11. Valves and Piping

7/24/2019 11. Valves and Piping

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Module 11

PIPINGS and VALVES


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Course Contents

1. Pipe

2. Piping standard

- Nominal pipe diameter - Scedule num!er

- Piping standards code

- "u!es

- #ittings and oter piping au$iliaries

%. Metod o& 'oining sections - "readed

- (ell and spigot

- #langed

- )elded connection

- #itting*. "+pes o& &langed 'oints

,. E$pansion 'oints

. (linds

. Spaces


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Course Contents

/. Val0es

- "+pes o& 0al0es

. Val0es

- Gate 0al0e

- Glo!e 0al0e

- iapragm 0al0e

- Plug 0al0e

- (all 0al0e

- (utter&l+ 0al0e

- Needle 0al0e

- Cec3 0al0e - Sa&et+ 0al0e

14. #unction o& 0al0e

11. (asic control &unction o& 0al0es


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Course Contents

14. Application o& Val0e t+pes

11. Val0e ratings

12. Val0e operation and maintenance

1%. o5s and don5t &or !etter 0al0e ser0ice

1*. Pressure relie0ing de0ices

- 6o7 ig pressure de0elops

- "+pes o& pressure relie0ing de0ices

1,. e&inition o& pressure relie& terms


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Pipes

8 Piping s+stems are te arteries and 0eins o& a petrocemical plant'ust as te+ are in te uman !od+. In a petrocemical9 piping

s+stems andle all li:uids9 solids9 gas or 0apor.8 Material is &re:uentl+ stored and andled in te &luid state. Most &luid

cannot !e andled in open cannels !ut re:uired closed ducts.

8 In ancient tese ducts 7ere ollo7ed logs and later te+ 7ere madeo& section o& 7ood or o& potter+.

8 e0elopment o& iron !rougt a!out te manu&acture o& cast iron and7rougt iron pipes.

8 An+ structural material no7 a0aila!le is used &or pipe in application7ere its peculiar ad0antages are most 0alua!le.


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Piping Standards

Nominal pipe diameter

Pipe si;es are !ased on te appro$imate diameter and are reported as

nominal pipe si;es. Altoug te 7all tic3ness 0aries depending on

te scedule num!er9 te outside diameter o& an+ pipe a0ing a gi0en

nominal si;e is constant and independent o& te scedule num!er. "is

permits te use o& standard &ittings and treading tools on pipes o&

di&&erent scedule num!ers


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Piping Standards

Scedule num!er

8 Pipes 7ere originall+ classi&ied on te !asis o& 7all tic3ness

as standard ? 1444 Ps@Ss

7ere Ps ? sa&e 7or3ing pressure

Ss ? sa&e 7or3ing &i!er stress


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Piping Standards

Scedule num!er

8 "en scedule num!ers are in use at present.

8 "ese are 149 249 *49 49 /49 1449 1249 1*49 14

8 #or pipe diameters up to 14 in9 scedule *4 corresponds to te

&ormer standardB pipe and scedule /4 corresponds to te

&ormer e$tra strongB pipe.


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Piping Standards

Scedule num!er

6o7 te+ came up 7it te &ormula(ursting pressure o& a tin 7alled c+linder ma+ !e estimated &rom

te &ollo7ing e:uation>

P!? 2S"tm@m 7ere> P!? !ursting pressure S"? tensile strengt

tm? minimum 7all tic3eness

m? mean diameter


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Piping Standards

Scedule num!er

A sa&e 7or3ing pressure Ps can !e e0aluated &rom e:uation i& te

tensile strengt is replaced !+ a sa&e 7or3ing &i!er stress Ss

Ps? 2Sstm@m


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Piping Standards

Piping standard codes

8 "e American National Standards Institute


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Piping Standards

Piping standard code


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Piping Standard

"u!ing

Copper tu!ing9 !rass tu!ing are used e$tensi0el+ in industrial

operations. Fter metals9 suc as nic3lel and stainless steel9 are also

a0aila!le in te &orm o& tu!ing.

Altoug pipe speci&ications are !ased on standard nominal si;es9

tu!ing specs are !ased on te actual outside diameter 7it a

designated 7all tic3ness.

Con0entional s+stem9 suc as te (irmingam 7ire gauge


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Piping Standard

#ittings and oter piping au$iliaries

8 #ittings9 &langes9 0al0es9 &lo7 meters9 steam traps and man+ oter

au$iliaries are o&ten rated on te !asis o& te sa&e operating

pressure as

2, psi lo7 pressure 12, psi - standard

2,4 psi e$tra ea0+

%44 to 149444 - +draulic


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Metod o& Hoining Sections

Metod o& 'oining sections

"e metods o& 'oining sections are generall+ similar &or all

materials. "e principal metods in0ol0e are

1. "readed

2. (ell and spigot

%. #langed

*. )elded connections

,. #itting


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"readed Hoints

8 "readed pipe is most commonl+ encountered iin industr+ !ecause

practicall+ all small si;es o& pipe are 'oined !+ tismetod9 7eterall small si;es o& pipe are 'oined !+ tismetod9 7eter

&a!ricated o& steel9 7rougt iron9 cast iron9 !rass9 or plastic.&a!ricated o& steel9 7rougt iron9 cast iron9 !rass9 or plastic.

8 "is s+stem is simple !ecause te outside diameters o& te pipe are"is s+stem is simple !ecause te outside diameters o& te pipe are

3ept constant 7it a tolerance o& 1@* in. o0ersi;e and 1@%2 in.3ept constant 7it a tolerance o& 1@* in. o0ersi;e and 1@%2 in.undersi;e9 and te inside diameters o& &ittings are 3ept 7itin teundersi;e9 and te inside diameters o& &ittings are 3ept 7itin te

same limits9 regardless o& materials.same limits9 regardless o& materials.

8 "e tolerance &or te 7all tic3ness o& te di&&erent materials 0aries"e tolerance &or te 7all tic3ness o& te di&&erent materials 0aries

!ut is usuall+ 12., per cent.!ut is usuall+ 12., per cent.

8 Pipe larger tan 12in. Is rarel+ treaded9 and te outside diameterPipe larger tan 12in. Is rarel+ treaded9 and te outside diametercorresponds to te nominal pipe si;e.corresponds to te nominal pipe si;e.

8 Standard lengts o& pipe are &rom 1 to 22 &eet.Standard lengts o& pipe are &rom 1 to 22 &eet.


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(ell and Spigot Hoints

(ell and spigot connected pipe andle more &luid tan an+ oter

connection since it is te most practical t+pe o& 'oint in large pipe

si;es 7en pipes are made o& materials oter tan steel. "ese

'oints are usuall+ cal3ed 7it oa3um and lead !ut te mecanical

'oint is !ecoming more popular !ecause o& te tigter 'oint9 simplicit+

o& installation9 greater latitude o& angular displacement and

e$pansion. "ese 'oints ma+ !e loc3edB 7it a groo0e in te spigot

7ic pre0ents pulling apart te 'oint9 roll onB 7it a ru!!er gas3et

tigtened 7it a !olted ring or scre7ed glandB9 7it a ring gland

dra7n up against te gas3et 7en scre7ed into treads in te !ell.

Materials &or pipe 'oined in tis manner are usuall+ cast iron9 cla+9

or concrete9 altoug glass9 plastic and cement as!estos are

sometimes emplo+ed.


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)elded Connections

8 "e modern trend &or pipe in si;es a!o0e 2 in. is to7ard more

7elded connections. No treading9 cal3ing9 or !olts is needed9 and

no gas3ets are re:uired 7en te s+stem is &used into an un3no7n

line o& material.

8Pipe ends needs no treatment oter tan scar&ing

pieces &rom pipe sections.

8 #ittings and 0al0es are o& steel and are o& t7o t+pes9 !utt 7eld and

soc3et 7eld. "e !utt 7eld &ittings are o& te same dimension as te

pipe9 and te soc3et 7eld &ittings a0e enlarged ends similar to

treaded &ittings9 !ut te pipe slips into place and is &illet 7elded.


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#ittings

"readed 'oint &ittings

8 Couplings 'oin successi0e straigt lengt o& pipes 7it no cange

in direction or si;e.

8 Deducing couplings used 7en si;e is to !e reduced or enlarged.

8 El!o7s used 7en direction is to canged


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#ittings



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#ittings



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#ittings

)elded connections

#ittings are o& steel and are o& 2 t+pes9 !utt 7eld and soc3et 7eld.

"e !utt 7eld &ittings are o& te same dimension as te pipe9 and te

soc3et 7eld &ittings a0e enlarged ends similar to treaded to

treaded &ittings9 !ut te pipe slips into place and is &illet7elded.7elded.

#ittings are similar to e:ui0alent treaded t+pe.#ittings are similar to e:ui0alent treaded t+pe.


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#ittings

(ell and spigot connections

#ittings#ittings Jo& te same materials as te pipeK are similar in t+pe and

&unction to tose &or treaded pipe.


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#ittings

Compression &ittings

8 Compression &ittings are 7idel+ used &or small si;ed tu!ing at !ot

lo7 and ig pressure. "ese are con0enient and e&&icient9

particularl+ i& te connection is to !e !ro3en.


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#langed Hoints

#langed 'oints are te most common metod &or 'oining pipe in si;es

2 inces and a!o0e. "e use o& &langes allo7s &or ma3ing te piping

up in sections tat are eas+ to andle and also allo7s access &or

cleaning9 draining9 etc.

1. Soc3et 7elding &langes

2. Slip on 7elding &langes

%. "readed &langes

*. )elding nec3 &langes

,. Lap 'oint &langes


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#langed Hoints

Soc3et 7elding &langes

8 Soc3et 7elding &langes are 7idel+ used &or moderate ser0ice9

particularl+ in te smaller si;es9 !ecause o& te ease o& &it p and

alignment. Altoug usuall+ 7elded at te &lange u! onl+9 te pipe

end ma+ also !e 7elded 7itout a0ing to re&ace te &lange. "e

pipe end 7eld can !e ground to pro0ide a smoot !ore.


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#langed Hoints

Slip-on )elding #langes

8 Slip-on &langes are popular &or normal ser0ice conditions !ecause o&

te ease o& &it up and alignment and te greater tolerance

permissi!le in cutting te pipe to lengt. Decommended &a!ricationpractice is to 7ed at !ot te &lange u! and te pipe end.


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#langed Hoints

"readed #langes

8 "readed &langes are 7idel+ used !ecause no 7elding e:uipment is

re:uired &or assem!l+ and !ot te pipe and &lange can !e

completel+ sal0aged upon dismantling. Accuratel+ cut9 clean9

tapered pipe treads dimensioned to ANSI A2. 1 Pipe "reads9

assure strong9 tigt 'oints.


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#langed Hoints

)elding Nec3 #langes

8 )elding nec3 &langes are designed to !e !utt 7elded to te pipe.

"e long tampered u! rein&orces te &lange9 permits stress-

relie0ing9 magna&lu$ing or $-ra+ing te 7eld9 7en re:uired9 and

remo0es te &lange &ace &rom te eat a&&ected ;one. "ese

ad0antages ma3e 7elding nec3 &langes particularl+ suita!le &or

se0ere ser0ice in0ol0ing ig pressure9 e$treme temperatures9 or

a;ardous &luids.


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#langed Hoints

Lap Hoint #langes

8 Lap 'oint &langes9 7ile re:uiring a separate end connector9 pro0ide

a 'oint in 7ic te product does not come in contact 7it te &lange.

In addition9 te a!ilit+ o& te &lange to rotate simpli&ies assem!le and

alignment o& !olting on s+stems re:uiring &re:uent dismantling.

8 Scre7ed &langes must !e seal 7elded a&ter te scre7ed 'oint is

made up tigt. "reading o& pipe a!o0e 2B is di&&icult and tis t+pe is

not used too o&ten.

8 Slip-on &langes are 7idel+ used !ecause o& teir lo7 cost9 ease o&

&it-up and alignment9 o7e0er9 te+ are not too good &or ser0ice7ere te temperature and pressure &luctuate. In some ser0ices

corrosion o& te internal 7eld ma+ !e a pro!lem.


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#langed Hoints

Lap Hoint #langes


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#langed Hoints

Lap Hoint #langes


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E$pansion Hoints

E$pansion Hoints

8 All metals e$pand 7it increasing temperature. Steel pipe is no

e$ception to tis rule. E$pansion must !e considered to

accommodate te cange in lengt in te cange &rom atmosperic

temperature to operating temperature. E$pansion 'oints are used to

a!sor! te e&&ect o& te increased lengt 7it temperature. "ese

can !e !ends or corrugated e$pansion 'oints. "e attaced piping

must !e properl+ ancored and guided to direct te e$pansion to

utili;e te e$pansion to utili;e te e$pansion 'oint most e&&ecti0el+.


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(linds

(linds are a piping item used e$tensi0el+ in te plant. A !lind is used

to pro0ide positi0e isolation in !et7een piping &langes and tus

insure tat an+ lea3age tat ta3es place 7ill !e to te atmospere

and not troug te pipe.

8 Normall+9 !linds are used to prepare 0essels or tan3s &or entr+

and to isolate e:uipment and piping in order to pro0ide

complete sa&et+ in 7elding.

8 (linds are also used &or +drostatic testing !ut in tis case te+

must !e o& special design in order to andle te test pressures

tat 7ill !e in0ol0ed.


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Spacers

Spacers are re:uired 7en tere is a !lind o& apprecia!le tic3ness

to !e used. It is ordinaril+ impossi!le to spring te &langes &ar

enoug apart to install a !lind o& tic3ness !e+ond in.

8 nder te a!o0e conditions a spacer is re:uired to ta3e up te

space occupied !+ te !lind 7en te e:uipment is returned to

operating condition.

8 Sometimes te !lind and te spacer are attaced to eac oter

and in tis case it is 3no7n as &igure / or spectacle !lind.


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Val0es

8 Val0es are used &or te control o& 0olume and pressure o& &luids

mo0ing troug piping or in enclosed 0essels. "e+ ma+ !e

operated automaticall+ or !+ and. "+pe o& construction is as 0aried

as te operations 7itin te plant eac is designed &or te ser0ice

to !e per&ormed.


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Val0es

"+pes o& 0al0es

1. Gate 0al0es

2. Glo!e 0al0es

%. iapragm 0al0es

*. Plug 0al0es,. (all 0al0es

. (utter&l+ 0al0es

. Needle 0al0es

/. Cec3 0al0es. Sa&et+ 0al0es


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Val0es

Gate 0al0es

8 "e gate 0al0e is pro!a!l+ te most 7idel+ used 0al0e in plantoperations9 particularl+ in te larger si;es o& piping installations andtose o& te most se0ere ser0ice.

8 It consists o& a main !od+ and a stem 7ic raises or lo7ers a

gateB across te &luid &lo7. In ig pressure installations te gatesmust !e o& ea0+ construction and are sometimes di&&icult to open.Some are motor operated and some a0e a small !+-pass line &ore:uali;ing te pressure on !ot sides o& te gate !e&ore opening.

8 "e rising stem gate 0al0e is used in !ot 7ater and process piping.

It re:uires more o0erall space &or installation9 !ut is used to anad0antage in andling corrosi0e streams tat tend to damage stemtreads in oter t+pe 0al0es.


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Val0es

Gate 0al0es


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Val0es

Gate 0al0es

used to minimi;e pressure drop in te open position and to stop &lo7 rater tan to regulate it.


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Val0es

Glo!e 0al0es

8 "e essential &eature o& tis t+pe 0al0e is a glo!ular !od+ 7it aninternal9 ori;ontal partition a0ing a circular opening in 7ic isinserted a ring or seat. "e glo!e or disc seats on tis ring to e&&ectsut-o&&.

8 "e 0al0e opening is so arranged tat &lo7 troug it must ma3e t7o

4-degree canges o& direction. "is results in a relati0el+ igpressure drop9 or resistance to &lo7.

8 "e glo!e 0al0e is generall+ used in small si;ed piping &or trottlingor control. "e+ are used principall+ in steam or air ser0ice 7eretrottling and a positi0e sut-o&& is desira!le.

8 Installation sould !e suc tat &lo7 is up troug te seat ring andagainst te !ottom o& te disc or glo0e. "is 7ill pre0ent openingdi&&iculties caused !+ te accumulation o& de!ris a!o0e te disc."is sould !e a0oided.


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Val0es

Glo!e 0al0es


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Val0es

Glo!e 0al0es - o&&er ease in trottling


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Val0es

iapragm 0al0es


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Val0e

iapragm 0al0es

limited to ,4psi9 e$cellent &or &luid containing suspended solids

iapragm 0al0es


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Val0es

Plug 0al0es8 "e plug 0al0e9 or coc39 is a conical plug 7itin a !od+. Its cie&

ad0antage is in its tigt sut o&&. A one :uarter


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Val0es

Plug 0al0e &or trottling ser0ice9 little li3eliood o& lea3age 7en

closed.


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Val0es

(all 0al0es8 (all 0al0es are adaptations o& plug 0al0es using !all-saped discsinstead o& conical plugs located 7itin te !od+. A ole troug tecenter o& tis disc pro0ides te straigt-troug &lo7 7ic iscaracteristic o& !all 0al0es. (all 0al0es are used to sut o&& orpermit &ull &lo7 o& &luid troug te 0al0e.

8 (all 0al0es a0e all te ad0antages o& plug 0al0es in terms o&e$cellent &lo7 caracteristics - :uic3 opening9 straigt-troug &lo79minimum tur!ulence9 tigt closure and compactness - plus teadditional ad0antage o& not re:uiring an+ lu!rication or sealant."e+ acie0e tigt closure !+ esta!lising a controlled s:uee;e o&te !all against te sear rings 7ic are made o& plastic materialsuc as te&lon.


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Val0e

(all 0al0es


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Val0es

(utter&l+ 0al0es8 "e !utter&l+ 0al0e deri0es its name &rom te 7ing-li3e action o& te

disc 7ic operates at rigt angles to te &lo7. Frdinaril+9 te+ are

not intended &or tigt sut o&&9 !ut resilient seats a0e !roadened

teir possi!ilities and te+ are no7 &re:uentl+ ad0ertised as a0ing

!u!!le tigtB closure.


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Val0es

(utter&l+ 0al0e


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Val0es

Needle 0al0es8 Needle 0al0es are designed to gi0e 0er+ &ine control o& &lo7 in small

diameter piping s+stems. "e+ get teir name &rom teir sarp-

pointed conical disc and matcing seat. "e stem treads are &ine

so tat more turns o& te and 7eel are re:uired to increase or

decrease te opening troug te seat.


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Val0es

Needle Val0es o&&er &lo7 ad'ustment on small lines


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Val0es

Cec3 0al0es8 Cec3 0al0es are automatic in operation. "e+ pre0ent &lo7 in one

direction9 !ut allo7 it in te oter. "ese 0al0es sould !e care&ull+

cec3ed &or direction o& &lo7 in lines.

8 S7ing cec3 0al0es are unsuita!le &or use in 0ertical lines. Note

importance o& correct installation o& a cec3 0al0e in relation to te

stream &lo7. suall+ te 0al0e !od+ as &eatures tat indicate correct

direction.

8 Sometimes an arro7 indicates te direction o& &lo7 permitted troug

te 0al0e. o not rel+ upon a cec3 0al0e to gi0e &ull sut-o&& against a

!ac3 &lo7. Fnl+ on special occasions9 Jautori;edK 7ill te cec3 0al0e

!e depended upon to pre0ent !ac3 &lo7 o& li:uid or oter a;ardousmaterial 7en opening lines into oter s+stems or to te atmospere.

Al7a+s use a !loc3 0al0e 7en possi!le.


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Val0es

Sa&et+ 0al0es8 Sa&et+ 0al0es are installed in strategic locations to pro0ide pressure

relie& &or process e:uipment su!'ected to e$cessi0e pressure.

8 A sa&et+ 0al0e consists o& si$ !asic parts spring9 spindle or stem9

ad'usting scre79 disc9 no;;le or seat9 and !od+. Sa&et+9 or relie&9

0al0es are intended &or emergenc+ protection onl+ and sould not!e used as an operating 0al0e.

8 #re:uent poppingB o& a relie& 0al0e contri!utes to teir &ailure9

tere&ore9 te+ sould set at 2, a!o0e 7or3ing pressure. #or

e$ample9 relie& 0al0es on te discarge o& reciprocating pumps 7ill

relie0e 7it eac pump stro3e i& te set pressure is too lo7.Continuous pounding o& te disc upon te seat causes damage and

resultant lea3age o& te 0al0e.


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Val0es

Sa&et+ 0al0es


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Pressure Delie0ing e0ices

Con0entional Delie& Val0e

# i F& V l


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#unctions F& Val0es

8Piping s+stem9 in order to e&&ecti0el+ per&orm te &unction o&transporting &luids &rom te point to anoter9 need de0ices to control

or regulate te &lo7 o& &luids. Altoug de0ices are a0aila!le 7ic

!+ suita!le instrumentation automaticall+ regulate or control te &lo7

o& &luids in response to &lo79 le0el9 pressure9 temperature9 or oter

control signals onl+ manuall+ operated de0ices 7ill !e discussed

in tis section. Cec3 0al0es9 relie& 0al0es9 steam traps9 drain

0al0es9 etc altoug not manuall+ operated are also discussed in

tis section.

8 Manuall+ operated 0al0es are de0ices 7ic are opened or closed

!+ turning a and 7eel or mo0ing9 rotating or oter7ise

manipulating a and le0er or 7renc. Gate9 glo!e9 plug9 !all9

diapragm and !utter&l+ 0al0es are in tis categor+.


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(asic Control #unctions F& Val0es

8 Starting and stopping #lo7

"o start or stop te &luid &lo7 is te &unction &or 7ic 0al0es are

most generall+ used. Gate9 plug9 !all9 !utter&l+ and diapragm

0al0es e&&ecti0el+ per&orm tis &unction 7it 0er+ little pressure drop

troug te 0al0e.8 Degulating and trottling #lo7

Degulating or trottling &lo7 is most e&&icientl+ per&ormed 7it glo!e9

angle9 or needle 0al0es. "ese 0al0es are seldom used in si;e

a!o0e / inces !ecause o& te di&&icult+ opening and closing te

larger 0al0es against pressure.(utter&l+ and diapragm 0al0es are also e&&ecti0e as regulating or

trottling 0al0es at limited &luid &lo7 caracteristics.


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(asic Control #unction F& Val0es


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Application F& Val0e "+pes

Gate 0al0es

8 "e Principal caracteristic o& a gate 0al0e is te &act tat te

&lo7 troug te 0al0e is stopped !+ sliding a relati0el+ &lat

sur&ace9 called a gate or disc9 across te &lo7 pat o& te &luid

and started !+ mo0ing te disc into a cam!er in te 0al0e!onnet out o& te &lo7 pat. Gate 0al0es are most e&&ecti0e &ull+

closed or &ull+ opened. )en &ull+ opened te &luid &lo7s

troug te gate 0al0e in a straigt line 7it 0er+ little pressure

drop.


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Glo!e 0al0es

8 Glo!e 0al0es are named a&ter te glo!ular sape o& teir !od+.

"e+ are most suita!le &or trottling &luid &lo7s !ecause o& teir t+pe

o& seating arrangements9 o7e0er9 te+ can also !e used in &ull+

sut o&& and &ull+ open ser0ice

8 Glo!e 0al0es seating is parallel to te line o& &lo7 7it all contact!et7een seat and disc ending 7en &lo7 !egins.

8 "e &luid &lo7 troug a glo!e 0al0e &ollo7s a canging course

7ic causes resistance to &lo7 and considera!le pressure drop.

6o7e0er9 in order to control te &luid &lo7 7e must sacri&ice some

pressure drop.


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Angle 0al0es

8 Angle 0al0es are similar to te design o& glo!e 0al0e !ut a0e less

resistance 7ic results in less pressure drop.

8 "e angle 0al0e e&&ecti0el+ utili;es glo!e 0al0e seating principle

7ile pro0iding &or a 4 degree turn in piping. It is less resisting to

&lo7 tan te glo!e 0al0e it displaces. De:uires &e7er 'oints sa0esma3e-up time and la!or.


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Needle 0al0es

8 Needle 0al0es are designed to gi0e 0er+ &ine control o& &lo7 in small

diameter piping s+stems.

8 Generall+ used in cemical in'ections to process and deli0er+ lines


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Plug 0al0es

8 "e plug 0al0e is o&ten re&erred to as te oldest mem!er o& te 0al0e

&amil+9 o7e0er9 tis is onl+ true o& te non-lu!ricated t+pe 7ic

ma+ !e considered a modi&ication o& te simple coc3.

8 "e non-lu!ricated plug 0al0e is an e0olution o& te simple plug

coc3. All te ad0antages o& te simple plug coc3 are maintained !utte tendenc+ o& te plug to sei;e or !ind as !een o0ercome !+

canges in te design and construction o& te plug 0al0e. "is as

!een accomplised !+ te use o& 0arious plastics or oter materials

7it lo7 &riction 0alues &or contact or sealing sur&aces. As a result o&

tese canges non-lu!ricated plug 0al0es are no7 a0aila!le &or a

muc greater range o& ser0ice conditions.

8 "e&lon


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Plug 0al0es


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(all 0al0es

8 (all 0al0es are adaptations o& plug 0al0es using !all-saped discsinstead o& conical plugs located 7itin te !od+. A ole troug tecenter o& tis disc pro0ides te straigt-troug &lo7 7ic iscaracteristic o& !all 0al0es. (all 0al0es are used to sut o&& orpermit &ull &lo7 o& &luid troug te 0al0e.

8 (all 0al0es a0e all te ad0antages o& plug 0al0es in terms o&e$cellent &lo7 caracteristics - :uic3 opening9 straigt-troug &lo79minimum tur!ulence9 tigt closure and compactness - plus teadditional ad0antage o& not re:uiring an+ lu!rication or sealant."e+ acie0e tigt closure !+ esta!lising a controlled s:uee;e o&te !all against te sear rings 7ic are made o& plastic materialsuc as te&lon.


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(all 0al0es


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(utter&l+ 0al0es

8 "e+ are 7idel+ used in te municipal &ield &or te control o& 7ater

&lo7.

8 (utter&l+ 0al0es are e$cellent &or andling large &lo7 o& gases and

li:uid at relati0el+ lo7 pressure.

8 "e !utter&l+ 0al0e in &ull open position as relati0el+ lo7 pressuredrop and minimum tur!ulence since te disc position is parallel to

te &luid &lo7. Some o& te ad0antages o& !utter&l+ 0al0es are little

ead room re:uired9 ligt in 7eigt9 dura!ilit+9 lo7 initial cost and

ease o& operation. 6o7e0er9 te+ are limited in pressure and

temperature applications.


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Cec3 0al0es

8 "e principal &unction o& a cec3 0al0e is to automaticall+ pre0ent

re0ersal o& te direction o& te &luid &lo7. Pressure o& te &luid &lo7ing

troug te cec3 0al0e 3eeps it open re0ersal o& te &lo7 closes

it. Most manu&acturers plainl+ mar3 cec3 0al0es &or direction o&

&lo7. "e design o& cec3 0al0es are relati0el+ simple and are

a0aila!le in tree !asicall+ di&&erent t+pes - s7ing cec39 li&t cec39

and !all cec3.



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Cec3 Val0es

8 sed to pre0ent re0ersal o& &lo7 1. S7ing cec3 0al0e

- Normal design is &or use onl+ in ori;ontal lines

2. Li&t cec3 0al0es

- Vertical li&t cec3 0al0e &or installation in 0ertical line9 7ere

te &lo7 is normall+ up7ard - Glo!e cec3 0al0e &or use in ori;ontal lines

- Angle cec3 0al0e used &or installation 7ere a 0ertical line

7it up7ard &lo7 turn ori;ontal

%. "ilting dis3 cec3 0al0e

- Ma+ !e installed !ot ori;ontall+ and 0erticall+. Less pressure

drop at lo7 0elocit+ !ut greater at ig 0elocit+. Arrests

slamming.


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S7ing cec3 0al0e

8 S7ing cec3 0al0es a0e a disc9 inged at te top9 7ic seats

against a macined seat in te tilted !ridge 7all opening. "e disc

s7ings &reel+ in an arc &rom te &ull+ closed position to one pro0iding

uno!structed &lo7. "e &luid &lo7s troug te !od+ in a straigt line.

"e straigt line &lo7 results in lo7 pressure drop !ecause o& te

minimum resistance to &lo7.



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Cec3 Val0es

S7ing cec3 0al0e



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"ilting dis3 cec3 0al0e

Cec3 0al0es


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Li&t Cec3 Val0e

8 "e li&t cec3 0al0e as a disc e:uipped 7it a sort guide9 usuall+

a!o0e and !elo79 7ic mo0es 0erticall+ in integral guides in te

cap and !ridge 7all. #luid &lo7 mo0ing troug te !od+ in a

&re:uent canging course 3eeps te 0al0e open.

8 )en &lo7 stops gra0it+ or re0erse o& &lo7 direction automaticall+closes te 0al0e !+ &orcing te disc against te seat. Li&t cec3

0al0es pro0ide a tigter seal against !ac3 &lo7 tan can !e acie0e

7it te s7ing cec3 0al0e.

8 Li&t cec3 0al0es can onl+ !e used in ori;ontal pipe lines and are

generall+ used in con'unction 7it glo!e and angle 0al0es.


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Li&t cec3 0al0e


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(all Cec3 Val0e

8 (all cec3 0al0es are similar to li&t cec3 0al0es e$cept tat a !all is

used in place o& te li&t disc &or closure purposes. "e !all is pused

a7a+ &rom te seat during &luid &lo7 and closes rapidl+ 7en &lo7

stops or is re0ersed. "is 0al0e as e$tensi0e use in piping s+stems

mo0ing ot oils and can onl+ !e used in 0ertical lines.


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Stop-Cec3 or Non-Deturn Val0e

8 A special and more complicated cec3 0al0e called te stop-cec3

or non-return 0al0e is essential to te sa&e operation o& a !oiler.

"eir design must con&orm to te ASME (oiler Construction Code

&or Non-Deturn Stop 0al0es. "e 0al0es are intended to per&orm &our

important &unctions in !oiler steam piping>

1. Act as an automatic non-return 0al0e pre0enting !ac3&lo7 o&

steam &rom te connected main steam eader into te !oiler in te

e0ent o& &ailure o& tat !oiler.


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/1


8 Stop-Cec3 or Non-Deturn Val0e


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Stop-Cec3 or Non-Deturn Val0e


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Sa&et+ 0al0es

8 Applications o& sa&et+ 0al0es 7ill !e discussed separatel+ later in

tis module under pressure relie0ing de0ices.


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Val0e Datings

Most 0al0e manu&acturers compl+ 7it MSS Standard Mar3ingS+stem SP-2, in te identi&ication o& teir 0al0es. "e &ollo7ings+m!ols are generall+ used>

S - Steam

F - Fil

G - Gas

) - )ater

L - Li:uid

General purpose 0al0es ma+ so7 t7o ser0ice ratings. Fne is asteam rating9 !ased on a speci&ic pressure@temperature condition."e second rating is &or cold ser0ice.


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Val0es Datings

8 Steam Datings

Steam ratings are used as a !asis &or determining te suita!ilit+ o& a

material &or a gi0en application. #or lo7er temperatures te sa&e

7or3ing pressure o& a material is usuall+ greater tat te steam

rating.

8 Cold Datings

Most 0al0es a0e t7o ser0ice ratings. In addition to te steam

rating9 e$plained a!o0e9 cold ser0ice ratings are usuall+ designated

!+ te mar3 )FG9 7ic stands &or cold 7ater9 oil9 or gas9 non-soc3.


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V l F ti A d M i t


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2

Val0e Fperation And Maintenance

Variations in Stem Fperation o& Gate9 Glo!e and Angle Val0es

1. Dising stem 7it outside scre7 and +o3e. In tis construction te

stem scre7 remains outside te 0al0e !od+ 7eter 0al0e is opened

or closed. Stem treads are not su!'ected to te e&&ects o& &luids in

te line - suc as caused !+ corrosion9 erosion9 sediment9 etc. "is

construction also permits con0enient lu!rication o& stem treads.

"e rising stem so7s at a glance te position o& te disc.

Ade:uate eadroom must !e pro0ided &or te rising stem 7en te

0al0e is opened9 and te stem sould !e protected against damage7en raised.


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o5s And on5t #or (etter Val0e Ser0ice


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o s And on t #or (etter Val0e Ser0ice

1. on5t e$pose 0al0es to damaging !lo7s. Val0es can5t !e a!usedand still operate e&&icientl+. A !ent stem not onl+ cripples 0al0es9 !utma+ cause a sutdo7n tat results in costl+ dela+ and repair.

2. on5t o0erloo3 lea3s !ig and small. A lea3 in a 0al0e o&ten can

!e remedied simpl+ and in a urr+9 i& caugt in time. Stem lea3snormall+ can !e &i$ed !+ sligtl+ tigtening te pac3ing nut or gland.

Stu&&ing !o$ lea3s usuall+ can !e stopped !+ merel+ pullingB up tepac3ing nut. Fn !olted glands9 care must !e ta3en to tigten !olts

e0enl+O as se0erel+ co3ing te gland 7ill !ind te stem. I& testu&&ing !o$ must !e repac3ed9 tis repair sould !e sceduled &or:uali&ied maintenance mecanics.


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o5s And on5t #or (etter Val e Ser ice


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o5s And on5t #or (etter Val0e Ser0ice


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14%


Sa&et+ Val0es

8 An automatic pressure relie0ing de0ice actuated !+ te static

pressure upstream o& te 0al0e9 and caracteri;ed !+ rapid &ull

opening or pop action upon opening.

8 It is used &or steam9 gas or 0apor ser0ice.

8 Dated capacit+ is reaced at %9 14 or 24 percent o0erpressure9depending upon applica!le code.



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14*

Sa&et+-relie& 0al0e8 Sa&et+ relie& 0al0e is an automatic pressure relie0ing de0ice

actuated !+ te static pressure upstream o& te 0al0e andcaracteri;ed !+ an ad'ustment to allo7 eiter a popB or a nonpopB action and a no;;le t+pe entrance

8 Suita!le &or use as eiter a sa&et+ or relie& 0al0e9 depending onapplication.

8 Sa&et+9 relie& and sa&et+ relie& 0al0es are installed in strategic

locations to pro0ide pressure relie& &or process e:uipment su!'ectedto e$cessi0e pressures. "ese 0al0es consist o& si$ !asic parts>spring9 stem9 ad'usting scre79 disc9 no;;le or seat9 and !od+.

8 Dated capacit+ is reaced at % or 14 percent o0erpressure9depending upon code and@or process conditions. Pressure relie0ing0al0es are intended &or emergenc+ protection onl+ and sould not

!e used as an operation 0al0e. #re:uent poppingB o& a relie& orsa&et+ 0al0e contri!utes to teir &ailure and are tere&ore set at 2,- ,4 a!o0e te 7or3ing pressure.


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Con0entional and !alance sa&et+ 0al0e8 Con0entional sa&et+ 0al0es operate satis&actoril+ onl+ 7en tere is

relati0el+ constant !ac3 pressure. Canges in !ac3 pressure can

seriousl+ a&&ect its operational pressure and &lo7 capacit+

8 (alance 0al0es operate satis&actoril+ under 0ar+ing !ac3 pressure

as tis as little in&luence on per&ormance


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e&inition o& Pressure Delie& "erms


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2. F0erpressure8 Pressure increase o0er te set pressure o& te primar+ relie0ing

de0ice is o0er pressure

8 It is te same as accumulation 7en te relie0ing de0ice is set at

te ma$imum allo7a!le 7or3ing pressure o& te 0essel



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%. Accumulation8 Pressure increase o0er te ma$imum allo7a!le 7or3ing pressure

o& te 0essel during discarge troug te sa&et+ or relie& 0al0e9

e$pressed as a percent o& tat pressure.



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*. Ma$imum allo7a!le 7or3ing pressure8 "e ma$imum allo7a!le 7or3ing pressure o& an un&ired pressure

0essel is tat pressure determined !+ code re:uirements9 te

metal material o& construction and its operating temperature9

a!o0e 7ic te 0essel ma+ not !e operated

8 #or a gi0en metal temperature9 tis pressure is te igestpressure at 7ic te sa&et+ de0ice ma+ !e set to open.


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11*


. (lo7do7n8 "e reduction in &lo7ing pressure !elo7 te set point re:uired &or

a de0ice to close

8 Is te di&&erence !et7een te set pressure and te reseating

pressure o& a sa&et+ or relie& 0al0e

8 E$pressed as percent o& te set pressure or psi


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Electric Solenoid


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11

"ermal Val0e


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11. Valves and Piping

Documents

Transcript of 11. Valves and Piping