Procedure For Pwht
This document was uploaded by user and they confirmed that they have the permission to share it. If you are author or own the copyright of this book, please report to us by using this DMCA report form. Report DMCA
Overview
Download & View Procedure For Pwht as PDF for free.
More details
- Words: 1,067
- Pages: 5
Loading documents preview...
PAGE NO.- 1 OF 5
LARSEN & TOUBRO LIMITED MSQ (EPCC-1) UPGADATION PROJECT PROCEDURE FOR POST WELD HEAT TREATMENT
DATE:-03.11.07 REV.NO.- 0 PROCEDURE NO.LT/MSQ/P/PWHT/010
CONTENTS:
1.0
PURPOSE
2.0
REFERENCE DOCUMENT
3.0
PWHT
4.0
EQUIPMENTS MATERIALS
5.0
INSPECTION
6.0
SAFETY
APPROVED BY L & T
REVIEWED / APPROVED BY JACOBS
PAGE NO.- 2 OF 5
LARSEN & TOUBRO LIMITED MSQ (EPCC-1) UPGADATION PROJECT PROCEDURE FOR POST WELD HEAT TREATMENT
1.0
DATE:-03.11.07 REV.NO.- 0 PROCEDURE NO.LT/MSQ/P/PWHT/010
PURPOSE: This procedure provides information; method and control for Post Weld Heat Treatment (PWHT) of AG/UG piping at IOCL Panipat Refinery –MSQ Project.
2.0
REFERENCE DOCUMENT: •
• • •
ASME B 31.3 (Latest revision) ABS Spec. SW-231 Approved WPS Approved Welding specification charts
3.0
POST WELD HEAT TREATMENT (PWHT)
3.1
The Heat Treatment is performed by electrical resistance heating coils or by induction. Heating elements of NI-Cr wire of suitable gauge, insulated with porcelain beads, shall be wrapped all round the weld portion and heated electrically. The method is by locally heating a circumferential band including the entire weld and adjacent area of base metal.
3.2
Heating elements are wrapped with an overlap of 75mm either side of weld with sufficient mineral wool to shield the heat. Heat is controlled by varying the electrical energy manually and / or using timer control. Width of the heating band shall be six times the wall thickness of thickest part for girth butt welds.
3.3
Width of the insulation shall be 12 times the thickness of thickest part.
3.4
Care shall be taken so that exposed pipe surface temperature shall not exceed 50% of the peak temperature or 400° C whichever is minimum.
3.5
Weld joints shall be free from grease, oil, etc. prior to PWHT.
3.6
Before PWHT, Line No. & Joint No., dia, type of joint, Recorder No., Calibration date, Starting time and date etc. shall be written on the SR chart, duly signed and sealed by L&T QC Engineer. After completion of PWHT , recorders shall be opened presence of L&T QC Engineer and charts verified with joints for PWHT. PWHT shall be carried out at a temperature range as given below.
3.7
APPROVED BY L & T
REVIEWED / APPROVED BY JACOBS
PAGE NO.- 3 OF 5
LARSEN & TOUBRO LIMITED MSQ (EPCC-1) UPGADATION PROJECT PROCEDURE FOR POST WELD HEAT TREATMENT
Description Heating Rate Cooling Rate Holding Temperature Holding Time
To be Followed at site 150 ± 10 150 ± 10 620 ± 10 1 hr / 25mm (Minimum 1hr)
DATE:-03.11.07 REV.NO.- 0 PROCEDURE NO.LT/MSQ/P/PWHT/010
Requirement as per ASME B 31.3 200° C / Hr Max. 200° C / Hr Max. 593° C to 649° C 1 hr / 25mm (Minimum 1hr)
3.8
HEATING AND COOLING RATES
3.8.1
Heating and cooling rate shall be as per 3.7 above.
3.8.2
Whenever not specified, the heating rate above 300° C, and cooling rate after soaking up to 300° C , shall be followed.
3.8.3
Controlled heating shall be started from 300° C and controlled cooling shall be up to 300° C
3.8.4
Corrective action should be adopted during power interruption and shall be decided on case to case basis.
3.8.5
HOLDING TIME
3.8.6
Holding / Soaking time shall be as per 3.7 above.
3.8.7
The following guidelines shall be used to determine the thickness and subsequent selection of the soaking time of PWHT. For butt welds, the thickness shall be the thickness of the material at the weld. • For fillet welds, the thickness shall be the throat thickness. • For branch welds, the thickness shall be governed as per relevant clauses of B 31.3 • For combination of different welds in a component, the maximum in the definition given above shall govern. •
3.9
HARDNESS TEST
3.9.1
Maximum hardness value of welds after PWHT shall be as per specification.
APPROVED BY L & T
REVIEWED / APPROVED BY JACOBS
PAGE NO.- 4 OF 5
LARSEN & TOUBRO LIMITED MSQ (EPCC-1) UPGADATION PROJECT PROCEDURE FOR POST WELD HEAT TREATMENT
DATE:-03.11.07 REV.NO.- 0 PROCEDURE NO.LT/MSQ/P/PWHT/010
3.9.2
Hardness testing shall be carried out using Portable Telebrinell / Poldi / or any PMC approved harness tester.
3.9.3
Whenever hardness value is more than 200 BHN, re-PWHT shall be carried out as per this procedure.
3.9.4
Hardness Value after PWHT shall be recorded for each weld in the approved format. LT/PNCP/AU/PWHT-HARD/006
3.9.5
One hardness test per weld shall be performed on weld metal and Heat affected zone.
3.10
NUMBER OF THERMOCOUPLES SIZE OF PIPE Up to 4” dia Above 4” – 8” dia Above 8” – 24” dia Above 24” dia
NO OF THERMOCOUPLES One Two Three Four
4.0
EQUIPEMENTS / MATERIALS
4.1
TEMPERATURE RECORDERS
POSITION OF THERMOCOUPLES Bottom Top and bottom (180° apart) 120° apart 90° apart
The recorders shall be six-pointer suitable for 1000°C & 1200°C range, having continuous recording chart having copper lead with colour dots. Each recording instrument will give information and immediate indication of a thermocouple open circuit condition. Calibration certificate for each recorder shall be available for review. Revalidation of calibration shall be carried out at site once in every 6 months. 4.2
TEMPERATURE CONTROL SYSTEM The temperature control system shall guarantee a post weld heat treatment within the limits of the specification.
4.3
THERMOCOUPLES EXTENSION CABLE Copper constantan compensating cables shall be used. The Copper lead (+ve) shall be connected to the Chromel Conductor (non-magnetic) and the Nickel Lead (-ve) shall be connected to the Alumel Conductor (magnetic)
APPROVED BY L & T
REVIEWED / APPROVED BY JACOBS
PAGE NO.- 5 OF 5
LARSEN & TOUBRO LIMITED MSQ (EPCC-1) UPGADATION PROJECT PROCEDURE FOR POST WELD HEAT TREATMENT
DATE:-03.11.07 REV.NO.- 0 PROCEDURE NO.LT/MSQ/P/PWHT/010
4.4
THERMAL INSULATION The insulation consists of mineral wool, wrapped around heating elements. The insulation shall extend a minimum distance of 150mm beyond the outer edges of heated band. The total insulation covering will be such as to provide minimum heat loss.
4.5
THERCOUPLE All thermocouples shall be of the Chromel Vs. Alumel type, type K . thermocouples shall be fixed using Capacitor discharge Method. Calibration reports of thermocouples shall be submitted for review prior to start of work.
5.0
INSPECTION & DOCEMENTATION Documents shall be maintained in format No. LT/MSQ/PWHT-HARD/024
6.0
SAFETY All safety precautions shall be taken as per safety requirements of the project. Proper permit shall be obtained as required, prior to start of job.
APPROVED BY L & T
REVIEWED / APPROVED BY JACOBS
LARSEN & TOUBRO LIMITED MSQ (EPCC-1) UPGADATION PROJECT PROCEDURE FOR POST WELD HEAT TREATMENT
DATE:-03.11.07 REV.NO.- 0 PROCEDURE NO.LT/MSQ/P/PWHT/010
CONTENTS:
1.0
PURPOSE
2.0
REFERENCE DOCUMENT
3.0
PWHT
4.0
EQUIPMENTS MATERIALS
5.0
INSPECTION
6.0
SAFETY
APPROVED BY L & T
REVIEWED / APPROVED BY JACOBS
PAGE NO.- 2 OF 5
LARSEN & TOUBRO LIMITED MSQ (EPCC-1) UPGADATION PROJECT PROCEDURE FOR POST WELD HEAT TREATMENT
1.0
DATE:-03.11.07 REV.NO.- 0 PROCEDURE NO.LT/MSQ/P/PWHT/010
PURPOSE: This procedure provides information; method and control for Post Weld Heat Treatment (PWHT) of AG/UG piping at IOCL Panipat Refinery –MSQ Project.
2.0
REFERENCE DOCUMENT: •
• • •
ASME B 31.3 (Latest revision) ABS Spec. SW-231 Approved WPS Approved Welding specification charts
3.0
POST WELD HEAT TREATMENT (PWHT)
3.1
The Heat Treatment is performed by electrical resistance heating coils or by induction. Heating elements of NI-Cr wire of suitable gauge, insulated with porcelain beads, shall be wrapped all round the weld portion and heated electrically. The method is by locally heating a circumferential band including the entire weld and adjacent area of base metal.
3.2
Heating elements are wrapped with an overlap of 75mm either side of weld with sufficient mineral wool to shield the heat. Heat is controlled by varying the electrical energy manually and / or using timer control. Width of the heating band shall be six times the wall thickness of thickest part for girth butt welds.
3.3
Width of the insulation shall be 12 times the thickness of thickest part.
3.4
Care shall be taken so that exposed pipe surface temperature shall not exceed 50% of the peak temperature or 400° C whichever is minimum.
3.5
Weld joints shall be free from grease, oil, etc. prior to PWHT.
3.6
Before PWHT, Line No. & Joint No., dia, type of joint, Recorder No., Calibration date, Starting time and date etc. shall be written on the SR chart, duly signed and sealed by L&T QC Engineer. After completion of PWHT , recorders shall be opened presence of L&T QC Engineer and charts verified with joints for PWHT. PWHT shall be carried out at a temperature range as given below.
3.7
APPROVED BY L & T
REVIEWED / APPROVED BY JACOBS
PAGE NO.- 3 OF 5
LARSEN & TOUBRO LIMITED MSQ (EPCC-1) UPGADATION PROJECT PROCEDURE FOR POST WELD HEAT TREATMENT
Description Heating Rate Cooling Rate Holding Temperature Holding Time
To be Followed at site 150 ± 10 150 ± 10 620 ± 10 1 hr / 25mm (Minimum 1hr)
DATE:-03.11.07 REV.NO.- 0 PROCEDURE NO.LT/MSQ/P/PWHT/010
Requirement as per ASME B 31.3 200° C / Hr Max. 200° C / Hr Max. 593° C to 649° C 1 hr / 25mm (Minimum 1hr)
3.8
HEATING AND COOLING RATES
3.8.1
Heating and cooling rate shall be as per 3.7 above.
3.8.2
Whenever not specified, the heating rate above 300° C, and cooling rate after soaking up to 300° C , shall be followed.
3.8.3
Controlled heating shall be started from 300° C and controlled cooling shall be up to 300° C
3.8.4
Corrective action should be adopted during power interruption and shall be decided on case to case basis.
3.8.5
HOLDING TIME
3.8.6
Holding / Soaking time shall be as per 3.7 above.
3.8.7
The following guidelines shall be used to determine the thickness and subsequent selection of the soaking time of PWHT. For butt welds, the thickness shall be the thickness of the material at the weld. • For fillet welds, the thickness shall be the throat thickness. • For branch welds, the thickness shall be governed as per relevant clauses of B 31.3 • For combination of different welds in a component, the maximum in the definition given above shall govern. •
3.9
HARDNESS TEST
3.9.1
Maximum hardness value of welds after PWHT shall be as per specification.
APPROVED BY L & T
REVIEWED / APPROVED BY JACOBS
PAGE NO.- 4 OF 5
LARSEN & TOUBRO LIMITED MSQ (EPCC-1) UPGADATION PROJECT PROCEDURE FOR POST WELD HEAT TREATMENT
DATE:-03.11.07 REV.NO.- 0 PROCEDURE NO.LT/MSQ/P/PWHT/010
3.9.2
Hardness testing shall be carried out using Portable Telebrinell / Poldi / or any PMC approved harness tester.
3.9.3
Whenever hardness value is more than 200 BHN, re-PWHT shall be carried out as per this procedure.
3.9.4
Hardness Value after PWHT shall be recorded for each weld in the approved format. LT/PNCP/AU/PWHT-HARD/006
3.9.5
One hardness test per weld shall be performed on weld metal and Heat affected zone.
3.10
NUMBER OF THERMOCOUPLES SIZE OF PIPE Up to 4” dia Above 4” – 8” dia Above 8” – 24” dia Above 24” dia
NO OF THERMOCOUPLES One Two Three Four
4.0
EQUIPEMENTS / MATERIALS
4.1
TEMPERATURE RECORDERS
POSITION OF THERMOCOUPLES Bottom Top and bottom (180° apart) 120° apart 90° apart
The recorders shall be six-pointer suitable for 1000°C & 1200°C range, having continuous recording chart having copper lead with colour dots. Each recording instrument will give information and immediate indication of a thermocouple open circuit condition. Calibration certificate for each recorder shall be available for review. Revalidation of calibration shall be carried out at site once in every 6 months. 4.2
TEMPERATURE CONTROL SYSTEM The temperature control system shall guarantee a post weld heat treatment within the limits of the specification.
4.3
THERMOCOUPLES EXTENSION CABLE Copper constantan compensating cables shall be used. The Copper lead (+ve) shall be connected to the Chromel Conductor (non-magnetic) and the Nickel Lead (-ve) shall be connected to the Alumel Conductor (magnetic)
APPROVED BY L & T
REVIEWED / APPROVED BY JACOBS
PAGE NO.- 5 OF 5
LARSEN & TOUBRO LIMITED MSQ (EPCC-1) UPGADATION PROJECT PROCEDURE FOR POST WELD HEAT TREATMENT
DATE:-03.11.07 REV.NO.- 0 PROCEDURE NO.LT/MSQ/P/PWHT/010
4.4
THERMAL INSULATION The insulation consists of mineral wool, wrapped around heating elements. The insulation shall extend a minimum distance of 150mm beyond the outer edges of heated band. The total insulation covering will be such as to provide minimum heat loss.
4.5
THERCOUPLE All thermocouples shall be of the Chromel Vs. Alumel type, type K . thermocouples shall be fixed using Capacitor discharge Method. Calibration reports of thermocouples shall be submitted for review prior to start of work.
5.0
INSPECTION & DOCEMENTATION Documents shall be maintained in format No. LT/MSQ/PWHT-HARD/024
6.0
SAFETY All safety precautions shall be taken as per safety requirements of the project. Proper permit shall be obtained as required, prior to start of job.
APPROVED BY L & T
REVIEWED / APPROVED BY JACOBS
Related Documents
Procedure For Pwht
February 2021 1
Utpa Procedure For Welds
January 2021 0
Outline Procedure For Tahbso
January 2021 1
Pwht Exemption By Twi
February 2021 1
- Weld Overlay Procedure For Inconel
March 2021 0
Specific Procedure For Lining Kiln Outlet_rk2
March 2021 0More Documents from "Waka Ongeti"
Procedure For Pwht
February 2021 1
Electrical Audit
February 2021 1
Thermodynamics Theory + Questions.pdf
January 2021 0
Pregate17-mech.pdf
January 2021 1
Basic G And M Codes
January 2021 1