak oil, when the world will produce its most oil in history, has been projected for 2020-2030, before starting a gradual decline," said Nelson, adding that some projections have called for peak oil to arrive as early as 2010.

Trends

Nelson noted that some future trends for casting applications include specialty alloys and duplexed metals because the extreme working conditions will demand it.

Taylor also shared the industry dynamics that favor casting use. Because the oilfield industry tends to be very volatile ("boom to bust in a matter of months"), he said production runs of equipment and parts have become much shorter. "Manufacturers don't want to invest the money in forging dies when foundry patterns can be purchased more economically.

As more manufacturers move toward compliance with the new industry specifications (which many existing product lines do not meet), he said that "design changes can be accomplished more economically with foundry tooling to produce a near-net-shape part."

This article was adapted from one that originally appeared in the Fall 2002 issue of Engineered Casting Solutions.

For More Information

"Blowout Preventers Guard Against Oil Well Disasters," p. 1-8, Casteel, Steel Founders' Society of America, Barrington, IL (Spring 1980).

"Setter Cast than Fabricated," Geoff J. Marston, p. 108-112, The Foundryman, (March 1990).