Welding tehnology for steel P460NL2

Abstract

This paper presents the development of welding technology for P460NL2 steel with a thickness of 30 mm. The technology was developed for the purpose of producing housings in which the device PIG-Pipeline Inspection/Intervention Gauge intended for testing and maintenance of pipelines is installed. In this particular case, the housings were intended for cleaning pipelines for the transport of acid-aggressive gases. The material was selected in accordance with NACE MR0175/ISO 15156 and ASME BPVC IKS standards. The welding technology is made for butt joint, root pass with GMAW, and other layers filled with SAW. Preheating and heat treatment after welding were performed to restore the structure. Standard tests are conducted such as: metallography, hardness test, tensile test and toughness, and the results are presented and commented in this paper. In conclusion, the welding technology gives satisfactory results, but, in terms of meeting the specifics of the NACE MR0103 and MR0175 standards, it shows increased hardness in the transition zone, in the HAZ.