C-1901 PIPING WORK AT PETRONAS PENAPISAN MELAKA
HEAT TREATMENT PROCEDURE
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29/03/2018
HEAT TREATMENT PROCEDURE
Rev.
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Issued For Approval
MZM
Reviewed by,
Approved by,
C-1901 PIPING WORK AT PETRONAS PENAPISAN MELAKA
HEAT TREATMENT PROCEDURE
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Table of Contents
1.
Introduction ................................................................................................................................. 3
2.
Abbreviation ................................................................................................................................ 3
3.
References ................................................................................................................................... 3
4.
Joint Details ................................................................................................................................. 4
5.
Heat Treatment Cycle ................................................................................................................ 4
6.
Heating Machine ......................................................................................................................... 4
7.
Temperature Controls ............................................................................................................... 4
8.
Thermocouples ........................................................................................................................... 4
9.
Thermocouple Positions .......................................................................................................... 4
10.
Thermocouples Compensating Cable .............................................................................. 4
11.
Temperature Recording........................................................................................................ 5
12.
Insulation.................................................................................................................................. 5
13.
Heat Treatment Interruption ................................................................................................ 5
14.
Safety precaution ................................................................................................................... 6
Appendix 1: Local Heating Report ................................................................................................ 7
Appendix 2: Heat Treatment Cycle ................................................................................................ 9
Appendix 3: Thermocouple Location ......................................................................................... 11
C-1901 PIPING WORK AT PETRONAS PENAPISAN MELAKA
HEAT TREATMENT PROCEDURE
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1.
29/03/2018
Introduction
This procedure describes the method for carry-out localized Heat Treatment to the welded
components.
2.
Abbreviation
QA/QC
IFA
DOC
HT
3.
–
–
–
–
Quality Assurance / Quality Control
Issued For Approval
Document
Heat Treatment
References
ASME B31.3 - 2016
–
Process Piping
C-1901 PIPING WORK AT PETRONAS PENAPISAN MELAKA
HEAT TREATMENT PROCEDURE
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4.
29/03/2018
Joint Details
Piping P-Number (P-No.) to be PWHT are as below:
a) P-4,
b) P-5A
c) P-15E
5.
Heat Treatment Cycle
Heat treatment cycle and processes throughout the repair work stage with reference to design
code is provided by Main-Contractor and illustrated in Appendix 2.
Note: Refractory dry-out cycle shall be provided by Main-Contractor.
6.
Heating Machine
Electrical resistance heating by the application of ceramic heater pads (elements) and
induction heating by the application of a bundle of coil around the area to be heat treated
7.
Temperature Controls
The heating elements shall be grouped into independent control zone, each shall be attached
with a respectively numbered thermocouple (for control & monitor purposes).
Each circuit of the heating elements shall be controlled in manual/semi manual mode through
contactor or energy regulators or it shall be made automatic controlled by pre-set programmer
control unit.
8.
Thermocouples
Thermocouples shall be K Type made from nickel-chromium/nickel/aluminium wire to BS1041,
Part IV, or equivalent. Certifications shall be made available and indicate a tolerance of less
than +/- 0.75% throughout the temperature range from 400 degree C to 800 degree C.
Thermocouples shall be attached to the work piece by the direct wire capacitance discharge
method. The gap between the two wires per work piece junctions shall not exceed 5mm.
9.
Thermocouple Positions
The thermocouple recommended positions for PWHT on piping joints are detailed in Appendix
3.
10.
Thermocouples Compensating Cable
Copper/constantan compensating cable shall be used for extension of the thermocouple to
the recording instrument.
C-1901 PIPING WORK AT PETRONAS PENAPISAN MELAKA
HEAT TREATMENT PROCEDURE
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The copper lead (+ve) shall be connected to the nickel-chromium conductor of the
thermocouple (non-magnetic), and the constantan lead (-ve) shall be connected to the nickelaluminium conductors (magnetic).
11.
Temperature Recording
Temperature recorders shall be calibrated at intervals not greater than 12 months. It shall have
certification traceable to a national standard and recorded with the certificate being kept and
a sticker should be stuck on the instrument.
The temperature recorder shall be of the potentiometric self-compensating type, calibrated in
degree Celsius with respect to a nickel-chromium /nickel-aluminium thermocouple, type K.
The recording chart speed shall be set at 25 or 50 mm/hour and shall be checked during
calibration. Prior to start, recording chart shall be signed by inspector.
12.
Insulation
High temperature ceramic fibre blanket, minimum 25mm thick and density of 96kg/m3, shall
be provided for the purpose of insulation.
Insulation shall extend for a minimum distance of 200mm beyond the outer edges of the heater
zone, or as may be determined by the ruling specification.
The number of layers may be adjusted to meet the variations of wall thickness, diameter,
gradient requirements and site conditions.
Wherever possible, each end shall be blanked off internally before heat treatment to limit
convection effects.
13. Heat Treatment Interruption
An interruption to the heat treatment process is defined by the failure by one or more
thermocouples to maintain the specified heating, cooling rates, temperature differentials or to
achieve the soak temperature. This may be the result of power loss, equipment failure or
operator error.
Once the discrepancies have been identified, the heat treatment cycle shall be placed into
hold whilst investigation take place to determine if the fault can be rectify and remedial work
carried out safely with a minimum of delay. The heat treatment may be restarted afterward.
A check shall be made of the temperatures of all controlling thermocouples, whichever finding
had identified any of discrepancies i.e. below the set point, it shall be raised at a rate no greater
C-1901 PIPING WORK AT PETRONAS PENAPISAN MELAKA
HEAT TREATMENT PROCEDURE
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than that specified by the code or specific procedure until the overall temperature differential
is within the acceptable limits.
If the interruption occurs during the soak period, then the temperature of any thermocouple
which falls below the minimum specified soak temperature shall be re-established at a rate no
greater than that specified by the code or procedure.
The soak time shall be extended to ensure all the thermocouples have recorded temperatures
within the soak range for the minimum soak time.
In the event that the heat treatment chart indicates discrepancies i.e. overall temperature
differentials are increasing between thermocouples which exceed the code / procedure given
value, then the heating or cooling rates shall be reduced, or the process put on hold. A note
shall be made on the heat treatment chart and the client advised. If the differentials cannot be
corrected, the client is to be consulted as to whether or not the heat treatment is continued.
If remedial work cannot be carried out in time (to effectively restore the heat treatment cycle),
the process shall be aborted after consultation with the client. The heat treatment cycle shall
be re-started at another time.
A note of interruption and at a time it happened shall be made on the heat treatment chart. A
non-conformance report shall be raised.
14. Safety precaution
Prior start works, all heat treatment equipment shall be inspected and tested by qualified
electrician inspector and approved for site work. The relevant machine certificate shall be
provided during inspection.
Power supply connection from DB board/electrical tapping point to machine shall be
established by qualified electrician with adequate power cable specs.
During heat treatment process, the work area shall be cordoned off with red white barricade
tape and safety hazard signage shall be displayed mentioned “Hot work in progress” Only
authorized personnel shall be allowed inside the work area.
Heat treatment personnel shall wear appropriate PPE such as hand glove and N95 dust mask
when fit-up the ceramic fibre insulation on the work piece. The MSDS shall be provided for
guideline during installation at site.
C-1901 PIPING WORK AT PETRONAS PENAPISAN MELAKA
HEAT TREATMENT PROCEDURE
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Appendix 1: Local Heating Report
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C-1901 PIPING WORK AT PETRONAS PENAPISAN MELAKA
HEAT TREATMENT PROCEDURE
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Heat Treatment report will have minimum information listed as below.
Report Number
Procedure No.: _______________________ Revision No.: __________ Date: ________________
Governing Code: ___________________________________________________________________
Workpiece Identification Number:______________________________________________________
Material Specification: _______________________________________________________________
Component Dimensions: ____________________________________________________________
Thermocouple, Heater, and Insulation Layout Drawing Number:______________________________
Thermal Cycle
Heating Rate: __________________°______/hour (specify max. or min.) above __________ ° ____
Hold Temperature Range: _______________ ___° to _______________________________ ° _____
Minimum Hold Time: ________________ hours
Maximum Hold Time: __________________ hours
Cooling Rate: _______________°______/hour
(specify max. or min.) above __________ ° _______
C-1901 PIPING WORK AT PETRONAS PENAPISAN MELAKA
HEAT TREATMENT PROCEDURE
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Appendix 2: Heat Treatment Cycle
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HEAT TREATMENT PROCEDURE
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DEHYDROGENATION
Degassing (dehydrogenation) process for old joint is as below:
Appendix 3: Thermo
PRE-HEAT
Preheat temperature during welding is 150°C.
150°C/hr
Holding Temperature:
350°C
Holding Time:
1 hr
PRE-HEAT
Preheat using heating pad as below:
Ambient Cooling
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C-1901 PIPING WORK AT PETRONAS PENAPISAN MELAKA
HEAT TREATMENT PROCEDURE
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POST-WELD HEAT TREATMENT CYCLE
PWHT Heating and Cooling rates shall be governed under ASME B31.3 (Section 331.1.4) as
below: -
Cooling rate from 315°C down to ambient temperature for the weld may be allowed to cool
naturally. Whilst keeping the whole weld seam insulated, insulation may be removed at 150
°C.
PWHT Soaking temperature is defined in ASME B31.3 (Table 331.1.1) as table below: -
Appendix 3: Thermocouple Location
C-1901 PIPING WORK AT PETRONAS PENAPISAN MELAKA
HEAT TREATMENT PROCEDURE
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Below figures shows the generic arrangement on locating thermocouples depending on NPS
of pipes. Thermocouple to be used to control the temperature (normally on the weld) is
compulsory while monitoring thermocouple is subjected to accessibility and equipment
environment.
Min. Heated Band Width (7t)
t
(1)
Legend
(4)
D Nominal Diameter
O Rear
X Front
X O (3)
(2)
Figure 1: Butt Welds between Pipes of Equal Thickness
NOTES:
1.
2.
3.
4.
For D < 6” T/C (I) only required.
For 6” < D < 12.T/Cs (I) & (2) only required.
For 12” < D < 20”. T/C (1 to 4)
Additional thermocouples to be fitted at the weld centreline as required for control.
Min. Heated Band Width
3.5 t 1
t1
3.5 t2
(1)
t2
Legend
(4)
X O (3)
D Nominal Diameter
O Rear
X Front
(2)
Figure 2: Butt Welds between Pipes of Unequal Thickness
NOTES:
1.
2.
3.
4.
For D < 6” T/C (I) only required.
For 6” < D < 12.T/Cs (I) & (2) only required.
For 12” < D < 20”. T/C (1 to 4)
Additional T/Cs to be fitted at 1.5t1, or 1.5t2 positions as required for control.
C-1901 PIPING WORK AT PETRONAS PENAPISAN MELAKA
HEAT TREATMENT PROCEDURE
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D2
t2
Row A
D1
(1)
t1
(2)
X O (3)
Row B
Row C
(4)
1.5 t 1
Row D
3.5 t 2
1.5 t 1
3.5 t 1
3.5 t 1
min.
min.
Legend
D Nominal Diameter
O Rear
X Front
Minimum Heated Zone
Figure 3: Pipe to Branch Welds
NOTES
1. Additional T/Cs shall be fitted on Rows A.B.C. & D as required for control
purposes.
2. For D2 < 6”. T/Cs 2.3 & 4 not required.
3. For 6” >D2 < 12”. T/Cs 3 & 4 not required.
4. For 10” < D2 <20”. T/C 4 not required.