Change electrode manufacture, vendor in welding WPS.

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.

Stainless steel become Magnetic (304, 316, 321, 347 series)

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)

BS EN 287-1 vs BS EN ISO 9606-1 WPQR

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

PWHT weld stress relieve concept

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

Weld Hot Crack vs Cold Crack

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

Weld Crack causes and remedies

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

Stainless steel welding and sensitiztion

Stainless steels are iron-based alloys that contain a minimum of 10.5% chromium.  This chromium reacts with the air and forms a very thin but very tenacious chromium oxide layer which is what prevents stainless from rusting. There are 5 types of stainless steels that are categorized depending on additional alloying elements.  One thing they all have in common is the minimum chromium content of 10.5%. The five types are: Austenitic Stainless Steels Ferritic Stainless Steels Martensitic Stainless Steels Duplex Stainless Steels Precipitation Hardening Stainless Steels Out of these five, austenitic stainless are the most common and familiar types of stainless steels. They exhibit … Continue reading Stainless steel welding and sensitiztion

Hydrogen Induced Cracking (HIC) in welding

Hydrogen Induced Cracking (HIC), also called hydrogen assisted cracking (HAC) and cold cracking, is a common welding defect when welding heavy steel sections and steels with high carbon content. In the above mentioned article we explained that you need three things in order to have cold cracking: source of hydrogen, susceptible microstructure and a certain level of stress.  If you can eliminate one you eliminate the potential for cold cracking.  When we ignore this, whether by choice or by ignorance, we are in trouble.  However, many weldments fail due to hydrogen induced cracking even when good welding procedures are in … Continue reading Hydrogen Induced Cracking (HIC) in welding

CWI welding inspector notes

Today we’ll cover 5 more very important concepts that are governed by the AWS D1.1 Structural Welding Code (Steel).  These concepts can show up as questions in the Certified Welding Inspector (CWI) Exam. As stated in our article from last week, in this exam you don’t have to explain your answers, you simply have to choose the right answer (multiple choice exam). As long as you can find the answer in the codebook you are good. However, it is very important to know why the code imposes certain limits and requirements. Below are 5 more fundamental principles that must be … Continue reading CWI welding inspector notes