Before Welding
There are several checkpoints before welding that have to be checked in order to arrive at the right and correct weld. Pre-welding inspection basically aims at determining any feature or variation that is likely to affect the welding process and/or the resulting welded joint. Here are the key aspects to inspect before welding:
Availability of Welding Procedure Specification (WPS), Work Procedure, Quality Assurance Plan, Working Documents (WD)
Joint identification, fit-up groove design, fit up dimensions
Method of fit-up (i.e clear requirements)
Accessibility for welding, welding platforms
Provision of window opening in fit up groove (if required)
DE-preservation & cleanliness of joint
Cleaning of pipe inside
Proper supporting of joint
Fit up clearance report
Availability of calibrated welding machines & baking ovens
Purging arrangement including dam type and location
Purity and type of purging gas
Preheating arrangements (if required)
Filler material color coding, identification and baking arrangement
Welding sequence
Qualified welder
Separately identified tools & tackles, in case of SS material
Proper shielding/wind protection arrangements for joint
Materials:
- To ensure that the electrodes, used for welding the base metals of the joints, and the filler metals correspond to the welding procedure of the type, grade and specification.
- Instruct your painting crew not to paint graph woods and other surfaces for visibility of flaws for rust, oil, grease or any other parasitic material on the surface. In regard to the surface it may involve cleaning or wiping to the set standard depending on the application.
Fit-Up:
- Before the pieces that are intended to be welded, there are several things that need to be done and one of these critical issues is the fit-up which literally means that the gap between two pieces to be joined must fit the other and this provides the right position of the pieces.
- See to it that the orientation of the joining surfaces ( eg: Specifically concerning the type of weld used (e. g. , butt joint, filet weld, groove weld), the WPS is followed.
Joint Preparation:
- The operation of the seam to be welded should be successfully completed by preparing or flattening or creating a limited groove depending on the type of welding that is going to be done.
- It is also important that any joint root opening or gap as defined is within the tolerance.
Welding Equipment:
- Measures of working conditions of the source and the welder apparatus as well as the apparatus accessories are; The power of the source and the welder apparatus and the type and capacity of the components of the apparatus accessories.
- Ensure that the tungsten instructor of the welding machine is well set on the identified welding process identified in the welding procedure.
Electrodes/Filler Wire:
- They should check on the electrodes or the filler wire that they did not have any impurities, they are of the right type, and the diameter is correct.
- Thus, storage of electrodes and filler wire in appropriate containers should be more done in view of the fact that they may be affected by factors such as moisture.
Shielding Gas and Flow Rates:
- The shielding gas and flow rates are specifically the shields gases with complimentary flow rates in the welding process.
- As for the shielding gas type there has to be a proper one and the flow rate – as required by the welding procedure specifications.
- Make sure cylinders are well connected and also make sure that the cylinders being used are in good condition.
Welding Procedure:
- Before selecting the specification, it is required to refer to the WPS to check if this document is relevant to the materials, joints, and welding procedure used.
- Make sure WPS is on and version has been selected for the project.
Safety Precautions:
- That all the outlined safety measures and the use of appropriate personal protective equipment as adequate ventilation, isolation barriers or other PPE as goggles, masks, gloves or helmets and the likes are adhered to.
- Ensure that fire fighting equipment and first aid equipment are well positioned within the areas that are to be used for teaching and learning.
Workpiece Cleanliness:
- The workpiece should not have on it any item like oils, paints, rust or any thing that can affect the quality of weld that is to be done.
- Use appropriate procedures of cleaning that may either be solvent cleaning or abrasive cleaning depending on the situation.
Surface Condition:
- Look for any defects on the surface inclusive of judge cracks or other defects that exist on the base metals that should be welds.
- If included in the planning of the welding procedure, perform non-destructive testing (NDT).
Alignment and Clamping:
- Ensure that the various limbs or segments are well placed and fixed in some vise or some holder in a manner that cannot be moved when the welding process has begun.
Tack Welds:
- All tack welds developed on the various sections before the actual final welding process involving the utilization of Weld-Metal Consumables should be examined. The assessment of tack welds must meet the quality objectives that have been set down.
Work Area and Ventilation:
- Make sure that going to work is secure or else be assured if there are any barriers within the working space or if it is clean.
- Ensure that the required amount of fresh air necessary for the evacuation of welding fumes and gasses existing in the working area is available.
It is very necessary to conduct a pre-welding check before welding starts so that welding begins with the right material and equipment and also the joint has been correctly set. This minimizes chances of making mistakes that may affect the quality of the welded joint and provides a means of control to achieve the wanted standard.
what is the purpose of inspection in welding
Inspection in welding serves several important purposes in ensuring the quality, safety, and reliability of welded structures and components.The primary objectives and purposes of inspection in welding are as follows:
Quality Assurance: Quality control is a very essential aspect in the welding work in order to ascertain that the job done is correct. This implies assessing that the welding process conforms to certain codes and standards as well as the specifications of the particular project.
Defect Detection: Some of the goals of welding inspection include; identifying welding defects that can include crack, porosity, incomplete penetration and other discontinuities which may have adverse effects on the strength of the joint to be welded.
Safety Assurance: Welding has been used in many industries and applications in construction, engineering and infrastructures, automobile, aerospace and many more.
Compliance with Standards: This is relevant in establishing that the welding work that is being done is up to the industrial standards, codes and laws that govern the society. This is particularly true in fields that handle products that have to be safe and of particular quality such as the nuclear power industry, aerospace industry and pressure vessel manufacturing industries.
Prevention of Costly Failures: In a manner of speaking it is easier and more economical to establish welding defects and rectify them during the welding process and not after the failure has been caused. This is because welding defects, if noticed, can be addressed before the structure or the component is put to use and this is cheaper.
Documentation and Record Keeping: Some of the record and documentation for inspection are; Welding process records, Welding material records, Welding parameters records, Welding inspection records, Record of welding results and Welding rectification record. This documentation is vital in the areas of tracking and quality which are quite important.
Weld Procedure Qualification: It can also entail the acceptance or otherwise of procedures used in welding with regard to the particular work. This entails conducting assessments to ensure that the procedure is effective and as outlined by the set standards.
Verification of Welder Qualification: It may also involve the assessment of the welders’ certification and /or qualification to perform certain welding tasks. The Welder qualifications are very significant in the sense that it would only admit the right and competent personnel to weld.
Progress Monitoring: In the welding process, inspection is used to look at the work that is in progress, the quality of the weld done and also to make a change on the factors used in welding in order to improve on quality and production.
Client and Regulatory Requirements: Regularly the inspection is compulsory because the clients need it, regulatory authorities demand it or it is a stipulated industry practice for a given project.
Thus, welding inspection is an important process that has to be performed during welding activities in various sectors. It avoids defects, assures the quality and dependability of the weld structures and provides data that can be applied for compliance and tracing.
Before welding procedure
Before starting any welding procedure, it is important to follow these steps:
- Look at the Welding Procedure Specification or WPS. The WPS is a document that declares all the features of the process, electrode/filler metal, shielding gas and others willow welding current/voltage. The WPS should be suitable for the material types which are going to be welded and the quality of weld desired.
- Prepare the joint. The surfaces to be joined should not have any form of scale, rust or any other forms of contamination from the surfaces. The joint must also be properly fitted, when the two pieces of material are to be joined there must be a certain clearance between them.
- Establish the right kind of welding equipment to apply. The welding tools and equipment should be fit to use and accurately adjust. This means that the welding machine should be of the right power in order to produce the right amount of current or voltage in the welding process.
- Choose proper welding electrodes to use. It must also be the correct shielding gas and filler metal to be used on the type of welding process and the base material.
- When riding make sure that you are wearing the right protective outfits. Welding is dangerous work therefore one has to make sure they have put on the appropriate clothing when welding like a helmet, gloves, and sleeves.
Once these steps have been completed, the welding process can begin.
Here are some additional tips for before welding:
- Inspect the work area. Ensure that the working environment is clean and free from any dangers that may hinder the flow of work.
- Secure the workpiece. The workpiece must lie stationary and thus should be fixed on the fixture either through c -clamping or tack-welding.
- Preheat the workpiece. Some welding methods can only be applied if the material being used has been brought to a certain temperature level referred to as preheat. Preheat makes sure that the weld does not crack or have any other imperfections.
- Test the welding parameters. If possible, it is recommended to check these welding parameters on the spare piece of material first.
By following these tips, you can help to ensure that your welding procedures are safe and produce high-quality welds.
Welding inspection procedure
Even more significant, a welding inspection procedure can be defined as the plan that offers details on how a weldment is to be assessed. They incorporate a sequence of steps which if an individual were to follow they would be in a position to establish the existence and type of weld flaw.
The activities carried out in a welding inspection procedure will be done frequently or infrequently depending on the weldment type and acceptable quality level. However, a typical welding inspection procedure will include the following steps:Nevertheless, the specifics activities which would normally be conducted during welding inspection would include the following:
- Visual inspection: However, it will be observed here that there will be no crack, porosity and undercut among other defects and therefore, the weld is checked by eye.
- Dimensional inspection: The length of that particular insert is also measured so that one can ensure that the insert has the right length required for the weld.
- Non-destructive testing (NDT): There are other NDT techniques that may be used to assess the internal faults on the weld They are; * X-Ray * Ultrasound * Magnetic particle test
- Destructive testing (DT): However, to study the quality of the weld, the ultrasonic testing and the radiography investigations are carried out: DT methods are bend tests and tensile tests.
A detailed description of the plan for the welding inspection should be in the welding procedure specification (WPS). The WPS is a document that contains the welding parameters that also includes the check on the weldment.
Here is a more detailed description of each step in a typical welding inspection procedure:Here is a brief description of each step in a format of a general flowchart of a welding inspection:
Visual inspection:
The overall appraisal of the state of the welded structures is a non-destructive assessment whose most common method is the external assessment or the visual assessment. It is used in the identification of any apparent defects that may be on the weld seam for instance; crevices, Bernie’s and undercut. Visual inspection which could be done without destroying the weld by approving it to the naked eye or using the magnifying glass or weld inspection mirror.
Dimensional inspection:
A weld is also inspected for its dimensions to ensure that it meets the necessary or required dimensions; this is known as dimensional inspection. This entails measurement on the weld width, height and thickness of the weld. In performing dimensional inspection, the following equipment are used; the calipers, the ruler and weld gauges.
Non-destructive testing (NDT):
These are diagnostic methods such as NDT which assess the weld interior to check for defects. Of all the methods of NDT applicable in welding inspection the most popular methods include; X-ray testing, ultrasonic testing, and MST.
- RT uses x-ray or gamma ray to build an image of the weld. This picture can be applied to search for deficiencies, for instance, crack, porosity and inclusions.
- UT sends sound waves across the weld and then captures an image of that weld. This image can be used to detect defects such as those shown in the following figures: cracks porosity and delamination.
- MT uses a magnetic field to surface the weld and identify the defects that are on the skin of the weld. This method is mainly applied to examine ferrous materials like the steel materials.
Destructive testing (DT):
DT is employed to assure assessment of the mechanical properties of a weld. Among all the DT methods, the most frequently applied one in welding inspection is bend testing, as well as tensile testing.
- Bend testing is applied for determination of the weld’s ductility. The weld is then bent up to a desired angle with the help of a curved metal bar called the mandrel. If the weld cracks during bending it will mean that the weld material is not tough enough and will readily crack.
- Tensile testing is used often to evaluate such factors as the spot weld strength. A specimen or part of the weld cross-section is subjected to tensile stress until fracture occurs. Through measuring the force that is needed to pull the two metals apart, one can determine the tensile strength of the weld.
The welding inspection procedure is the last critical step that will help create the desired welded structures. In this way, according to the general points of the welding inspection procedure, the weldment and the weld itself can be thoroughly checked, regardless of defects that could have formed.