Pumping Station Desing - Second Edition by Robert L. Sanks, George Tchobahoglous, Garr M. Jones

Figure

4-17.

Typical

underground

thrust

block

details. Courtesy

of

Wilson

&

Company,

Engineers

&

Architects.

Figure

4-18.

Typical thrust

blocks

for

exposed

pipes,

(a)

Combination

thrust

block

pipe

support;

(b)

thrust

block/

pipe

support

for

emerging

pipe.

Courtesy

of

Wilson

&

Company,

Engineers

&

Architects.

from

the

resultant

force

acting

on the

bend (see Exam-

ple

3-5)

and the

allowable soil bearing pressure.

For

the

resultant force,

use

whichever

of the

following

is

greater:

(1) the

total (working plus water hammer)

pressure

or (2) the

pipeline test pressure.

The

allow-

able horizontal bearing pressure

can

best

be

found

by

calculating

the

Rankine passive pressure

from

the

principles

of

soil mechanics,

or it can be

found

in

tables

[9]

(see also DIPRA

[1

1]

or UBC

Table 29-B).

The

concrete

in

thrust blocks should have

a

mini-

mum

compressive strength

of

13,800

kPa

(2000

lb/in.

2

)

at

28

days.

The

bearing area should

be

poured directly

against

undisturbed earth. Figures 4-17

and

4-18

show

typical

thrust block details.

The use of

thrust blocks should

be

considered with

great

care. They

are

only

as

good

as the

stability

of

the

soils used

for

reaction backing.

In

locations where

the

soils

may be

disturbed

by

future

excavations (yard

piping, treatment plant sites, busy streets, etc.), reli-

ance

on

thrust blocks (particularly

for

large diameters

and

high-pressure pipeline systems)

is not a

very

good idea. Instead,

the use of

restrained (lugged

or

harnessed) joints

and

trench friction

is a

better

approach.

Cleanouts

Cleanouts should

be

installed

in

sludge

and

slurry

lines that carry grease, grit,

or

other substances (such

as

lime) that

may

form

deposits

in the

pipe (typical

designs

are

shown

in

Figures

4-19

and

4-20). Lime-

carrying waters

are

especially troublesome,

so use

troughs instead

of

pipe

where

possible.

Figure

4-19.

Underground

pipe

cleanout.

Courtesy

of

Wilson

&

Company,

Engineers

&

Architects.

Figure

4-20. In-line cleanouts

for

exposed

pipe.

Courtesy

of

Wilson

&

Company,

Engineers

&

Architects.

Special cleanouts

are

required

for flowmeters, and

a

suitable system

is

shown

in

Figure 20-12.

Pig

Launching

and

Recovery

Typical

pig

launching

and

recovery stations

are

shown

in

Figures

4-21

and

4-22.

The pig

stop, Figure 4-23,

is

placed

in the pig

retrieval pipe prior

to the

pigging

operation.

The

2

l

/

2

D

barrel length

is

standard,

but if

space

is

tight,

I

1

I

2

D can be

used (although

not

with

deZurik

pigs). Pressure gauges

are

unnecessary.

The

best

way to

determine whether

the pig has

gone

is to

isolate

the

launch barrel

and

insert

a rod

through

the

launching

valve quick-connect.

At the

retrieval end,

listen

for the

sound

of the pig

arriving.

Figure

4-21.

Typical

pig

launching

station.

Courtesy

of

Brown

and

Caldwell

Consultants.

Figure

4-22. Typical

pig

retrieval station. Courtesy

of

Brown

and

Caldwell

Consultants.

Figure

4-23.

Typical

pig

stop.

Courtesy

of

Brown

and

Caldwell

Consultants.

4-9.

Special

Piping

and

Plumbing

The

requirements

for

conveying small

flows of

wash-

down

water,

fuel,

cooling water,

and

sump drainage

are

entirely

different

from

the

foregoing. Pipes

for

fuel,

wash water, seal water,

and air are

small

and

comparatively

inexpensive even when constructed

of

materials

such

as

copper

or

stainless

steel.

Special

piping

materials

are

listed

in

Table

4-16.

Water

If

water

is

needed

for

lavatories

or

wash-down, galva-

nized

steel

with

threaded connections

is

practical

because

the

pipe would rarely exceed

38 mm

(1

1

^

in.)

in

diameter. Pipe

fittings

are

usually made

of

mallea-

ble

iron. Thread compound

or

Teflon™

tape should

be

applied

to

threads. There should

be

enough strategi-

cally

placed unions

to

allow

for

dismantling

and

replacement.

Threaded pipe

must

have

a

wall thick-

ness

no

less than standard weight

per

ANSI

B36.10.

Copper tubing,

with

joints soldered with tin-

antimony

(ASTM B 32, Grade SbS), is also practical.

Because

there

is

evidence that lead

can

leach into

the

water,

avoid lead-based solder. Copper, however,

is

cor-

roded

by

hydrogen

sulfide.

So

copper

or

brass piping

and

tubing should

be

used

with

caution

in

areas

of

wastewater

pumping stations exposed

to a

hydrogen

sulfide

atmosphere. Copper tubing also should

not be

allowed

to

come

in

contact with prefabricated wood

trusses

that

have been treated

with

ammonium

sulfate

fire-retardant

material, because

the

ammonium

sulfate

is

very corrosive

to

copper. Require that

the

copper tub-

ing

be

attached

to

wood trusses

by

pipe hangers,

and

not

just attached directly

to or

laid directly

on the

wood.

PVC

could

be

used

in

Schedule

40 for

solvent-

welded joints

or

Schedule

80 for

threaded joints,

but it

requires closely

spaced

supports.

Since

galvanized

steel

pipe

within corrosive atmospheres, such

as wet

wells, corrodes quickly,

a

more satisfactory material

is

stainless

steel

or

PVC.

Stainless-steel pipe

in

most pumping station ser-

vices

is

covered

by

ASTM

A 312 for 3

through

750

mm

(V

8

through

30

in.)

and A 778 for 75

through

1200

mm (3

through

48

in.)

for

material;

for

dimen-

sions,

it is

covered

by

ANSI

B36.19

(not ANSI

B36.10).

Note that

the

minimum wall thickness

for

threaded pipe

is

Schedule

4OS.

Fittings

50 or 75 mm

(2

or 3

in.)

and

smaller should

be

threaded

and

should conform with ASTM

A 403 and

ANSI

B

16.3

(see

the

previous discussion

on the

applicability

of

threaded joints).

Fittings

larger than

75 mm (3

in.)

should

be

butt welded, grooved end,

or flanged

and

should conform

to

ASTM

A 403 or A

774,

and

ANSI

B

16.9.

The

wall thicknesses

for the

pipe schedules

for

stainless-steel pipe

are as

follows:

•

Schedule

4OS

for

stainless-steel pipe

is the

same

as

Schedule

40 for

carbon steel pipe

in

sizes

of 10 in.

and

smaller.

•

Schedule

4OS

for

stainless-steel pipe

is the

same

as

standard weight

(

3

/

8

-in.

wall)

for

carbon

steel

pipe

in

sizes

of 12 in. and

larger.

•

Schedule

80S for

stainless-steel pipe

is the

same

as

Schedule

80 for

carbon steel pipe

in

sizes

of 8 in.

and

smaller.

Note that

the

letter

S

always follows

the

Schedule

number

for

stainless steel,

for

example,

4OS.

Threaded

Joints

Threaded malleable iron

fittings and

couplings (ANSI

B

16.3)

can be

used with steel pipe

and are

usually

cheaper than forged steel

fittings

conforming

to

ANSI

B16.ll.

Threading conforms

to

ANSI

B

1.20.1

for

both

malleable iron

and

forged steel

fittings.

Forged

steel

fittings

(90°

and 45°

elbows,

tees,

crosses, couplings, caps, plugs,

and

bushings) con-

forming

to

ANSI

B16.ll

are

available

in

sizes

of 3

through

100 mm

(V

8

in.

through

4

in.) Assembling

and

disassembling threaded

fittings and

joints larger

than

50 to 75 mm (2 to 3

in.)

is

labor intensive,

so

only

small pipes

are

connected

by

threaded

fittings.

Unions

at

strategic locations

are

needed

for

disas-

sembly.

Steel

unions conform

to MSS

SP-83;

mallea-

ble

iron unions conform

to

ANSI

B

16.39.

Van

Stone

Flanges

Van

Stone

flanges are

especially economical

for

stainless-steel

piping.

The flange can be

carbon steel

or

ductile iron because

it is not in

contact

with

the

liquid

and, hence, does

not

have

to be

corrosion

resistant

unless

the

concern

is for

external corrosion.

The

joint

is

made

by

roll

flaring the end of the

pipe.

A

slip-on

flange can

then

be

placed over

the

pipe

to

make

the

connection. Such

flanges are

especially

attractive

with

stainless-steel pipe,

but

where

flanged

joints

would

be

exposed

to

corrosive conditions

(as

Abbreviation

ABDI

ABS

ACP

ALUM

ARCI

BR

CASST

CCP

CISP

CML

CMP

CPE

CPVC

CTEL

CTXL&C

CU

DIP

DWV

FRP

FXL&C

GALVS

HDPE

PCCP

PP

PPLS

PTFELS

PVC

PVC (G)

PVDF

PVDFLS

RCP

RCPP

RPMP

SP

SST

VCP

WSP

YOL

Piping

material

Abrasion-resistant ductile iron

Acrylonitrile-butadiene-styrene

Asbestos cement pipe

Aluminum

pipe

Acid-resistant cast iron

Brass

Carpenter

20

stainless steel

Concrete cylinder pipe (pretensioned)

Cast-iron soil pipe

Cement-mortar-lined steel pipe

Corrugated metal pipe

Corrugated

polyethylene

Chlorinated polyvinyl

Coal-tar enamel-lined steel

Coal-tar

epoxy

-lined

and

-coated

steel

pipe

Copper

Ductile

iron pipe

Drain,

waste,

and

vent copper tubing

Fiberglass-reinforced plastic pipe

Fusion-bonded

epoxy-lined

and

-coated steel pipe

Galvanized

steel pipe

High-density

polyethylene

Prestressed concrete-cylinder pipe

Polypropylene

Polypropylene-lined steel pipe

Polytetrafluoroethylene-

(Teflon™)

lined steel pipe

Polyvinyl

chloride (pressure) pipe

Polyvinyl

chloride (gravity) pipe

Polyvinylidene

fluoride

(KYNAR™)

pipe

PVDF-lined

steel pipe

Reinforced

concrete pipe (gravity)

Reinforced

concrete pressure pipe

Reinforced

plastic mortar pipe

Steel pipe

Stainless-steel pipe

Vitrified

clay pipe

Welded

steel pipe

Yolloy™

Standard

None

ASTM

D

1527,

D

2661,

D

2751,

D

2680,

F

409,

F 545

AWWA

C400, C402; ASTM

C 296

ASTM

B

241,

B 361

ASTM

A 518

ASTM

B 43

ASTM

B

464,

B 474

AWWA

C303

CISPI

301; ASTM

A 74, A 888

AWWA

C200, C205, C208; ASTM

A 53, A

134,

A

135,

A

139,

A

234,

A

283,

A

570,

A 572

AASHTO

M36

ASTM

F

405,

F

667, ASTO M252

ASTM

D

1784,

F

437,

F

439,

F

441,

F 493

AWWA

C200, C203; ASTM

A 53, A

134,

A

135,

A

139,

A

234

AWWA

C200,

C210;

ASTM

A 53, A

120,

A

134,

A

135,

A

139,

A

234

ASTM

B42 75, B 88

AWWA

C150, C151,

Cl 10,

ClIl,

C115;

ASTMA

395,

A

436

ASTM

B 306

ASTM

D

2310,

D

2992,

D

2996,

D

2997;

PS-15-69;

AWWA

C950

AWWA

C213; ASTM

A 53, A

120,

A

134,

A

135,

A

139,

A

324

ASTM

A 53

AWWA

C906

AWWA

C301

ASTM

D

2146,

D

4101

ASTM

F 492

ASTM

F 423

ASTM

D

1784,

D

1785,

D

2464,

D

2466,

D

2467,

D

2564;

AWWA

C900,

C905

ASTM

D

2688,

D

3034

None

ASTM

F 491

ASTM

C 76, C 679

AWWA

C300,

C302; ASTM

C

361

ASTM

D

3517,

D

3262;

AWWA

C950

ASTM

A 53, A

134,

A

135,

A

139,

A

324,

A

283,

A

570,

A

572,

A

795;

AWWA

C200

ASTM

A

240,

A

312,

A

403,

A

774,

A 778

ASTM

C

301,

C 700

AWWA

C200, C208

ASTM

A

7

14

Table 4-16.

Piping

Materials

and

Standards

in a

wastewater pumping station

wet

well),

specify

stainless-steel

flanges.

Diesel

Fuel

Service

Both

the

Uniform

Fire

Code

and the

Standard Fire

Prevention Code require that steel piping

for flamma-

ble

and

combustible liquids have

a

wall thickness

determined

in

accordance with ANSI

B

3

1.3

and

B31.4

with

a

minimum wall thickness

of

standard

weight.

ANSI B31.1,

B31.3,

and

B31.4

also contain

design guidelines

for flammable fluid

piping, which

are

summarized

as

follows:

•

Prohibited pipe:

(1)

furnace

butt-

welded

steel,

(2)

cast iron,

(3)

copper,

(4)

brass,

(5)

aluminum,

and

(6)

thermoplastic (aboveground).

•

Prohibited connections:

(1)

cast, malleable,

or

wrought

iron threaded couplings,

(2)

cast-iron

flanges,

unless

integral with cast-iron valves, pres-

sure

vessels,

and

other equipment.

•

Required:

(1)

double welding

for

slip-on

flanges

and

(2) flat

facing

connecting steel

flanges to

cast-

iron flanges.

•

Recommended materials:

(1)

seamless steel such

as

ASTM

A 53

Type

S, (2)

welded steel with straight

seam

conforming

to

ASTM

A 53

Type

E,

ASTM

A

134, ASTM

A

155,

or (3) API SL

electric resistance

or

double-

submerged

arc

welded with allowable

stresses

no

higher than

for

ASTM

A 53

Type

S

with

an

appropriate longitudinal joint

efficiency

factor

included.

•

Recommended:

(1)

welded joints between steel

components where practicable,

(2)

where bolted

flanged

joints

are

necessary, gaskets suitable

for the

service,

(3)

where threaded joints

are

necessary,

at

least Schedule

80

(extra strong) pipe with extreme

care

in

assembly

to

assure leak tightness,

(4)

steel

or

ductile iron

for

valves,

fittings, and

other piping

components

for

systems within plants

or

buildings

that

contain equipment with open

flame or

parts that

operate

at

temperatures over

26O

0

C

(50O

0

F),

and (5)

black

steel

—

never

galvanized steel, because

the

zinc

contaminates

the

fuel

and the

galvanizing

sometimes

flakes off and can

clog

fuel

metering ori-

fices.

The

UFC

Section

79. 305

requires that under-

ground piping incorporate swivel

joints

where

the

pip-

ing

leaves

the

dispensing location

and

just before

connecting

to the

tank

fittings.

Swivel joints incorpo-

rate ball bearings

and

permit rotation

and

movement

from

one to

many degrees

of

freedom.

Sewers

Cast-iron

soil

pipe (CISP)

50

through

375 mm (2

through

15

in.)

and

larger

is

suitable

for use as

drain-

pipe inside buildings

if it is

installed above

the floor

with

no-hub ends

and

with neoprene sealing sleeves

and

Type

301 or 303

stainless-steel clamps

(in

accor-

dance with

CISPI

301).

For

buried service

or

service

under

slabs

and

buildings,

use

hub-and-spigot ends

(see also ASTM

A 74

standards).

In

lieu

of

CISP,

ABS

pipe

is

frequently used;

for

drainpipe smaller than

50

mm

(2

in.)

use

steel, copper,

or

PVC.

Dry

Chlorine

Gas

As

recommended

in

ANSI

B31

and by the

Chlorine

Institute

[18],

make

the

piping arrangements

as

simple

as

possible. Keep

the flanged or

screwed joints

to a

minimum. Slope

the

pipe

to

allow drainage, avoid

low

spots, allow

for

expansion

due to

temperature changes,

and

be

sure

that

the

pipe

is

well supported.

Details

of

materials

and

construction

can be

obtained

from

Pamphlet

No. 6 of the

Chlorine Insti-

tute

[18].

Other publications

may

also

be

applicable

to

pumping stations

[19-25].

After

assembly

and

pres-

sure testing, chlorine

gas

piping must

be

thoroughly

cleaned

and all

moisture must

be

removed.

Chlorine

Solutions

Chlorine solutions

can be

carried

in PVC

piping.

All

fittings

should

be

plastic, glass,

or

Hastelloy™.

Most

metals, including

316

stainless steel, corrode rapidly

in

concentrated chlorine solutions.

Air

Use

stainless steel

or

copper.

Do not use PVC

because

heat destroys plastic pipe.

Do not use

galvanized steel

because moisture

in the air

corrodes

it, and

although

dryers

can be

added

at the

compressor, maintenance

cannot always

be

ensured.

Design

of

Plumbing

Systems

Plumbing work

in a

pumping station usually includes

roof drainage, toilet

fixtures, floor

drains,

and

sump

pumps

in

addition

to the

necessary water, waste,

and

vent

piping

and a

water heater.

Storm

Drainage

The

sizing

of

roof drains, horizontal conductors,

and

vertical leaders

or

downspouts (usually covered

in the

applicable plumbing code)

is

based

on

roof area

and

historical

rainfall

intensity. Storm drainage, including

roof

and

area drains, catch basins,

and

foundation

drains,

should

(1)

connect

to a

storm drain,

(2)

dis-

charge through

a

trap into

a

combined sewer,

or (3) be

drained

to

grade

if

neither

(1) nor (2) is

available.

In

addition

to any

sump receiving subgrade sanitary

waste,

a

separate

sump

may be

required

by

code

for

foundation

drainage.

Roof

drainage piping

often

conveys water

at a

tem-

perature below

the

dew-point temperature

of air in the

building,

so

condensation tends

to

occur

on the

pipe.

The

horizontal conductors

(at

least) should

be

insu-

lated

to

prevent dripping

from

such condensation,

especially

if the

pipes pass over

or

near electrical

equipment.

The

materials usually used

for

storm drainage pip-

ing

include galvanized

steel

pipe, galvanized cast-iron

drainage

fittings,

cast-iron soil pipe

and

fittings,

and

polyvinyl

chloride plastic

pipe

and

fittings.

Both

storm

and

sanitary drain

lines

buried below

floors

should

be

encased

in

concrete when

the floor is

poured

to

protect them

from

corrosion

and

settlement.

Sanitary

Drainage

Sanitary soil, waste,

and

vent piping sizes

and

arrangements must conform

to the

applicable plumb-

ing

code. Equipment drains receiving pump seal water

can

be

enlarged

hub

drains raised above

the floor or

regular

floor-mounted

drains

fitted

with

a

funnel

strainer. Cleanouts should

be

located

on

both sanitary

and

storm drainage lines

at

15-m

(50-ft)

intervals

to

permit easy cleaning.

Cross Connections

Protection

of the

potable water supply against con-

tamination

is

vital. Reduced-pressure principle back-

flow

preventers,

or an

equivalent approved means

of

protection, must

be

installed

in the

branch pipe that

supplies equipment connections, hose bibbs,

or

hose

valves.

Backflow

preventers should

be

located above

the

flood

level with

a

proper

air gap in

their drain con-

nections. They must

be

tested

at

least annually

to

ensure

safe

operation,

and the

care

of

backflow

pre-

venters should

be

included

in the O&M

manual.

Some codes

do not

permit

the

installation

of

back-

flow

preventers,

but

require potable water

to be

dis-

charged through

an air

break into

a

tank,

from

which

it

may

be

pumped

to

potentially contaminating uses.

Interior hose bibbs should

be

conveniently located

for

easy wash-down

of the

station,

and

exterior hose

bibbs should

be

frostproof

in

cold climates.

Sumps

To

prevent

frequent

pump starts, sumps

for

subgrade

drainage should

be

sized

to

hold

at

least

two to

three

times

the flowrate

capacity

of the

installed

sump

pump below

the

lowest inlet. Install duplex pumps

and

a

sump high-level alarm

if

damage

to

other equipment

could

follow

failure

of a

single pump. Each pump

should

discharge individually through

a

check valve

and

a

gate valve before joining

in a

common discharge

riser to the

gravity

flow

waste line.

If the

piping sys-

tem of a

sump pump

can be

subjected

to

freezing

tem-

peratures,

it

should either

(1) be

designed

to be

self-

draining

or (2) be

protected

by

heat tracing

to

prevent

the

formation

of

ice.

So

that

occasional

solids

can be

passed, sump

pumps

should

be of the

semiopen impeller type with-

out

an

inlet screen. Submersible pumps have

the

advantage

of

being inherently

floodproof,

provided

their control panel

is

located above

the flood

level.

Mercury-type

float

switches

are

recommended

in

the

sump. They

are

arranged

(1) to

alternate

the

opera-

tion

of

duplex pumps,

(2) to

start

the

second pump

if

the first

does

not

handle

the

load

for any

reason,

and

(3)

to

energize local

and

remote alarms

if the

design

HWL is

exceeded.

The

pumps should

be

capable

of

continuous

operation.

Specify

a

manual

"test"

posi-

tion

on

pump

selector

switches

to

permit periodic

manual

tests

of

pump operation,

and

state

the

recom-

mended frequency

of

testing

in the O&M

manual.

The

pumps

and

their wiring, controls,

and

alarms must

be

explosionproof

if

open

to a

space

classified

as

hazard-

ous

by

Articles

500 to 502 of the

NEC.

4-10.

References

Anyone responsible

for

designing

or

selecting piping

should have

a

minimum library

of

reference materials

that

includes design handbooks, standard codes

and

specifications,

and one or

more manufacturer's cata-

logs

for

each

of the

piping materials

in the

chapter.

Manufacturers'

catalogs

often

contain most

of the

needed

design methods

and

useful

excerpts

from

stan-

dard specifications.

Because some

of

these publications

are

revised

occasionally, obtain

the

latest edition. Codes, stan-

dards,

and

specifications

are

listed

in

Appendix

E. The

addresses

of

publishers

are

given

in

Appendix

F.

1.

Crocker,

S.,

M. L.

Nayyar,

and R. C.

King,

Piping

Handbook,

6th

ed.,

McGraw-Hill,

New

York (1992).

2.

Deutsch,

D.

J.,

Process Piping Systems, Chemical

Engineering, McGraw-Hill,

New

York

(1980).

3. Langelier,

W. E,

"The

analytical control

of

anti-

corrosion water treatment,

"

Journal

of the

American

Water

Works

Association,

28,

1500-1521

(October

1936).

4.

Merrill,

D.

T.,

and R. L.

Sanks,

"Corrosion control

by

deposition

of

CaCO

3

films. A

practical approach

for

plant

operators,"

Journal

of

the

American

Water

Works

Association, Part

I, 69,

592-599

(November 1977);

Part

II, 69,

634-640

(December 1977); Part

III,

70, 12-

18

(January 1978).

5.

Merrill,

D. T, and R. L.

Sanks, Corrosion Control

by

Deposition

of

CaCO

3

Films.

A

Handbook

of

Practical

Application

and

Instruction.

American Water Works

Association, Denver,

CO

(1978).

6.

Pisigan,

R.

A.,

Jr.,

and J. E.

Singley, "Calculating

the

pH of

calcium carbonate saturation," Journal

of the

American

Water

Works

Association,

77,

83-91

(October 1985).

7.

Pisigan,

R.

A.,

Jr.,

and J. E.

Singley, "Effects

of

water

quality parameters

on the

corrosion

of

galvanized

steel,"

Journal

of the

American

Water

Works

Association,

77,

76-82

(November 1985).

8.

Pigg,

B.

J.,

"Asbestos cement

pipe,"

ASTM

Standardization

News,

pp.

56-57

(April 1988).

9.

AWWA

Mil,

Steel

Pipe—

A

Guide

for

Design

and

Installation,

2nd

ed.,

American Water Works

Association, Denver,

CO

(1985).

10.

Sanks,

R.

L.,

Water

Treatment

Plant Design

for the

Practicing

Engineer,

Ann

Arbor Science Publishers,

Ann

Arbor,

MI

(1978).

11.

DIPRA, Handbook

of

Ductile Iron Pipe,

6th

ed.,

Ductile

Iron Pipe Research Association, Birmingham,

AL

(1984).

12.

Handbook

of

PVC

Pipe, Design

and

Construction, Uni-

BeIl

PVC

Pipe Association, Dallas,

TX

(1991;

updated

frequently).

13.

AWWA

M9,

Concrete Pressure Pipe, American Water

Works

Association, Denver,

CO

(1979).

14.

Spangler,

M.

G.,

Soil Engineering,

2nd

ed.,

International

Textbook Company,

Scranton,

PA

(1960).

15.

Spangler,

M.

G.,

"Underground

conduits

—

an

appraisal

of

modern

research"

(with discussions), Transactions

of

the

American Society

of

Civil Engineers,

113,

316-

374

(1948).

16.

Piping

Engineering, Tube Turns Division, Louisville,

KY

(1974).

17.

MSS,

Pipe

Hangers

and

Supports, Selection

and

Application, Manufacturers Standardization Society,

Inc.,

of the

Valve

and

Fittings Industry, Arlington,

VA

(1976).

18.

"Piping

systems

for dry

chlorine,"

13th

ed.,

Pamphlet

6,

The

Chlorine Institute,

Inc.,

Washington,

DC

(April

1993).

19. The

Chlorine Manual,

5th

ed.,

The

Chlorine Institute,

Inc., Washington,

DC

(1986).

20.

"Non-refrigerated liquid chlorine

storage,"

5th

ed.,

Pamphlet

5, The

Chlorine Institute,

Inc.,

Washington,

DC

(October 1992).

21.

"Chlorine vaporizing systems,"

4th

ed.,

Pamphlet

9,

The

Chlorine Institute,

Inc.,

Washington,

DC

(November 1994).

22.

"Chlorine

pipelines,"

3rd

ed.,

Pamphlet

60, The

Chlorine Institute,

Inc.,

Washington,

DC

(April 1990).

23.

"Estimating

the

area

affected

by

chlorine

releases,"

2nd

ed.,

Pamphlet

74, The

Chlorine Institute,

Inc.,

Washington,

DC

(February

1991).

24.

"Refrigerated liquid chlorine

storage,"

2nd

ed.,

Pamphlet

78, The

Chlorine Institute,

Inc.,

Washington,

DC

(June 1994).

25.

White,

G.

C.,

Handbook

of

Chlorination,

2nd

ed.,

Van

Nostrand

Reinhold,

New

York

(1986).

4-11. Supplementary

Reading

1.

Steele,

A.,

Engineering Plumbing Design, Miramar,

Los

Angeles,

CA

(1977).

2.

Lindsey,

F.

R.,

Pipefitters

Handbook,

3rd

ed.,

Industrial

Press,

New

York

(1967).

3.

Procedures

for

Pipewelding,

National Association

of

Plumbing,

Heating, Cooling Contractors, Washington,

DC

(1983).

4.

Singley,

J.

E.,

et

al.,

Corrosion Prevention

and

Control

in

Water

Treatment

and

Supply

Systems, Noyes, Park Ridge,

NJ

(1985).

Engineers typically lavish much attention

on

pumps

but

little

on

valves, which

are

just

as

important

for the

proper functioning

of a

pumping

station.

The

discus-

sion

of

valves

and

actuators

in

this chapter

applies

mainly

to the

control

of the

pumped

fluid.

Small

valves

for

auxiliary purposes (e.g., seal water,

fuel,

and

plumbing)

are

only

briefly

mentioned.

Most valves

in a

pumping station

are for

isolation

service and,

as

such,

are

either open

or

closed.

Actua-

tors

are

usually manual

for

valves smaller than

600

mm

(24

in.),

and

power-driven actuators

are

usually

used

for

valves larger than

900 mm (36

in.).

Check

valves respond

to flow

direction

and

open

and

close

automatically. Pump control valves serve

a

dual

func-

tion

as

check valves,

and the

powered actuators

are

programmed

to

open

and

close

slowly enough

to

con-

trol transient pipeline pressures within acceptable lim-

its.

If

used

at

all, control valves

are the

most important

valves

in a

pumping station. Flow-control valves

(or

valves

that modulate to control flow or pressure) are

used

in

small sizes

for

cooling-water

or

seal-water

piping.

Pressure-control valves

are

sometimes used

in

distribution

systems

to

separate regions

of two

differ-

ent

pressures.

In

pumping stations, surge relief

or

surge

anticipation valves

arc

occasionally used

to

relieve high-pressure surges.

The

associated design considerations

of

cavitation,

noise, actuator sizing,

and

vibration

are

specific

for

Chapter

5

Valves

CARL

N.

ANDERSON

BAYARD

E.

BOSSERMAN

Il

CHARLES

D.

MORRIS

CONTRIBUTORS

Casi

Cadrecha

Joseph

E.

Lescovich

Harvey

W.

Taylor

the

brand

and

model

of the

valve used and, hence,

are

not

discussed

here.

Designers

should

be

aware, how-

ever,

of the

problems

and

explore them thoroughly

with

the

manufacturer.

Additional information

of

value

can be

found

in

the

literature

and in the

following references: Cook

[1], O'Keefe [2], Deutsch

et

al

[3],

AWWA

Mil

[4],

the ISA

Handbook

of

Control

Valves

[5], Lyons [6],

and

others

[7—11].

Photographs

and

drawings that

depict

the

various valves

and

show

how

they work

are

so

readily obtainable

from

manufacturers that

few are

reproduced

here.

References

to a

specification

or

standard

are

given

in

abbreviated

form

(such

as

ANSI

B

16.34) because such

designations

are

sufficient

for

identification.

The

titles

of

references

are

given

in

Appendix

E

together with

other standards that

may not be

referenced but, never-

theless,

aid in the

selection

and

specification

of

valves.

Addresses

of

publishers

are

given

in

Appendix

F. The

dangers

in

referencing

a

standard without

carefully

reading

the

entire work

are

discussed

in

Section 1-4.

5-1.

Designing

for

Quality

Choosing

the

right kind, style,

and

even make

of

valve

in

the

right situation

is

vital

to the

proper functioning

of

the

station.

A

valve proper

for one

installation

may

be

improper

for

another. Style (and even model

and

maker)

has a

profound

effect

on

satisfactory service.

The

problem

of

selection

is

complicated

by the

fol-

lowing

considerations:

(1) a

valve satisfactory

in one

location

may not be

satisfactory

in

another location

even

if

conditions

are

only slightly

different;

(2)

mak-

ers of

several styles

of

valves

may

make some good

ones

and

some poor ones;

(3)

models

are

changed

from

time

to

time

and a

valve, once poor,

may now be

good; and,

finally,

(4) it is

extremely

difficult

to

write

specifications

to

comply with

the

law, allow competi-

tive

bidding,

and

still obtain

a

satisfactory valve.

Familiarity

with

the

various manufactured products,

which

is the key to

good selection,

can be

achieved

by

•

Interviewing many manufacturers' representatives

(but

with

critical skepticism),

and

•

Discussing valves with expert consultants

and

with

users

—

the

operators

and the

utility managers.

Note that many makes

or

models

of

valves look alike

but

differ

significantly

in

quality.

A

valve

is

probably

of

high

quality

if a

competitor agrees.

The

best valves

are

expensive,

so a

misplaced emphasis

on low

initial cost

makes procurement

of

satisfactory valves

difficult

at

best. Valves

are the

heart

of the

hydraulic system;

if

they

fail,

the

system

fails.

In the

long run,

a

cheap valve

will

have proved

to be the

most expensive. Skimping

on

valves

is the

wrong

way to try to

save money.

Good quality

can be

obtained

by

incorporating into

the

specifications such items

or

criteria

as

listed below.

•

Materials:

Abrasion-,

corrosion-,

and

cavitation-

resistant materials

of

construction

—

especially

for

seats (see Table

5-1).

Table

5-1.

Typical

Valve

Seat

Materials

Type

specification

Life

Remarks

Resilient

seats

Buna

N

Good General-purpose elastomer

for

water

and

wastewater. Economical,

suitable

for

most water

and

sewage uses.

Leather Good Usually impregnated with various waxes

to

improve qualities.

Sometimes used

for

water,

not

sewage.

UHMW

3

Very

good

Very

abrasion-

and

chemical-resistant;

not

expensive.

Teflon™

Poor Impervious

to

chemical

attack, creeps

too

much

for

normal use;

expensive.

Viton™

Poor

Use

only

for

aggressive liquids

or

high temperatures,

creeps

somewhat.

Natural

rubber Good Suitable only

for

fresh

water.

Rigid

seats

Bronze

ASTM

B 62, B 584 (34

Tremendous variation Most common seat material, least resistant

to

erosion

or

corrosion.

alloys),

B 16, B 371

among alloys

Stellite

SAE, J775,

AMS

5373, Excellent Expensive; best

of all for

resistance

to

both corrosion

and

erosion.

5375,5378,

5380,

5385,5387,

5788

Stainless

steel

Specification

Erosion

b

Corrosion

b

Remarks

44OC

ASTM A276, alloy

1 5

Most resistant

to

erosion, highest

S44004

hardness.

420

ASTM

A276

alloy

2 5

S42000

17-4

PH

ASTM

A564,

alloy

3 3

S17400

410

ASTM

A276,

alloy

4 4

S41000

405

ASTM

A276,

alloy

5 4

S40500

316

ASTM A276, alloy

6 1

Highest resistance

to

corrosion.

S31600

304

ASTM A276, alloy

7 2

Least resistant

to

erosion.

S30400

a

Ultra-high-molecular-weight

polyethylene.

b

1

signifies

the

best

resistance.

Pumping Station Desing - Second Edition by Robert L. Sanks, George Tchobahoglous, Garr M. Jones

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