Under Pressure Welding on CO2 Pipelines: The Effect of Thermal Decay on Mechanical Properties

2016 ◽  
Author(s):  
Simon Slater ◽  
Julian Barnett ◽  
Peter Boothby ◽  
Robert Andrews
Keyword(s):  
Mechanical Properties ◽  
Natural Gas ◽  
Carbon Capture And Storage ◽  
Cooling Time ◽  
Welding Parameters ◽  
Significant Finding ◽  
Low Carbon ◽  
Dense Phase ◽  
Pressure Welding ◽  
Decay Times

Whilst there is extensive industry experience of under pressure welding onto operational natural gas and liquid pipelines, there is limited experience for Carbon Dioxide (CO2) pipelines, either in the gaseous or dense phase. National Grid has performed a detailed research program to investigate if existing natural gas industry under pressure welding procedures are applicable to CO2 pipelines, or if new specific guidance is required. At IPC 2014 a paper was presented (IPC2014-33223) that dealt with the results from one part of a comprehensive trial program, which defined the cooling time from 250 °C to 150 °C (T250-150) in CO2 pipelines and compared them to the typical decay times for natural gas pipelines. The results from this part of the work identified that maintaining the pre-heat using the established guidance in T/SP/P/9 during under pressure welding on dense phase CO2 pipelines would be very difficult, leading to potential operational issues. The previous paper gave a brief summary of the effect that cooling time had on the mechanical properties. The aim of this paper is to present the findings of the T800-500 weld decay trials in more detail including the full testing programme, detailing the affect that variables such as CO2 phase, CO2 flow velocity and the welding parameters had on the weld and heat affected zone (HAZ) hardness. The main finding is that although there is an indication that a higher cooling rate measured in the weld pool (characterized by the cooling time from 800 °C to 500 °C) leads to increased hardness in the HAZ region, there are no clear correlations. No hardness values were recorded that were considered unacceptable, even for the dense phase CO2 case which delivered the fastest cooling time. A significant finding was the requirement for controlling the buttering run procedure. A discussion of the critical aspects, including the link between weld cooling time and hardness, is presented with guidance on how this essential variables need to be controlled. The paper is aimed at technical, safety and operational staff with CO2 pipeline operators. Read in conjunction, this paper and the previous IPC paper form a comprehensive review of this critical work that is contributing to the development of dense phase CO2 transportation pipelines and will facilitate the implementation of Carbon Capture and Storage (CCS)1 projects which is a critical part of the transition to a low carbon economy.

Under Pressure Operations on Dense Phase CO2 Pipelines: Issues for the Operator

2014 ◽  
Author(s):  
Julian Barnett ◽  
Richard Wilkinson ◽  
Alan Kirkham ◽  
Keith Armstrong
Keyword(s):  
Natural Gas ◽  
Flow Velocity ◽  
Wall Thickness ◽  
Gaseous Phase ◽  
Operating Conditions ◽  
Cooling Time ◽  
Phase Behaviour ◽  
Pipeline System ◽  
Dense Phase ◽  
Pressure Welding

National Grid, in the United Kingdom (UK), has extensive experience in the management and execution of under pressure operations on its natural gas pipelines. These under pressure operations include welding, ‘hot tap’ and ‘stopple’ operations, and the installation of sleeve repairs. National Grid Carbon is pursuing plans to develop a pipeline network in the Humber and North Yorkshire areas of the UK to transport dense phase Carbon Dioxide (CO2) from major industrial emitters in the area to saline aquifers off the Yorkshire coast. One of the issues that needed to be resolved is the requirement to modify and/or repair dense phase CO2 pipeline system. Existing under pressure experience and procedures for natural gas systems have been proven to be applicable for gaseous phase CO2 pipelines; however, dense phase CO2 pipeline systems require further consideration due to their higher pressures and different phase behaviour. Consequently, there is a need to develop procedures and define requirements for dense phase CO2 pipelines. This development required an experimental programme of under pressure welding trials using a flow loop to simulate real dense phase CO2 pipeline operating conditions. This paper describes the experiments which involved: • Heat decay trials which demonstrated that the practical limitation for under pressure welding on dense phase CO2 systems will be maintaining a sufficient level of heat to achieve the cooling time from 250 °C to 150 °C (T250–150) above the generally accepted 40 second limit. • A successful welding qualification trial with a welded full encirclement split sleeve arrangement. The work found that for the same pipe wall thickness, flow velocity and pressure, dense phase CO2 has the fastest cooling time when compared with gaseous phase CO2 and natural gas. The major practical conclusion of the study is that for dense phase CO2 pipelines with a wall thickness of 19.0 mm or above, safe and practical under pressure welding is possible in accordance with the existing National Grid specification (i.e. T/SP/P/9) up to a flow velocity of around 0.9 m/s. The paper also outlines the work conducted into the use of the Manual Phased Array (MPA) inspection technique on under pressure welding applications. Finally, the paper identifies and considers the additional development work needed to ensure that a comprehensive suite of under pressure operations and procedures are available for the pipeline operator.

Under Pressure Welding and Preheat Temperature Decay Times on Carbon Dioxide Pipelines

2014 ◽  
Author(s):  
Simon Slater ◽  
Robert Andrews ◽  
Peter Boothby ◽  
Julian Barnett ◽  
Keith Armstrong
Keyword(s):  
Heat Transfer ◽  
Carbon Dioxide ◽  
Natural Gas ◽  
Cooling Rate ◽  
Gaseous Phase ◽  
Transfer Model ◽  
Dense Phase ◽  
Pressure Welding ◽  
One Dimensional ◽  
Decay Times

Whilst there is extensive industry experience of under pressure welding onto live natural gas and liquid pipelines, there is limited experience for Carbon Dioxide (CO2) pipelines, either in the gaseous or dense phases. National Grid has performed a detailed research programme to investigate if existing natural gas industry under pressure welding procedures are applicable to CO2 pipelines, or if new specific guidance is required. This paper reports the results from one part of a comprehensive trial programme, with the aim of determining the preheat decay times, defined by the cooling time from 250 °C to 150 °C (T250–150), in CO2 pipelines and comparing them to the decay times in natural gas pipelines. Although new build CO2 pipelines are likely to operate in the dense phase, if an existing natural gas pipeline is converted to transport CO2 it may operate in the gaseous phase and so both cases were considered. The aims of the work presented were to: • Determine the correlations between the operating parameters of the pipeline, i.e. flow velocity, pressure etc. and the cooling rate after removal of the preheat, characterised by the (T250–150) cooling time. • Compare the experimentally determined T250–150 cooling times with the values determined using a simple one dimensional heat transfer model. • Define the implications of heat decay for practical under pressure welding on CO2 pipelines. Small-scale trials were performed on a 150 mm (6″) diameter pressurised flow loop at Spadeadam in the UK. The trial matrix was determined using a one dimensional heat transfer model. Welding was performed on a carbon manganese (C-Mn) pipe that was machined to give three sections of 9.9 mm, 19.0 mm and 26.9 mm wall thickness. Trials were performed using natural gas, gaseous phase CO2 and dense phase CO2; across a range of flow velocities from 0.3 m/s to 1.4 m/s. There was relatively good agreement between the T250–150 cooling times predicted by the thermal model and the measured T250–150 times. For the same pipe wall thickness, flow velocity and pressure level, the preheat decay cooling times are longest for gaseous phase CO2, with the fastest cooling rate recorded for dense phase CO2. Due to the fast cooling rate observed on dense phase CO2, the T250–150 times drop below the 40 second minimum requirement in the National Grid specification for under pressure welding, even at relatively low flow velocities. The practical limitation for under pressure welding of pipelines containing dense phase CO2 will be maintaining sufficient preheating during welding. The results from this stage of the technical programme were used to develop the welding trials and qualification of a full encirclement split sleeve assembly discussed in an accompanying paper (1).

scholarly journals Structure and mechanical properties of joint between hard magnetic alloy 25H15K and low carbon steel processed by pressure welding

2015 ◽  
Vol 5 (2) ◽  
pp. 161-164
Author(s):  
A. F. Aletdinov ◽  
G. F. Korznikova ◽  
A. V. Korneva ◽  
R. M. Galeyev ◽  
A. V. Korznikov
Keyword(s):  
Mechanical Properties ◽  
Carbon Steel ◽  
Low Carbon Steel ◽  
Magnetic Alloy ◽  
Low Carbon ◽  
Pressure Welding ◽  
Hard Magnetic Alloy

Prediction of Hardness in Heat Affected Zone of 9%Ni Steel

2012 ◽  
Vol 455-456 ◽  
pp. 406-412 ◽  
Author(s):  
Chun Yan Yan ◽  
Shun Zhen Yang ◽  
Jian Hua Zhao ◽  
Wu Shen Li
Keyword(s):  
Natural Gas ◽  
Heat Affected Zone ◽  
Empirical Equation ◽  
Good Description ◽  
Liquefied Natural Gas ◽  
Cooling Time ◽  
Welding Parameters ◽  
Calculation Results ◽  
Parameters Calculation ◽  
Storage Facilities

Various methods have been introduced to predict postweld hardness of the heat affected zone (HAZ) for 9% Ni steel which is a primary steel adopted in the construction of liquefied natural gas (LNG) storage facilities. Two models were derived for the evaluation of the HAZ hardness, and then validated. The formulae developed in this investigation are sufficient to predict the hardness of the HAZ for 9% Ni steel . For the model using a rule of mixture, it is suggested that the morphology of martensite should be taken into consideration. Since the prediction of hardness depends on the calculation of the critical cooling time and hardness of microstructural constituents, a formula to estimate the hardness of martensite in HAZ was given. For empirical equation relating welding parameters, calculation results were found to give a fairly good description of the postweld HAZ hardness.

Cooling Curve Based Estimation of Mechanical Properties in High Strength Steel Welds

2016 ◽  
Vol 879 ◽  
pp. 1760-1765 ◽  
Author(s):  
Rahul Sharma ◽  
Uwe Reisgen
Keyword(s):  
Mechanical Properties ◽  
Welding Process ◽  
High Strength Steels ◽  
High Strength ◽  
Structural Steels ◽  
Cooling Time ◽  
Cooling Curve ◽  
Welding Parameters ◽  
Steel Welds ◽  
Welding Processes

The application of high strength steels in welded structures relies on easy to use quality assurance concepts for the welding process. For ferritic steels, one of the most common methods for estimating the mechanical properties of welded joints is the cooling time concept t8/5. Even without experimental determination, the calculation of cooling time with previously introduced formulas based on the welding parameters leads to good results. Because high strength structural steels and weld metals with a yield strength of 960 MPa contain higher quantities of alloying elements, the transformation start temperature Ar3 is found to be outside of the range of 800 °C to 500 °C. This leads to inadequate estimation results, as the thermal arrest caused by the microstructural transformation in this case is not considered. In this work the usage of the well-proven cooling time concept t8/5 is analyzed using high strength fine grained structural steels and suitable welding filler wires during gas metal arc and submerged arc welding processes. The results are discussed taking into account the microstructure and the transformation behavior. Based on the experimental work, an improved concept is presented.

scholarly journals Low carbon renewable natural gas production from coalbeds and implications for carbon capture and storage

2017 ◽  
Vol 8 (1) ◽  
Author(s):  
Zaixing Huang ◽  
Christine Sednek ◽  
Michael A. Urynowicz ◽  
Hongguang Guo ◽  
Qiurong Wang ◽  
...  
Keyword(s):  
Natural Gas ◽  
Carbon Capture ◽  
Carbon Capture And Storage ◽  
Gas Production ◽  
Low Carbon ◽  
Natural Gas Production ◽  
Renewable Natural Gas ◽  
And Storage

scholarly journals EFFECTS OF WELDING CURRENT ON THE SHAPE AND MICROSTRUCTURE FORMATION OF THIN-WALLED LOW-CARBON PARTS BUILT BY WIRE ARC ADDITIVE MANUFACTURING

2020 ◽  
Vol 58 (4) ◽  
pp. 461
Author(s):  
Van Thao Le ◽  
Quang Huy Hoang ◽  
Van Chau Tran ◽  
Dinh Si Mai ◽  
Duc Manh Dinh ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Additive Manufacturing ◽  
Carbon Steel ◽  
Low Carbon Steel ◽  
Welding Current ◽  
Welding Parameters ◽  
Low Carbon ◽  
Microstructure Formation ◽  
Thin Walled ◽  
Wire Arc Additive Manufacturing

Wire arc additive manufacturing (WAAM) is nowadays gaining much attention from both the academic and industrial sectors for the manufacture of medium and large dimension metal parts because of its high deposition rate and low costs of equipment investment. In the literature, WAAM has been extensively investigated in terms of the shape and dimension accuracy of built parts. However, limited research has focused on the effects of welding parameters on the microstructural characteristics of parts manufactured by this process. In this paper, the effects of welding current in the WAAM process on the shape and the microstructure formation of built thin-walled low-carbon steel components were studied. For this purpose, the thin-walled low-carbon steel samples were built layer-by-layer on the substrates by using an industrial gas metal arc welding robot with different levels of welding current. The shape, microstructures and mechanical properties of built samples were then analyzed. The obtained results show that the welding current plays an important role in the shape stability, but does not significantly influence on the microstructure formation of built thin-walled samples. The increase of the welding current only leads to coarser grain size and resulting in decreasing the hardness of built materials in each zone of the built sample. The mechanical properties (hardness and tensile properties) of the WAAM-built thin-walled low-carbon steel parts are also comparable to those of wrought low-carbon steel, and to be adequate with real applications.

scholarly journals Study the effect of Welding Current on the microstructure and strength of dissimilar weld joint AISI 303/AISI 1008

2021 ◽  
Vol 14 (1) ◽  
pp. 67-75
Author(s):  
Firas Hameed
Keyword(s):  
Mechanical Properties ◽  
Low Carbon Steel ◽  
Welding Current ◽  
Optical Microscope ◽  
Welding Parameters ◽  
Welding Time ◽  
Low Carbon ◽  
Dissimilar Weld ◽  
Steel Aisi ◽  
Joint Quality

The welding of metals is one of the most important processes that require high control for obtaining a good quality of weldments. The joining of dissimilar metals is a more complex operation compared to the joining of similar metals due to the differences in physical metallurgical and mechanical properties. In this article, austenitic stainless steel AISI 303 stud was welded to low carbon steel AISI 1008 plate using arc stud welding (ASW) process. An experimental procedure was applied to estimate the effect of welding parameters namely welding current and welding time on the microstructure and mechanical properties of the joint. The optical microscope V83MC50 was used to show microstructure properties while both the micro-Vickers Hardness and tensile test were adopted to evaluate the mechanical properties. The results revealed that the presence of carbides at the fusion zone FZ towards AISI 303 leads to the maximum value of hardness (501) HV. The best welding parameters were 600 AMP 0.25 second at which joint strength of 515 MPa was recorded. Welding time was the most important parameter in the ASW process followed by welding current, proper selection of welding time, and current welding produces good joint quality

The Mechanical Properties of 20MnSi Steel and Welding Research

2013 ◽  
Vol 281 ◽  
pp. 395-399
Author(s):  
Qing Hui Wang ◽  
Hua Wu ◽  
Tao Chen
Keyword(s):  
Mechanical Properties ◽  
Uniform Elongation ◽  
Controlled Rolling ◽  
Welding Parameters ◽  
Performance Tests ◽  
Controlled Cooling ◽  
Pressure Welding ◽  
Transmission Electron ◽  
Mechanics Performance ◽  
Welding Joints

The microstructure, mechanical properties, precipitation of micro alloying elements and welding performance of self-designed 20MnSi steel were investigated, by means of metallographic microscope , transmission electron microscope, electroslag pressure welding and mechanics performance tests, etc.The results show that,with the actions of microalloy V and controlled rolling and controlled cooling technique, tensile strength (Rm) and yield strength (Rel) of the test bar could respectively reach 730 MPa and 560 MPa, uniform elongation (Agt %) of 13.5%, which has met the seismic performance index. And we found that a lot of dispersion particle V (CN) precipitated in the ferritic matrix and grain boundary place, which have a good precipitation strengthening and refining grain effect. In addition, based on the welding parameters reasonable controlling, it can make the mechanical properties of welding joints changes not beyond the design range, and satisfy the use requirement.

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