Pile Foundation in sandy soil

We are installing 450 mm dia cast-in-situ bored pile in sandy soil. Our consultancy is forcing us to use epoxy coated steel (12 mm and 8 mm) for the piles because of the uplift pressure on piles (according to them). Please help me in proving the point that uplift pressure couldn't be dealt with epoxy coated steel. (I need strong and reasonable points). I am continuously searching in google but till now I have failed.