Choosing the Correct Heavy-Duty Fastening Torque Tool

In nearly every heavy industrial application, turning threaded fasteners - nuts and bolts - is generally viewed by two criteria: (1) the need to fasten tightly enough to prevent movement of parts and achieve a good seal without exceeding the fastener's elasticity level, and (2) successful removal of fasteners after long periods of environmental exposure to harsh conditions. Yet, ensuring you select the right torque tool for the job can be crucially influenced by the type of torque power it delivers.

When installing heavy-duty fasteners, there are times when you want just a little more power, or in other instances, a lot more power. After all, when it comes to turning nuts and bolts, especially stubborn corroded ones, what could be more basic than power?

The seemingly apparent answer to that question can be profoundly consequential: You need controlled power. That is, controlled "torque." Not only that, ideally you need smooth torque, with continuous rotation. Otherwise, you could outdo yourself and strip threads, break bolt heads or even cause personal injury.

Historical approaches to working with heavy-duty threaded fasteners have aimed at sheer torque power, using long lever arms and heavy hammers on slugging wrenches. More recently, the hydraulic wrench has been viewed as the solution to many problems that require serious torque. But hydraulic wrenches are notorious for their heavy ratchets, bulky compressors and laborious operation. And they're not cheap.

Technicians are finding that the best solution for applying torque power today is with a complete range of torque control products, including manual and powered torque wrenches and torque multipliers. From less than a few foot pounds up to more than 100 thousand foot-pounds, these torque control tools provide "continuous" torque, making it easier and often safer to assemble and service-threaded fasteners while reducing application problems and tool costs.

The advantages of continuous rotation, as provided by torque multipliers, are especially beneficial when it comes to heavy-duty torque fastening applications. Hydraulic tools operate through a hydraulic ram that extends and retracts, ratcheting the head. This is a long and tedious process that requires the operator to activate and stand by the pump with a hand-held controller.

On the other hand, continuous rotation tools eliminate the ratcheting and hammering, producing the correct torque values through smooth, constant gear manipulation. Mountz Torque Multipliers are a good example of continuous torque for heavy-duty use and are proven to achieve the correct torque values in a quicker, more cost-efficient manner.
A shop foreman working at a worldwide supplier of steam turbines, compressors and other turbomachinery for the oil and gas markets, replaced a hydraulic torque wrench system with a Mountz, Inc. CLS pneumatic torque multiplier at an oil field maintenance facility in Louisiana.

"The hydraulic system was bulky. You had all those lines to fight, and you had to lug the pump with you whenever you worked off site," said the shop foreman, "Also, you had to keep ratcheting the system up until we got enough torque on the bolts. With the new Mountz system, you just set the gauge, and when the multiplier shuts off you know you've got the correct torque value."

The shop foreman says the pneumatic torque multiplier system is also more compact and easier to work with. "It's a lot lighter and really portable. My mechanics like to work with it," he adds.

A foreman-mechanic that works for a valve manufacturer, says his department acquired a pneumatic torque multiplier from Mountz, Inc. to fasten the hub connections on subsea BOPs (Blow Out Preventers) used under oil drilling platforms. The company designs and manufactures valve and flow control products for the process industries in the petroleum, gas, chemical and power generation fields, had previously rented hydraulic torque wrenches for BOP hub connections.

"With a hydraulic wrench, properly torquing the hubs on some preventers used to take about three hours. With our new Mountz pneumatic torque multiplier, I can get it done in 30 to 40 minutes," the foreman-mechanic says. "In our business any time you can speed up an operation and still do it right, that's what you're looking for."

The Mountz torque multiplier, the foreman-mechanic says is much more portable and easier to use, and that weight alone is a significant factor. "The ratchets on the hydraulic wrenches are the heavy part. You just can't manhandle them. I used to hang them with an overhead crane. The pneumatic wrench is much more convenient. It weighs about 40 lbs., and one man can carry it easily," the foreman-mechanic explains. He also says the new pneumatic multiplier is considerably less expensive in purchase price.
But continuous rotation and control of proper torque tools is not just for big jobs. At a medical manufacturer facility, Mountz torque multipliers are used to meet stringent construction standards required for manufacturing custom wheel chairs.

"We're making wheel chairs that are prescribed by physicians," says the manufacturing engineer. "We are under the scrutiny of the FDA to ensure patient comfort and safety. That requires meeting official Good Manufacturing Procedure standards by providing them with accurate torque specs for critical components of the chairs."

But what about cost? Continuous rotation tools actually offer a more cost-effective solution to torque fastening. Comparing a hydraulic and continuous rotation tools capable of 3,000 ft. lbs., the continuous tool costs nearly half that of a typical hydraulic system.

"Equally important," the manufacturing engineer adds," proper torque application is also vital for worker comfort, productivity and safety, including the avoidance of 'repetitive use' problems such as carpal-tunnel syndrome."

In some instances, the effort required to set up and tighten fasteners can put operators at risk due to fatigue and resulting tool slippage.

For instance, a technical specialist for a military aerospace manufacturer, says adjoining the upper wing structure of the airplane involves a difficult connection due to the interference of the surrounding structure and the requirement for 460 ft. lbs. of torque on the bolts.

"We used to do it by hand. It took two employees with breaker bars, manual torque multipliers, and wooden blocks to brace it all up. Now we use a pneumatic torque tool, which is much faster and safer," technical specialist says.

Everyone should appreciate the significance of the safety and choosing the correct tool for the application, not only in terms of saving lives and injuries, but the high associated costs.