Heat-treatment-training-manual-ppt.ppt

HEAT TREATMENT

TRAINING MANUAL MAY-2001

(REV.-0)

1

HEAT TREATMENT MANUAL This Manual is compiled by Mr K S Rao (QA), Mr S P Ghiya (Inspection ) and Mr N M Bodalia (M FS) Under the guidance of Mr P D Lohidakshan (Weld Engg & Prod Engg ) 2

INDEX TOPIC

PAGE NO.

1 . INTRODUCTION ON HEAT TREATMENT

4- 24

2 . FURNACE PARTS AND ATTACHMENTS

25- 37

3. STD. OPERATING PROCEDURES(HFS)

38- 47

4 . STD. OPERATING PROCEDURES(PFS)

48- 56

5 . STD. OPERATING PROCEDURES(MFS)

57-69

6 . STANDARD PRACTICES FOR LSR

70-74

7 . GOOD ENGINEERING PRACTICE

75-88

8 . CODE EXTRACT(REFERENCE ONLY) 89- 101 9 . ANNEXURES

102- 118 3

General • Only qualified supervisors and operators including LSR operators shall be authorised to operate furnace. • A list of qualified personnel shall be prepared by QA and published periodically. • Thjs manual is prepared on the basis of experience and feedback, taken from various personnel. • This manual is for reference only.

4

HEAT TREATMENT • • • •

WHAT IS HEAT TREATMENT ? WHY IS IT REQUIRED ? TYPES OF HEAT TREATMENT HEAT TREATMENT AT HZW

5

WHAT IS HEAT TREATMENT • MATERIALS TREATED BY APPLICATION OF HEAT NORMALLY DONE IN SOLID STATE • VARIOUS SOURCES OF HEAT • PARAMETERS ARE HEATING RATE,SOAKING TEMP,SOAKING TIME,COOLING RATE AND COOLING MEDIA 6

WHY IS IT REQUIRED ? • TO ENHANCE MATERIAL PROPERTIES / EASE IN FABRICATION BY CHANGING – Strength,Improve corrosion resistance – Toughness/Ductility – Hardness,Dimensional stability etc – Remove diffusible hydrogen to avoid hydrogen cracking • CARRIED OUT IN FABRICATION INDUSTRIES ,STEEL PLANTS, FOUNDRY, 7 FORGING SHOPS etc..

MATERIALS HEAT TREATED • METALS & ALLOYS – SINGLE PHASE – MULTIPHASE

• ALLOYS – Single Phase : Copper Nickel – Multiphase : Steels-LAS,QT

• METALS (Single phase ) – Titanium,Al,Ni,Cu etc.. 8

MATERIALS HEAT TREATED CRITERIA • COLD WORKED to NORMAL – All materials

• UNEQUILIBRIUM PHASES to EQUILIBRIUM:(Stabilise Microstructure & Phases) – Stainless Steels ,Maraging Steels

• STRESSED to UNSTRESED – All Materials

• CREATION OF UNEQUILIBRIUM CONDITIONS – Steels

9

MATERIALS HEAT TREATED MATERIALS CATEGORY • • • •

C-Mn , C-Mo , Cr-Mo , Ni -Steels, QT Stainless Steels-Austanitic.Martensitic Steels enhanced by Heat Treatments Non Ferrous Materials; Titanium alloys, Aluminum alloys

10

TYPES OF HEAT TREATMENT • • • • • • •

NORMALIZING ANNEALING STRESS RELIEVING SOLUTION ANNEALING-Mainly SS HARDENING TEMPERING AGING 11

IRON CARBON DIAGRAM

12

Iron Carbon Diagram Portion related to Heat Treatment

13

NORMALIZING • The steel is heated to 40° C above the upper critical temperature(910 ºc) followed by cooling in the still air. Normalizing is done to achieve the following : • To get Uniform structure and reduce chemical gradients • To change Mechanical properties, – UTS,YS – Hardness – Impact properties

• To refine the grains

14

ANNEALING • In this process, the steel is heated from 10 to 50°C above the upper critical temperature(910ºc) and held for the desired length of time; followed by very slow cooling in the furnace Annealing is done to achieve following :

• to soften the steel and improve ductility • to relieve internal stresses caused by previous treatment 15

SOLUTION ANNEALING In Stainless steels , it is heated to 1050°C or above ,and held for the desired time; followed by quenching/blowing the air(cooling to room temperature within few minutes). Solution annealing is done on stainless steel and non ferrous alloys to achieve following: • To soften the material • To dissolve carbide precipitation formed at grain boundaries during manufacturing process 16 • To improve Corrosion Resistance

AGING The Material is heated to a certain temperature, and held for the desired time; followed by normally for precipitation hardened alloys or cooling in air Aging is done on materials susceptible for aging characteristics : Maraging Steels • Normally increase in strength • To Improve Toughness/Ductile-brittle transition temp. 17

AGING Maraging Steels M250

• Temperature : 485 C • Normally 3 Hrs 15 mts • Heating Rate : 200 C per hr per inch • Cooling Rate : Cool in Air / Quench in water 18

STRESS RELIEVING The steel is heated to a temperature below or close to the lower critical point, followed by desired rate of cooling and there is no change in grain structure. Stress relieving is done to achieve following : • To reduce Internal Stresses (residual Stresses)

• To soften the steel partially • To improve ductile-brrittle transition temp. and

equalize impact values

19

STRESS RELIEVING C-Mn , C-Mo , Cr-Mo (< 2% Cr) • C - Mn Steels , C - Mo Steels,Cr-Mo Steels – SA 515Gr 70 , SA204GrA, SA387GR11CL1

• Temperature : 593 C Min – Normally 600 - 640 C,650-690 C

• Time : 15 minutes min – Time : 1 hr / inch

• Heating Rate : 200 C per hr per inch • Cooling Rate : 260 C per hr per inch

20

STRESS RELIEVING Cr-Mo Steels Cr - Mo Steels (Cr >2%) – SA 335P22 ,SA335P5

• Temperature : 676 C Min – Normally 680 - 700 C 2.25Cr – 704 - 720 C 5 Cr

• Time : 15 mts min – Time : 1 hr / inch

• Heating Rate : 200 C per hr per inch • Cooling Rate : 260 C per hr per inch

21

STRESS RELIEVING Ni -Steels • Nickel Steels : 1,2,3% Ni – SA 203 GrA ,D

• Temperature : 593 C Min – Normally 600 - 640 C,650-690 C

• Time : 60 mts min – Time : 1 hr / inch

• Heating Rate : 200 C per hr per inch • Cooling Rate : 260 C per hr per inch 22

STRESS RELIEVING Steels enhanced by Heat Treatments • Q&T Steels : – 9.5% Ni Steels , SA 517 Gr E

• Temperature : 538 C Typ – Normally < 600 C

• Time : Minimum 15 minutes to 2 Hr – Time : 1 hr / inch

• Heating Rate : 200 C per hr per inch • Cooling Rate : 260 C per hr per inch

23

FURNACE PARTS AND THEIR ATTACHMENTS

24

LAYOUT OF A TYPICAL FURNACE (Electrical or Gas fired ) FURNACE THERMOCOUPLE COMPENSATING CABLE

JOB

RECORDER

CONTROLLING BURNER

P.I.D.

25

THERMOCOUPLES • PRINCIPLE OF A THERMOCOUPLE

• THERMOCOUPLE MATERIALS • TYPES OF THERMOCOUPLES BEING USED IN HZW 26

PRINCIPLE OF THERMOCOUPLE The basic principle of thermoelectric thermometry is that a thermocouple develops an emf which is a function of the difference in temperature of its measuring junction & reference junction. If the temperature of reference junction is known, the temperature of the measuring junction can be determined by measuring the emf generated in the circuit. 27

THERMOCOUPLE MATERIAL REQUIREMENT 1. High coefficient of thermal emf. 2. Continuously increasing relation of emf to temperature over a long range.

3. Freedom from phase changes or other phenomenon giving rise to discontinuity in temperature emf relationships. 4. Resistance to oxidation, corrosion and contamination.

5. Homogeneity and reproducibility to fit an establish temperature & emf relationship. SPEED OF RESPONSE MAY BE IMPROVED AND RADIATION & CONDUCTION ERRORS MAY BE REDUCED 28 BY THE USE OF SMALL DIAMETER THERMOCOUPLES.

TYPES OF THERMOCOUPLE BEING USED IN HZW K type : Material Nickel based Properties :

:

Chromel ( 10 %Cr )

+

Alumel

+ ( 2 % Al )

Non-Magnetic +

Magnetic

In this type of thermocouple, the wires are joined at one end only to form a point-type temperature sensor. Instrumentation converts the millivolt signal to related temperature. 29

TYPES OF THERMOCOUPLE BEING USED IN HZW contd... K type :

Dia : Insulation coated

2.5 mm Bare(ceramic)

0. 7 mm Refractory

Attachment

Mech

Capacitor

Usability

Reusable

Disposable

Location

PIT F/c

except PIT F/c

Color

-

30

Red & Yellow

CONSTRUCTION OF A K TYPE THERMOCOUPLE White Color

White/yellow

+Ve

pid

-Ve Blue Color

Red Color

White/yellow

White Color

Welded junction

recorder

-Ve Compensating cable

Accuracy : 0.75%

Red Color

+Ve

Thermocouple wire

31

‘S’ TYPE THERMOCOUPLE Accuracy : 0.25 % •

‘S’ TYPE THERMOCOUPLE ARE THE STANDARD THERMOCOUPLES.

•

IT IS USED FOR CALIBRATING “K” Type THERMOCOUPLES.

•

MATERIAL OF CONSTRUCTION 90% PLATINUM + 10% RHODIUM PLATINUM

•

OXIDATION RESISTANCE , SO MORE LIFE . 32

ISSUE METHODOLOGY For DISPOSAL TYPE • Users will send their requirement of thermocouple

through Consumable slip ( mentioning HTR No ) to QA

• QA shall issue the same . • QA shall issue identification sticker duly attached

• Users shall ensure availability of identification sticker on unused wire . • See Annexure-12 for further details 33

COMPENSATING CABLE COMPENSATING CABLE IS DEFINED AS A PAIR OF WIRES HAVING SUCH EMF TEMPERATURE CHARACTERISTICS RELATED TO THE THERMOCOUPLE WITH WHICH THE WIRES ARE INTENDED TO BE USED, THAT WHEN PROPERLY CONNECTED TO THERMOCOUPLE THE EFFECTIVE REFERENCE JUNCTION IS IN EFFECT TRANSFERRED TO THE OTHER END OF THE WIRES.

MATERIAL ==> +ve COPPER ( white ) -ve COPPER NICKEL (blue ) for “ K “ TYPE .

See Annexure-9 (Annexure Page 1-4) for further details 34

P.I.D. PID = PROPORTIONAL INTEGRAL DERIVATIVE

• • • •

•

PID FUNCTIONS BOTH AS PROGRAMMER AND CONTROLLER PID CONTROLLER CAN BE ZONE WISE PROGRAMME IS MADE IN SEGMENTS AS PER DIFFERENT STAGES OF HEAT TREATMENT DIGITAL DISPLAY IS AVAILABLE FOR PROGRAMME TEMPERATURE AND FURNACE TEMEPERATURE TYPICAL OR REPETITIVE HEAT TREATMENT CYCLE CAN BE STORED IN PID(PROGRAMMER)

35

RECORDER TYPES OF RECORDER PAPERLESS --

WITH COLOUR DISPLAY SCREEN ,HARD DISC AND FLOPPY DRIVE. NOT USED IN HZW.

•WITH PAPER -- CURRENTLY BEING USED IN HZW. •24 CHANNEL -- CURRENTLY BEING USED IN PFS( CHINO MAKE-- model no.I003 /Graph ET 001).

•12 CHANNEL -- CURRENTLY BEING USED IN MFS1 AND HFS1 ( CHINO MAKE -- model no. EH100 / Graph ET 201). COMPENSATING CABLES ARE CONNECTED BEHIND THE RECORDER SCREEN IN CHANNELS. •X-AXIS IS FOR TEMPERATURE (RANGE = 0 TO 1200’C) •THE SCALE ON X-AXIS IS NON-LINEAR.

•Y-AXIS IS FOR GRAPH SPEED. •VARIOUS SPEED OF GRAPHS ARE 12.5, 25, 50, 100 MM / HOUR •WE GENERALLY KEEP 25 MM / HOUR.

36

GRAPH PAPER • GRAPH PAPERS ARE USED FOR PLOTTING THE FURNACE TEMPERATURE VIA THERMOCOUPLE. THEY ARE FITTED ON THE RECORDER. • GRAPH PAPER RECOMMENDED ON RECORDER ONLY TO BE USED • GRAPH PAPER FOR MFS1 AND HFS1 FURNACE ==> ET 201 CHINO MAKE, JAPAN GRAPH PAPER FOR PFS FURNACE ==> ET 001 CHINO MAKE, JAPAN • THE LENGTH OF ONE BUNDLE OF GRAPH PAPER IS GENERALLY 2000 MM. • DOTTING TYPE RECORDER INK (CHINO MAKE, JAPAN) IS USED IN RECORDER FOR PLOTTING OF GRAPH. USUALLY , 6 COLOURS ARE FILLED FOR PLOTTING. 37 • SEE ANNEXURE-10 FOR FURTHER DETAILS

STANDARD OPERATING PROCEDURE FOR HFS-1 FURNACE

38

( ZONE-2 )

1640

( ZONE-4 )

( ZONE-6 )

( ZONE-8 )

BURNER

1650

7900 (BOGIE WIDTH )

1650 3575 ( ZONE-1 )

3575 ( ZONE-3 )

14300.

3575 ( ZONE-5 )

3575 ( ZONE-7 )

HFS-I FURNACE SKETCH

39

9000

1. PROJECT NO:

2. SECTION NO : 9500

3. CHARGE NO : 4. H. T. REQ. NO :

BURNER 1195

7900 BOGGIE WIDTH

1050

8700

HFS-I FURNACE SKETCH

40

STANDARD OPERATING PROCEDURE FOR HFS-1 FURNACE 1.

Receive the job as per HT request.

2.

Receive heat treatment request duly approved by metallurgy engineer.

3.

Ensure that Insp. Clearance is available prior

to loading for job. 4.

Load the supporting arrangement as per the attached annexure -3

5.

Ensure the spider arrangement as per attached annexure - 5

6.

Fix the thermocouples at locations shown in furnace charge.

7.

Check the entire job as per check list (annex.-I). 41

STANDARD OPERATING PROCEDURE FOR HFS-1 FURNACE 9.

Move the bogie inside the furnace

10.

Pass the thermocouples through ports and connect it with compensating cables

11.

Set the program as per heat treatment request. Secure it and then run it in fast mode as check. Bring it back to the initial segment and hold.

12.

Insert heat treatment chart in recorder and adjust the speed of the graph.

13.

Clear inspection of job and get the signature of inspector on graph paper for firing the furnace.

14.

Check LPG level, pressure and temperature in the 42 storage tanks and note down in logbook.

STANDARD OPERATING PROCEDURE FOR HFS-1 FURNACE 15.

Switch on the power supply

16.

Close the bogie door

17.

Follow the procedure for startup of furnace in zone-I

18.

Start the blower from the field push button station provided

19.

Give power supply to the ignition panel

20

When the “system healthy” contact comes from the instrument panel, the lamp for the “system healthy”

signal is on. This indicates that the combustion air pressure and gas pressure are within the specified limits 21.

Now the firing on the cycle can start.

43

STANDARD OPERATING PROCEDURE FOR HFS-1 FURNACE 22.

Open the pilot and main gas valves

23.

Press start cycle button on doing so the cycle starts

and purging start indicator lamp is on. 24.

After 3 minutes ( time adjusted through timer ) the purging is completed and ignition start lamp is ON

At the same time the purging start lamp gets OFF. 25.

After 10 seconds the ignition start lamp gets OFF By this time the pilot burner should have been fired and the pilot flame is established.

26.

Flame healthy signal LED gets on which is provided on the flame sensor relay. This can be viewed through the glass window provided in the ignition panel. 44

STANDARD OPERATING PROCEDURE FOR HFS-1 FURNACE 27.

Due to certain length of pipe between the burner and solenoid valves, which may contain air, the burner may not light up in the first attempt. In that case, repeat the above mentioned procedure.

28.

Once the main flame is established, the control is passed on to the temperature controller.

29.

For startup of furnace in other zones, follow the same steps no 16 to 27 mentioned above.

30.

After all zones are started, start recording time and temperature from recorder every 30 minutes in the logbook.

31.

Conduct spot checks for heat treatment every 4hours 45 and fill the spot check format.

STANDARD OPERATING PROCEDURE FOR HFS-1 FURNACE 32.

Monitor the heat treatment process and graph till

the completion to ensure that it is as per program and heat treatment request. 33.

After heat treatment cycle is completed, shut off

all LPG supply valves and let furnace run with blowers on for 15 minutes. 34.

Open the bogie door. Disconnect thermocouples

from compensating cable. 35.

Submit the graph and duly filled spot check formats to inspection for approval of heat treatment. 46

STANDARD OPERATING PROCEDURE FOR HFS-1 FURNACE 36.

Retrieve the thermocouples from the ports and the bogie out of the furnace.

37.

Allow the job to reach room temperature.

38.

Remove the thermocouples from the job carefully without damaging the junction of thermocouples and

without making impression on parent material of job. 39.

Unload the job from the bogie and move the bogie inside the furnace.

40.

Close the furnace. Shut off the main power supply. 47

STANDARD OPERATING PROCEDURE FOR PFS FURNACE

48

125T Bogie hearth furnace -- PFS

49

PFS FURNACE SKETCH 5600

5500

2650

BURMER

BOGGIE WIDTH

1460

1050

1235

4100

50

STANDARD OPERATING PROCEDURE FOR PFS FURNACE 1.

Receive the job as per HT request.

2.

Receive heat treatment request duly approved by metallurgy engineer.

3.

Ensure that Insp. clearance is available prior to loading for job.

4.

Load the job on the bogie as per the heat treatment furnace request.

5.

Ensure the supporting arrangement as per the attached annexure-I.

6.

Ensure the spider arrangement as per annexure- II.

7.

Fix the thermocouples at locations shown in furnace charge. 51

STANDARD OPERATING PROCEDURE FOR PFS FURNACE 8.

Check the entire job as per check list attached as annexure-III

9.

Move the bogie inside the furnace.

10.

Pass the thermocouples through ports and connect it with compensating cables.

11.

Insert heat treatment chart in recorder and adjust the speed of the graph.

12.

Clear inspection of job and get the signature of inspector on graph paper for firing the furnace.

13.

Check LPG level, pressure and temperature in 52 the storage tanks and note down in logbook.

STANDARD OPERATING PROCEDURE FOR PFS FURNACE 14.

Switch on the power supply.

15.

Close the bogie door.

16.

Switch on ID blower first and then the air blower and maintain pressure at about 800mm WG by slowly opening the suction valve.

17.

Ensure that pressure of LPG from yard to inlet of pressure regulator is always less than 20psi (1.5kg/CM2).

18.

Open the inlet valve to the regulator and open the outlet valve.

19.

If pressure exceeds 1600 mm WG , isolate the pressure by lifting the handle of safety shut off 53 valve.

STANDARD OPERATING PROCEDURE FOR PFS FURNACE 20.

Immediately start lighting the pilot burners and adjust the flame with the air valve .

21.

Open the isolating valve for pressure gauge and adjust the pressure regulator by turning the screw provided in the stem so that the pressure is maintained at about 1000mm WG.

22.

Light up alternate main burners and adjust the flame lengths uniformly.

23.

Lock the doors by pneumatic locking.

24.

After all zones start, record time and temperature from recorder every 30 minutes in the logbook. 54

STANDARD OPERATING PROCEDURE FOR PFS FURNACE 25.

Conduct spot checks for heat treatment every 4 hours and fill the spot check format. Monitor the heat treatment process and graph per heat treatment request.

26.

After the heat treatment cycle is completed, shut off all LPG valves and let furnace run with blowers on for 15 minutes.

27.

Open the bogie door. Disconnect thermocouples from compensating cables.

28.

Submit the graph and duly filled spot check formats to inspection for approval of heat treatment.

55

STANDARD OPERATING PROCEDURE FOR PFS FURNACE 29.

Retrieve the thermocouples from the ports and move the bogie out of the furnace.

30.

Allow the job to reach room temperature.

31.

Remove the thermocouples from job carefully and without marking impression on parent material of

job. 32.

Unload the job from bogie and move the bogie inside the furnace.

33.

Close the furnace. Shut off the power supply.

56

STANDARD OPERATING PROCEDURE FOR PIT FURNACE IN MFS-I

57

FIRE BRICK

CERMIC BLANKET OUTER SHELL

GROUND LEVEL CERMIC FIBER SLABER BLOCK

HEATING ELEMENT BAFFLE

INSULATING CASTABLE ROOF CERAMIC BLANKET

3700 1/D OF BAFFLE

4150 ( REFRACTORY I/S )

BLOWER

4020

125

250

TROLLEY STRUCTURE 1380

PIT FURNACE SKETCH

4961

1000

58

STANDARD OPERATING PROCEDURE FOR PIT FURNACE 1.

Receive heat treatment request duly authorized by metallurgy engineer.

2.

Receive the job for heat treatment with inspection clearance.

3.

Put the job either on support or on heat treatment fixture inside the furnace.

4.

Ensure that equal clearance is available on all sides between job and baffle.

5.

Ensure that the furnace is calibrated.

6.

Connect thermocouples with compensating cable to PID.

59

STANDARD OPERATING PROCEDURE FOR PIT FURNACE 7.

Set the program in the programmer as per heat treatment request.

8.

Take a trial run of program to ensure the accuracy.

9.

Calibrate all 5 PID’s prior to starting the furnace.

10.

Insert the graph inside the recorder and take the signature of inspector on the graph paper.

11.

Close the furnace door.

12.

Start the furnace by giving power supply ‘ON’

60

STANDARD OPERATING PROCEDURE FOR PIT FURNACE 13.

Start recording the time and temperature in the logbook every 30 minutes.

14.

Ensure that the cycle is functioning as per program.

15.

After the heat treatment is over, open the furnace cover.

16.

If the job calls for water quenching, lift the job and dip it in quench tank.

17.

It the job calls for air cooling in still air, lift the job and put it outside on supports in open air. 61

STANDARD OPERATING PROCEDURE FOR PIT FURNACE 18.

It the job doesn’t call for anything above, allow the job to cool down in furnace.

19.

Keep the job outside after removing from furnace.

20.

Submit the heat treatment graph to inspection for approval of heat treatment cycle.

21.

Close the furnace cover after the furnace is cooled down to room temperature. 62

PROCEDURE FOR EMPTY FURNACE CALIBRATION Calibration of PIDS ( indicator & controller ) 1.

Connect the millivolt source to the temperature indicator or controller by a compensating cable. Care should be taken to clean the wires and terminals thoroughly before connections are made.

2.

The millivolt output for various temperature ranging from 00C to 10000C in steps of 500C is fed to the indicator / controller.

3.

After the millivolt value / temperature reading displayed is steady, the reading of indicator/controller shall be noted.

63

PROCEDURE FOR EMPTY FURNACE CALIBRATION 4.

If the error in the indicated readings is more than the specified accuracy ( +/- 10C ), then correction to be carried out for the indicator / controller and points 1 to 4 shall be repeated till the specified accuracy is obtained is obtained.

Calibration of recorder 1.

Connect the millivolt source to the recorder by a compensating cable. Care should be taken to clean the wires and terminals thoroughly before the connections are made. 64

PROCEDURE FOR EMPTY FURNACE CALIBRATION 2.

The millivolt output for various temperature ranging from 400 C to 10000C is fed to the recorder and is allowed to plot on a graph.

3.

The graph thus obtained is reviewed for time and temperature values. These values should meet the accuracy requirements.

4.

If there is error in the values plotted on the graph, then correction to be carried out for the recorder and points 1 to 4 shall be repeated till the specified accuracy is obtained.

65

PROCEDURE FOR EMPTY FURNACE CALIBRATION EQUIPMENT REQUIRED

ACCURACY

1.

20 Nos. big K-type thermocouples

+/- 0.25%

2.

10 Nos. small K-type thermocouples

+/- 0.25%

3.

Millivolt source (wahl unit )

( 1 micro volt at 1000 micro volts ) 4.

Heat treatment fixture.

5.

Temperature indicators (PID)

6.

Recorder

+/- 10C

+/- on temperature scale. +/- minutes on time scale. 66

PIT FURNACE CALIBRATION PROCEDURE 1.

Ensure that the PIDs are calibrated as mentioned above.

2.

Ensure that the recorder is calibrated as mentioned above.

3.

Ensure that all the thermocouples used are calibrated.

4.

Ensure that the thermocouples are attached to the heat treatment fixture as shown in sketch-I.

5.

Place the heat treatment fixture inside the furnace with thermocouples in position.

6.

Close the furnace lid. Start the furnace and the recorder. 67

PIT FURNACE CALIBRATION PROCEDURE 0

7.

Set the temperature of controller to 400 C.

8.

After reaching the set temperature, it is allowed to stabilize for half an hour.

9.

Measure and record the temperature indicated by each of the 20 thermocouples. The temperature is to be read through WAHL UNIT.

10.

Three sets of readings are to be taken for each thermocouples at an interval of 10 minutes.

11.

Also record the readings indicated by each of the thermocouples at an interval of 10 minutes. 68

PIT FURNACE CALIBRATION PROCEDURE 12.

The temperature is then raised in steps of 50 C up to

10000C. ( I. e. 4000C, 4500C, …….., 9500C, 10000C. ) The measured temperature is stabilized for 30 minutes. PID reading are also to be recorded along with this.

13.

The allowed temperature variation with respect to the set temperature is +/- 50C up to 8000C and +/- 100C above 8000C.

14.

This is allowed to plot on the graph and thus obtained for time and temperature values.

15.

Calibration of furnace is valid for 1 year.

69

STANDARD OPERATING PRACTICES FOR LOCAL STRESS RELIEVING

70

LOCAL STRESS RELIEVING WHY • •

Local SR to be done only when furnace SR not feasible When only certain components to be PWHT

HOW •

Can be done by Electrical / Gas / diesel / Induction etc..

•

DETAILS ON ENSURING PWHT TEMP. IN WELDMENT AREA

•

Soaking band(SB) = Widest weld width ‘x’+ ’t’ or 2 inches whichever is less from edge of weld Heating band width (HB) • Induction stress level • Through thickness criteria • SB + 4 rt where r = Inside radius, t = thickness Insulation band width (IB) • Axial gradient 71 • HB + 4 rt

•

•

LSR -BAND WIDTH Soak band X

Weld width ‘X’ + lesser of 1T or 2”

t Heating band Insulation band

72

LOCAL STRESS RELIEVING SET UP 1. Provide multitonne roller on one end of vessel during LSR ofcircular seam when job is horizontal. 2. If both ends are open during LSR, provide insulation from inside. If not possible , prevent airflow so that temperature on inside surface do not drop down. 3. Spider/prop shall be provided in such a way that upper portion of spider / prop is not welded with inside surface to allow contraction/expansion of shell surface. 4. Spider/prop shall be between 200- 500mm from heating zone. 5. Temporary attachments, provided for holding insulation, shall be within soak band only. 6. Minimum two thermocouples shall be provided from inside, when accessible. 73

LOCAL STRESS RELIEVING SB+HB+IB

LSR of C/S

Spider or prop

No Welding at top Multitonne roller

200 to 500mm from heating band

74

GOOD ENGG. PRACTICES FOR FURNACE CHARGES &LSR

75

SUPPORTING ARRANGEMENTS 1.

Heat Treatment request shall be as per Annexure-7

and Annexure-8. 2.

Minimum distance between floor of the furnace and lower most part of the job shall be 300mm.

3.

The distance between burner flame and saddle support as well as furnace wall and job shall be 600mm.

4.

Minimum 90 degree saddle to be used, however 120 degree saddle is desirable.

76

SUPPORTING ARRANGEMENTS

600mm

burner

450mm

900 600mm

300mm(point no:2)

5. Saddle shall be arranged in such away that open end of the vessel is maximum 450mm from saddle support. 6. Saddle shall be located as close to spiders (temporarily arranged to control deformation) as possible. 77

SUPPORTING ARRANGEMENTS 7. Spiders shall be provided as per annexure-5 8

Saddle supports shall be selected as per annexure.-3

9. Spiders or vertical prop shall be provided at open ends, center and below man way/nozzles above 24” 10. Avoid gap between saddle support and job surface

78

SUPPORTING ARRANGEMENTS

Zero gap Supporting arrangement

11. Locking/clamping of job, restricting the movement (axial/lateral) during heat treatment shall be avoided. 12. All long nozzles projecting outside job surface shall be supported.

79

SUPPORTING ARRANGEMENTS 13. Checklist shall be prepared and attached with HT request before furnace is fired as per Ann-1 14. Spot check report shall be filled by supervisor as per Annexure-2 during job is being heat treated. 15. Moonplate support and welding inside surface prior to release for Heat treatment as per Annexure-4 16. General idea about thermocouple locations and its attachments is as per Annexure-6 80

GENERAL

1. Blocking the flame of the burner is not desirable 2. Burner shall have blue flame and not yellow 3. Flame shall not directly impinge on job 4. All burners shall be fired at a time 5. Keep all job nozzles open during heat treatment

6. Above “24” nozzles / manways shall be located towards bottom 81

GENERAL

Gasket machined surface

Temp. support Furnace floor

7. Deoxidization agent shall be applied on all machined and gasket faces 8. Gasket / machined face of loose assemblies shall not be touching any object. 82

THERMOCOUPLES 1. All the thermocouples shall be tagged with aluminum sheet and identification hard punched on it. (For PIT furnace only)

2. Minimum two thermocouples to be attached for any charge.

83

THERMOCOUPLES 3. Minimum 8 thermocouples to be used for a charge in HFS- I furnace if the job occupies all 8 zones 4. Maximum distance between two thermocouples for a sample job is as shown in annexure- 6 5. PTC shall have separate thermocouple

84

THERMOCOUPLES ATTACHMENTS 1. Use only TAU-90 capacitor Discharge Welding machine for thermocouple connection

2. Use WPS:999-154 R0 for attachment of thermocouple for cs/alloy steel material 3.

Only trained person by welding engineering shall attach thermocouple

4. A list of qualified person shall be by Welding Eng. 85

THERMOCOUPLES ATTACHMENTS 5.

Clean surface prior to attachment.

6.

Two wire of thermocouple shall be attached one after another. Gap between two wire of a thermocouple shall be max. 3.0mm Only calibrated thermocouple shall be used.

7.

8.

Calibration shall be by QA. 9.

After PWHT, thermocouple area shall be ground

and DP shall be carried out. 10. For further details see Annexure-11 & 13-(page 1&2) 86

THERMOCOUPLES ATTACHMENT UNIT

87

SPECIAL NOTE IF THE TEMPERATURE OF HEAT TREATMENT EXCEEEDS

650-DEGREE

CENTIGRADE,

THE

MATERIAL AND SIZE OF SPIDERS AND SUPPORTS TO BE DECIDED BY PLANNING AND APPROVED BY

DESIGN.

88

CODE EXTRACTS •FURNACE PWHT •LSR

89

REQUIREMENT OF HEAT TREATMENT AS PER ASME-SEC VIII Div.-1 • SERVICE CONDITION

(UW-2)

• MATERIAL

(UG-85, UW-40,UCS-56,UAT-80,UHA-32,UNF-79)

• THICKNESS

(UG-85, UW-40,UCS-56,UAT-80,UHA-32,UNF-79)

• LOW TEMERATURE OPERATION • COLD WORKING

(UCS-68) (UG-79)

• CUSTOMER SPEC.

90

CODE EXTRACT FOR HEAT TREATMENT ( 1 ) The soak band shall contain the weld, heat affected zone and a portion of base metal adjacent to the weld being heat treated. The minimum width of this volume is the widest width of weld plus 1T or 2 inches, whichever is less, on each side or end of the weld. The term ‘T’ is the nominal thickness. ( 2 ) The operation of postweld heat treatment shall be performed either by heating the vessel as a whole in an enclosed furnace or heating the vessel in more than one heat in a furnace, provided the overlap of the heated sections of the vessel is at least 5 feet ( 1.5m). When this procedure is used, the portion outside of the furnace shall be shielded so that the temperature gradient is not harmful. The cross section where the vessel projects from the furnace shall not intersect a nozzle or other 91 structural discontinuity.

CODE EXTRACT FOR HEAT TREATMENT ( 3 ) When the vessel is required to be postweld heat treated, and it is not practicable to postweld heat treat the completed vessel as a whole or in two or more heats; any circumferential joints not provisionally heat treated may be thereafter locally postweld heat treated by heating such joints by any appropriate means that will assure the required uniformity. ( 4 ) While carrying out local postweld heat treatment, the soak band shall extend around the full circumference. The portion outside the soak band shall be protected so that the temperature gradient is not harmful. ( 5 ) Heating a circumferential band containing nozzles or other welded attachments in such a manner that the entire band shall be brought up uniformly to the required 92 temperature and held for the specified time.

CODE EXTRACT FOR HEAT TREATMENT ( 6 ) Where more than one pressure vessel or more pressure vessel part are postweld heat treated in one furnace charge, thermocouples shall be placed on vessels at the bottom, center, and top of the charge or in other zones of possible temperature variation so that the temperature indicated shall be true temperature for all vessels or parts in those zones. ( 7 ) Postweld heat treatment, When required, shall be done before the hydrostatic test and after any welded repairs. A preliminary hydrostatic test to reveal leaks prior to PWHT is permissible. ( 8 ) For pressure vessels or parts of pressure vessels being post weld heat treated in a furnace charge, it is the greatest weld thickness in any vessel or vessel part which has not previously been postweld heat treated. 93

CODE EXTRACT FOR HEAT TREATMENT ( 8 contd...) The nominal thickness is the total depth of the weld exclusive of any permitted weld reinforcement.  For groove weld, the nominal thickness is the depth of the groove.  For fillet welds, the nominal thickness is the throat dimension.  If a fillet weld is used in conjunction of groove weld, the nominal thickness is the depth of the groove or the throat dimension, Whichever is greater.  For stud welds, the nominal thickness shall be the diameter of the stud. ( 9 ) For P–1 material ( carbon steel), minimum holding temperature during postweld heat treatment shall 94 be 1100 Deg. F ( 593 Deg.c).

CODE EXTRACT FOR HEAT TREATMENT P. NO.

HOLDING TEMP.

1 ( CARBON STEEL) & 3 (LOW ALLOY STEEL)

1100 DEG. F(593’ C)

NOM. THICKNE SS UPTO 2”

SOAKING PERIOD

OVER 2” TO 5”

2 HOURS , PLUS 15 MIN. FOR EACH ADDITIONAL INCH ABOVE 2” 2 HOURS , PLUS 15 MIN. FOR EACH ADDITIONAL INCH ABOVE 2”

OVER 5 ”

1 HR. PER INCH. , HOWEVER 15 MINUTES MINIMUM

* POST WELD HEAT TREATMENT IS MANDATORY ON P-NO.3 GR. NO. 3 MATERIAL IN ALL THICKNESSES.

95

CODE EXTRACT FOR HEAT TREATMENT ( 10 ) Postweld heat treatment is mandatory in Following conditions : • For welded joints over 1. 5” nominal thickness. • For welded joints over 1.25” nom. Thickness through 1.5” nom. Thickness, unless preheat is applied at a min. Temperature of 200’F ( 94‘c ) during welding. • Vessels or parts of vessels constructed of base material with corrosion resistant integral or weld metal overlay cladding or applied corrosion resistant lining material shall be postweld heat treated when the base material is required to be postweld heat treated. In applying this rule, the determining thickness shall be the total thickness of base material. 96 • When the PWHT is a service requirement.

CODE EXTRACT FOR HEAT TREATMENT

SERVICE CONDITION • LETHAL SERVICE PWHT IS MANDATORY

• EXEMPTIONS ARE FEW

97

CODE EXTRACT FOR HEAT TREATMENT ( 11 ) Postweld heat treatment is not mandatory for carbon steel jobs (P1 material ) in Following conditions (UG2):  If groove welds is not over ½” in size or fillet weld with a throat thickness of ½” or less used for attaching non pressure parts to pressure parts provided preheat to a minimum temperature of 200’F is applied when the thickness of pressure Part exceeds 1.25”.  If studs are welded to pressure parts provided preheat to a minimum temperature of 200’F is applied when the thickness of the pressure parts exceeds 1.25”.  for corrosion resistant weld metal overlay cladding or for welds attaching corrosion resistant applied lining provided preheat to a minimum temperature of 200’f is maintained during application of the first layer when the thickness of the pressure 98 part exceeds 1.25”.

CODE EXTRACT FOR HEAT TREATMENT •

The temperature of furnace shall not exceed 800’F

( 4270C) at the time when the vessel or part is placed in it.

•

Above 8000F( 4270C), the rate of heating shall not be more

than 4000F Per hour (2000C/Hour) divided by the maximum metal thickness of the shell or head plate in inches, but in no

case more than 4000F Per hour( 2220C Per hour ). • During the heating period, There shall not be a greater variation in temperature throughout the portion of the vessel

being heat treated than 2500F( 1390C) within any 15 feet ( 4.6m) interval of length.

99

CODE EXTRACT FOR HEAT TREATMENT •

During the holding period, there shall not be a

greater difference than 1500f ( 830c) between the highest and the lowest temperature the portion of the vessel being heated

• During

the

heating

&

holding

periods,

the

furnace

atmosphere shall be so controlled as to avoid excessive oxidation of the surface of the vessel. The furnace shall be of such design as to prevent direct heat impingement of the flame on the vessel. •

0

0

Above 800 F ( 427 C), The rate of cooling shall not be

more than 5000F Per hour (2780C/Hour) divided by the

maximum metal thickness of the shell or head plate in inches, 0

0

but in no case more than 500 F Per hour ( 278 C Per hour). 100

CODE EXTRACT FOR HEAT TREATMENT when it is impractical to postweld heat treat at the temperature specified in table mentioned in Sr.. No. 9, It is permissible to carry out the post weld heat treatments at lower temperatures for longer periods of time as shown in table below : DECREASE IN TEMP. BELOW MIN. SPECIFIED TEMPERATURE IN ‘F 50 (10’C)

MINIMUM HOLDING TIME AT DECREASED TEMPERATURE (NOTE 1) 2 HOURS

NOTES

100(38’C)

4 HOURS

----

150(68’C)

10 HOURS

2

200(94’C)

20 HOURS

2

----

NOTES : 1. MINIMUM HOLDING TIME FOR 1” THICKNESS OR LESS ; ADD 15 MINUTES PER INCH OF THICKNESS FOR THICKNESS GREATER THAN 1”. 2. THESE LOWER POSTWELD HEAT TREATMENT TEMPERATURES PERMITTED ONLY FOR PNO.1 GROUP NO. 1 AND 2 MATERIALS. 101

102

103

104

105

SELECTION OF SPIDERS AT OPEN ENDS FOR HEAT TREATMENT 100

90

80

70

60

50

40

30

20

10000

10

SHELL THICKNESS

Annexure-5

9500 9000 8500 8000 7500 7000 ISMB 250 ISMB 250 BOX SEC

ISMB 250

6000 5500 5000 4500 4000 3500

ISMB 150

3000 2500 2000 ISMB 125

ISMB 150

1500 1000

100

90

80

70

60

ISMB 150

50

40

30

ISMB 125

20

500

10

SHELL DIAMETER

6500

SHELL THICKNESS DATA FOR ABOVE CHANNELS: DESIGNATION WT/ MTR.(KG) WEB HT FLG WD FLG THK WEB THK ISMB 125 13 125 75 7.6 4.4 ISMB 150 14.9 150 80 7.6 4.8 ISMB 250 37.3 250 125 12.5 6.9 ISMC 250 30.4 250 80 14.1 7.1

106

107

HT REQUEST

Annexure-7

108

HT CHARGE

Annexure-8

109

Usage of compansating cable

Annexure-9 page 1 of 4

110

Usage of compansating cable

Annexure-9 page 2 of 4

111

Usage of compansating cable

Annexure-9 page 3 of 4

112

Usage of compansating cable

Annexure-9 page 4 of 4

113

Information on Graph Paper Usage

Annexure-10

114

Mechanical v/s capacitor discharge attachments Annexure-11

115

Thermo. Couple Procurement Procedure

Annexure-12

116

Thermo. Couple Attachment Procedure

Annexure-13 page 1 of 2

117

Thermo. Couple Attachment Procedure

Annexure-13 page 2 of 2

118