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Mud pump frames at assembly illustrate the need for precise bore-to-bore alignment between sides of the frame to locate the crank and pinion shafts.
This HBM helps EWECO be productive with its flexible, traveling-column design. The column can move close to the table for work on this eccentric crank or far away for frame work.
Growing worldwide demand for natural gas and oil has pushed up prices. Gasoline and diesel fuel are hitting record prices at the local station, much to the chagrin of car and truck drivers. Of course, increased demand and higher prices encourage energy companies to find new sources in the ground. This means more well drilling wherever oil and gas deposits are likely to be reached.
That’s good news for companies that make supplies for the oilfield industry, companies such as EWECO in Magnolia, Texas. EWECO is a major manufacturer of mud pumps and related components. “We’ve seen more growth in this market lately than we’ve seen in 30 years. Our backlog is bigger than it’s ever been,” says Michael Williams, president of the company.
Every oil or gas well drilling site needs at least one mud pump; some sites may have two or three. Mud pumps are large pieces of equipment that force “mud” down a well hole so that small pieces of drilled rock can be carried up with the mud as it is sucked back out of the hole. Successful, economical well drilling can’t happen without a mud pump, and if a mud pump fails, drilling stops. According to Mr. Williams, EWECO pumps have a reputation for durability and long life in the field, so his company’s pumps are in great demand right now. He attributes the quality of these pumps to highly efficient designs, high-quality materials and accurate machining of critical components. Moreover, he likes to say that EWECO wrote the book on mud pumps, but some of the best chapters are still being written.
Keeping up with the current rush of orders while maintaining its manufacturing standards is a challenge for EWECO. “Our customers expect to have their pumps delivered when promised; issues with our machinery can’t be offered as excuses,” Mr. Williams says.
Recently the company underwent an expansion to their manufacturing facilities by adding two new HBMs and 50,000 square feet of floor space. The new expansion is served by a pair of 40-ton cranes to meet the need for newer, larger units. If the necessary capacity to satisfy the market demand could not be found under its own roof, then outsourcing would be the only alternative. However, EWECO is both a pioneer and a leader in the mud pump market, and they would rather keep this technology in-house, if possible. EWECO faces pressures from low-cost regions of the world that seek to copy components. Mr. Williams says that copies are typically not made of the same durable materials that EWECO uses and the life of the components is far lower.
Mud pumps can be many feet long and are designed to be delivered on flatbed trucks. Many units are being packaged for sale to companies in the North Sea and provinces in the former Soviet Union. One key feature of EWECO pumps is the large, rigid rectangular frame that gives an assembled pump its stability and durability in the field. Other large components include valve bodies and manifolds. The size and shape of these workpieces call for horizontal machining. Indeed, EWECO relies on HBMs in its shop. The shop has 14 HBMs, all from Nomura (distributed in the United States by SB Machine Tools, Schaumburg, Illinois).
The newest machine is a Nomura HBA-135. This machine has an extra meter of Z-axis travel compared to other models considered for the application. Not only does this extra travel allow several operations to be combined in one setup, but the accuracy of this travel establishes the foundation for the precise, efficient operation of the pumps when assembled and tested. In fact, the ability to machine large, complex components accurately helped make it possible for the company to introduce its new five-piston series of mud pumps last February. These new pumps achieve much more efficient operation than the company’s popular three-piston models.
Although the five-piston designs have more components and a more complex mechanical operation, they have an uptime record as good as the simpler three-piston versions.
“Without the capability of our horizontal machines, EWECO could not have launched this new product line,” Mr. Williams says. “As it is, the new pumps are expected to add double-digit growth to our sales in 2008. We’ve been able to reach new markets and hit our sales targets because of the efficiency and accuracy of our HBMs,” he says.
Reaching Growth GoalsMr. Williams’ father, Ellis, gave the company both its name and its spirit. EWECO stands for Ellis Williams Engineering Company. The elder Mr. Williams was a pioneer in the oilfield business who highly valued efficiency and innovation. These are two characteristics that his son says he now pursues with the same drive. The father’s legacy reaches back to the 1940s, when he began his career with Continental-Emsco. At that time, the industry still used steam-powered pumps. However, the demand for more power and greater portability eventually made the steam versions obsolete, ushering in the age of the twin-cylinder pump powered by electric motors. The twin-cylinder model D-175, designed by Mr. Williams, became a mainstay of the industry. The need for still more power brought about models such as the D-225 and the D-550. Eventually, a 1,600-hp version, the D-1600 was developed. In 1967, the elder Mr. Williams’ development efforts prompted a change from the Duplex series to what he called the Triplex series. The Triplex used three cylinders instead of two, thus distributing loads more evenly among components and increasing both pump life and performance. At the time, the idea was considered revolutionary. It was well-received in the market, making the Triplex the industry staple that it is to this day, the younger Mr. Williams says.
Years ago, industry needs encouraged changes to pump design, and today, needs are again testing the limits of current technology. Much of the current oil supply is found under shallow sands, and it is being consumed at record paces. Any newly found deposits of oil are deeper and under more layers of rock. Reaching those deposits would be impossible if it were not for an engineered fluid that drillers simply call “mud.” This slurry of dissolved clay and polymers is aptly named—it has the consistency and density of wet cement.
Mud, according to Mr. Williams, has about a dozen functions in an oil well. Perhaps its most important functions are to carry bits of drilled rock back to the surface and to keep the cutting tip cool. A more advanced drilling method allows drilling mud to act as a hydraulic power supply. Instead of turning the whole drill string (the entire length of pipe down the well hole), the hydraulic energy carried by the mud is used to turn just the cutting tip, making it possible to drill deeper and through more rock than previous technology allowed. Using this technique, drilling can penetrate at an angle (directional drilling), avoid difficult layers of rock and hit deposits previously considered too costly to reach. To perform directional drilling successfully, acoustic data must be retrieved from the mud being pumped into the hole. This data is referred to as MWD (measurement while drilling) and LWD (logging while drilling). Acoustic reflections from the hole and surrounding rock layers indicate the depth and direction of the cutting tip. They also reveal information about rock layers surrounding the tip. However, a major source of interference to this technique is the mud pump itself. As the pistons move in and out, forcing material down the hole, resulting pressure variations cause acoustic pulses that must be filtered from the MWD/LWD systems.
In February 2008, EWECO released the Quintiplex series mud pump. The Quintiplex has five cylinders instead of three. Using five cylinders reduces pressure variations by more than 70 percent, thus reducing mud “noise” on the drill string and, in turn, allowing more accurate MWD/LWD readings. Increasing the number of cylinders decreases the load each component is required to carry by more than 40 percent, compared to Triplex pumps of the same horsepower. Although this new design increases the working life of each component, it multiplies their number. Every component, no matter how well designed or well built, will eventually wear out or need to be replaced, so the complex Quintiplex design heightened the importance of precise manufacturing to extend the useful life on critical components. The company’s HBMs have to support this mandate.
Reaching Between Two ExtremesWhile many configurations exist for HBMs, EWECO has found a size and arrangement that works well for them. “I’ve had floor models, but I prefer the table type. The accuracy of every machining operation downstream is controlled at the HBM. It took me a long time to understand that,” Mr. Michaels explains. Some HBMs provide Z-axis travel by moving a saddle, which has a rotary table mounted to it, to and from a fixed column. Other HBM configurations have a flexible traveling column. In this design, the table is mounted to a saddle that only moves in the X axis. It cannot move to or away from the spindle. For this type of machine, Z-axis motion is accomplished by moving the column to and from the fixed table. At EWECO, the traveling-column design is critical to the overall mud pump accuracy because it allows both sides of the frame to be machined in the same setup without moving the part. With the traveling column, the Z axis can be fully retracted from the table to allow the large rectangular frame to rotate about B axis. When the rotation is complete, the second side can be milled to complete the part. According to Mr. Williams, the B axis of the Nomura HBA-135 can be positioned accurately within 3 arc seconds, thus making the bore-to-bore alignment of the crank bores very good. While fully retracting the Z axis represents one extreme of travel, being able to reach the table requires another extreme—that of the Z-axis stroke. This why the extra meter of travel in this axis is essential.
Rigid Frames Help EWECO Reach Long LifeThe frame of the mud pump influences the overall life of the pump because it holds the crank (also called the eccentric), the input shafts and the idler shafts in alignment. The Quintiplex, according to EWECO, is the first pump to have a balanced eccentric crankshaft. It is important to be able to get close to the crankshaft when doing layout work so components fit as they should during assembly. When asked about the traveling-column feature and how important it is to manufacturing the pump successfully, Mr. Williams replied, “If we couldn’t back the column out of the way and machine the frame in one setup, we’d have to redesign the whole product.”
However, the extra-long Z axis isn’t the only must-have feature of EWECO’s HBMs. The quill design produces and transmits a great deal of torque and thrust for heavy machining.
Spade Drilling Works The QuillAccording to Mr. Williams, the balanced crankshaft and rigid, accurate frame allow precise alignment of gears, pinions and shafts. Yet, the real workhorses of the pump are its pistons, cylinders, valves and manifolds. Mud is a thick and abrasive material, so it naturally causes wear on cylinders and pistons. However, these components can be serviced in the field, whereas the valves and manifolds are not designed to be replaced on a regular basis. For this reason, they are made of either 4130 or 4340 steel, which resist wear. Manifolds can be as long as 48 inches and can have drilled holes as wide as 5 inches in diameter.
EWECO uses a spade-drilling process to make holes in these parts. Spade drilling requires substantial torque, and EWECO depends on its HBMs to deliver this high drilling force. For example, the three-speed gearbox on the HBA-135 is capable of generating nearly 3,000 foot pounds of torque. The lowest programmable spindle speed is 5 rpm. Using the higher gears yields a maximum 2,500 rpm. According to builder, the gearbox design allows the spindle to reach maximum torque throughout its speed range. The HBM’s 5.3-inch diameter quill is nitride hardened and ground to a mirror finish. This finish increases the amount of surface area in contact with the quill sleeve for greater rigidity.
The spindle quill can feed with a maximum of 7,000 pounds of force and reach a maximum depth of 27.5 inches. For holes too deep to complete from one side, the hole is drilled on the first side, then rotated and drilled on the second side. At EWECO, a mismatch where the holes meet is unacceptable, so the HBM must be accurate and precisely aligned. Mr. Williams reports that the HBMs meet this requirement, even under heavy machining loads.
The combination of the traveling-column configuration, extra Z-axis travel and high-torque/low-rpm capability makes the HBM a very flexible machine tool for EWECO. The company’s success with its new five-cylinder mud pump product line reflects the importance of this flexibility in today’s market. Flexibility is also the key to thriving in the future if and when market conditions change. As Mr. Williams points out, past experience has been a good teacher.
Being Flexible Helps Reach New MarketsThe search for new sources of oil and gas hasn’t always been as intense as it is today. As recently as 10 years ago, the price of a barrel of oil was $11. During that time, no one was paying to explore for new oil because the market seemed to be flooded. When well drilling slowed dramatically as a result, EWECO relied on its flexible approach to manufacturing to reach markets that were not energy-related to support the business. In addition to oil well drilling, mud pumps can be used to dispose of saltwater and to remove flood water. Pumping cement is also a significant market for mud pumps because they are more reliable than equipment in use for this application. Also during this last drilling slump, EWECO expanded into industrial water blasting. Perhaps the most innovative application of the mud pump was in the field of horizontal directional drilling. This method is used to drill under rivers, highways or subways. It helps in laying pipelines and adding to communications networks when excavating the site would be undesirable.
Mr. Williams believes that keeping flexible machinery such as the HBM in his manufacturing base means EWECO can respond to similar opportunities as they emerge in the future, without having to outsource production of components.