This paper presents basic information on fusion welding processes used to weld pressure pipes. More specifically, it looks at the technical improvements of the past 20 years. It details the changes to the GMAW process achieved when Lincoln Electric Company introduced the STT GMAW approach, which revolutionized the industry. It then explains how this new GMAW process allowed welding shops to achieve root pass penetration and fusion that rivaled those achieved with GTAW but with much higher productivity and far less experienced welders. The STT also facilitated the automatization of pressure pipe welding. We will show the impact on quality and productivity for carbon steel. This paper results from reviewing several research articles and from shop experiments performed in a welding shop in Hamriyah Free Zone UAE

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.

In-service welding is applied for repairs or modifications for pipelines or pipework/equipment that lead to significant economic advantages by avoiding the costs of disrupting the pipeline’s operation decommissioning, draining of fluid inside piping, purging and it maintaining a continuous supply of products to customers. Moreover, in-service welding on pipelines or piping is uncommon practice due to the high risk caused by excessive heat input during weld or accelerated cooling rates. Referring to API 1104, there are two primary concerns with welding onto in-service pipelines. The first concern is to avoid “burning through,” where the welding arc causes the pipe wall to be breached. The second concern is for hydrogen cracking, since welds made in-service cool at an accelerated rate as the result of the flowing contents’ ability to remove heat from the pipe wall. This paper explores the development of an online welding procedure to weld stainless steel 304L, making branch connections to meet business requirements without disrupting the operation.