Abstract The axial resistance of pipelines is an important design input, influencing a variety of analyses such as buckling and axial walking. As such, accurate assessment of the frictional behaviour of the soil-pipeline interface is necessary to properly model axial behaviour. Smooth polymer coated pipelines are commonly used subsea, yet despite their common application, limited guidance exists in the main governing standards concerning the expected level of axial friction to be used in design. Related guidance that does exist (e.g. BSI, 2016) suggests a minimum friction coefficient of 0.55 for sand-pipeline interfaces. This paper reviews various aspects of sand-polymer direct shear interface testing that must be considered and presents the results of some experimental research TechnipFMC have undertaken in collaboration with the University of Bristol. These results indicate that a sand-pipeline friction coefficient of 0.55 is often unrealistic for smooth polymer coated pipelines and in many design scenarios a lower frictional coefficient is more appropriate. The experimental test program considered the main factors believed to influence axial friction of smooth polymers on sand including D 50 grain size, sand density and a range of stress levels (including the low stresses expected for subsea pipelines). All tests were conducted fully saturated to mimic subsea conditions and the roughness of the pipe coating samples was thoroughly characterised. TechnipFMC project experience has found that use of lower axial friction is sometimes beneficial (e.g. axial feed-in to trigger buckle initiation). In other cases, a higher axial friction may be better for design (e.g. limiting axial walking). Being able to better characterise the friction range is therefore important to ensure a robust design and to assist in avoiding more costly mitigation measures where they may not actually be needed.

Abstract Offshore pipeline projects have been expanded to deeper water region and the linepipes are required to have higher resistance against collapse by external pressure. The collapse resistance is mainly dominated by pipe geometry and compressive yield strength. For deep water application, diameter to thickness ratio (D/t) and pipe roundness are key factors. On the other hand, the mechanical properties in each circumferential position is dramatically changed by cyclic deformation through a pipe forming process. Therefore, in order to improve compressive yield strength of pipes, it is important to consider the Bauschinger effect caused by pipe expansion. The mechanism of this effect is understood that internal stress is generated by accumulation of dislocation and it reduces reverse flow stress. In this study, the microscopic deformation behavior was analyzed from FEM calculation, it was found that multi-phases microstructure enhanced the microscopic heterogeneous deformation adjacent to the boundary between soft and hard phases. Therefore, homogenized microstructure inhibits the Bauschinger effect. In addition, the materials of offshore pipeline should have other properties such as low temperature toughness and sour resistance. It is well known that fine grained microstructure improves the lower temperature toughness. For achieving high compressive yield strength and good lower temperature toughness, the effect of chemistry and rolling condition were investigated to obtain fine and homogeneous microstructure. Based on laboratory results, mill trial tests were carried out for Grade X65 linepipes with heavy gauge by TMCP. Full scale collapse test was also conducted after pipe coating heating. In this paper, material design concept and its mechanical properties of developed pipes were introduced.

Abstract As offshore pipeline projects have expanded to deeper water regions with depths of more than 2,000 m, linepipes are required to have higher resistance against collapse by external pressure. Collapse resistance is mainly controlled by the pipe geometry and compressive yield strength. In UOE pipe, the compressive yield strength along the circumferential direction changes dramatically due to tensile pre-strain that occurs in pipe forming processes such as the expansion process. In order to improve the compressive yield strength of pipes, it is important to consider the Bauschinger effect caused by pipe expansion. As the mechanism of this effect, it is understood that internal stress is generated by the accumulation of dislocations, and this reduces reverse flow stress. Compressive yield strength is also changed by the thermal cycle associated with application of fusion-bond epoxy in pipe anti-corrosion coating by the induction heating process. In the typical thermal heat cycle of this coating process, the maximum heat temperature is from 200 °C to 250 °C. In this case, compressive yield strength increases as an effect of the thermal cycle, resulting in increased collapse resistance. Thus, for deep water application of UEO linepipe, it is important to clarify the conflicting effects of the Bauschinger effect and the thermal heat cycle on compressive yield strength. Based on this background, in this study, the combined effect of the Bauschinger effect and the thermal heat cycle on compressive stress is investigated by conducting tensile pre-strain tests and simulation of the thermal cycle associated with coating. Compressive yield strength was obtained for several pre-strain and thermal cycle conditions, and the collapse pressure was calculated by an FE analysis based on the obtained compressive yield strength. This study discusses the effect of tensile pre-strain on the collapse pressure of linepipes with these simulated thermal heat cycles.

The increasing of deepwater oil field developments brings a growing need for thermal management to prevent hydrate and wax formations in the subsea production system, due to the low environment temperature and long distance transportation. Pipeline insulation coating is a typical strategy for thermal management. In a subsea production system, pressure, temperature, flow rate and length of each flowline vary, leading to a different thermal performance of the fluid inside. Therefore, the insulation coating should be carefully designed from the overall perspective to minimize the total material volume, thus reducing the cost. In this paper, an optimization model for the insulation material volume of a wellhead-manifold-FPSO production system is proposed. Then, the best insulation thickness of each sub-sea flowline can be determined under given flow parameters and temperature requirements. The factor that defines the temperature drop from riser base to the top termination is introduced and analyzed. There is a proper temperature drop factor associated with the insulation material volume for subsea flowlines, as well as a proper insulation capacity for the risers. This optimization model can define the subsea system insulation and provide reliable results for cost estimation.

The TurkStream pipeline project is designed to transport approximately 32 billion cubic meters of natural gas annually from Russia to Turkey under the Black Sea, with more than 85% of the deep-water route being deeper than 2000 m. The offshore section is intended to consist of two parallel lines, each approximately 900 km long. The preliminary stages of the front end engineering design (pre-FEED) phase was managed by INTECSEA. To support the analyses and design of the deepest portions, a full scale collapse test program was performed by C-FER Technologies (C-FER). This collapse test program, which included 62 full-scale collapse and pressure+bend tests, 54 medium-scale ring collapse tests, and hundreds of small-scale tests, was primarily aimed at measuring, quantifying and documenting the increase in pipe strength and collapse resistance resulting from the thermal induction heat treatment effect (thermal ageing) that arises during the pipe coating process. Two grades of 32-inch (813 mm) outside diameter (OD) line-pipe, SAWL450 and SAWL485 with wall thicknesses of 39.0 mm or 37.4 mm, respectively, were supplied from various mills for testing. The collapse test program objectives were as follows: • Determine the collapse resistance of line pipes originating from various pipe mills; • Determine the pressure+bend performance of line pipes originating from various pipe mills; • Measure the effect of thermal ageing on material and collapse testing results, including the impact of multiple thermal cycles; and • Evaluate the results of medium-scale ring collapse tests as compared to full-scale tests. This paper presents selected results of this work, along with some comparisons to predictive equations.

Current design practice limits the concrete strain to approximately 0.2% in a simplified design criterion. In most standard cases, this has proved to be safe and adequate. However, in recent years, the pipeline industry is extending into more remote, harsher environments and larger diameter pipelines. The use of the simplified design criterion has, in some circumstances, resulted in too strict installation requirements which limit the number of relevant installation vessels. This paper presents some findings on the concrete strain for submarine pipelines with concrete weight coating (CWC) derived from the numerical program performed within the scope of Phase 1 of the joint industry project “Design of concrete coating for submarine pipelines”. Non-linearities in the concrete weight coating, anti-corrosion coating (ACC) and steel material properties, as well as large deformation and the sequence of load application were included in the numerical model. The results from the numerical analyses have been well validated against existing experimental data, and the numerical model was subsequently used in an extensive parametric study, where the behaviour of concrete coated pipelines was investigated for monotonic and reversed bending with nominal strain up to 0.4%. These numerical results can be used to widen the applicable range of the simplified concrete crushing criterion in DNVGL-ST-F101 (2017), and to formulate a rational approach for the design of pipeline concrete weight coating under typical installation and operation conditions. The rational design approach will allow for a wider range of installation vessels to select from for installation of the pipeline, and relaxation of the installation weather window criterion.

This paper aims to perform a numerical analysis of application effects of a superhydrophobic paint by completely coating the blades of a model-scale marine propeller in order to make it a superhydrophobic surface (SHS). First, a two-dimensional study was conducted. Two foils were analyzed for several hydrophobic conditions, varying the slip length. Pressure and skin friction distributions were shown. There is an increase of lift-to-drag ratio with hydrophobicity, but followed by an increase in suction pressure. In three-dimensional case, a propeller was simulated for several hydrophobic conditions, comparing thrust, torque and efficiency coefficients and pressure and friction distribution. Results with propeller showed that an increase in slip length is not always followed by an increase in efficiency, with an apparent efficiency gain limit. For the imposed simulation conditions, from the limit of gain, efficiency no longer increases with hydrophobicity, but its area of low pressure continues to grow.

A good coating is one with high performance and durability; has a low surveillance and maintenance requirement; is easily applied with no health risks and finally is cost effective. It is unlikely that a single type of coating would be able to satisfy all these needs. Thus, a decision support tool is needed to help identify the most appropriate choice. This paper presents three simple methods for this selection process, and allows the judgment of more than one expert to be aggregated in order to reach a consensus. An example is presented which demonstrates the application of these methods, by providing the decision-maker the ability to weigh options and set priorities in deciding on the best compromise solution for a corrosion coating material.

This paper presents a numerical model that is used to estimate the structural response of a submarine pipeline with concrete weight coating subjected to loadings commonly encountered in pipeline installation and operation phases. Findings from parametric studies performed with the numerical model are used to widen the applicable range of the simplified concrete crushing criterion in DNV-OS-F101 (2013) and formulate a rational approach for the design of pipeline concrete weight coating under typical installation and operation conditions. The rational design approach will allow for potential selection from a wider range of installation vessels and relaxation of the installation weather window criterion. The design method also provides insights into the strain concentration in the field joint at different strain levels, which is used to assess the field joint welding integrity for pipeline in free spans and in high strain conditions. The numerical model considers nonlinearities in steel and concrete material stress and strain, as well as complex adhesive behaviour of the anti-corrosion coating. Good agreement is obtained between the numerical results and existing experimental data for all the sections along the pipeline model where comparisons are made on moment–strain global behaviour, sliding from the concrete coating, hot spot strain near the field joint and concrete strain. The numerical program is performed within the scope of Phase 1 of the joint industry project called “Design of concrete coating for submarine pipelines”. Laboratory tests to check and improve the numerical model are planned for Phase 2.

Accidents by trawling impact have the potential of environmental consequences, in terms of safety, monetary values and reputation. Aware of this situation a technology development plan on “Pipeline subject to high interference loads” has been established at STATOIL in close collaboration with GASSCO. The overall achievement is to adapt and introduce more reliable assessment methods in the load and response of pipelines under a trawling impact scenario. Polymeric coating systems have been manly designed and used as thermal isolating material for flow assurance; and little attention has been addressed to mechanical benefits to dissipate energy by large deformation. This property is of special interest to handle impact events typically found during the trawl board impact scenario. The experimental results show the beneficial effect of polymeric coating to protect the steel pipe against indentation when compared to an uncoated system. The results presented in this work focus on new developed analytical expressions to predict the force-dent response of polymeric coated steel pipes using a numerical-experimental research methodology. The proposed equations are validated against experimental tests and the findings indicate fairly good predictions.

This paper presents the design and development of a friction-based coupling device for a fiber-optic monitoring system capable of measuring pressure, strain, and temperature that can be deployed on existing subsea structures. A summary is provided of the design concept, prototype development, prototype performance testing, and subsequent design refinements of the device. The results of laboratory testing of the first prototype performed at the National Aeronautics and Space Administration (NASA) Johnson Space Center (JSC) are also included. Limitations of the initial concept were identified during testing and future design improvements were proposed and later implemented. These new features enhance the coupling of the sensor device and improve the monitoring system measurement capabilities. A major challenge of a post-installed instrumentation monitoring system is to ensure adequate coupling between the instruments and the structure of interest for reliable measurements. Friction-based devices have the potential to overcome coupling limitations caused by marine growth and soil contamination on flowlines, risers, and other subsea structures. The work described in this paper investigates the design and test of a friction-based coupling device (herein referred to as a friction clamp) which is suitable for pipelines and structures that are suspended in the water column as well as for those that are resting on the seabed. The monitoring elements consist of fiber-optic sensors that are bonded to a stainless steel clamshell assembly with a high-friction surface coating. The friction clamp incorporates a single hinge design to facilitate installation of the clamp and dual rows of opposing fasteners to distribute the clamping force along the structure. The friction clamp can be modified to be installed by commercial divers in shallow depths or by remotely operated vehicles in deep-water applications. NASA-JSC was involved in the selection and testing of the friction coating, and in the design and testing of the prototype clamp device. Four-inch diameter and eight-inch diameter sub-scale friction clamp prototypes were built and tested to evaluate the strain measuring capabilities of the design under different loading scenarios. The testing revealed some limitations of the initial design concept, and subsequent refinements were explored to improve the measurement performance of the system. This study was part of a collaboration between NASA-JSC and Astro Technology Inc. within a study called Clear Gulf. The primary objective of the Clear Gulf study is to develop advanced instrumentation technologies that will improve operational safety and reduce the risk of hydrocarbon spillage. NASA provided unique insights, expansive test facilities, and technical expertise to advance technologies that will benefit the environment, the public, and commercial industries.

Concrete Weight Coating is used in offshore industry to provide for pipeline vertical and lateral stability against waves and currents and to guarantee protection against fishing activities. Reinforced concrete coating of adequate strength, especially in case of thick coatings for stringent in-place stability requirements, entails additional bending stiffness and consequently strain concentration at field joints, thus significantly affecting the state of stress and strain on the pipe steel during laying firstly, and then during operations. Attention of the offshore pipeline industry has been focused in the development of experimental and theoretical activities in a more scientific way, which aimed to satisfy the need of a better knowledge in this field. Both analytical and FEM solutions are available in the free literature and relevant standards to predict the contribution of concrete coating layer on global pipeline strength and deformation capacity and simplified threshold values for the concrete damage are provided, as well. Generally, for installation analysis purpose, a pipeline with equivalent mechanical behavior (bending moment-curvature relationship) and physical (weight) properties is used in installation and operation analyses. No assumptions are typically made on concrete damage evolution to evaluate the decay of pipe capacity beyond the elastic range. In this paper new advances in modelling the mechanical behavior of concrete coated joints are discussed. In particular an advanced ABAQUS finite element model is proposed to take into account the effect of concrete coating damage on the overall capacity. The following effects have been accounted: • Non-linear stress-strain relationship of the steel at large usage factors/curvatures on the strain concentration at the field joint. • Concrete coating damage evolution on global pipeline bending stiffness. In this paper: • The state-of-the-art about published materials, numerical studies and design approaches on concrete material modelling and concrete coated pipes is briefly presented; • A FEM based analysis methodology is drawn and proposed for the strength and deformation capacity assessment of a concrete coated pipe; • The FEM model is calibrated on available full scale tests; • The results of a project case study performed with ABAQUS FE Model are given.

The process piping on subsea production systems (SPS) is normally made of solid corrosion resistant alloys (CRAs). However, some process components are made of low alloyed steels (LASs) which are internally cladded with a CRA. These components require post weld heat treatment (PWHT) to improve the properties in the LAS heat affected zone (HAZ). In order to avoid PWHT during on-site welding to adjoining piping systems, it has been common to weld a buttering layer (e.g. 15 – 20mm long) on to the connecting end of the LAS. The buttering layer consumable has traditionally been an austenitic nickel alloy, Alloy 625/725. The LAS HAZ and the buttering layer are thereafter PWHT’d and machined prior to on-site welding to the adjoining piping system. By this, it is not necessary to perform PWHT on the on-site (e.g. tie-in or closure) dissimilar welds. In the beginning of the century, some operators experienced cracking along the fusion line interface between the nickel alloy buttering and the LAS. These problems were typically experienced during start-up or prior to first production. An extensive research programme was established in order to determine the causes and remedial actions. A group sponsored project led by TWI was performed to understand the failure mechanisms and essential parameters leading to hydrogen assisted cracking, (HAC) of dissimilar metal welds (DMWs). Recommendations were made related to LASs chemistry, welding parameters, bevel geometry and especially PWHT time and temperature. Based on these recommendations there have been only a few incidents with cracking of such welded combinations before 2013 and onwards. Since then Statoil has experienced four off incidents with cracking of dissimilar welds on subsea LAS components. Common for these incidents are that they have been in operation for about 15 years and the cracking happened during cold shut-down periods. This paper presents key observations made and lessons learnt from the incidents summarized above. The main focus has been on environmental fracture mechanics-based testing of samples charged with hydrogen by cathodic protection (CP). Variables have been pre-charging temperature and time, as well as testing temperature. The testing has revealed strong dependency between the operating temperature (i.e. shutdown versus operation) and the sensitivity to HAC. Further, the investigations have shown that the integrity of the coating, as an effective barrier to hydrogen ingress, is the main feature to prevent HAC on this kind of DMWs. The investigation of the four off cracked welds showed clearly that the insulating polyurethane (PU) coating was heavily degraded by hydrolysis at higher temperatures. This exposed the dissimilar weldments to CP which contributed to the hydrogen charging of the weldments. The paper gives also result that show that it is not only PWHT’d LAS (e.g. type 8630M, 4130 and F22M) with dissimilar welds that may suffer from this failure mechanism. Testing has shown that as-welded F65 steel /Alloy 59 combinations may also suffer when charged with hydrogen and tested at low temperatures (e.g. shut down temperature).

Offshore pipelines are occasionally subjected to accidental impact loads from trawl gear or anchors, which may damage the pipeline. This study reports the results of material and component tests carried out on offshore steel pipes and an adhering polymer coating. The polymer coating is primarily applied for corrosion protection and thermal insulation. Despite not necessarily being designed for it, the polymer coating does have some structural capacity, and it is this capacity that is the main topic of investigation herein. In design codes and guidelines, coating is traditionally not accounted for when determining the energy absorbed by a pipeline during impact. This makes the estimates provided overly conservative. The goal of this experimental work is then to investigate whether a typical polymer coating makes any significant contribution to the energy absorption properties of a pipeline cross-section during impact. To this end, both dynamic and quasi-static denting tests of full-scale pipe cross-sections are carried out. All pipes tested have a length of approximately 1 m. The sharpest indenter from the guidelines is used, as a sharper indenter is more likely to penetrate compared with a blunter one. Based on the tests, the polymer coating can absorb a notable part of the kinetic energy delivered to the system. More tests with different coating and pipe thicknesses are needed to quantify this effect.

This paper presents a study of traditional netting materials subjected to disinfecting chemicals during fish farming and treatment of net cages. A series of tests were performed in order to study the effect of various concentrations of disinfecting chemicals on the tensile strength of Raschel knitted Nylon netting materials. Simulated spill of diluted hydrogen peroxide to the jump fence during de-lousing did not affect the strength of the applied new and used knotless nylon netting samples. Hydrogen peroxide reacted with biofouling forming gas bubbles, but this did not result in reduced netting strength. The performed tests did not indicate any effect on netting strength from a simulated single, traditional bath disinfection as performed at service stations applying the disinfectant Aqua Des containing peracetic acid. However, increasing the Aqua Des concentration from 1 to 10 % resulted in a strength reduction of 3–6 %. Simulated spill of concentrated Aqua Des on the jump fence of a net with copper coating residuals resulted in a severe reduction in strength of 45 %. This strength loss was probably a consequence of chemical reaction between copper and Aqua Des, and uncoated netting did not experience any loss in strength subjected to the same chemical exposure. These findings from application of Aqua Des should also apply to other peracetic acid disinfection chemicals with trade names as for example Perfectoxid and Addi Aqua.

The expansion of umbilical functionality to include power cables and high temperature fluid transportation (for applications such as gas lift) has led to the requirement for a high temperature steel tube riser umbilical, as shown in Figure 1. The combination of the elevated temperature and the dynamic service conditions create a unique design brief for steel tube umbilicals. The following paper presents a case study evaluating a steel tube riser umbilical capable of transporting hot gas at 70°C from an FPSO to a well head at approximately 800m water depth. The material selection for the steel tube is super duplex stainless steel (SDSS) and due to the high temperature, the corrosion resistant coating selected to ensure corrosion resistance in seawater at 70°C is fusion bonded epoxy protected with a bonded polypropylene outer layer (3LPP). The fatigue performance of the dynamic steel tube umbilicals is highly dependent on the frictional loads between the components developed due to tension and bending. This loading is most critical in the bend stiffener location at the riser umbilical’s interface with the FPSO structure. The fatigue critical component is usually determined to be one of the super duplex steel tubes within the umbilical. The frictional loads are a function of the coefficient of friction between the interacting components and the contact load developed between the layers of helically wound components. This contact load increases with tension. The paper considers the effects of the polypropylene material selection and the elevated operating temperature on the friction interface between the steel tubes. The work assesses the corresponding change in fatigue damage through the service life in comparison to more common temperatures and materials used in dynamic steel tube umbilicals. Changes in contact load between elements of a friction interface are known to affect the friction coefficient. The contact load across all interfaces has been varied to help understand how the coefficient of friction may be affected by different tensile loads or umbilical designs. Including this variable in the test program also ensures that the friction is quantified at a contact load relative to the design case considered. To assess the differences in friction a scope of component level friction testing is presented and the results are processed through umbilical local fatigue analysis software to establish the implications on fatigue performance. The umbilical structure is designed to free flood in between the components in service, and the bend stiffener region is submerged for the design case in question. Full scale flex-fatigue testing of the dynamic umbilical and the bend stiffener are however conducted in a dry environment. The impact of this on the severity of the test and in comparison to the in-service condition are assessed using component level wet and dry testing to provide changes in friction for sensitivity analysis. In addition to the loading on the tubes, the fatigue performance of the material being loaded is also considered. the fatigue performance of welded super duplex tubing has previously been tested and documented at ambient room temperature conditions and therefore the effect on the welded steel tube fatigue performance due to the increase in temperature for this application has been quantified to ensure the proposed design curve is suitable. cyclic bending stress experienced by the steel tubes during dynamic service (2).

The early response of coated circular plates subjected to near-field underwater explosion in the experiment (Chen et al., 2015, Marine Structures, 40, pp. 247–266) is simulated using a numerical solver that coupling the Runge-Kutta discontinuous Galerkin method to the finite element method (RKDG-FEM), in which the interactions of the gas bubble, shock waves, deformable structures and cavitation are taken into account. The coupling procedure is based on the modified ghost fluid method with special treatments for the RKDG method. Good agreements are observed between the numerical results and the experimental results of the bare steel plate, the steel plate coated with rubber and the steel plate coated with foam. The calculations show that the soft coating material can reduce the pulse width of the pressure load and the foam coating has a superior protective performance.

A simulation method for under-film corrosion has been developed for epoxy coated steel panels within a ship’s Water Ballast Tank (WBT) environment. The incubation and extension of coating failure is simulated by using two-dimensional cellular automaton, and the steel diminution is simulated by modifying IACS CSR-H’s 3-phases probabilistic model. Analysis parameters are determined by using the results of onboard exposure and cyclic corrosion tests performed by Shiotani et al. (2012, 2015). The change in corroded surface shape of epoxy coated scribed steel panels made of conventional steel and corrosion resistant steel (CRS) exposed in an ore carrier’s WBT for 4.8 years is simulated. The simulated coating deterioration (blister) area and the corroded surface profile agree well with those measured. This demonstrates the effectiveness of the developed simulation method and the determined parameters. The differences in analysis parameters between conventional steel and CRS suggest that CRS can reduce the harmful effect of the active corrosion region on the remaining coating life at the blister’s frontline and the corrosion under the blister.

In order to improve the corrosion resistance of the drill pipe, the alumina ceramic membrane is coated on the surface of aluminum alloy drill pipe of offshore platform by micro arc oxidation technology. This paper mainly focuses on the experimental work to determine the effect of the nano-MoS 2 content in the solution on the micro morphology, element content and corrosion resistance of the coating. The results show that the amount of nano-MoS 2 particles has big influence on the making of micro-arc oxidation (MAO). The thickness of MAO coating is increased with the adding of nano-MoS 2 particles. Besides, the size of the coating is first increased then decreased, and the surface of coating become more compact and smooth with the increase of the amount of nano-MoS 2 particles. Also, the corrosion resistance of MAO coating is improved as the amount of MoS 2 increases. The corrosion rate is decreased from 0.032g.m −2 .h −1 to 0.024g.m −2 .h −1 when the addition amount of nano-particles increased from 0.5g/L to 2g/L.

One of the major concerns in terms of Structural Integrity for Steel Catenary Risers (SCR) or Fatigue Sensitive Flowlines (FSFL) consists on their strength to withstand dynamic loading along their service life. SCR and FSFL systems always experience more considerable fatigue loading due to floating structures adopted for deep and ultra-deep water oil and gas recovery, as well as for free spanning due to seabed geography and marine currents. In this context, a Double Joint (DJ) Welding Procedure Specification (WPS) has been developed to comply with stringent fatigue requirements, as well as to assess their actual fatigue behavior. The benefits of having DJ are: improving the installation time (S-lay, J-lay or reel-lay) having half of the welding joint performed out of the firing line and reducing the need of Field Joint Coating by two, which results on decreasing project’s cost. This DJ development is focused on a more productive WPS applicable for sour service environments and fatigue endurance requirements considering a Narrow Groove (NG) with J-Bevel design, STT ® root pass, SAW for fill and cap passes in 1G welding position. The obtained WPS results are presented on an X65 Steel pipe grade, 273.1 mm OD and 25.4 mm WT.