what are the welding procedure?

Answer 1

As welding becomes a modern engineering technology it requires that the various elements involved be identified in a standardized way. This is accomplished by writing a procedure which is simply a "manner of doing" or "the detailed elements (with prescribed values or range of values) of a process or method used to produce a specific result." The AWS definition for a welding procedure is "the detailed methods and practices including all joint welding procedures involved in the production of a weldment." The joint welding procedure mentioned includes "the materials, detailed methods and practices employed in the welding of a particular joint."

A welding procedure is used to make a record of all of the different elements, variables, and factors that are involved in producing a specific weld or weldment. Welding procedures should be written whenever it is necessary to:

-Maintain dimensions by controlling distortion
-Reduce residual or locked up stresses
-Minimize detrimental metallurgical changes
-Consistently build a weldment the same way
-Comply with certain specifications and codes.

Welding procedures must be tested or qualified and they must be communicated to those who need to know. This includes the designer, the welding inspector, the welding supervisor, and last but not least, the welder.

When welding codes or high-quality work is involved this can become a welding procedure specification, which lists in detail the various factors or variables involved. Different codes and specifications have somewhat different requirements for a welding procedure, but in general a welding procedure consists of three parts as follows:

A detailed written explanation of how the weld is to be made
A drawing or sketch showing the weld joint design and the conditions for making each pass or bead
A record of the test results of the resulting weld.
If the weld meets the requirements of the code or specification and if the written procedure is properly executed and signed it becomes a qualified welding procedure.

The variables involved in most specifications are considered to be essential variables. In some codes the term nonessential variables may also be used. Essential variables are those factors which must be recorded and if they are changed in any way, the procedure must be retested and requalified. Nonessential variables are usually of less importance and may be changed within prescribed limits and the procedure need not be requalified.

Essential variables involved in the procedure usually include the following:

-The welding process and its variation
-The method of applying the process
-The base metal type, specification, or composition
-The base metal geometry, normally thickness
-The base metal need for preheat or postheat
-The welding position
-The filler metal and other materials consumed in making the weld
-The weld joint, that is, the joint type and the weld
-Electrical or operational parameters involved Welding technique.

Some specifications also include nonessential variables and these are usually the following:

-The travel progression (uphill or downhill)
-The size of the electrode or filler wire
-Certain details of the weld joint design
-The use and type of weld backing
-The polarity of the welding current.

The procedure write-up must include each of the listed variables and describe in detail how it is to be done. The second portion of the welding procedure is the joint detail sketch and table or schedule of welding conditions.

Tests are performed to determine if the weld made to the procedure specification meets certain standards as established by the code or specification. If the destructive tests meet the minimum requirements the procedure then becomes a qualified procedure specification. The writing, testing, and qualifying procedures become quite involved and are different for different specifications and will be covered in detail in a later chapter.

In certain codes, welding procedures are prequalified. By using data provided in the code individual qualified procedure specifications are not required, for the standard joints on common base materials using the shielded metal arc welding process.

The factors included in a procedure should be considered in approaching any new welding job. By means of knowledge and experience establish the optimum factors or variables in order to make the best and most economical weld on the material to be welded and in the position that must be welded.

Welding procedures take on added significance based on the quality requirements that can be involved. When exact reproducibility and perfect quality are required, the procedures will become much more technical with added requirements, particularly in testing. Tests will become more complex to determine that the weld joint has the necessary properties to withstand the service for which the weld is designed.

Procedures are written to produce the highest-quality weld required for the service involved, but at the least possible cost and to provide weld consistency. It may be necessary to try different processes, different joint details, and so on, to arrive at the lowest-cost weld which will satisfy the service requirements of the weldment..

Answer 2

Any procedure in essence means how to do that particular operation - whether it is welding or anything else.

In a non-regulated industry any commercial outfit may have its own in-house welding procedure based on commercial as well as their own technical know how.

But it is not the same in a regulated industry where work has to be performed in accordance with some specific codes like:

ASME Boiler and Pressure Vessel code applicable in north America and in many other parts of the world.

ANSI Chemical pressure Piping code applicable to petrochemical industry - there is more than one applicable standard.

In these areas welding procedures alone are not sufficient - welding procedure as well as the welding process need to be qualified and certified - which means adhering to a good quality program like ISO 9001.

Answer 3

Just like any work of art, welding too requires a thorough knowledge of the basics in order to master its different processes.
To begin with welding is the process through which materials are joined together to form a firm joint. Usually metals or thermoplastics are used in this process. What makes welding different from the other metal joining techniques like brazing and soldering, is the fact that when two metals are joined together in this process, a decent amount of 'melting' of the metals takes place.
Some of the best welding methods are:

i. Shielded Metal Arc Welding
ii. Gas Metal Arc Welding
iii. Flux-Cored Arc Welding
iv. Submerged Arc Welding
Shielded metal arc welding uses an electrode which has the flux around it. This flux is the protectant for the puddle around the electrode. The electrode holder on the other hand holds the electrode as it melts away in the welding process. The slag on the other hand protects the weld puddle from atmospheric contamination of any kind. Gas Metal Arc Welding on the other hand uses a wire feeding gun. This wire feeding gun feeds the wire at an adjustable speed and flows an inert gas (Argon gas) or a mix of carbon dioxide and Argon over the weld puddle to protect it from atmospheric contamination.
Flux-Cored Arc Welding is quite similar to Gas metal arc welding. The only exception is that this method of welding uses a special tubular wire filled with flux. Depending on the filler, you can either use or not use the tubular wire. While the Submerged Arc Welding makes use of an automatic fed consumable electrode along with a blanket of granular fusible flux. In this method of welding the molten weld and the arc zone are constantly protected from the atmospheric contamination as it is “submerged” under the flux blanket.
These are some of the basic ways in which welding can be done.

Answer 4

I am not sure if i understand the question, but I will try. Basically the common ones are arc welding, gas welding and tig welding. Resistance welding is rather limited. Or is it that you want to know about how to make a perfect weld for a horizontal, vertical butt weld.....hell, ishould not have answered this q, ask me a precise q on what u want to know about welding an i will tell you. I weld all positions cos i need to in my job

Answer 5

The question may be remodelled as " What are the various Welding Procedures? "
Then the answer would be joining of two metal parts by melting the parent metal. The welding process can be carried out on two pieces of same metal or of two different metals . The process can be carried out without any filler material or using filler material from same or a third metal.
The welding can be carried out in open , it can be carried out in a shield of protective gas or a shield of flux powder.
The source of heat may be an electrical arc, or a heating flame (like oxy-acetylene), or induction amongst most popular.
One thing common in all the welding processes is that the process is carried our above 640 degrees centigrade.
If joining by melting is carried out below 640 degrees centigrade and above 320 degrees centigrade, the process is called brazing.

Answer 6

Weld procedures are what the engineer is supposed to develop to tell the welder how to weld to particular pieces of metal together. They can change based on metal types, position, type of joint, design efficiency of the joint, whether or not the weld is on a coded vessel or coded equipment (like receivers or boiler tubes).

Answer 7

open the electric source, wait for 5 minutes, test the welding tip with a moist sponge, if the sponge burn, then it's enough heat for weld.

Answer 8

For what? You need to be much more specific?