AWS A4.4M pdf free download
AWS A4.4M pdf free download.Standard Procedures for Determination of Moisture Content of Welding Fluxes and Welding Electrode Flux Coverings.
4. Sample Preparation, Handling, and Storage All electrode coverings and fluxes shall be analyzed without conditioning2 unless otherwise specified by the applicable welding or welding consumable standards. If conditioning is employed, that fact, along with the method used for conditioning, and the time and tempera- ture involved in the conditioning, shall be noted on the test record.
4.1 Electrode Coverings. The sample for moisture deter- mination shall comprise the covering from the center por- tion of at least three electrodes. The covering can be removed by bending the electrode, causing flaking of the covering from the core. Care shall be taken to handle the covering sample with clean residue-free gloves, clean tongs, or other contaminant-firee means. Alternatively, a clean, dry pliers can be used to chip the covering from the core. The intent is to leave the covering in relatively large pieces. Do not pulverize or grind into smaller bits, as this will promote errors in analysis. This should result in suf- ficient sample for initial analysis and at least one retest, as necessary. If not to be analyzed immediately, the sam- ple shall be placed in a clean, dry sample vial or bottle and sealed. Since electrode covering will interact with the headspace inside the sample vial over time, a sufficient quantity of covering shall be sampled to completely fill the vial, thus minimizing headspace. Analysis should be completed as soon as practicable after sampling.
4.2 Welding Fluxes. Sufficient flux shall be sampled for a single analysis. If not to be analyzed immediately, the sample shall be placed in a clean, dry sample vial or bot- tle and sealed. Since flux will interact with the headspace inside the sample vial over time, a sufficient quantity of flux shall be sampled to completely fill the vial, thus minimizing headspace. Analysis should be completed as soon as practicable after sampling.
5. Equipment/Instrumentation Requirements The essential elements of an analytical system for analysis of water content in electrode coverings and fluxes include a combustion system in which the sample is heated in an oxygen carrier gas, and a detection system in which the water content of the oxygen carrier gas is measured. Maintaining system integrity and using high purity carrier gas ensure that the water delivered to the detection system is derived from the sample. Samples are heated in a combustion boat (either nickel or nickel-lined), placed inside a combustion tube at 980°C (1800°F) in order to remove any moisture. In addition, any other potential hydrogen oxidizes to form water. The oxygen carrier gas transports the resulting water vapor to a detection device. This method of com- busting a sample in oxygen will deliver to the detection device a quantity of water over the combustion period. The device shall be capable of measuring that quantity of water within 0.2 μL or 0.2 mg. Two such detection sys- tems are known which satisfy this requirement. One is Karl Fischer Titration, while the other is Infrared Detection.AWS A4.4M pdf download.
