CWI welding exam notes
If you have taken or hope to take the CWI exam you probably have searched for some practice exam questions. In practicing for the code book portion of the test you may have come across a few questions for which you could find the answer, but didn’t really understand the importance of the question or the reasoning behind the answer. These are fundamental questions. Ones we constantly have to explain to our customers as part of sound fabrication instruction. So without further ado here they are: Welding shall not be done when the ambient temperature is… Answer: Below 0˚F [-20˚C] … Continue reading CWI welding exam notes
Welding fatigue assessment
Designing for fatigue is very different than designing for static loads. One of the biggest challenges is being able to estimate the loads, timing of the loads and duration of the loads. If you look at a bridge you have to estimate the number of vehicles going on the bridge every day, the weight of these vehicles, and other forces and loads acting on the bridge such as its own weight (steel and concrete), wind loading, and pre-existing stresses such as those caused by welding. Four of the main factors that will affect the fatigue life of a welded structure … Continue reading Welding fatigue assessment
WPS Variables AWS D1.1
A Welding Procedure Specification has several variables which should be carefully specified. The values selected for the variables discussed below have a significant impact on weld soundness and mechanical properties. It is critical that these values be appropriate for the specific requirements of applicable code and job specifications. Some of the most important variables in a WPS are the following. Process – The ideal welding process is that which provides the highest efficiencies while still achieving at the very least the minimum required mechanical properties. Common arc welding processes are SMAW, GTAW, FCAW-S, FCAW-G, GMAW, SAW. Electrode Specification – This is the specification … Continue reading WPS Variables AWS D1.1
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
What is Piping Leak test
LEAK TEST Prior to initial operation, and after completion of the applicable examinations required by para. 341, each piping system shall be tested to ensure tightness. General Requirements for Leak Tests Requirements in para. 345.2 applies to more than one type of leak test. Preparation for Leak Test: 345.3 will be followed as below guide chart: How many Types of LEAK TEST? + Para 345.4 Hydrostatic Leak Test + Para 345.5 Pneumatic Leak Test + Para 345.6 Hydrostatic-Pneumatic Leak Test + Para 345.7 Initial Service Leak Test + Para 345.8 Sensitive Leak Test + Para 345.9 Alternative Leak Test Record: + Para 346 RECORDS Document refer ASME B31.3 – 2019 Continue reading What is Piping Leak test
AMARINE 