The free pdf file of Twenty (20) Module 7 Q&A model of 2000 version: Module 7 AWS CWI QUESTIONS ANSWERS (pdf) DOWNLOAD The Below – Twenty-four (24) Questions are model of 2018 version Module 6: Welding Heat Treatment and … Continue reading AWS CWI Questions and Answers (Module 6)
Fully killed is the term to describe de-oxidized steel. After the steel is made, it is then poured into the continuous caster to make a long slab of steel. Think of a sausage maker – molten steel goes in at the top and rectangular slab comes out the bottom. This is called casting. During casting, small carbon monoxide bubbles can form between the steel grains if the oxygen is not removed. If you’ve ever painted a door and seen bubbles in the paint once you apply it you’ll recognize the similarities. To stop these bubbles appearing you paint slower, but … Continue reading The project requires Killed Steel treatment on Pipe, Plate MTC.
”In the welded condition many stainless steels are susceptible to rapid intergranular corrosion or stress corrosion cracking. This is because the heat from welding sensitizes the base metal heat affected zone (HAZ) and the weld. Sensitization is the condition where chromium carbide precipitation at the grain boundaries (from a heating process, e.g., welding, hot forming, hot bending, service temperature, etc.) reduces the amount of chromium in solution in the stainless steel. The temperature range for sensitization to occur for austenitic stainless steels is approximately 700 °F to 1500 °F. Since the carbides precipitate in the HAZ or weld deposit at … Continue reading Stainless steel 347H and PWHT
If welding is to be performed according to a welding procedure specification, it is possible that changing the electrode manufacturer will invalidate the approval of the procedure to the code/standard on which it was based. The manufacturer or ‘trade name’ of the electrode can be classed as an essential variable in a given weld procedure. The extent to which re-qualification is necessary will vary from code to code. For example, in EN ISO 15614-1[1] and in the UK standard BS 4515:2004[2], approval is only restricted to the specific make of electrode if impact testing is required as part of the procedure qualification. On the … Continue reading Change electrode manufacture, vendor in welding WPS.
Austenitic stainless steels with around 10-12% nickel (e.g. grades 304, 316, 321 and 347) are predominantly non-magnetic due to the face centered cubic (fcc) crystal structure of the austenite phase, which imparts so-called ‘paramagnetic’ (i.e. non-magnetic) behavior. Although a number of second phases, e.g. inclusions or ferrite stringers, may exist in wrought austenitic stainless steel products, the structure is almost exclusively made up of the austenite phase and hence they are essentially non-magnetic. However, weld metals made with filler metal compositions matching the 300 series austenitic steels (e.g. 308, 309, 316 and 347 types) are designed to have a small … Continue reading Stainless steel become Magnetic (304, 316, 321, 347 series)
ISO 9606-1 has been cited in the Official Journal of the European Union as harmonized with the Pressure Equipment Directive (PED), with effect from 1 March 2018. This FAQ gives a quick summary of the transition between the standards for welder qualification BS EN 287-1 and BS EN ISO 9606-1 and provides recommendations on how to apply them. Please note that this article is not authorized to give official interpretations of BS EN ISO standards and the answer below is an opinion only, and cannot be taken as a definitive answer. No liability rests with this post for any damages … Continue reading BS EN 287-1 vs BS EN ISO 9606-1 WPQR
Stress-relieving is a form of post-weld heat treatment. In stress-relieving we heat a material to a specific temperature; hold it at this temperature for a specified amount of time in order to reduce or eliminate residual stresses, and then cool it at a slow enough rate to prevent these stresses from redeveloping. In most cases, stress relieving is done to regain dimensional tolerance and to reduce distortion. Distortion occurs due to the rapid and uneven heating and cooling of the weld metal and the surrounding base metal. As the molten weld metal cools it contracts and does so at a … Continue reading PWHT weld stress relieve concept
We recently helped out a customer in determining why some of their welds were cracking. It was determined that cracking on their parts was due to rapid cooling and improperly sized welds. The discussions we had before and after determining the cause were quite interesting. We went over the typical causes of cracking with our customers. Here is a brief summary of our meetings. Please note that these are not all the causes for cracks. Generally speaking, we can separate cracks in two groups, which have to do with the timing of the cracks: hot cracking and cold cracking. Essentially … Continue reading Weld Hot Crack vs Cold Crack
Cracks on welds are never good. Welding codes always have allowances for porosity, undercut, weld sizes, and even weld profiles. However, there is never an allowance for cracks. Being a linear discontinuity, a crack will tend to propagate through the weld and into the base metal with relative ease, especially in cyclically loaded structures. So naturally we want to avoid cracks at all costs. Below is a list of 6 mistakes you need to avoid in order to reduce cracking susceptibility. 1- Using a matching filler metal – there is a misconception that because codes list matching filler metals (to base … Continue reading Weld Crack causes and remedies
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