Nuts & Bolts

Careful attention is given to selecting the correct flange and gasket, whilst selection of the correct fasteners is often neglected. All elements of a flange assembly must be suitable if a leak free joint is to be obtained and maintained; bolts, studs, and nuts, are the fasteners that allow this to occur. This section deals with bolts, studs, screws, nuts, washers, bolting procedure, and their importance with relation to flanges.

Bolting Criteria

Bolting criteria for a given flange is determined by the associated standard. For example, a flange of a certain size and class may have the following pre-defined factors:

• Number of bolts required.
• Length of bolt required. 
• Diameter of bolt required.
• Material of bolt required. 
• Position of bolts on the flange blade. 

The number of bolts required will always be a multiple of 4 e.g. 4, 8, 12, 16 etc. As the size and class of a flange increases, so too does the number of bolts required and their diameter.