I am going to be up front here. This post is the exact same as our previous post about gramophone finish on flange faces. Since gramophone and phonographic finishes are the same thing, we are re-posting the same content with a different title in an attempt to fool the search engines and capture people who are looking for information about phonographic finishes. So, here is the post explaining about both types of flange face finishes:
There has been a virtual explosion of inquiries coming into our company for pipe flanges with a gramophone finish. Piping Supplies has only seen a handful of request for quotations in the past which call for a gasket face with a gramophone finish. Why all of the interest now and what the heck is a gramophone finish anyway?
Flange facing has several properties, one of which is the surface finish or roughness. The surface finish is specified in terms of RMS, root mean square, or sometimes Ra, roughness averaging, in micrometers. The commercial flange bible, ANSI B16.5, section 6.4.5, says flange faces shall have a roughness of 125 – 250 RMS unless otherwise agreed upon between the manufacturer and user. The finish can be either serrated concentric or serrated spiral in style.
Now think about that last statement about a flange face being a serrated spiral. Do you have or remember vinyl records and a record player? The grooves on a record are a spiral toward the center that the needle rides through recreating sound. The face of any part machined on a lathe creates this same spiral finish. That is why you will sometimes hear a gasket face called a phonographic or, more rare, a gramophone finish. If the tool is fed across the face slower then there are more small or overlapping grooves and a smoother face. If the tool is fed across the face faster then there are less overlapping grooves and a rougher face.
The phonograph and gramophone were developed at similar times in the late 1800’s. The phonograph was first invented by Thomas Edison using turning cylinders to play recordings. Alexander Graham Bell improved on the design and called his the graphophone. Shortly after the name gramophone was coined by Emile Berliner when he introduced the flat disks we know today as a record.
When you see an inquiry for a flange (or valve or flanged fitting) which calls for a phonographic face or gramophone face, call the flange experts at Piping Supplies. We will make your parts in RECORD time.