IS 15680 (2006): Guidelines for selection of steam trapsIS 15680:2006 Applications Trap Choice n) Available with screwed/S W/B W/flanged end connection. 2.3.1.3 Typical application

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IS 15680 (2006): Guidelines for selection of steam traps[MED 1: Boilers and Pressure Vessels]

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IS 15680:2006

Indian Standard

GUIDEL~ES FOR SELECTION OF STEAM TRAPS

ICS 27.040

0 BIS 2006

BUREAU OF INDIAN STANDARDSMANAK BHAVAN, 9 BAHADUR SHAH ZAFAR MARG

NEW DELHI 110002

Ju~ 2006 Price Group 3

—.—— ——..—______ --

.

Boilers and Pressure Vessels Sectional Committee, ME 01

,FOREWORD

This Indian Standard was adopted by the Bureau of Indian Standards, after the draft finalized by the Boilers andPressure Vessels Sectional Committee had been approved by the Mechanical Engineering Division Council.

This standard is based on the experience of the manufacturer and the user organization, prevalent design and operationof steam traps.

The composition of the Committee responsible for the formulation of this standard is given at Annex A.

For the purpose of deciding whether a particular requirement of this standard iscomplied with the final value, observedor calculated, expressing the result of a test or analysis shall be rounded off in accordance with IS 2: 1960 ‘Rules forrounding off numerical values (revised’ _The number of significant places retained in the rounded off value should besame as that of the specified value in this standard.

*>

IS 15680:2006

Indian Standard

GUIDLINES FOR SELECTION OF STEAM TRAPS

1 SCOPE

This standard covers principle of operation and guidelinesfor selection and operation of various types of steam traps.

2 VARIOUS TYPES OF.STEAM TRAPS

2.1 Density Operated Traps

2.1.1 Ball Float with Thermostatic Air Vents

2.1.1.1 Operation

Air entering the trap is immediately discharged through ahigh capacity auxiliary air vent. Condensate causes theball float to rise and place the modulating discharge valvein a position that will pass the condensate continuously asit enters the trap. The condensate level in the trap body ismaintained above the discharge valve to provide a positiveseal against the loss of steam.

.2.1.1.2 Special features

a)

b)

c)

d)

e)

o

g)

h)

j)

k)

Discharge condensate continuously as rapidly as itforms;

High air venting capacity through auxiliarybalanced pressure air vent, which is self-adjustingfor varying steam pressures;

High thermal efficiency at both light and heavyloads;

Continuous modulating discharge does not createpressure disturbances, which may cause erraticcontrol in air heating coils, shell and tubeexchangers, etc;

Steam lock release (S.L.R.) facility available;

in line inlet and outlet facility, easy installation atlow cost;

Robust, fair resistance to water hammer;

Fails in closed position, so no wastage of steamenergy;

Unaffected by changes in inlet pressure;

Suitable for high condensate loads;

m) Available with screwedsocket welde~flanged endconnection; and

n) Available with in-builtiseparate strainers.

2.1.1.3 Typical applications

Air unit heaters, hot water heaters, heat exchangers,

converters, dryers, re-boilers, jacketed pans and all processequipment.

2.1.1,4 Limitations

a) Cannot be used where trap is fitted with air ventand degree of superheat is more than 10O°C,and

b) Water hammer can damage float.

2.1.2 Inverted Bucket Traps

2.1.2.1 Operation

The trap body is normally filled with condensate tomaintain a seal around the inverted bucket, which servesas a float to operate the discharge valve. Live steamentering the bucket floats it to close the valve. During theclosed period, condensate collects in the piping at the inletside of the valve until steam floating the bucket leaksthrough a small hole in the top of the bucket and permitsthe bucket to drop and open the valve. The condensate isdischarged. followed by steam, which is required to actuatethe float mechanism. Air can pass through the small holeat the top of the bucket.

2.1.2.2 Special features

a) Good resistance to water hammer,

b) Simple and robust mechanism and easy to maintain,

c) Intermittent discharge,

d) Discharge condensate and air at steam temperature,

e) Operate on superheated steam,

~ Operate against any back pressure,

g) Available with in-builtiseparate strainers, and

h) Available with screwedsocket welded/flanged endconnection.

2.1.2,3 Typical applications

High pressure indoor steam main drips and submergedheating coils, ketiles.

2.1.2,4 Limitations

a)

b)

c)

I

Low thermal efficiency under varying loads andpressures and some steam loss for operation,

Must maintain water seal to avoid continuousdischarge of steam,

Must be protected from freezing,

IS 15680:2006

d)

e)

.

Discharge condensate continuously as rapidly as itforms, and

Bleed hole in bucket has very limited air-ventingcapacity.

.2.2 Temperature Operated Traps

2.2,1 Balanced Pressure Thermostatic Traps

2.2.1 ;I Operation

The trap is operated by a flexible thermostatic elementfilled with a fluid, which when heated or cooled evaporatesor condenses. Internal pressure changes expand orcontract the element and position the attached valve head.On start-up the coId elements is contracted, and the-wideopen valve remains open to discharge air and sub-coolscondensate. When steam reaches the trap, the elementexpands and closes the trap. When condensatesurrounding the capsule cools to approximately 10°C to20°C below steam temperature (depending on the filling)the trap opens to discharge condensate.

2.2.1.2 Special features

a) High air venting capacity fQr fast start-up,

b)

c)

d)

e)

o

g)

h)

j)

k)

Large capacity in small size,

Self adjusting – will operate without adjustmentsat all pressures within its range,

Will not freeze if given free discharge,

Use same valve sizes for all pressures within itsoperating range,

Minimum parts,

Operates in vacuum systems,

Modulating discharge,

Operate on moderate superheated steam,

Discharges condensate close to steam temperature(5- l@C sub-cooling),

m) Reacts to temperature changes immediately,

n) Ensure prevention of live steam loss,

p) Available with in-built strainers, and

q) Available with screwed/SW/flanged endconnections.

2.2.1.3 Typical application

Steam radiators, low and medium pressure submergedheating coil, sterilizers, steam tracer, steam mains, pressesand dryers.

2.2.1.4 Limitations

a) Not suitable for highly superheated steam,

b) Limited resistance to water hammer and corrosion,and

c)

2.2.2

Not suitable for applications in which condensatemust be dischargedas fast as it is formed.

Bi-metallic Thermostatic Trap

2.2.2.1 Operation

The operating principle is based on a“balancebetween thesteam force (pressure dependent), trying to open thedischarge valve, and the opposing hi-metal force(temperature dependent) which tends to close it. The trapis adjusted so that all saturated steam temperature thehi-metallic force will prevail, while with under-cooledcondensate and air, the force of pressure will prevail andopen the valve trap, the required under-cooling should beminimum possible through out the designed pressurerange. Being the steam force a curve while the hi-metallicforce a straight line, an additional compensating springwill break the straight line to make it follow the curve ofsteam more closely making field adjustment unnecessary.

2.2.2.2 Special features

a)

b)

c)

d)

e)

o

g)

h)

j)

Modulating discharge,

Condensate is discharged below steam temperature(20 °C/30”C). Sub-cooling temperature can beadjusted on field,

A compensating spring between the hi-metallicelement and-the valve steam ensures that the trapoperation follows the steam curve closely. Thespring does not induce valve spring,

May be used on superheated steam,

Valve steam acts as a checked valve,

Resist water hammer and vibration,

Replaceable internal parts,

Efficient discharge of air and non-condensablegases, and

Freeze proof full size ‘Y’ pattern integral strainer.

2.2.2.3 Typical applications

Tracing lines, tank heaters, marine applications.

2,3 Kinetic Energy Operated Traps

2.3.1 Thermodynamic Disc Traps

2.3.1.1 Operations

Condensate and air raise the disc and flow freely throughthe trap. When steam reaches the trap, the velocity underthe disc is instantly increased and recompression abovethe disc snaps it on to its seats to give a tight shut off.Heat loss from the small control chamber, which is filledwith a steam, condensate mixture, causes the chamberpressure to decrease to a point at which the valve discopens again to discharge condensate.

2

2.3.1.2 Special features

a) Compact and light weight;

b) High resistance to water hammer;

c)

d)

e)

9

g)

h)

j)

k)

Long life due to hardened seat and disc;

Only one moving part;

Efficient operation under varying loads andpressures;

Fast response to changing loads;

Discharges condensate at steam temperature,prevent water logging;

Discharges air and non-condensable gases;

Freeze proo~

Operates on superheated steam;

m) Available with in-built strainers; and

IS 15680:2006

Applications Trap Choice

n) Available with screwed/S W/B W/flanged endconnection.

2.3.1.3 Typical application

Steam main drips, high pressure and superheat, steamtracer lines, unit heaters.

2.3.1.4 Limitations

a) Not suitable for pressures below 0.25 bar, and

b) Some models limited 50 percent back pressures,others suitable for 80 percent of back pressures.

3 TYPICAL CHART FOR ST-EAM TRAPSELECTION AND APPLICATIONS

D = thermodynamic disc traps,

T = balanced pressure thermostatic traps,

hi-metallic thermostatic traps,

inverted bucket traps, and

ball float with thermostatic air vent traps.

Steam MainsTracing Lines

Tank

HeaterBatteries

to

Pans

Heat

Exchangers

D~ing

Cylinders

Presses

hens

Storage tanksOil tanksAsphalt tanksDye vatsEvaporators

BlendersSuction heatersUnit heatersDrying roomsGreenhouse coilsFin coils

Sugar dryersJacketed pansTilting kettlesBrew kettlesCandy kettlesCheese kettles

Submerged coilsWater heatersFuel oil pre-heatersPlating tanks

Paper dryersPulp dryersRotary dryersCalendars

Plywood pressesMoulding pressesTire mould pressesVulcanizing pressesMilk dryers

Dressing sterilizersPressure cookersAutoclavesDrum dryers

Ironing MachinesTurbines

Marine Applications

D–TD-B

B-T

G-1

G- I

G–I

G- I

D-T

G-T

I-DD-1D-B

3

IS 15680:2006

ANNEX A(Forewor~

COMMITTEE COMPOSITION

Boilers and Pressure Vessels Sectional Committee, ME 01

Organization

Central Boilers Board, New Delhi

Alstom Power Boilers Ltd, Durgapur/Delhi

Bharat Heavy Electrical Ltd, Tiruchirapalli

Bharat Heavy Plate& Vessels Ltd, Visakhapatnam

Bureau Veritas, Mumbai

Central Electricity Authority, New Delhi

Central Mechanical Engineering Research Institute (CSIR), Durgapur

Chief Inspector of Boilers, Chennai

Dcpanment of Atomic Energy, Mumbai

Development Consultants Pvt Ltd, Koikata

Directorate General of Factory Advisory Services & Labour Institute,

Mumbai

Engineers India Limited, New Delhi

Indian Boilers Manufacturers’ Association, hlumbat

brdian Gil Corporation Ltd, Vadodara

Indian Register of Shipping, Mumbai

Industrial Boilers Ltd, Mumbai

Larsen & Toubro Ltd, Mumbai

Moyd’s Register Asia, Mumbai

Mecon Limited, Ranchi

National Thermal Power Corporation Ltd, Noida

Oil Industries Safety Directorate, New Delhi

4

Representative(s)

SHRtV. K. GOEL (Chairman)StuuM. L. AHUJA (Alternate)

SHRI RAMESHT, YAVAGAL

SHW P. K, PAL (4/ferns/e)

SHRI G, UMA SHANKSR

SHJUK. PADMANABAN(Alfernale)

SHRtM. S. V. S. N. MURTHY

SHRI C. H. RAMANAIAH(Alrernate)

SHRIA, U, M, RAO

SHRI V, KUMAR (Aliernate)

SHRIA. K. GUPTA

SHRJD. K. GILHOTRA(Alternate)

SHJUP. R. SAMADDAR

SHRJP. K. SEN (Alternate)

SHRIT. K. THAMBITHURAI

SHRITHIRU K. REGUNATH(Alterna/e)

SFiRIH. S, KUSHWAHA

SHN K, K. VAZE (Alrernale)

SHRI.DIPAKK. SARKAR

SHRJASIM KUMAR DE (A/ferrrufe)

SHRI M. S, TYAGI

SHRI P. K. SAXE~A (A1/ernate)

-St+R1V, J, N.ALGIRKAR

SHRIA. K. MALIK (Alternate)

SHRIN. B. TAPASWI

SHRI U. S, PRASAD

SHRI R. K. SABHARWAL(A//e.rrrafe)

SHRIA. K. SHARMA

SHRI 1. MAJUMDAR(A//ernate)

SHRI R. N. ENGINEER

SHRI G. K. SADE~AR

SHRI S. S. IYER (Alternate)

SHRI B. SARASWAT

SHtu P. K. BANERJEE(A[ferna/e)

SHRI OM PRAKASH

SHRI B. K. VERMA (A//ernate)

SHRI D, K. JAIN

SHJUP. K, DEV (Alternate)

SttRtS, C, GUPTA

SHRI SHAMSHERSINGH (A//ernate)

IS 15680:2006

Organization

Petroleum and Explosive Safety Organization, Nagpur

Projects & Development India Ltd, Noida

Tata Iron and Steel Company Ltd, Jamshedpur

The Anup Engineering Ltd, Ahmedabad

The Indian Sugar and General Engg Co~oration, Yamuna Nagar

Therrnm Babxoxk & Wilcox Limited, Pune

Welding Research Institute, Tiruchirapall i

la personal capacity (Qua[iquest Industrial Services, 26 Manak &hayNe~v Delhi)

BIS Dirmtorate General

I{epresenlalive(s)

SHRI M. ANB~NATklAN

SHRIA. N. BISWAS(Alternate)

SHRIA. K, GUPTA

St+ruR. P. SmHA (Alternate)

DRM. D. MAHESHWARI

SHRIC. B. LUNAWAT(A/lerna/e)

SHKIG. N.V MOHANRAIU

SHRI R. D. CIRISTV (A//ernate)

SHRI SUNIL UPPAL

SHRI DHARMENDERSHARMA(A/ternafe)

SHRI S. A. VANCHINATH

SHRI TAMAL DUTTA (A/ferns/e)

StIRI G. UMA SHANKER

SHRI M. G. K. RAO

SHRI C. K. VEDA. Scientist ‘F’& Head (MED)

[Representing Director General (Ex-oflcio)]

Member Secreta~SHRIC, K. VEDA

“Scientist ‘F’ & tiead (MED), BIS

5

1

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This Indian Standard has been developed from Doc : No. ME 01 (0232).

Amendments Issued Since Publication

Amend No. Date of Issue Text Affected

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