Weld overlay, also known as cladding or hardfacing, is a process where one or more metals are joined together via welding to the surface of a base metal (substrate) as a layer. This is usually done to improve the base metal’s durability, corrosion resistance, or other properties. In the case of a steel pipe, a weld overlay can be used to enhance the pipe’s resistance to wear and corrosion.
A common method for weld overlay is a process called Submerged Arc Welding (SAW). In this process, a welding arc is submerged in a flux, which prevents atmospheric contamination. Other methods can include Gas Metal Arc Welding (GMAW), Gas Tungsten Arc Welding (GTAW), and Plasma Transferred Arc Welding (PTAW).
The weld overlay process involves the following steps:
Overall, the weld overlay process can significantly improve the performance and lifespan of a steel pipe, making it a valuable technique in many industrial applications.
Base materials that can be weld overlay:
Base material | standard |
Steel Pipe | API LX series, API 5L Gr.B series, ASTM A53 B series, ASTM A106 series, ASTM A333 GR 6 series, ASTM A312 series, ASTM 671 series, ASTM 691 series |
flange | ASTM A105 series, ASTM A350 series, ASTM A694 series, ASTM A182 series, API K series, ASTM A29 4140 series, etc. |
Pipe fittings | ASTM A234 series, ASTM A420 series, ASTM A860 series, ASTM A516 series, etc. |
Corrosion-resistant materials that can weld overlay:
Welding consumables | Trademark |
Stainless steel | 304, 316L, 321, 347, 310S, 904L, 309L, 317L, S31254, etc. |
F | 625, 825, C22, C276, 400, K500, etc. |
Copper-nickel alloy | B10(C70600), B30(C70500), etc. |
Bronze and copper-nickel alloys | Aluminum bronze, tin bronze, silicon bronze, nickel aluminum bronze, B10 (C70600), B30 (C70500), etc. |
Duplex steel | S31803, S32750, S32760, etc. |
Iron-based alloy | TP405, TP409, TP410, etc. |
Titanium | TA1、TA2、TA3等 |
Cobalt based alloy Stellite | 6, 12, 21, etc. |
Implementation standards:
API Spec 5LD | | Specification for corrosion-resistant alloy composite steel pipes covered or lined |
ANSI/API Spec 6A | | Wellhead and Christmas Tree Equipment Specifications |
ISO 15614-7 | | Metal Material Welding Process Specification and Qualification-Welding Process Qualification Experiment Part 7: Surfacing Welding |
SYT 6623-2012 | | Specification for corrosion-resistant alloy composite steel pipes covered or lined |
NB/T47014 | | Welding process qualification standards for pressure equipment (including corrosion-resistant surfacing welding process assessment, composite metal material welding process assessment) |
ISO 3834-2 | | Quality requirements for fusion welding of metallic materials – Part 2: Complete quality requirements |
NACE MRO175/ISO 15156 | | Oil and gas industry-Hydrogen sulfide-containing environmental materials used in oil and gas extraction |
API PR 582 | | Guide to Welded Pipes for the Chemical, Oil and Gas Industry |
DNV-OS-F101 | | Subsea pipeline system specifications |
API 17D | | Design and operation of subsea production systems – subsea wellhead and Christmas tree design |
API 6D | | Specifications for pipeline and duct valves |
SY/T 7464-2020 | | Corrosion-resistant alloy bimetal composite pipe welding and non-destructive testing technology |
Several different types of filler materials can be used in weld overlay, depending on the desired characteristics of the final product. The selection of a particular filler metal depends on the base metal and the service conditions the final product will be subjected to. Here are some common types of filler materials used in weld overlay for steel pipes:
Remember, the choice of filler material should be based on the application of the pipe, the type of base metal, and the environmental conditions the pipe will be subjected to. The correct choice can improve the lifespan and performance of the steel pipe.