Clean or replace your bolts, nuts & washers. Lubricate the bolt's, thread, nuts, washers and the underside of the head with graphite based compound
Flat washers are recommended to assure even distribution of the bolting force. Ensure lubricant doesn't contaminate gasket. Carefully insert the gasket between the mating surfaces
The use of a torque wrench is highly recommended. This assures a longer life and leak free performance. Whether an automotive head gasket or a flange gasket, it should be torqued