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Steel Pipes

CRA cladded pipes

What are CRA Cladded Pipes?

CRA refers to corrosion-resistant alloy. The CRA cladded steel pipe is composed of a conventional carbon steel or low alloy steel pipe and a corrosion-resistant alloy layer. The CRA layer is metallurgically bonded (cladded) to the internal or external surface of the steel pipe. The carbon steel or low alloy steel pipe is called base metal, or backing steel.

The CRA layer is usually called cladding material. This is economically favorable for large-diameter heavy pipelines since the relatively much thinner CRA layer not only retains enhanced corrosion-resistant properties but also reduces the cost to the minimum. The CRA clad steel pipes are widely used in pipeline transportation systems in the petroleum and natural gas industries. They are also extensively used for marine applications, chemical plant, and power plant, etc.

CRA cladded steel pipe

The carbon steel or low alloy steel pipe is called base metal, or backing steel. The CRA layer is usually called cladding material or lining. This is economically favorable for large-diameter heavy pipelines since the relatively much thinner CRA layer not only retains enhanced corrosion-resistant properties but also reduces the cost to the minimum.

The CRA cladded steel pipes are widely used in pipeline transportation systems in the petroleum and natural gas industries. They are also extensively used for marine applications, chemical plant, and power plant, etc.

Material Selection and Standard Specification

Base materials of the CRA clad steel pipes include seamless or welded line pipes of API, ASTM etc.

The CRA cladding or lining material covers an extensive range of stainless steels and nonferrous alloys: SS 304, SS 316, SS 317, Duplex, Alloy 254 SMO 904, Incoloy alloy 825, Inconel alloy 625, Hastelloy C-276, Inconel alloy 59, Alloy 31, AL6NX, Alloy 20, Monel alloy 400, Titanium, Zirconium and some copper alloys.

Generally, CRA cladded pipes shall be manufactured as per API 5LD. The base material (steel pipe) conforms to API 5L, ASTM A106, ASTM A333, ASTM A335, etc. The cladding material shall conform to ASTM A240, A263, A264, A265, B898, B424, B443, B619, B622, B675, B265, B551.

Manufacturing of CRA Cladded Steel Pipes

The CRA clad steel pipe is a bimetallic pipe composed of an internal (and in some cases external) CRA layer that is metallurgically bonded to the backing steel. The cladding may be bonded by hot rolling, coextrusion, Weld Overlay, explosion bonding, powder metallurgy, or some other process that produces a metallurgical bond.

Weld Overlay

CRA cladded steel pipe with Weld Overlay

Weld Overlay, also known as cladding, hardfacing, weld cladding, or weld overlay cladding, is a process where one or more metals are joined together via welding to the surface of a base metal as a layer. This is normally done to improve the material by adding either a corrosion resistant or hardfacing layer to it. Surfaces prepared in this way can even be highly customized by layering and alloying multiple different materials together.

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