Why EGB safety v/v lifting pressure is more than that of BOILER safety valve lifting pressure. ?

The EGB is circulated with feed water by boiler water circulating p/p and the boiler takes suction from the boiler steam drum. Hence the pressure of feed water in the EGB will be the pressure of steam drum and circulating p/p dis. pressure. So, the safety valve setting of EGB will be higher than of its counterpart in boiler.