What are serrated flange nuts for?
Serrated flange nuts are hex nuts with built-in non-spinning washers with serrations on the bottom. This kind of flange nut is used to help prevent loosening when vibrations are present.
When would you use a serrated flange?
The flange may be serrated to provide a locking action. On a serrated flange nut, the serrations are angled such that they keep the nut from rotating in the direction that would loosen the nut. Because of the serrations they cannot be used with a washer or on surfaces that must not be scratched.
Do serrated nuts work?
Serrated tooth nuts work well for oversized or irregularly shaped holes, since the flange covers any discrepancies and serrations cover the entire bearing surface.
Are all flange nuts serrated?
Flange nuts are available both non-serrated and serrated to provide locking action. The serrations on Serrated Flange Nuts displace material on the mating surface when the nut is wrenched into place, forming a connection which resists loosening.
What is serrated flange?
Serrated flange surfaces consist of concentric circular grooves, or a continuous spiral groove (also known as ‘phonographic’) machined onto the flange sealing surface. Serrated flange surfaces use non-metallic (soft) and semi-metallic gaskets.
What is meant by serrated finish?
A serrated finish, either concentric or spiral, is required with 30 to 55 grooves per inch and a resultant roughness between 125 and 500 micro inches. This allows for various grades of surface finish to be made available by flange manufactures for the gasket contact surface of metal flanges. Serrated Finish.
Do flange nuts need washers?
Flanged headed nuts and bolts have been developed to eliminate the deficiencies that have been found with the use of washers. Standard washers are typically softer than the nuts and bolts that they are used with and can often plastically deform under the high compressive stress that they must sustain.
What is serrated surface?
Serration is a saw-like appearance or a row of sharp or tooth-like projections. A serrated cutting edge has many small points of contact with the material being cut.
What are the types of serrated finish provided on flange face?
47 Flanges are the Stock Finish, Spiral Serrated Finish, Concentric Serrated Finish, Smooth Finish and Cold Water Finish.
- The Stock Flange Finish.
- The Spiral Serrated Finish.
- The Concentric Serrated Finish.
- The Smooth Finish.
- The Cold Water Finish.
What is AARH in flange?
The most commonly used parameter for measurement and interpretation of surface roughness is Arithmetic Average Roughness Height (AARH). AARH is the average height of irregularities, on the surface under observation, from the mean line as shown in the following figure.
Should flange faces be painted?
So for corrosion protection of internally lined pipe with raised face flanges, YES you must definitely coat the faces.
What is RA in flanges?
The flange surface finish for the sealing area is commonly represented by the symbol Ra. Irregularities in the surface can impact upon the effectiveness of the gasket’s ability to close potential leak paths and the friction values needed to keep the gasket in position.
Are flat face flanges serrated?
The most common flange face surface designs are smooth and serrated. Flat face (FF) flange surfaces and raised face (RF) flange surfaces require serrations if built to industry standards.