23 September 2023

Flanges | Pipe Flanges | Classification of Flanges

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1. How can flanges be classified based on Pipe Attachment?

Answer: –

Flanges can be classified based on pipe attachment as: –

1.) Slip – on:- The Slip-on type flanges are attached by welding inside as well as outside. These flanges are of forged construction.

2.) Socket Weld: – The Socket Weld flanges are welded on one side only. These are used for small bore lines only.

3.) Screwed: – The Screwed-on flanges are used on pipe lines where welding cannot be carried out.

4.) Lap Joint: – The Lap Joint flanges are used with stub ends. The stub ends are welded with pipes & flanges are kept loose over the same.

5.) Welding Neck: – The Welding neck flanges are attached by butt welding to the pipe. These are used mainly for critical services where the weld joints need radiographic inspection.

6.) Blind: – The Blind flanges are used to close the ends which need to be reopened.7.) Reducing. : – The reducing flanges are used to connect between larger and smaller sizes without using a reducer. In case of reducing flanges, the thickness of flange should be that of the higher diameter.

7.) Integral: – Integral flanges are those, which are cast along with the piping component or equipment.

2. How can flanges be classified based on Pressure- temperature ratings?

Answer: –

Flanges are classified based on pressure temperature ratings as: –
A. 150
B. 300
C. 400
D. 600
E. 900
F. 1500
G. 2500

Pressure temperature rating carts in the standard ASME16.5 specify the non-shock working gauge pressure to which the flange can be subjected to at a particular temperature.

3. How can flanges be classified based on facing?

Answer: –
Flanges are classified based on facing as: –
A. Flat face. (FF)
B. Raised face. (R/F)
C. Tongue and groove. (T/G)
D. Male and female. (M/F)
E. Ring type joint. (RTJ)

4. How can flanges be classified based on face finish?

Answer: –
Flanges are classified based on face finish as: –
A. Smooth finish.
B. Serrated finish.

5. Where the smooth finish flange & serrated finish flange finds its use?

Answer: –
The smooth finish flange is provided when metallic gasket is provided and serrated finish flange is provided when non-metallic gasket is provided.

6. What are the types of serrated finish provided on flange face?

Answer: –
A. Concentric or
B. Spiral (Phonographic)

7. How the serration on flanges is specified?

The serration on flanges is specified by the number, which is the Arithmetic Average Rough Height (AARH).

8. Where the concentric serration is insisted for face finish?

Answer: –
Concentric serration are insisted for face finish where the fluid being carried has very low density and can find leakage path through cavity.

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