What is AARH finish?

AARH stands for Arithmetic Average Roughness Height. It is used to measure the roughness (rather smoothness) of surfaces. 125 AARH means 125 micro inches will be the average height of the ups and downs of the surface.

How is AARH measured?

AARH is the average height of irregularities, on the surface under observation, from the mean line as shown in the following figure. The symbol Y1 to Y8 represents the peak heights which are measured from the mean line. Arithmetic Average Roughness Height is usually measured in micro-inches and denoted by symbol “Ra”.

What is flange face finish?

The facing finish or face finish of a pipe flange manufactured in accordance with ASME B16. 5 refers to the smoothness or roughness of the facing surface. In a bolted flange joint, the flange face is in direct contact with the gasket.

What is flange surface finish?

The flange face surface is the area where the sealing element (gasket) is installed. 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.

What does RTJ flange mean?

A Ring type joint flange(RTJ) is a machined metallic ring with a deep groove cut into its face. This groove rests a metal ring which gets compressed when the connecting bolts of the flange are tightened. This compression results in a leak-proof, close-fitting seal on the pipe or connection.

What is flange serration?

The flange face has small grooves as you can see in the image. This machining is known as a serration. Flange face can be smooth or serrated type. Soft material of gaskets is set in this serration and prevent liquid or gas from passing from flange joint.

What is the difference between RF and RTJ flange?

Answer: RF means “Raised Face.” RTJ means “Ring Type Joint.” RF flanges seal with a flat gasket, formerly made of asbestos but now made of more environmentally friendly material, designed for installation between the raised faces of two mating flanges (both with raised faces).

Can you use a raised face flange with a flat face flange?

Flat face flanges are never to be bolted to a raised face flange. 1 says that when connecting flat face cast iron flanges to carbon steel flanges, the raised face on the carbon steel flange must be removed, and that a full face gasket is required.

Is a lap joint flange raised face?

The lap joint flange can be used in sizes and pressure classes similar to that of a weld-neck flange. The nature of this joint means that the stub end facing is also the flange facing, which makes it raised faced, and the gasket seating surface.

Can a RF flange mate to a FF flange?

RF flanges are commonly used on forged steel or forged stainless steel flanges. An RF flange uses a gasket called a ring gasket. FF flanges are made specifically to mate with other FF flanges. These flanges are often made from cast instead of forged metal.