8/9/2019 Roughness Value

1/2

APPENDIX 1 : Recommended roughness values

Suitable values of

s

(mm)

Good Normal Poor

Classification ( Go od and Norm al assumed

new and clean unless otherwise stated)

Smooth materials (pipes)

Drawn non-ferrous pipes of aluminium, brass,

copper, lead etc, and non-metallic pipes

of Alkathene, glass, perspex, PVC-U* etc

Asbestos-cement

Metal

Spun bitumen or concrete lined

# Cast

iron,

epoxy lining, coupling joints

# Ductile

iron,

Polyethylene lining, push-fit joints

# Ductile

iron,

Polyurethane lining, push-fit joints

Wrought iron

Rusty wrought iron

Uncoated steel

# Rusty steel

# Steel, epoxy lining, push-fit joints

Galvanised

iron,

coated cast iron generally*

Uncoated cast iron

Tate relined pipes

152mmx51mm corrug'd plate, unpaved circular pipe, running

ful l

2 2

76mmx25mm corrug'd plate, unpaved circular pipe, running

ful l

22

Old tuberculated water mains as follows:

Slight degree of attack

Moderate degree of attack

Appreciable degree of attack

Severe degree of attack

(Good:

up to 20 years use; Normal: 40 to 50

years use; Poor: 80 to 100 years use)

Wood

Wood stave pipes, planed plank conduits

Concrete

# Prestressed

Precast conc rete pipes with O ring joints

Spun precast concrete pipes with O ring joints

Monolithic construction against steel forms

Monolithic construction against rough forms

Clayware

Glazed or unglazed pipe:

With sleeve joints

With spigot and socket joints

and O ring seals

-- dia < 0-150 m

-- dia > 0-150 m

Pitch fibre

(lower value refers to full bore flow)

# Glass reinforced plastic (GRP)

uPVC

# Twin-walled, with coupling joints

Standard, with chemically cemented joints

Standard,

with spigot and socket joints, O ring seals

at 6 to 9 metre intervals

0015

~

0015

0 0 3

0 15

0015

0 0 3

0 0 6

0 15

0 15

50

25

0 6

1 5

6 0

15

0003

003

0 0 3

0015

0 0 6

0 0 3

0 0 6

0 6

0 03

0 15

0 0 6

0 15

0 3

0 3

60

30

1 5

3 0

15

30

0 0 6

0 0 3

0 15

0 06

0 15

3 0

0 06

0 3

0 15

0 3

0 6

0 6

-

3 0

6 0

30

60

0-3

0-03

0-6

0-06

~

0003

0 0 3 *

0 003

0 0 3

0 0 6

0 0 3

0-06

0 006

0 0 3

1 5

0 03

0 0 6

0 0 6

0 3

0 6

0 0 6

0 15

0 15

0 6

1 5

0 15

0 6

0 3

1 5

0 15

0 06

40

8/9/2019 Roughness Value

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APPENDIX 1 : Recommended roughness values (continued)

Suitable values of

s

(mm)

Good Normal Poor

Classification ( Goo d and Norm al assumed

new and clean unless otherwise stated)

New relining of sewers

Factory manufactured GRP

Brickwork

Glazed

Well pointed

Old,

in need of pointing

Slimed sewers (see specific coverage in text in page 9)

Sewers slimed to about half depth; velocity, when

flowing half full, approximately 0-75 ms

1

:

Concrete, spun or vertically cast

Asbestos cement

Clayware

uPVC

Sewers slimed to about half depth; velocity, when

flowing half full, approximately 1-2 ms

1

:

Concrete, spun or vertically cast

Asbestos cement

Clayware

uPVC

Sewer rising mains (see specific coverage in text in page 9)

All ma terials, operating as follows

Mean velocity 0-5 ms

Mean velocity 0-75 ms

Mean velocity

ms

1

Mean velocity

-5 ms

Mean velocity 2 ms

0-03

0 6

1 5

1 5

3 0

15

3 0

6 0

30

- 1

-1

-1

3-0

3-0

1-5

0-6

6 0

6 0

3 0

1-5

Concrete channels (after

Yen

23

following from Chow

24

)

Trowel finish

Float finish

Finished with gravel on bottom

Unfinished

Shortcrete, or Gunite, good section

Shortcrete, or Gunite, wavy section

Unlined rock tunnels

Granite and other homogeneous rocks

Diagonally bedded slates

(values to be used with design diameter)

Earth channels

Straight uniform artificial channels

Straight natural channels, free from shoals,

boulders and weeds

The background to the values given here is in the sub-section of the text entitled Recommended

roughness sizes

in

pages 9 and 10.

This sub-section should be consulted before adoption of any

of the values in this table.

~

~

0 3

0 15

0 0 6

0 0 3

0015

0 5

1 5

3 3

2 0

5 0

10

60

15

150

1 5

0 6

0 3

0 15

3 0

1 5

0 6

0 3

0 15

1 5

3 3

7 0

7 0

14

33

15 0

300

60

300

3 0

1 5

0 6

0 3

30

15

6 0

1 5

1 5

3 3

5 0

18

18

43

70

300

600

150

600

41