The idea came from Beerenbergers doing sandblasting offshore. They wanted to improve both HSE performance and productivity. Sandblasting is a widespread and effective pre-treatment method used in surface treatment (painting). The problem is the excessive noise levels that occur when compressed air expands as the grains of sand are blasted against the surface at 700 kph.
Inspired by the hunting rifle
If, say, you are sandblasting inside a tank, it is not uncommon to be exposed to noise levels of up to 125 decibel (dBA). After one hour and 53 minutes working at this noise level the worker must be given “quiet time” for the rest of the day. On board a platform this means downtime, which is not an effective use of time. "Some of our people in the workshop who are keen hunters were asked to tackle the challenge of reducing noise. They were inspired by the silencers on their hunting rifles. So we began developing a silencer that could be attached to the blasting nozzle using the same principle as on the barrel of a gun,” says Tom Sørensen, Technical Responsible Surface Treatment at Beerenberg.
Length is an issue
A silencer works by its surface absorbing the sound. The greater the surface of the silencer, the more sound is absorbed. “Even though size matters, you have to weigh up multiple factors. The longer the silencer, the less space there is to sandblast. A long silencer also gives the sand air resistance over longer distances before it hits the workpiece, which in turns make the sandblasting less effective.”
200 per cent increase in hours worked
The silencer exhibited by Tom Sørensen can be scaled to achieve the desired effect. He envisages that the company will develop silencers with fixed silencing values, for example 3, 5 and 8 dB. “If you silence the noise when working in tanks by 5 dB, for example, it is possible to sandblast for almost six hours as opposed to less than two hours, representing a 200 percent increase in hours worked. In practice this means that crews can be reduced from six to two people in order to fill a full working day offshore. The silencer will therefore generate significant savings, improve HSE performance and help reduce the environmental footprint.”