heat treatment manual

HEAT TREATMENT M A N U A L F O R

POWER SECTOR

BHARAT HEAVY ELECTRICALS LIMITED POWER SECTOR / CORPORATE QUALITY

NAME DESIGNATION / DIVISION V.KANDHSAMY AGM/ PSSR QLY, Chennai UM DESHPANDE AGM/ CQ, SECUNDRABAD

Dr. K.P.DHANDAPANI DGM / WTC-TIRUCHY P.ELANGOVAN DGM / PC- Chennai A.SUKUMARAN Manager/ SAS Cel l - TIRUCHY D.DEVASAHAYAM Manager/ PSSR-QLY, Chennai

PREPARED BY

R.JANARTHANAN Dy. Manager/ PC-Chennai

APPROVED BY

A.V.KRISHNAN

GENERAL MANAGER / CQ, NEW DELHI

DOCUMENT NO. PSQ-HTM-COM R01 / 11 06

ISSUE DATE 13.11.2006

COPY NO. ID No. :

DATE OF ISSUE

CONTROLLED COPY / INFORMATION COPY

ISSUED BY

ISSUED TO :

I M P O R T A N T

THIS HEAT TREATMENT MANUAL PROVIDES BROAD BASED

GUIDELINES FOR HEAT TREATMENT WORK AT SITES.

HOWEVER, SITES MUST ENSURE ADHERENCE TO THE PRIMARY

DOCUMENTS LIKE CONTRACT DRAWINGS, ERECTION WELDING

SCHEDULE, PLANT / CORPORATE STANDARDS, WHEREVER

SUPPLIED, STATUTORY DOCUMENTS, WELDING PROCEDURE

SPECIFICATIONS, CONTRACTUAL OBLIGATIONS, IF ANY AND

SPECIAL INSTRUCTIONS ISSUED BY MANUFACTURING UNITS

SPECIFIC TO THE PROJECT.

STATUS OF AMENDMENTS

Sl.No. Reference of Sheet(s) Amended

Amendment No. & Date Remarks

HEAT TREATMENT MANUAL FOR POWER SECTOR CHAPTER - 1

TABLE OF CONTENTS

Chapter Description Page No.

1 Heat Treatment Procedure - Boiler and Auxiliaries 8-22

2 Heat Treatment Procedure - Steam Turbine, Turbo- Generator and Auxiliaries

23-24

3 General 25 1. Testing of Temperature Indicating Crayons 26 2. Compatibility Test for Heat Treatment System 27-28


CHAPTER-1

HEAT TREATMENT PROCEDURE - BOILER AND AUXILIARIES


1. HEAT TREATMENT PROCEDURE - BOILER AND AUXILIARIES

1.0 PURPOSE:

1.1 This procedure provides information, method and control for Pre-Heat (PH) and Post

Weld Heat Treatment (PWHT) of welds at sites.

2.0 DOCUMENT:

2.1 The following documents are referred in preparation of this procedure:

2.1.1 ASME Sec.I

2.1.2 ASME B31.1

2.1.3 Indian Boiler Regulations

2.1.4 AWS D1.1

2.1.5 Welding Manual

2.2 The following are to be referred as Primary Documents:

- Contract drawings

- Erection Welding Schedule or equivalent

- Plant / Corporate standards, where supplied

- Welding procedure specification, where supplied

- Contractual obligations, if any.

2.2.1 Where parameter for preheating and PWHT are not available in the primary documents,

reference may be made to this procedure.

2.2.2 Where such parameters are not contained either in the primary documents or in this

procedure, reference may be made to Manufacturing Units.

3.0 PROCEDURE:

3.1 Pre Heating (PH):

3.1.1 When parts of two different thicknesses are welded together, the preheating requirements

of the thicker shall rule


3.1.2 When parts of two different P numbers are joined together, the material requiring higher

preheat shall govern (please refer Welding Manual for P numbers).

3.1.3 Preheating shall be checked using thermal chalk (temperature indicating crayons) prior

to start of welding as well as at frequent intervals during welding. It is preferable to

have a thermocouple and a temperature recorder in case of alloy steels of

thickness > 50 mm.

3.1.4 In case of any interruption during welding, preheating temperature shall be maintained

at joint by wrapping dry thermal insulating blankets to ensure slow and uniform cooling.

3.1.5 Preheating Methods:

3.1.5.1 Preheating shall be applied by any of the methods given below:

a. Electrical resistance heating

b. Induction heating

c. Oxy-acetylene or other gas torches

3.2 Post Weld Heat Treatment (PWHT):

3.2.1 The method shall be by locally heating a circumferential band including the entire weld

and adjacent area of base metal, by induction or electrical resistance heating.

3.2.2 Heat band for PWHT.

3.2.2.1 For Boilers:

a. When heat treating welded joints in components in the boiler proper, width of the

heated circumferential band (W) on either side of the weld, W = 3 times the width

of the widest part of the weld groove but in no case less than twice the width of

weld at reinforcement.

b. When used in post weld heat treatment in sections - W = 3 times the plate

thickness.

c. For nozzle and other welded attachments - W must be wider than the nozzle or

attachment or 3 times the wall thickness.

3.2.2.2 For Piping:

W = 3 times the wall thickness of thickest part. In case of nozzles and attachment welds, the width of the heat band shall extend beyond the nozzle or the attachment wall on each side by at least twice the higher thickness and shall extend completely around the header.


3.2.2.3 Other Pressure Vessels:

Heat bandwidth, placement of thermocouple, preheat and PWHT information shall be

obtained from the supplier.

3.3 Condition of Welded Joints:

3.3.1 The weldment shall be free of grease, oil etc. prior to PH/PWHT.

3.4 Temperature Measurement for PWHT:

3.4.1 Post weld heat treatment temperature shall be measured and monitored by use of

thermocouples with calibrated recorders.

3.4.2 The periodicity of calibration of the equipment shall be as per calibration procedure.

3.4.3 Where the soaking temperature is found to be lesser than specified, the PWHT cycle

shall be repeated.

3.4.4 In case of interruption during PWHT, the following actions are to be taken, depending

on the stage during which interruption occurred.

a. Interruption during heating cycle:

- The whole operation to be repeated from the beginning.

b. Interruption during soaking:

- The joint can be treated subsequently for the balance left over soaking

period.

c. Interruption during cooling:

- Ensure slow cooling by covering with insulation to a minimum width of 1.5 times

the outer diameter applied equally about the centre line of weld, till the

temperature reaches around 300 C.

3.5 Thermocouple (t/c) Fixing:

3.5.1 Thermocouples shall be used for recording Post Weld Heat Treatment temperatures.

3.5.1.1 Following are guidelines regarding number and placement of thermocouples:

3.5.1.2 Minimum of two thermocouples per weld.

3.5.1.3 Thermocouples located 180 apart.

3.5.1.4 Thermocouples located at top and bottom of weld.

3.5.1.5 Thermocouples located at a distance of approximately 1.5 times of the wall thickness

about the centre line of weld.

3.5.1.6 One point of the 6/12 points recorder shall be used for recording ambient temperature.


3.5.2 The following guidelines may be used for attaching thermocouples to job:

a. For capacitor discharge method: Thermocouple elements should be attached within 6 mm of each other.

b. For other type of t/c: Insert the elements in a SS tube of internal diameter approximately 6 mm. Apply force on tube and crimp it. Place this t/c and weld the crimped button to the pipe in area of interest. Do not weld the elements.

c. Insulate the t/c leads suitably and protect t/c ends from direct radiation from heating elements.

3.5.3 For Bunched Tubes:

3.5.3.1 Where a bunch of closely placed tube welds (e.g. Super Heater/Reheater Coils) require to be Post Weld Heat Treated, the same shall be grouped together as if they form a single component.

3.5.3.2 In such cases attachment of a minimum of three thermocouples, two at the end tubes and one at the middle is recommended.

3.6 Soaking Time:

3.6.1 Wherever not specified the soaking time shall be as per Tables I, II and III.

3.6.2 The following guidelines shall be used to determine the thickness and subsequent selection of the soaking time of PWHT:

a. For butt welds, the thickness shall be the thickness of the material at the weld. For bar stock, the thickness shall be the diameter.

b. For fillet welds, the thickness shall be the throat thickness.

c. For partial penetration branch welds, the thickness shall be the depth of the groove prior to welding.

d. For repairs, the thickness shall be the depth of the groove as prepared for repair welding.

e. For combination of different welds in a component, the maximum thickness in the definitions given above shall govern.

3.6.3 Soaking time is to be reckoned from the time temperature of the joint crosses the

recommended lower temperature of the cycle, to the time it comes down below the same recommended lower temperature of the cycle.

3.7 Heating and Cooling Rates:

3.7.1 Wherever not specified, the heating rate above 300 C and cooling rate after soaking

upto 300 C shall be as follows: This is applicable for all materials.


Thickness of Material Maximum Heating Rate Above 300 C

Maximum Cool ing

Rate Upto 300 C

25 mm

> 25 50 mm

> 50 75 mm

> 75mm

220 C/hour

110 C/hour

75 C/hour

55 C/hour

220 C/hour

110 C/hour

75 C/hour

55C/hour *

* For structural - 65 C/ hour (Max.)

3.8 Temperature Records:

3.8.1 All the heat treatment cycles may be controlled w ithin 10 C around the midpoint of the recommended range of temperature for the material.

4.0 POST WELD HEAT TREATMENT (PWHT) JOB CARD:

4.1 Prior to start of PWHT operations, a job card may be prepared including details of weld

reference, soaking time, soaking temperature, maximum rates of heating and cooling, temperature recorder details, date of PWHT as per sample format.

4.2 On completion of PWHT the actuals may be recorded on the job card.

4.3 A chart number shall be given to each chart.

5.0 HEAT TREATMENT OF P-91 WELDS :

5.1 Please refer Welding Manual vide document No. PSQ-WDM-COM for heat treatment of

welds in P-91 materials.

5.2 HEAT TREATMENT OF T-91 WELDS:

5.3 Please refer Welding Manual vide document No. PSQ-WDM-COM for heat treatment of

welds in T-91 materials


5.4 HEAT TREATMENT OPERATOR REQUIREMENTS:

The operator for the Heat Treatment shall be a qualified Electrician and should be

conversant in the operation & maintenance of heat treatment machines & Process. He

should be trained properly by the concerned Welding / Electrical Engineer in order to

handle/ maintain the machines / process without any trouble / problem.

6.0 LIST OF TABLES:

Table-I Weld preheat and PWHT for tubes and pipes outside diameter 102 mm.

Table-II Weld preheat and PWHT for Boiler Header welds.

Table-III Weld preheat and PWHT for pipes outside diameter > 102 mm.

Table-IV P Number and Group Number for Base Materials.

Table-V Pre-heat and PWHT for Non-Pressure Parts including Structurals.

Table-VI Preheat for Flame Cutting.

7.1 Pertinent Records like Job card, PWHT Charts, shall be maintained.

7.0 RECORDS :


POST WELD HEAT TREATMENT (PWHT) JOB CARD

Project : ____________________

Card No. : ____________________ Date : ________________________

Unit No. : _____________________ Package : _____________________

Description :___________________ Temp. Recorder Details :

Weld Reference :_______________ 1. Make : _____________________

Material Spec. : ________________ 2. Type : _____________________

Size : Dia __________________ mm 3. Sl.No.: _____________________

Thick (t) ______________ mm 4. Chart speed: ________ mm / hour

NDE Cleared on :_______________ 5. Calibration Due on : __________

Report No. : _______________

Thermocouple Locations :

Minimum 2

d = 1.5 x t from weld centre

Heating Band = 6 x t

Insulation Band = 12 x t Date of PWHT _________________ Chart No. : _____________________

Start Time : ___________________ End Time :_____________________

Required Actual

Rate of Heating (Max) C/h

Soaking Temperature C

Soaking Time (Minutes)

Rate of cooling (Max) C

Ambient temperature recorded on the PWHT Chart: ____________

Contractor BHEL

Results : Accepted / Not Accepted Released for further processing


TABLE - I WELD PRE HEAT AND PWHT FOR TUBES & PIPES

OUTSIDE DIAMETER 102 mm (Applicable For Butt Welds And Socket Welds)

P. No. of

Material

Thickness

(mm) Preheat C PWHT C

P1 Gr 1& SA 106

Gr C (Note 1) 19 Nil Nil

9 Nil Nil P1 Gr 2

> 9 Nil 620 - 650

13 Nil Nil P3 Gr 1

> 13 80 (Note 2) 620 - 650

13 125 Nil (Note 3) P4 Gr 1

> 13 125 650 - 670

8 150 Nil (Note 3) P5 A Gr 1

> 8 150 700 - 750

P5 B Gr 2 All 220 730 - 760

P8 All Nil Nil

12 x 1M All 200 730 - 760

Note 1 : For SA 106 Gr .C w ith less than 0.25 % carbon content . Note 2 : Pre-heating is necessary for t>16mm. Note 3 : Less than 0.15 % carbon content .


TABLE - II

WELD PREHEAT AND PWHT FOR BOILER HEADER WELDS (NOTE - 3)

(Applicable For Welding of Header to Header Joints)

P. No. of Header Material

Thickness (mm)

Preheat C

Post Heating C

PWHT C

t 19 Nil Nil Nil

19 < t 25 Nil Nil 595 - 625

25 < t 75 100 Nil 595 - 625

P1Gr 1

t > 75 150 Nil 595 - 625

t < 19 Nil Nil 620 650

19 < t 25 Nil 150

for 2 hours 620 - 650

19 < t 75 100 150

for 2 hours

620 - 650

P1Gr 2

t > 75 150 150 for 2 hours

620 - 650

P4 Gr 1 All 150 Nil 640 - 670

P5 A (Note 1) All 150 250 for 2 hours 680 - 710

12 x 1M All 200 Nil 710-740

Note :

1. All P5A headers shall be inter stage heat treated at 700 - 750 C for 30 minutes

soaking prior to any cold straightening operation. In lieu of this, the straightening

can be done after final PWHT. Any P5A Header with weld thickness above

50mm requires inter stage H.T. at 700-750 C for 30 minutes soaking minimum

(max. shall be limited to 2.5 minutes/mm of thickness).

2. Soaking for PWHT shall be at the rate of 1 hour per 25 mm of thickest weld (but

not less than 30 minutes for carbon steel and 1 hour for alloy steel). Soaking

time for 12 x 1 M header material shall be 4 minutes per mm of the applicable

thickness with a minimum of 180 minutes.

3. Seal welding of Hand Hole Plates, Radiographic plugs and Screws can be

carried out after final PWHT, provided the preheat is carried out as per the

table. 4. For P number and Group number refer Table - IV.


TABLE - III WELD PREHEAT AND PWHT FOR PIPES

OUTSIDE DIAMETER >102 mm

BUTT WELDS Stub and Attachment welds Note 1 & 2

Throat 19 mm Throat > 19 mm P No. of Material

Thickness (mm) Preheat

C PWHT

C Preheat C

PWHT C

Preheat C

PWHT C

Post heat C

(Note 3)

19 Nil Nil Nil Nil Nil 595 - 625 Nil

>1925 Nil 595 - 625 Nil Nil Nil

595 - 625 Nil

>2575 150 595 - 625 150 Nil 150

595 - 625 Nil

P1 Gr 1 &

SA106 Gr C

>75 150 595 - 625 150 600-650 150

595 - 625 Nil

9 Nil Nil Nil Nil Nil 620 - 650 Nil

>919 Nil 620 - 650 Nil

600-650 Nil

620 - 650 Nil

P1 Gr 2 &

SA 106 Gr C

>19 150 620-650 150

600-650 150

620 - 650

150 for 2 hrs

75 125 640-670 125

650-680 125

640-670 Nil

P4 Gr 1

>75 150 640-670 150 650-680 150

640-670 Nil

Pipes 150 680 - 750 150 700-750 150

680-750

250 for 2 hrs

P5 A Castings & Forgings

220 680-750

150 700-750

150 680-750

250 for 2 hrs

P5B Gr2

+ P5B Gr2,

All 220 750-770

220 750-770

220 750-770

280 for 2 hrs

P5B Gr2 +

P5 A

All 220 730-760

220 730-760

220 730-760

280 for 2 hrs

Note :

1. Irrespective of the stub or attachment materials, the PWHT cycle shall be governed by the pipe

material.

2. Throat shall be specified in the drawing. Wherever flanges are welded to pipes combined throat

shall be taken into consideration.

3. Post heating shall be done immediately after welding.


4. For butt welds of different P group combinations, PWHT temp. may be as follows:

P1 + P3 - 620 to 650C

P1 + P4 - 640 to 670C

P4 + P5A - 680 to 720C

(For other P Group combinations, refer to Engineering)

5. a. For P1 & P3 materials soaking time shall be 1 hour per 25mm up to 50mm

thickness and 2 hours + 15 minutes for each 25mm thickness over 50mm.

b. For P4 & P5 materials, soaking time shall be 1 hour per 25mm up to 125mm

thickness and 5 hours + 15 minutes for each 25mm thickness over 125mm.

6. For P number and Group number refer Table IV.


TABLE - IV P NUMBER AND GROUP NUMBER FOR BASE MATERIALS

P.No Group

No. Common

Name Tubes Pipes Plates Forgings Castings Fittings

SA192 SA106GRB SA36 SA266CL1 SA216WCA SA234WPB

SA210GRA1 SA515GR55 SA352LCA

SA515GR60 SA352LCB

SA515GR65

SA516GR55

SA516GR60

P1 1

Carbon Steels

SA516GR65

SA210GRC SA106GRC SA515GR70 SA266CL2 SA216WCB SA105

SA516GR70 SA216WCC SA234WPC P1 2

Carbon Steels

SA299 SA352LCC

SA209T1 SA335P1 SA217WC1 P3 1

Carbon-Moly Steels

P3 1 CrMo Steels SA213T2 SA335P2 SA387GR2

SA213T12/ SA335P12 SA387GR12 SA182F12 SA217WC6 SA234WP12 P4 1

1CrMo/ 1CrMo Steels

SA213T11 SA335P11 SA387GR11 SA182F11 SA234WP11

P5A 1 2Cr1Mo Steels SA213T22 SA335P22 SA387GR22 SA182F22 SA217WC9 SA234WP22

P5B 2 9Cr1MoV Steels SA213T91 SA335P91 SA387GR91 SA182F91 SA234WP91

18Cr-8Ni Steels SA213TP304 SA376TP304 SA240TP304 SA182F304 SA351CF3 SA403

SA213TP304H SA376TP304H SA240TP321 SA182F321 SA351CF8

SA213TP347 SA376TP321 SA240TP347 SA182F347 SA351CF3M

SA213TP347H SA376TP347 SA336F304 SA351CF8M

SA213TP321 SA376TP347H SA336F321 SA351CF10

P8 1

SA336F347 SA351CF10M

P8 2 25Cr-20Ni Steel (Type 310) SA240TP310 SA182F310 SA351CK20

Note : IS1239 & API 5L GR B Pipes, IS2062 Plates may be treated as P No.1 Gr No.1 material.


TABLE - V

PREHEAT AND PWHT FOR NON PRESSURE PARTS INCLUDING STRUCTURALS

Gas Cutting Welding P.No. of Material / Material

Specification Thickness

(mm) Preheat

C Thickness

(mm) Preheat

C PWHT

C

P1 / IS 2062

50

> 50

Nil

100

38

> 38 63

> 63

Nil

100

120

600-650

a) All butt welds > 50 mm thick

b) Any welds to a tension member

IS 8500 540

Ceiling Girder

10< t < 200 150

600-650(Soaking time 2.5 Mts. Per mm.

Minimum 120 Mts )

P4

25

> 25

Nil

150

All 150

650-700

a) All butt welds in tension member

b) All fabricated com-ponents > 16mm thick (Note 3)

P5 All 150 All 150 680-730 All welds (Note 4)

NOTE :

1. All gas cut edges may be chipped off, ground or machined to remove the HAZ with

3mm minimum removal.

2. Clip angles above 10mm, used for beam connections, which are sheared to length,

shall require heat treatment.

3. All fabricated structural components of P-4 material, with any member above

16mm thickness, the entire assembly shall be post weld heat treated.

4. All welds of P5 material shall be post heated at 250C for 2 hours or 150 C for

4 hours immediately following welding.

5. Soaking time shall be as below :

a. P1 and P3 materials one hour per 25mm up to 50mm thickness and

2 hours + 15 minutes for each 25mm thickness over 50mm.

b. P4 and P5 materials one hour per 25mm up to 125mm thickness and 5 hours + 15 minutes for each 25mm thickness over 125mm.


TABLE - VI

PREHEAT FOR FLAME CUTTING

P.No. of Material Thickness (mm) Preheat C

P1 Gr 1 < 25 Nil

(Note 1) 25 100

P1 Gr 2

(Note 1) All 150

P3

(Note 1) > 100 150

P4

(Note 1) All 150

P5

(Note 2) All 150

NOTE :

1. For P1, P3 and P4 materials, when the flame cut edge will be machined

after cutting and when no forming operation is required after cutting, no

preheat is required for flame cutting.

2. P5 materials, except when the part is scheduled for hot forming, shall be

inter stage heat treated at 700-750C for 30 minutes minimum after

flame cutting and prior to any welding. As an alternative to this heat

treatment, a minimum 3 mm of the gas cut edge may be removed by

machining, grinding, chipping, etc.

HEAT TREATMENT MANUAL FOR POWER SECTOR 23 CHAPTER -2

2. HEAT TREATMENT PROCEDURE -

STEAM TURBINE, TURBO-GENERATOR AND AUXILIARIES

1 Procedure for Post Weld Heat treatment of Pressure Vessel as per ASME code Section VIII, Div.I

Please refer Plant Standard, HEEP, Haridwar - HW 0980814

2 For other Components Please refer Heat treatment Procedure-Boiler and Auxiliaries of Chapter-I

CHAPTER -2

HEAT TREATMENT PROCEDURE -



2. HEAT TREATMENT PROCEDURE -


1 Procedure for Post Weld Heat treatment of Pressure Vessel as per ASME code Section VIII, Div.I

Please refer Plant Standard, HEEP, Haridwar - HW 0980814

2 For other Components Please refer Heat treatment Procedure-Boiler and Auxiliaries of Chapter-I


CHAPTER - 3

GENERAL


3. GENERAL

1. TESTING OF TEMPERATURE INDICATING CRAYONS

1.0 SCOPE :

1.1 This procedure details the method of batch testing of Temperature indicating Crayons

(Thermal chalks).

2.0 PROCEDURE :

2.1 Setup:

2.1.1 Rig a test heating arrangement including a test pipe/plate heating arrangements with

controls and a calibrated temperature recorder/thermometer.

2.2 Heat the test pipe / plate (specimen) to a temperature 10 lower than the rated

temperature of the thermal chalk in study, monitoring the temperature through

thermometer/recorder.

2.3 Stroke the thermal chalk as close to the sensing point on the specimen.

2.4 Raise the temperature of the specimen gradually up to 10% higher than the rated

temperature of the thermal chalk in study, stroking the thermal chalk on the specimen

during this period.

2.4.1 When the thermal chalk changes to the specified colour or melts (depending on the

type), within 5 of the rated temperature, the thermal chalk is acceptable.

2.5 Consistent results for 2% of any brand and temperature will qualify the brand for the

rated temperature.

2.6 Where thermal chalks are accepted brand wise, they shall undergo this test at least

once a year.

3.0 RETESTS :

3.1 Any failure in the 2% sample chosen, will call for additional 4% for qualification of the

brand for the rated temperature.

3.2 Where retest results in further non-acceptance, the brand shall stand rejected for the

particular temperature.

4.0 RECORDS :

4.1 Records of testing and brands accepted/rejected including details of calibrated

devices used in the setup shall be maintained.


2. COMPATIBILITY TEST FOR HEAT TREATMENT SYSTEM

1.0 SCOPE :

1.1 This procedure provides for checking the compatibility and accuracy of

thermocouples, compensating cables, temperature recorder, connected in Heat

Treatment (HT) operations at sites.

2.0 HT TEST SYSTEM :

2.1 The thermocouple (type k-chromal-Alumel is generally used at sites) attached to a test

specimen with heating arrangements and controls, compensating cables, a calibrated

temperature recorder rigged together for the test HT system.

2.2 A calibrated (accuracy 0.5%) direct-reading thermometer (like a digital thermometer

with sensor) is used for verification.

2.0 PROCEDURE :

3.1 Attach the thermocouple as detailed in Chapter I of this manual.

3.2 Raise the temperature of the test specimen to around 200C and maintain the same.

3.3 Place the sensor of the direct reading thermometer as close to the thermocouple

junction as possible.

3.4 Wait till the temperature stabilises.

3.5 Note reading of the thermometer and that of the temperature recorder.

3.6 Repeat steps 3.2 to 3.5 for test specimen temperatures of 400 C and 600 C

3.7 Where the temperature read by the temperature recorder is within 10 C with respect

to the thermometer, the HT system is compatible.

3.7.1 Where the results are not within the tolerance specified above, further tests are to be

repeated to identify the fault either in thermocouple or compensating cable or both.

3.8 Adequate insulation of thermocouple, sensor from direct radiation of heat elements

shall be ensured as a precaution throughout the test.

3.9 This compatibility is recommended for each of the thermocouple available for use; this

procedure validates the thermocouple also.

4.0 RECORDS :

4.1 Records pertaining to the test, shall be prepared and maintained.


Compatibility Test for HT System

Site : Report No.

Date :

Details Temperature Recorder Thermometer

Make:

Model:

Sl. No.:

Range:

Test Results

Temperature Reading C Sl. No. t/c No. C/C. No.

Recorder Thermometer Difference C Results*

Record results (Accepted/Rejected) where rejected, record the faulty component as

required by 3.7.1

Witnessed by

(Name & Signature)