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Inconel 625 Weld Overlay on Carbon/ Alloy Steel Flanges

In mordern oil & gas industry, the crude oil or natural gas are usually extracted from deep layers below the ground. This requies large volume of various piping materials including valves, pumps, flanges, pipes, and fittings. The fluid contains rich content of hydrogen sulfide (H2S), carbon dioxide (CO2), and chloride ion (Cl) which are extremely corrosive and may attack the contact metal surface easily. Pitting corrosion and crevice corrosion are commonly seen under the circumstances.

crevice corrosion in pipeline

Macrostructure of crevice corrosion on the surface of a crude oil pipeline.

Pitting corrosion in pipeline

Macrostructure of pitting corrosion on the surface of a natural gas pipeline.

Pipe flanges, as the main connection components in crude oil or natural gas piping system, are generally furnished in carbon steel or alloy steel materials with corrosion-resistance alloy (CRA) weld overlay on its surface in contact with the fluid. The Inconel Alloy 625 is a prevalent corrosion-resistance alloy that can be used in the weld overlay process. By depositing a thick layer of Inconel 625 (UNS N06625) alloy onto the carbon steel or alloy steel substrate, we impart outstanding resistance to crevice & pittings corrosion, stress corrosion cracking, and oxidation, especially in severe service, while maintaining a relatively low cost. The weld overlay area may cover flange-bore internal surface, raised face, and RTJ face which are in contact with the fluid.

GTAW/TIG equipment for Inconel 625 overlay

GTAW/ TIG equipment for Inconel 625 weld overlay on carbon steel flanges.

The CRA Inconel 625 weld overlay on carbon/ alloy steel flanges can be done by submerged arc welding (SAW), shielded metal arc welding (SMAW), gas tungsten arc welding (GTAW/TIG), plasma arc welding, laser welding, and friction welding. Due to the relatively high dilution rate, corrosion resistance of the deposition may decrease in SAW. The plasma arc welding, laser welding and friction welding require more complex and costly welding equipment. The GTAW/ TIG is the most widely used optimum technique in Inconel 625 weld overly. It provides relatively low cost, stable arc during welding, low-dilution and excellent-quality welding deposition. The filler metal of GTAW shall be ERNiCrMo-3 in accordance with AWS A5.14 or ASME II SFA-5.14. They are furnished in the product form of bare welding rod or welding wire in either straight length, coiled, or spooled style.

Weld neck flange with Inconel 625 weld overlay

A weld neck flange, RTJ 600LB SCH80, ASME B16.5; Inconel 625 weld overlay on the sealing RTJ face and internal bore surface.

Typical sizes of Inconel 625 (ERNiCrMo-3) welding wires available include: Φ0.8mm, Φ0.9mm, Φ1.0mm, Φ1.14mm, Φ1.2mm, Φ1.6mm, Φ2.4mm, Φ3.2mm. Minimum order quantity (MOQ): 1 kg.



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    Hebei Metals Industrial Limited
    (Shijiazhuang Metalsin Pipeline Tech Co., Ltd)
    No. 176, Zhonghua South Street, Shijiazhuang, China.
    Tel: +86-311-89642206