Re: Flange face finishings

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.

63 AARH is specified for Ring Type Joints.

125-250 AARH (it is called "smooth finish") is specified for Spiral Wound Gaskets.

250-500 AARH (it is called "stock finish") is specified for soft gaskets such as Asbestos, Graphite sheets, Elastomers etc. If we use "smooth finish" for soft gaskets enough "biting effect" will not occur and hence the joint may develop leak.

Sometimes 'AARH' is referred also as 'Ra' which stands for Roughness Average and means the same.

Regards,

Selvaraj Perumal

• Original Message ----- From: "sankaranarayanan dalawai" <dmsbhawani@yahoo.com> To: <PipingDesign@yahoogroups.com> Sent: Wednesday, June 06, 2001 8:55 PM Subject: [PipingDesign] Flange face finishings

> Hello all,
> Can anybody tell me the difference between falange
> face finish 63 aarh / 125 /aarh / 125-250 aarh.What
> does that mean and which is smoother and which is
> rougher.
> Thanks,
> Sankar
>
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Received on Thu Jun 07 12:04:00 2001