BoltLife has performed several tests with traditional methods, using ultrasonic bolt load measurement in a controlled workshop environment and in actual offshore conditions.
The results of these tests were compared to the results of similar tests using a newly developed procedure for steel-on-steel bolted flanges.
The results were astonishing. The aforementioned assumptions have a large effect on the applied and remaining pre-load in the bolts. The effect under workshop conditions showed most bolts below the minimal required preload combined with a substantial scatter.
The offshore conditions showed an even worse picture with values as low as 30% of the minimal required pre-load, which was expected with the used torque, combined with a large scatter.
All measurement set-ups for the Checkline MAX II ultrasonic measurement device are made in our laboratory using equipment especially designed for this purpose. All set-ups were made before, and verified after the procedures.
It is not possible to use standard ultrasonic bolt measurement settings, as larger bolts are made in a different way and from different materials than the standard, smaller bolts. We have even found considerable differences between the batches in a single project produced by the same manufacturer.
The guidelines for these larger bolts are an extrapolation of the guidelines for smaller bolts. In general, all bolts larger than M36 or equivalent have a larger variety in characteristic behavior.
With this new procedure BoltLife shows that there is a lot to gain in the quality and durability of bolted connections. Having all bolts measured during the tightening process not only creates an accurate pre-load, but also provides the opportunity to periodically re-measure the bolts in the flange in actual load.
All in all, we distinguish from others in this industry through our revolutionary preload method. The achieved high and consistent preload with this system results in an exponential increase of the lifetime of your bolted connections and a decrease of the need for periodic check-ups. The accurate measurement values result in efficient bolt maintenance programs. This will lead to high cost savings at both installation and maintenance of the bolted connections while guaranteeing a high quality and certainty increase.
Are you interested in further information on our services? Feel free to contact us. We look forward to working with you!