Easy to use, easy to check. Critical bolting made safer.
Critical joints made simple
EcoStud has been developed to combat fastener fatigue failures and leaking
joints - a constant source of expensive problems. The EcoStud brings together
into a single, integral unit a high quality fastener and an accurate tension
controller. This unique combination brings verifiable quality right into the heart of
the joint making process.
The EcoStud indicates correct tension by a rotor on the end of the stud which
turns freely when the stud is loose but locks to finger pressure at the correct
stud tension. The fitter simply tightens the EcoStud until the rotor begins to grip,
and stops tightening when the rotor locks to finger pressure. Finally, all the stud
loads can be quickly verified by checking that all the rotors are still locked.
1 How it works
The EcoStud indicates when a pre-set elongation, and thus load, is present in
the stud. The rotor indicator (1) on the end of the EcoStud is normally free to
4 rotate in an air gap (2) which is accurately pre-set in our factory. In operation
when the stud is being tightened, it elongates slightly causing the head of the
gauge pin (3) to move towards the rotor. At the correct load in the stud the head
of the gauge pin contacts and locks the rotor. When the rotor locks to light finger
pressure the tightening is complete. Note the special annular tube around the
gauge pin (4) is a patented feature which ensures the gauge length and hence
load accuracy remains unaffected by the position of the nut along the stud.
Frequently asked questions
Does the nut have to be in a particular How do you set the air gap?
position for EcoStud to work? We apply the required set working load
No. The working nut face can be anywhere to the stud, lock the rotor in place under
up to two diameters from the end of the stud load then, when the load is removed the
without affecting the set load. correct air gap appears.
Can you overload an EcoStud? How is EcoStud protected
Tightening past the rotor lock point will eventually against corrosion?
lead to yielding - as it will with any stud. Just stop The mechanism is protected by a
tightening when the rotor locks and the EcoStud stainless steel cap with O-seal and
ensures you have the correct preload. packed with a grease approved to
Does the hole reduce the
strength of the stud? What is allowable temperature?
It reduces the ultimate strength by a few The design of EcoStud automatically
percent depending on stud diameter but compensates for temperature changes.
fatigue strength, which is the key factor, is However for applications requiring long
greatly improved by the correct preload term checking above 150˚C or below 0˚C
provided by EcoStud. contact our technical department.
If you have any other questions you would like to discuss please
contact our Technical Department on 0114 251 9050.
Variable Nut Position Variable nut position
does not affect accuracy
- A Safer Assembly
Unlike other systems, the unique patented design of the
EcoStud means it is not necessary to position the nut
accurately on the threads. No need to waste time trying to
position the nut in the right place, and no errors introduced
because the nut is not positioned exactly. Using an
EcoStud the nut can be positioned anywhere from the stud
end to two diameters in, without affecting the accuracy.
EcoStud makes a more reliable joint - simpler, quicker.
see VDI 2230 -5% +5% EcoStud
Stud preload is the key factor in preventing fatigue failure Hydraulic
in joints. Correct preload in the stud ensures that the flange Tensioner
itself absorbs nearly all of the vibration loading, leaving
very little to fatigue the studs. Once the designer has
selected the correct stud load EcoStud will ensure that it is
-30% +30% Torque
accurately reproduced on site. EcoStud gives an assembly Wrench
preload accuracy of ± 5%, far better than torque tightening
at ±30%, or hydraulic tensioning at ± 15%.
Gasketed and sealed pressure joints shrink
and expand so good control of stud load is
essential to prevent leaks. The simple EcoStud
finger and thumb test provides a quick and
effective check on stud preload at assembly
and throughout the working life of the joint.
Leaks can be stopped before they occur - a
far cheaper and safer way than breaking down
the joint or trying to stop a leak once a
leakage path has developed.
EcoStud technical data
Min Diameter 24 mm or 1 inch standard. Smaller sizes refer to tech dept.
Max Length Up to 5000 mm as standard
Control Cap Stainless steel
Rotor Stainless steel
Gauge Pin 12.9 Carbon steel as standard
Grease packing Calcium based grease to military spec. NATO G-403.
Stud material EcoStud technology can be supplied fitted to any type of stud material
Identification Marked in the top of the control cap
Certification All normal testing and certifications available
About Arnold Wragg
Arnold Wragg Limited is a first level supplier of fasteners and turned
parts to client requirements and recognised standards. AWL is part of
the Specialist Technologies Aerospace Group, an international group
with operations in UK, France and the USA, specialising in the supply
management of aerospace components, parts and equipment.
The group goal is to provide our customers with high quality products
and service at all times. Our aim is to establish a working environment
where the need for quality is fully recognised, understood and
implemented across the organisation. We aim to be the first choice
supplier for our customers.
The company is approved to ISO9001:2000 and EN/AS9100 quality
assurance standards. It is an approved supplier to Rolls Royce plc,
BAE Systems and GKN Aerospace.
Arnold Wragg Ltd
Parkway One Business Centre
Sheffield, South Yorkshire
Tel: 0114 251 9050
Fax: 0114 244 6635