Reducing Flange

To Suit ASME Class 150 Piping Systems -<Click here for main page> Reducing flanges can be grouped into 3 main configurations– Type 1, 2 & 3, The configuration is dictated by the proximity of the small bore bolt holes to the large bore bolt holes. Each type is designed so that they do not clash and that the nuts can be fitted successfully. Type 3 flanges have through holes for the large bore bolts and are used where there is a significant reduction in bores. Where the reduction is not so great and the periphery of the smaller bore mating flange would impinge on the nuts then a type 2 flange is employed with threaded bolt holes negating the use of nuts. Finally where the reduction in bores is quite small the bolt holes have to be staggered on / off centres so that they don’t clash – a type 1 reducing flange.

As a general rule, a type 3 is the design of choice, if this cannot be achieved, a type 2 should be specified, and if this doesn't work, then a type 1.  If you have site reasons for wanting to select another style, then a type 1 or 2 will always work where a type 3 does and a type 1 where a type 2 does.
As a general rule CRP reducing flanges are supplied with a tapered bore, but occasionally due to method of manufacture a parallel bore is supplied.  If you have a particular requirement e.g. parallel bores are often specified when equipment one one side of the flange requires more support then please specify this.

There is another style of reducing flange available where the inner pattern of holes is on a raised platform and the outer holes are scalloped from this.  This enables one to use type 3 style drillings  i.e. through bolts on the large side, removing the necessity to have double threaded holes on the reducing flange.  This is useful where one is coming up against items such as a threaded pad flange on a vessel.  CRP can produce these and many other special reducing flanges just call us to discuss.

Nominal Size Type Ø A D Liner
Thickness
DN1 DN2
In. In.
mm mm mm
3/4" 1/2" 1 98.5 30 5.0
1" 1/2" 1 108 30 5.0
1" 3/4" 1 108 30 5.0
1.1/2" 1/2" 1 127 30 5.0
1.1/2" 3/4" 1 127 30 5.0
1.1/2" 1" 1 127 30 5.0
2" 1/2" 3 152 30 5.0
2" 3/4" 2 152 30 5.0
2" 1" 2 152 30 5.0
2" 1.1/2" 1 152 30 5.0
3" 3/4" 3 190.5 35 5.0
3" 1" 3 190.5 35 5.0
3" 1.1/2" 2 190.5 35 5.0
3" 2" 1 190.5 35 5.0
4" 3/4" 3 228.6 35 5.0
4" 1" 3 228.6 35 5.0
4" 1.1/2" 3 228.6 35 5.0
4" 2" 3 228.6 35 5.0
4" 3" 2 228.6 35 5.0
6" 3/4" 3 280 40 5.0
6" 1" 3 280 40 5.0
6" 1.1/2" 3 280 40 5.0
6" 2" 3 280 40 5.0
6" 3" 3 280 40 5.0
6" 4" 2 280 40 5.0
8" 1" 3 343 35 5.0
8" 1.1/2" 3 343 35 5.0
8" 2" 3 343 40 5.0
8" 3" 3 343 40 5.0
8" 4" 3 343 40 5.0
8" 6" 2 343 40 5.0
10" 1" 3 406 35 2.5
10" 1.1/2" 3 406 35 2.5
10" 2" 3 406 35 2.5
10" 3" 3 406 35 2.5
10" 4" 3 406 35 2.5
10" 6" 3 406 35 2.5
10" 8" 2 406 35 3.5
12" 1" 3 483 40 3.5
12" 1.1/2" 3 483 40 3.5
12" 2" 3 483 40 3.5
12" 3" 3 483 40 3.5
12" 4" 3 483 40 3.5
12" 6" 3 483 40 3.5
12" 8" 3 483 40 3.5
12" 10" 2 483 40 3.5
14" 12" 1 483 40 3.5
16" 14" 2 483 35 3.5

For a quotation please contact us on 01706 756 400  or enquiry@crp.co.uk


Contact Details

Corrosion Resistant Products Ltd
Todmorden Road
Littleborough
OL15 9EG

Phone: +44(0)1706 756400
Fax: +44(0)1706 379567
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