New professional bolting technologies are transforming safety and efficiency on pipeline projects. Where once manual labour sledgehammers and flogging wrenches prevailed, today high precision tools are not only making the job safer to do, but also vastly improving the security of the result.
The sheer volume of bolting jobs on existing and emerging pipeline projects has lead to a radical rethink about the way private and government groups approach fastening and maintenance tasks.
Everyone has got smarter about safety, whether the job is an outback mining development, a high-pressure pipeline, an offshore resource project or a municipal flood control, water reticulation or irrigation scheme.
The charge has been led in large part by the major companies and the government organisations, whose managers know (and can count on the balance sheet if they do not) the terrible personal and financial costs of bad safety practices. The pace of change has been remarkable: Just 10 or 20 years ago, one would find whole teams sweating, cursing workers swinging at recalcitrant bolts with flogging wrenches and sledgehammers straight out of the 19th Century.
Today, one is much more likely to find a technically savvy single person doing the work of several people with a powerful hydraulic torque wrench or tensioner, and doing the job more quickly and more efficiently, with literally tons of force at his fingertips (courtesy of an array of professional bolting equipment - controlled tightening technology, including the advanced, ergonomic torque wrench technology from Enerpac).
Why hydraulic technology, anyway?
Whether the task is centred in a city works depot, or dispersed over a vast area of Outback, portability and ergonomics are keys to safety and efficiency.
To achieve a given torque, a hydraulic torque wrench can be designed to be much lighter and more compact, so as to fit into confined spaces easily. (And Enerpac’s high-pressure, 700 bar, steel equipment, for example, offers outstanding power-to-weight ratios, whether selecting the torque wrenches on which the article centres, or the hydraulic nuts and hydraulic tensioners encompassed in Enerpac’s broad family of controlled tightening technologies).
Portability and ergonomics, of course, translate into big gains in personal safety. But in addition to taking the sweat out of the exercise, the power and precision of hydraulics also provides certainty in the quality and consistency of the job.
Especially in heavy industry, particularly including pipeline flange and associated heavy fabrication tasks, bolted joints has to comply with specific safety demands, which can be stringent. There must be absolute certainty about the joint’s operational strength. And although manuals describe factors such as mounting, use, maintenance and operating conditions, designers and specifiers can never be completely certain that all this is complied with. Many designers therefore opt for safety by using more or heavier bolts than strictly necessary.
A better approach, however, is to employ the precision of a torque wrench, combined with verified calculations to achieve the correct residual bolt load, in accordance with designer requirements. This is particularly so for heavy joints, where high demands are made, and where torques of up to 50,000ftlb are used, such as for pressure vessels, flanges and heavy constructions.
Which type of torque wrench equipment?
The choice of torque wrench type and ancillary equipment depends on the application. Key aspects to consider are:
Accuracy and speed of operation. One is often useless without the other when embarking on highly repetitive tasks. Choose a tool that gives constant torque output to provide high accuracy across its full stroke (as in the case of the latest W and S Enerpac Hexagonal and Square drives).
Repeatability. Consistent torquing from one bolt to the next is crucial for applications ranging from fixed plant to mobile equipment, and especially equipment under pressure, such as tanks and pipelines. Obviously, unequal torquing in a series of bolts is an invitation to disaster, through weak points that are built into the structure. Any bolt that may come loose causes downtime and, if not spotted in time, can cause failures in equipment. Where a large number of fasteners must have equal strength, tools such as the W low profile hexagonal wrenches and versatile S series square drive have terrific and precise repeatability across the entire range.
Construction. Match tool to the toughness and duration of the job, because it can be a long drive back if something goes wrong. Steel comes into its own for rigorous, repetitive work, and the robust W and S Enerpac torque wrench types are designed for maximum durability in the long haul, day in, day out. Reputable suppliers will give good advice on the tool the user needs, because they know business, values user safety and want to see back as a satisfied user.
Weight and Effort. Modern tool design should not make the user pay a weight penalty, because even small increases in weight become larger and larger when the user is doing the same job over and over again. To prevent fatigue and risk setting in, choose tool with careful regard to weight, ergonomics, frequency of use and manoeuvrability around the job. Take the time to compare technologies such as the W low profile hexagonal wrenches for low clearance bolting applications. These weigh from only 1.4-5kg, while the versatile S series of double-acting square drive wrenches extends from 2.7-31kg.
Do not forget the pump. In addition to the wrenches themselves (or other hydraulically actuated controlled tightening technologies), consider the size and efficiency of the pumps you have to bring to the job. The pump may be a big tool the user will be using, so getting the power-to-weight performance is important. Compact and portable electric pumps are often a speedy and efficient solution for jobs close to base, where reliable power supplies are available. Prime among these are the ZU4T Series electric pumps available. Weighing between 32-36kg, these cool running pumps are a radically new design with fewer moving parts to reduce weight and friction. The pumps also require 18 per cent less current draw than comparable pumps. A self-priming first stage increases pump performance by supercharging the second stage piston pump, improving oil flow in both hot and cold weather operations. Patent-pending Z-class technology provides high bypass pressures for increased productivity, particularly in applications using long hose runs and in high pressure-drop circuits. Purpose-built bolting pumps such as the ZU4TE can be matched with pendant control for the safety of remote operation where required.
And what if there’s no power? Sometimes jobs just do not have easy access to pneumatic or electric power. Sometimes maintenance crews, for example, might have to drive (or fly) great distances. In these circumstances, it might be good to employ an alternative technology such as a torque multiplier. The beauty of these manual tools is that they can provide outputs as much as 70:1 times as great as the input.
Where a torque wrench is preferred and has to carry with it its own source of power, there are special lightweight hand pumps available from Enerpac. The light of these is the P Series of aluminium-based pumps with durable glass filled nylon reservoirs, weighing from 2.4 to 10kg. It is often advisable to select a two-stage type (which offers a fast actuating first stage for rapid setup, then a second stage delivering more power and greater oil flows for the job).
Can the tool get the job done? Generally, the rule of thumb is that the torque wrench should have 50 per cent more capacity than required for a particular task. That leaves a capacity reserve that can be necessary for unscrewing bolted joints. For heavy applications, wrenches of twice the capacity are sometimes used.
Is there enough space? Apart from capacity data, questions have to be answered like: is there enough height for using the wrench? and is there enough space around the nut? As far as available working space is concerned: when height is sufficient, a square drive will be satisfactory. But if height is limited, it will be better to choose a low model with cartridges. Through application of light, high-tech materials and one-piece wrench housing, the Enerpac torque wrenches are compact. The ratchet system has fine toothing, enabling high precision and preventing drive jamming. The double-acting cylinders give precise torque at high operating speeds. The compact high pressure design enables a high torque/weight ratio and offers more power reserve during operation. The revolving coupling can be turned 360 degrees at high pressure, so that the hoses can be positioned in any position. This is important when working in tight spaces.
Thanks to the light, compact construction, Enerpac’s latest wrenches are easy to handle and usable almost anywhere. Furthermore, the advantage of the hexagon cartridges and adapters is that these can be quickly replaced. No extra tools are necessary to do this.
Education, training and backup. As with all selections of tools for use in remote, rugged and high-safety environments, correct training and service backup is essential to get the precision, efficiency and safety from tools.