Evaluation of Steels for Arctic Line Pipe

High frequency - electric resistance welded (HF-ERW) pipe has been successfully used for many years for a number of applications. The benefits of HF-ERW pipe are considerable, including a higher dimensional tolerance and lower prices than seamless pipe and UO pipe. The conventional weld seam produced by HF-ERW, however, often has a relatively low toughness. We have developed an automatic heat input control technique based on ERW phenomena that relies on optical and electrical monitoring methods and has been shown to result in a significant improvement in the toughness. Shielding of the weld area must also be considered as a key factor in the formation of a sound weld. It has been shown that an inert cold gas (e.g., at room temperature) shielding technique is effective for maintaining a stable low oxygen state in the weld area that inhibits the formation of penetrator, a pancake oxide inclusions. Compared to the cold gas shielding technique, high temperature gas shielding, due to its higher kinetic viscosity coefficient, should make it easier to sustain a higher laminar flow, thus leading to a rather low air entrainment in the shielding gas. In addition, plasma is a much higher temperature state (∼6000 K), and the dissociated gases can react with the entrained oxygen; plasma jets should, therefore, enhance the overall shielding effects. Moreover, oxides on the strip edges can be expected to melt and/or be reduced by the high temperature plasma jets. Nippon Steel has developed a plasma torch that can generate a long and wide laminar argon – nitrogen – (hydrogen) jet. This paper describes the results obtained from our investigation of the effects of a plasma jet shield on the weld area of high strength line pipe with a yield strength grade of X65. Preliminary attempts in applying this novel shielding technique has been found, as expected, to demonstrate extremely low numbers of weld defects and a good low temperature toughness of the HF-ERW seam.

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Validation of EMAT ILI for Management of Stress Corrosion Cracking in Natural Gas Pipelines

Volume 2: Pipeline Integrity Management ◽

10.1115/ipc2014-33545 ◽

2014 ◽

Author(s):

Toby Fore ◽

Stefan Klein ◽

Chris Yoxall ◽

Stan Cone

Keyword(s):

High Resolution ◽

Natural Gas ◽

Stress Corrosion ◽

Stress Corrosion Cracking ◽

Corrosion Cracking ◽

Probability Of Detection ◽

Gas Pipelines ◽

Line Pipe ◽

Natural Gas Pipelines ◽

Electro Magnetic

Managing the threat of Stress Corrosion Cracking (SCC) in natural gas pipelines continues to be an area of focus for many operating companies with potentially susceptible pipelines. This paper describes the validation process of the high-resolution Electro-Magnetic Acoustical Transducer (EMAT) In-Line Inspection (ILI) technology for detection of SCC prior to scheduled pressure tests of inspected line pipe valve sections. The validation of the EMAT technology covered the application of high-resolution EMAT ILI and determining the Probability Of Detection (POD) and Identification (POI). The ILI verification process is in accordance to a API 1163 Level 3 validation. It is described in detail for 30″ and 36″ pipeline segments. Both segments are known to have an SCC history. Correlation of EMAT ILI calls to manual non-destructive measurements and destructively tested SCC samples lead to a comprehensive understanding of the capabilities of the EMAT technology and the associated process for managing the SCC threat. Based on the data gathered, the dimensional tool tolerances in terms of length and depth are derived.

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Niobium Microalloyed Line Pipe Steels: Technological Overview

ASME 2013 India Oil and Gas Pipeline Conference ◽

10.1115/iogpc2013-9828 ◽

2013 ◽

Cited By ~ 1

Author(s):

J. M. Gray ◽

S. V. Subramanian

Keyword(s):

Process Integration ◽

Target Strength ◽

Accelerated Cooling ◽

Pipe Steels ◽

Line Pipe ◽

Steel Technology ◽

Quantitative Understanding ◽

Line Pipe Steel ◽

Low Levels ◽

Evolution Of Microstructure

A quantitative understanding of hierarchical evolution of microstructure is essential in order to design the base chemistry and optimize rolling schedules to obtain the morphological microstructure coupled with high density and dispersion of crystallographic high angle boundaries to achieve the target strength and fracture properties in higher grade line pipe steels, microalloyed with niobium. Product-process integration has been the key concept underlying the development of niobium microalloyed line pipe steel technology over the years. The development of HTP technology based on 0.1 wt % Nb and low interstitial was predicated by advances in process metallurgy to control interstitial elements to low levels (C <0.03wt% and N< 0.003wt%), sulfur to ultra-low levels (S<20ppm), as well as in product metallurgy based on advances in basic science aspects of thermo-mechanical rolling and phase transformation of pancaked austenite under accelerated cooling conditions, and toughness properties of heat affected zones in welding of niobium microalloyed line pipes. A historical perspective/technological overview of evolution of HTP for line pipe applications is the focus of this paper in order to highlight the key metallurgical concepts underlying Nb microalloying technology which have paved the way for successful development of higher grade line pipe steels over the years.

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Heat-treated steels for line pipe and accessories

Metal Science and Heat Treatment ◽

10.1007/bf00673549 ◽

1977 ◽

Vol 19 (7) ◽

pp. 588-596

Author(s):

M. Semchyshen ◽

T. Wada

Keyword(s):

Line Pipe ◽

Heat Treated

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