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Welding Inspector requirement
Welding inspector is one of the inspection job within QA/QC department. He is hired to assist day to day quality control (QC) activities that are necessary to ensure that all welded items (start from before, during, and after welding) will meet specified requirements and be fit for their application during their life of service.
In order to make him able to do the job that will satisfy parties involved (fabricator - Client - or might third party), the welding inspector need to have the ability to understand and able to interpret the various QC procedures, familiar with international standards related to welding, having experience or practical ability of visual inspection, and it is a must to have sound knowledge of the welding technology.
Should you are interested to this type of job profession, just visit Welding Inspector Job Description.
In order to make him able to do the job that will satisfy parties involved (fabricator - Client - or might third party), the welding inspector need to have the ability to understand and able to interpret the various QC procedures, familiar with international standards related to welding, having experience or practical ability of visual inspection, and it is a must to have sound knowledge of the welding technology.
Should you are interested to this type of job profession, just visit Welding Inspector Job Description.
Welding Inspector
Are you searching Welding Inspection Job, have experience in Welding Inspection, and willing to work in Singapore? One of Connect Energy’s client in Singapore that involve in the Oil Gas Sector is opening job vacancy as Welding Inspector.
Responsibilities
- will assist to develop new welding techniques, methods and procedures with the welders to enhance the productivity
- To Ensure the requirements for welding, welder and welding activities are correctly specified and carried out in accordance to relevant codes, client specifications and contract standards.
- Responsible for Welding Inspection
Requirements
- Job base in in Singapore
- Holding a valid CSWIP 3.1 or 3.2 certification or equivalent.
- Having minimum 3 years relevant welding inspection experience.
- Able to start immediate
Job Duration
- 4 months contracts
Remuneration package :
- Shift rotations where rest day may not fall on Sunday
- Negotiable Salary
- 5.5 days week with overtime.
Closing Date :
18th November 2008
If you are meeting the above requirement of welding inspector vacancy, please forward your application and resume to bennyfong@connect-energy.com or fax @ +65-62934649.
CRACKS
3.1 Crack is an imperfection caused by a local rupture in the solid state, which may arise from the effect of cooling or stresses. Cracks are very significant than other type of imperfections, as crack will produce large stress concentration at the crack tip, making them more likely to cause fracture.
Type of cracks:
Base on the Nature of crack, cracks can be:
Hot crack can be solidification crack and liquation cracks.
This crack primarily occur in the grain-coarsened region of the HAZ, and also well known as cold cracking, delayed cracking or underbead / toe cracking. it is usually lies parallel to the fusion boundary, and usually a combination of intergranular and transgranular cracking.
There are three combination factors that will cause HAZ hydrogen cracking: Tensile stress, susceptible microstructure, high hydrogen concentration.
How to avoid Hidrogen Induced Crack?
Type of cracks:
- Longitudinal cracks
- transverse cracks
- crater cracks
- branching cracks
- in the weld metal
- in the HAZ
- in the parent metal
Base on the Nature of crack, cracks can be:
- Hot Crack
- precipitation induce crack
- cold cracks
- lamelar tearing
Hot crack can be solidification crack and liquation cracks.
- Solidification crack is a crack that occur in weld metal, usually along centreline of weld, as a result of solidification process. When it is happen? 1. if the weld has a high carbon or impurity content, 2. the depth to width ratio of the solidifying weld bead is large (depth and narrow), 3. disruption of the heat flow condition occurs such as stop/start condition.
- Liquation crack, occur in the coarse grain HAZ, as a result of heating the material to an elevated temperature, high enough to produce liquation of the low melting point constituents placed on grain boundaries.
This crack primarily occur in the grain-coarsened region of the HAZ, and also well known as cold cracking, delayed cracking or underbead / toe cracking. it is usually lies parallel to the fusion boundary, and usually a combination of intergranular and transgranular cracking.
There are three combination factors that will cause HAZ hydrogen cracking: Tensile stress, susceptible microstructure, high hydrogen concentration.
How to avoid Hidrogen Induced Crack?
- Apply preheat, it's mean to slow down cooling rate and avoid the formation of susceptible microstructures.
- maintain a specific interpass temperature
- postheat on completion of welding.
- apply PWHT
- Proper selection of process / consumable.
- clean joint from rust
- reduce residual stress
- blend the weld profile.
Definitions of Welding Imperfection
Reference : BS EN ISO 6520 - 1
Imperfection is any deviation from the ideal weld.
Defect is an unacceptable imperfection
According to BS EN ISO 6520-1, weld imperfections are classified into 6 groups. This weld imperfection in case of fusion of welding:
Imperfection is any deviation from the ideal weld.
Defect is an unacceptable imperfection
According to BS EN ISO 6520-1, weld imperfections are classified into 6 groups. This weld imperfection in case of fusion of welding:
- Cracks
- Cavities
- Solid Inclusions
- Lack of Fusion and penetration
- Imperfect shape and dimension
- Miscellaneous imperfections
2.1 - Term Definitions
The definition here are taken from British Standard (BS) 499-1:1991 "Welding terms and Symbols - Glossary for Welding, Brazing and Thermal Cutting.
1. Welding
A process or operation in which two or more parts are united by means of heat or pressure or both, in such a way that there is a continuity in the nature of the metal between the parts.
2. Brazing
A process of joining generally applied to metals in which, during or after heating, molten filler metal is drawn into or retained in the space between closely adjacent surfaces of the parts to be joined by capillary attraction. In general, the melting point of the filler metal is above 450 C but always below the melting temperature of the parent material.
3. Braze welding
The joining of metals using a technique similar to fusion welding and a filler metal with a lower melting point than the parent metal, but neither using capillary action as in brazing nor intentionally melting the parent metal.
4. Weld
A union of pieces of metal made by welding.
5. Joint
A connection where the individual components, suitably prepared and assembled, are joined by welding or brazing.
6. Type of Joint
*. Fillet Weld
*. Slot weld, a joint between two overlapping components made by depositing a fillet weld
round the periphery of a hole in one component so as to join it to the surface of the other
component exposed through the hole.
*. Plug Weld, A weld made by filling a hole in one component of a workpiece with filler
metal so as to join it to the surface of an overlapping component exposed through
the hole where the hole can be circular or oval.
complete root fusion. it is also commonly called as Complete Joint Penetration Weld
(CJP).
*. Partial Penetration Weld, a welded join without full penetration, also called as partial
joint penetration weld (PJP)
8. Features of The completed weld
1. Welding
A process or operation in which two or more parts are united by means of heat or pressure or both, in such a way that there is a continuity in the nature of the metal between the parts.
2. Brazing
A process of joining generally applied to metals in which, during or after heating, molten filler metal is drawn into or retained in the space between closely adjacent surfaces of the parts to be joined by capillary attraction. In general, the melting point of the filler metal is above 450 C but always below the melting temperature of the parent material.
3. Braze welding
The joining of metals using a technique similar to fusion welding and a filler metal with a lower melting point than the parent metal, but neither using capillary action as in brazing nor intentionally melting the parent metal.
4. Weld
A union of pieces of metal made by welding.
5. Joint
A connection where the individual components, suitably prepared and assembled, are joined by welding or brazing.
6. Type of Joint
- But Join, is a connection between ends or edges of 2 parts making an angle to one another of 135 degree to 180 degree (inclusive in the region of the joint.
- T-Join, is a connection between the end or edge of one part and the face of the other part, 5 ~ 90 Degree in the region of the join.
- Corner join, a connection between the ends or edges of two parts making an angle to one another of more than 30 degree but less than 135 in the region of the joint
- edge join, a connection between the edges of two parts making an angle to one another of 0~30 degree inclusive in the region of the joint
- cruciform joint, a connection in which two flat plates or two bars are welded to another flat plate at right angles and on the same axis.
- lap joint, a connection between two overlapping parts making an angle to one another of 0~5 degree inclusive in the region of the weld or welds.
- From Configuration Point of View
*. Fillet Weld
*. Slot weld, a joint between two overlapping components made by depositing a fillet weld
round the periphery of a hole in one component so as to join it to the surface of the other
component exposed through the hole.
*. Plug Weld, A weld made by filling a hole in one component of a workpiece with filler
metal so as to join it to the surface of an overlapping component exposed through
the hole where the hole can be circular or oval.
- From the Penetration Point of View
complete root fusion. it is also commonly called as Complete Joint Penetration Weld
(CJP).
*. Partial Penetration Weld, a welded join without full penetration, also called as partial
joint penetration weld (PJP)
8. Features of The completed weld
- Parent Metal, is metal to be joined or surfaced by welding.
- Filler metal, is metal added during welding.
- Weld metal, is all metal melted during the making of a weld and retained in the weld.
- Heat affected zone (HAZ), is part of the parent metal that affected (metallurgically) by the heat of welding or thermal cutting but not melted.
- Fusion line, is the boundary between the weld metal and HAZ in a fusion weld.
- Weld zone, is a zone containing the weld metal and HAZ
- Weld face, is the surface of a fusion weld exposed on the side from which the weld has been made.
- Root, is the zone on the side of the first run.
- Toe, is a boundary between a weld face and the parent metal or between runs. This area is a point where high stress concentration occur and often where the initiation points for different type of cracks happen. Toes must blend smoothly in to the parent metal.
- Excess weld metal or reinforcement, is a weld metal lying outside the plane joining the toes.
Welding History
Welding History
Welding is a process or an operation for joining two or more parts, usually metals, by means of heat or pressure or both, in such a way that there is continuity in the nature of the metal between the parts. So it can involve filler material or not.
For joining the material, it will need energy source. There are many type of energy sources that can be use for welding such as gas flame, electric arc, laser, electron beam and friction.
Welding process has been developed for many different of atmosphere such as open air, underwater and space. All atmosphere where welding to be done will cause hazard such as burns, electric shock, eyes damage, fume, ultraviolet.
In the end of 19th century, arc welding and oxyfuel welding were the first processes developed, and resistance welding following later.
Welding technology developed quickly during world war I and world war II since people need reliable and inexpensive joining methods for war purpose. Shielded metal arc welding (SMAW) was developed during this period, that now become most popular method.
Followed soon, semi automatic and automatic processes such as Gas Metal Arc Welding, Submerged Arc Welding, Flux Cored Arc Welding and Electroslag Welding were developed and also become famous. Development continued with the invention of laser beam welding and electron beam welding. And today, robot welding is becoming popular in the industrial welding for automatic process.
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