Section 6. In every town the sealer shall, at the expense of the town, provide therein accessible places for the safe and suitable keeping and preservation of the standards furnished by the commonwealth, which shall be used only as standards. The sealer shall have the care and oversight thereof; shall see that they are kept in good order and repair; and if any are lost, destroyed or irreparably damaged, shall, at the expense of the town, replace them by similar standards. Towns may effect insurance on such standards for their own benefit.