Buried arc transfer mode in welding

Buried-Arc Transfer The arc in carbon dioxide is very forceful. Because of this, the wire tip can be driven below the surface of the molten weld pool. With the shorter arcs, the drop size is small, and any spatter produced as the result of short circuits is trapped in the cavity produced by the arc—hence the name buried-arc transfer. The resultant welds tend to be more highly crowned than those produced with open arcs, but they are relatively free of spatter and offer a decided advantage of welding speed. These characteristics make the buried-arc process useful for high-speed mechanized welding of thin … Continue reading Buried arc transfer mode in welding

ASME IX QW-405.2 Position variable

New updates on ASME IX – 2019: Using qualification test coupon qualified in 2G, or 1G-Rotated position can develop a WPS to weld with “All” positions in production. ***Flashback to the ASME IX – 2015 & older: The Supplementary essential variable QW-405.2 applies to the test weld coupon when the Notch toughness tests are required by the applicable Fabrication/ End using Codes (Ex: ASME B31.3). In this case, the QW-405.2 will supersede the Non-essential variable QW-405.3 (Changes of weld progression), QW-405.2 becomes an essential variable and requires that a change from any position to Vertical uphill progression requiring Re-qualification of … Continue reading ASME IX QW-405.2 Position variable

Stainless steel discolour (sugaring) in welding

We receive several calls about welding stainless and the beautiful rainbow colors, or lack thereof, on the weld and heat-affected zone.  Is the tinting an indication of quality?  Are these colors acceptable? Do they show that the weld had enough heat to penetrate?  Why do they need to be cleaned?  The questions are endless. If you are one of the thousands that base their quality standards on Instagram posts please stop right now.  All the beautiful pictures of stainless welds are emphasizing the beauty of the rainbow colors in GTAW and GMAW welds.  This is producing a false expectation and the impression that … Continue reading Stainless steel discolour (sugaring) in welding

Heat treatment on TMCP steels

In marine, O&G, MOU construction: A large amount of high strength, heavy wall pipe is manufactured using a thermo-mechanically controlled processed (TMCP) steel plate. It is generally accepted that these steels are not designed for subsequent PWHT and may suffer some degradation in their mechanical properties when re-heated above critical temperatures. A number of standards, specifications and technical publications acknowledge the influence of PWHT on mechanical properties of the TMCP plate, but provide limited guidance (depend on supplier quality) on how it will affect the properties. Others refer directly to a detrimental effect, such as BS 4514-1, which states “when PWHT … Continue reading Heat treatment on TMCP steels

Preheating temperature distance range

Preheating is the requirement from both WPS Standard (Ex: ASME IX, AWS D1.1) and End using code (ASME 31.3, ASME VIII). The calculation and investigate on this item have been discussed in previous articles. In this article, we would like to introduce some ways to check the Preheating temperature during site surveillance: 1st – Follow WPS guideline: Ex: WPS 2nd – Specification of the project: Some project specs will somehow mention some certain requirements on this item. Ex: Specification mentions: 3rd – Reading in End using Code (Ex: AMSE B31.3): Preheating: the application of heat to the base material immediately before or … Continue reading Preheating temperature distance range

Hot pass in Welding terms

There are certainly many answers for what exactly does HOT PASS means in welding terminology and from where it actually evolved. Different people had a different opinion and they are as below mentioned. It is to fill the weld bevel. It is to melt and float out the wagon tracks left after the root pass. To release trapped gases, hydrogen entrapment at root weld to minimize the risk of Hydrogen induction cracking (HIC). A significant other is that a large majority of pipeline welds are done in a clamp and under some sort of stress. A root bead and hot … Continue reading Hot pass in Welding terms

Electrode flux types and selection (Part 2)

A lot more depends on the selection of the electrode type for successfully carrying out weld with SMAW process. A wrong selection of electrode type may lead to more defects, more repairs. The selection of the correct type of electrode coating results in weld metal with desired quality characteristics at low cost. In general, the welding electrode is selected in such a way that characteristics of weld metal are similar to or better than the base material while keeping in mind the welding position and weld joints design as they significantly affect the properties of the weld. The covering of … Continue reading Electrode flux types and selection (Part 2)

Electrode flux types and selection (Part 1)

CHOOSING THE RIGHT ELECTRODE FOR YOUR NEEDS It is important to consider both materials and technical aspects when selecting stick electrodes. BRIEF OVERVIEW Type, Name, Definition R, RR, Rutile: Standard electrode for universal use, fine to medium droplet transfer, good mechanical properties, welding positions PA, PB, PC, PE, PF, (PG limited use only). RB, Basic-rutile: Use as a combination of achievable, high toughness values and universal use with increased demands on the welder and the seam finishing work. B, Basic: Use for the requirement of high mechanical properties, average to coarse droplet transfer, poorly detaching slag, possible in all positions, please allow for redrying of … Continue reading Electrode flux types and selection (Part 1)

Wire electrode specifications

Flux-Cored Electrodes’ Usability Designators: What Do They Mean? Q: I am a new salesperson for a welding supply company. I have noticed that the AWS classification number for many of the flux-cored wires we carry are the same on the front end, but then have different dash numbers on the back end. Some example numbers are E71T-1, E71T-8, E71T-9, E71T-11, etc. Some wires even have two or three numbers on them. I have heard these “dash numbers” called performance capabilities numbers. But what exactly do they mean? Also, how can some wires have more than one AWS number? A:  The dash numbers you … Continue reading Wire electrode specifications