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Welder Qualification and Control Procedure
Cathodic Protection - Quality Control ProcedureDescription complète
Document No. : TTJ/QCP/DCP-001
Revision No. : 1
Date : 15-AUG-2011
Page 1 of 5
Quality Control Procedure Title: Distortion Control Procedure
DISTORTION CONTROL PROCEDURE
FOR
STRUCTURAL STEEL MEMBERS
Document No. : TTJ/QCP/DCP-001
Revision No. : 1
Date : 15-AUG-2011
Page 2 of 5
Quality Control Procedure Title: Distortion Control Procedure
Table of Contents
1.0
Introduction.…………………………………………………………………………3
2.0
Scope…………………..……………………………………………………………..3
3.0
Reference documents.……………………………………….…………………...3
4.0
Repairs After Distortion...………………………………………………………......3
5.0
Rectification Method ………………………………………………………………4
6.0
Equipments…………….………………………………………….………………….5
7.0
Responsibilities.………………………………………….…………………………..5
Document No. : TTJ/QCP/DCP-001
Revision No. : 1
Date : 15-AUG-2011
Page 3 of 5
Quality Control Procedure Title: Distortion Control Procedure
DISTORTION CONTROL PROCEDURE
1.0
INTRODUCTION:
Welding involves highly localized heating of the metal being joined together. The temperature distribution in the weldment is therefore non-uniform. Normally, the weld metal and the heat affected zone (HAZ) are at temperatures substantially above that of the unaffected base metal. Upon cooling of the welded joint, the distortion may occur. The distortion should be controlled by the following method. • • • • • •
2.0
-Amount of restraint -Welding procedure Specification -Weld joint design -Part fit up -Temporary bracket -Temperature Monitoring
SCOPE: This procedure covers the distortion control methods during the welding of structural steel members.
If a component were uniformly heated and cooled, the distortion would be minimized. Some of the factors to be considered to control the distortion listed below:
Document No. : TTJ/QCP/DCP-001
Revision No. : 1
Date : 15-AUG-2011
Page 4 of 5
Quality Control Procedure Title: Distortion Control Procedure 4.2
In assembling and joining the parts of a structure or built-up members the sufficient stiffeners shall be fixed prior to welding to minimize distortion and shrinkage.
4.3
All welds shall be made in a sequence manner that will balance the applied heat of welding while the welding progresses.
4.4
If any members have significant distortion and shrinkage should be rectified prior to fit-up to the main assembly.
4.5
While progression of welding, under the conditions of severe external shrinkage restraint, once the welding has started, the weld joint shall not be allowed to cool below to the specified preheat until the joint completed fully or sufficient weld has been deposited to ensure freedom from cracking.
4.6
5.0
The heating should be performed by the use of gas burners (Oxy-gas flames).
RECTIFICATION METHOD: 5.1
Flame straightening method is commonly used for rectification of structural members.
5.2
Prior to commencement of heating of the base plate, the stiffener plate shall be removed by gouging on both sides and the surface should be clean properly.
5.3
The maximum temperature for straightening shall not exceed 650ºC as per AWS D1.1 Clause 5.26.2, in all cases irrespective of whether conditions like cooling immediately by water or air.
5.4
Heating shall be carried out at the edge side of the base plate of the member.
5.5
The heated steel surface shall be measured by using a digital thermometer or tempil stick to ensure that the heat applied is adequate and to avoid excessive heating, which will affect the mechanical properties of steel material.
5.6
This method uses an ordinary flaring torch, which must be held in such a position of cone is at a distance of 15 to 25mm from the plate.
5.7
When using this method to heat up, the device shall be placed at the beginning of the heating zone for a period of time, but the temperature must in no case exceeds those specified temperature.
Document No. : TTJ/QCP/DCP-001
Revision No. : 1
Date : 15-AUG-2011
Page 5 of 5
Quality Control Procedure Title: Distortion Control Procedure
6.0
5.8
The heating temperature shall be monitored and controlled by Tempil stick or digital thermometer.
5.9
The moving speed of the flame must be monitored. The flame must be always in one direction and rapid cooling is not allowed.
5.10
During heating, straighten the base plate of the member by hammering shall be used to mechanically straighten the base plate.
5.11
The Non Destructive Test shall be carried out on the welded joints only after completion of straightening process.
5.12
This method is commonly used for fairing the distortion area, so as to fair the base plate back to its original state with in the tolerance limit.
5.13
The heating duration shall be based on the member joint thickness.
EQUIPMENTS: 6.1 6.2 6.3
7.0
Flaring torch Tempil stick or digital thermometer Hydraulic jack
RESPONSIBILITIES: 7.1
The supervisor has the direct responsibility and controls of the application of
this procedure to ensure that materials should not overheated during the straightening process. 7.2
The QA/QC shall monitor and inspect the process of flame straightening.
7.3
The QA/QC shall monitor and inspect the process of jacking during straightening.
