|A hydraulic flange provides a threadless, virtually leak-free connection to a port. When replacing a flange, the new flange needs to match the bolt pattern of the port on the connecting part. These bolt patterns are commonly drawn from standards, so determining the flanges needed is easy if the standard is known. If the standard is not known, the bolt pattern is a major factor used to determine the correct new flange. This paper will discuss how to determine the bolt pattern of the standard and share an easy way to measure key dimensions. Remember that a few OEM’s have designed special patterns that might not conform to any standards.