Friction stir welding procedure development was initiated on steel grades S460 G2+M and S690QL1 in plate wall thicknesses of 10 and 15mm. In order to tackle the challenges of the high mechanical loads on the tool as well as its premature wear, a combination of preheating and optimized weld backing set-up was implemented. The inductive preheating allowed a 28% reduction in welding torque and a significant reduction of the tool wear, particularly during the critical initial plunge of the tool within the base material. A comparison of Mo-based and W-based tool was performed, allowing identifying the W-based tool as having a better combination of high temperature strength and wear resistance. Different backing arrangements and materials were investigated. Ceramic backing inlays were used in order to reduce the heat loss at the root area and maintain an acceptable stirring of this zone to achieve full penetration welds. The welds quality was assessed via metallurgical examination, bend tests, and confirmed the possibility to perform sound full-penetration, one-sided welds. The contribution of the preheating to the process as well as the quality and mechanical properties of the welds will be discussed here.
REAFFIRMED IN 2019. Furnishes guidelines that provide corrosion control personnel, owners, operators, designers, manufacturers, and contractors information on corrosion control of prestressed concrete cylinder pipe (PCCP) and mortar-coated steel pipelines for water or waste water service through the application of cathodic protection. The guidelines presented are applicable to new or existing buried pipelines with or without a supplemental coating.
Apart from the well-tried cellulosic electrodes, in the range from E6010-E9010, there are
also low hydrogen grades of weld consumables, which are used in vertical downhill
position - commonly called as BVD (Basic Vertical Down) electrodes. In addition, the
seamless flux cored wires, are gaining prominence in the welding industry as a better
solution compared to the conventional cellulosic electrodes.
The development of BVD electrodes started because of the desire to use high-strength
TM pipe steels with relatively high toughness (e.g. X80). Cellulosic electrodes could not
meet the requirements for cold crack resistance and high toughness properties of the
weld metal. To a high degree, economical efficiency is determined by the achievable
deposition rate and the possible welding speeds. In comparison to basic vertical-up
electrodes, significant time advantage of 40-50% can be achieved with the use of BVD
electrodes for the fill and cap layers.
Seamless Flux Cored wires for pipeline applications follow a different manufacturing
approach compared to the conventional folded techniques and are much reliable with
consistent performance in terms of weldability and quality. The seamless FCAW wires,
offers a unique and trustworthy solution in terms of arc stability and low defect rates.
These wires are also suitable to be used under sour service applications having been
tested for Hydrogen Induced Cracking (HIC) and Sulfide Stress Cracking applications.