Transcript
AMIGOS TECHNICAL SERVICES ( S ) PTE LTD POST WELD HEAT TREATMENT PROCEDURE
Doc No
: ATS-PWHT-001
Revision No : 01 Date
:
POST WELD HEAT TREATMENT PROCEDURE
DESCRIPTION
NAME
SIGNATURE
PREPARED BY
REVIEWD BY
APPROVED BY
REVISION STATUS
S.NO
REVISION No.
DATE
DESCRIPTION
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AMIGOS TECHNICAL SERVICES ( S ) PTE LTD POST WELD HEAT TREATMENT PROCEDURE
Doc No
: ATS-PWHT-001
Revision No : 01 Date
:
CONTENTS Page 1.
Scope……………………………………………………………………………
3
2.
Heating Item / Work Volume, Location, Schedule………………………….
3
3.
Applicable Code & Specification……………………………………………..
3
4.
Heat Treatment ( PWHT ) Method……………………………………………
3–4
5.
Temperature Monitoring……………………………………………………….
4
6.
Precautions……………………………………………………………………..
4
7.
Important Measures During PWHT……………………………………….....
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8.
Temperature Ranges....………………………………………………………
5
9.
Temperature Control System…………………………………………………
6
10.
Personnel‟s Qualification……………………………………………………..
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11.
Report / Documentation………………………………………………………
6
12.
Heat Treatment Equipment………………………………………………….
7
Appendix 1
Sketch : Width of Heated & Insulted Zone ( LOCAL PWHT )
Appendix 2
Thermocouple Locations ( LOCAL PWHT )
Attachments
:
PWHT Report Form
( Specimen )
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AMIGOS TECHNICAL SERVICES ( S ) PTE LTD POST WELD HEAT TREATMENT PROCEDURE
Doc No
Revision No : 01 Date
1.
: ATS-PWHT-001
:
Scope This document covers the procedure for PWHT Work of High Pressure Piping system Weld joints by localized heating method for carbon and manganese steel, alloy steel materials and castings.
2.
HEATING ITEM / WORK VOLUME, LOCATION, SCHEDULE
HEATING ITEM Various sizes of piping welds range from Ø0.75” ~ Ø16” Thickness range : Less than 50.8mm Also structural weld joints of varying thickness
3.
APPLICABLE CODE & SPECIFICATION 1. 2. 3. 4. 5.
4.
ASME code Section VIII Div.1 2001 ED , chapter UCS-56 ASME B31.3 DNV-OS-C101 or DNV-OS-C201 AWS D1.1 Client‟s Specification
HEAT TREATMENT ( PWHT ) METHOD 4–1
Weld Joints shall be locally heat-treated in such manner that the entire Band be brought up uniformly to the required temperature and held for the specified period of time, in accordance with the codes specifications stated in the above section 3.
4–2
Minimum Required Heated Band Width: 1.
In Local PWHT of Butt Weld Joint, the minimum width of the Circumferential Heat Band, measured from CENTRE of the Weld, shall extend 2.5ѵRT beyond the edge of the weld. ( R = inside Diameter in mm ; T = pipe wall thickness in mm )
2.
3.
In Local PWHT of welded Branch Connection, the minimum Width of the heated band shall extend at least 2.5ѵRT beyond The edge of the weld joining the branch or attachment to the run pipe. In local PWHT of Bend or formed sections, the minimum width Of the heated band shall extend to 2.5ѵRT on each side of the Bent or formed area.
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AMIGOS TECHNICAL SERVICES ( S ) PTE LTD POST WELD HEAT TREATMENT PROCEDURE
Doc No
Revision No : 01 Date
4.
: ATS-PWHT-001
:
HEAT TREATMENT ( PWHT ) METHOD – CON’T
4–3
Thermal Insulation: (a) The insulation width, measured from the center of the weld, Shall extend at least 5ѵRT beyond the edge of the weld. (b) Density of 128Kg/m3 Ceramic fiber insulation blanket shall be Used the thermal insulation. (c) The insulation blanket will be kept in position with iron or steel Wire. (d) Wherever possible, the ends of piping should be sealed to Prevent internal air currents from creating excessively high Thermal gradients through the thickness of the piping. (e) After heat treatment , all materials shall be cooled in still air, Protected from rain and draught.
4–4
Thermocouple Location: (a) Thermocouple shall be firmly attached to the center of the Weld zone using a capacitance-discharge type thermocouple Welder. A demonstration will be carried out upon client‟s Request. (b) When tack welding thermocouple onto the work piece, Precautions shall be taken so as not to create defects such as Undercuts, arc strike, etc and the welded zone shall be Smoothly finished by grinder after heat treatment. (c) All thermocouple attachments shall be adequately insulated by High temperature misreading caused by the effect of radiation. (d) The miminum number/location of the thermocouple to be Attached to the work place shall be as follows:
Weld sizes ( NPS )
No.of T/C
(a) D≥6”
1 no
(b) 6”
