Weldable structural steels for fixed offshore structures. Technical delivery conditions

2001 ◽  
Keyword(s):  
Offshore Structures ◽  
Structural Steels

Evaluation of Methods to Predict Safe Welding Conditions and Maximum HAZ Hardness in Steel Welding

1995 ◽  
Vol 117 (1) ◽  
pp. 46-56 ◽  
Author(s):  
J. P. Tronskar
Keyword(s):  
Oil And Gas ◽  
High Strength Steels ◽  
Offshore Structures ◽  
Structural Steels ◽  
Gas Production ◽  
Carbon Equivalent ◽  
Chemical Compositions ◽  
International Institute ◽  
Empirical Formulas ◽  
Offshore Industry

During the last ten years new structural steels of improved weldability have been introduced. In particular, structural steels for the fabrication of offshore structures have been greatly improved in this respect throughout this period. These steels have lean chemical compositions which are generally outside the range for which the existing HAZ hardness criteria and the International Institute of Welding carbon equivalent (CEIIW) formula were originally developed. This paper presents the results from investigations of the weldability of three normalised (Re min 350 MPa) and three quenched and tempered (Re min 500 MPa) offshore structural steels. Weldability testing was conducted to study the relative performance of the different steels and to obtain a comparison between the capability of the different methods to predict safe welding conditions to avoid cold cracking in steel welding. It has become a widespread practice in welding high-strength steels to incorporate maximum HAZ hardness restrictions in fabrication specifications, particularly so in the offshore industry. Maximum HAZ hardness restrictions are often a point of contention between fabricators and their clients due to the difficulties often experienced in meeting these hardness requirements. Problems meeting maximum HAZ hardness requirements have been encountered for applications where maximum hardness HRC 22 or Vickers HV10 260 have been imposed for materials exposed to sour service in oil and gas production, processing and transportation. Many attempts have been made to develop empirical formulas for the estimation of maximum HAZ hardnesses. This paper presents some of the more successful approaches proposed to date and compares their performance.

Rosenhain Centenary Conference - 1. Engineering requirements 1.3 Materials requirements for offshore structures Keynote speech

1976 ◽  
Vol 282 (1307) ◽  
pp. 64-68
Keyword(s):  
Material Selection ◽  
Service Failure ◽  
Offshore Structures ◽  
Structural Steels ◽  
Adhesive Joints ◽  
Notch Toughness ◽  
Public Confidence ◽  
Line Pipe ◽  
Keynote Speech ◽  
Definition Of

Thanks to the careful organization of this conference, the unambiguous definition of its scope, prior circulation of papers, and the example to be followed as outlined by Kelly in his account of the work of Dr Rosenhain, it is possible at this stage to save precious discussion time by addressing the topic of engineering requirements for structural steels almost without preamble. The three papers in this session, on bridges by Harper, line pipe by Mercer, and offshore structures by Cotton, are completely complementary. Thus Harper, although obviously aware of the necessary inhibitions of the bridge designer, arising simply from the need to ensure safe erection, and long operating lives despite the rigours of wear and weather, and the maintenance of public confidence, shows such an open mind that he would consider the use of adhesive joints in future constructions. In so doing he implies the invitation to consider other far reaching ideas that could be introduced. Mercer’s paper is packed with information, in terms of numbers that stretch the imagination. Yet the sources are authoritative, and a fair impression is given of the challenge of pipeline construction to be expected through the next decade. Cotton gives a balanced comparison of the relative merits of concrete and steel offshore structures, not without confirmation that the former embody more steel than the latter. In addition, he mounts a vigorous challenge with regard to existing methods of quantifying notch toughness requirements, ranging from material selection, through fabrication procedures to quality control. He is quite specific in describing particular problems of other types of service failure, in need of the attention of the physical metallurgist

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