INTERNAL CLADDED PIPES / INTERNAL PIPE CLADDING

Internal Cladded Pipes are seamless and welded clad steel line pipe and lined steel line pipe with enhanced corrosion-resistant properties pipes which are extensively used in pipeline transportation systems in the natural gas & petroleum industries, marine applications, chemical plant, power plant, etc.

The corrosion-resistant alloy clad or lined pipe is made up of conventional carbon steel and a corrosion-resistant alloy layer. The internal or external surface of the steel pipes are bonded metallurgically (clad) or mechanically (lined) with corrosion-resistant alloy (CRA) layer. The CRA layer is the cladding material or lining whereas the base metal is carbon steel or low alloy pipe steel is the base metal. The thin CRA layer not only holds the corrosion-resistant properties but also reduces the cost thus making it economically viable for large diameter heavy pipelines. Click here for API 5L Pipe Sleeve.

This specification covers seamless and welded clad steel line pipe and lined steel line pipe with enhanced corrosion-resistant properties suitable for use in pipeline transportation systems in the petroleum and natural gas industries. The clad and lined steel line pipe specified herein is composed of a carbon steel backing or base material outside (in some cases inside and/or outside) and a corrosion-resistant alloy (CRA) layer or lining inside of the pipe. The base material conforms to API 5L (45th Ed.), product specification level (PSL) 2 and applicable annex(es), except as modified herein. Grades of base material covered by this specification include X42, X46, X52, X56, X60, X65, X70, X80, and grades intermediate to these. Grades of the CRA layer are LC 1812, 2205, 2506, 2242, 2262, unified numbering system (UNS) S31703, UNS N08904, UNS N10276, Alloy 31 (UNS N08031), Alloy 59 (UNS N06059), Alloy 254 SMO-11 (UNS S31254), Alloy 400 (UNS N04400), AL6NX (UNS N08367), and EN 1.4529 (UNS N08926). Other grades are subject to agreement between the purchaser and the manufacturer. The delivered product usually has square ends, but other special ends may be furnished by agreement between the purchaser and manufacturer. Included are nominal pipe sizes (NPS) 25 mm (1 in.) through 2134 mm (84 in.). Sizes greater than 2134 mm (84 in.) are outside of the range of API 5L (45th Ed.) but may be supplied up to 2500 mm (100 in.) by agreement, including requirements for materials.

Use hot rolling metallurgy composite plate or coil as material, modern advanced pipe-making technology (UOE, JCOE, COE and SAWH) to forming, SAWL or SAWH, and TIG etc. combined automatic welding process to complete welding. The welding quality is stable, and the product size accuracy is high. The composite plate or coil is manufactured by hot rolling technology, which can achieve metallurgical bonding of the atom between corrosion-resistant clad and the backing layer, the binding force reaches above 200MPa, the binding area rate can reach above 99.9%, and the performance is stable and reliable. The clad can meet the corrosion-resistant specific performance requirements, and the backing layer can meet the strength and rigidity condition the structure required.

Seamless or welded carbon steel pipe as the outer backing layer, and corrosion-resistant alloy pipe as the inner corrosion layer, using the limit elasticity hydraulic composite method innovated independently by the company achieves the composite between the inner and outer pipe and forms the mechanical liner pipe. Through the composite technology, the optimal composite effect of mechanical liner can be achieved, and the shear stress between inside and outside metal layer can reach 2.0MPa (the relative standard requires 0.2-0.5MPa). Meanwhile, we develops specially the pipe ends automatic overlaying technology and NC machine tools specialized for beveling, which can process complex shape bevels such as U-bevel, and guarantees the conformity of pipe mouth diameter and bevel size, so as to operate pipe jointing on site.

Internal cladded pipes supplied by our company can be of various sizes. Size can vary from 1″ (DN 25) to 100″ (DN 2500) with a minimum corrosion-resistant alloy layer of 2.5 mm in thickness and a maximum length of 15 meters. We thoroughly conduct heat treatments for both the base-metal pipe as well as the CRA layer.

Generally, the mechanical properties of the internal cladded pipes is determined by the properties of the base material alone. The mechanical properties of the CRA layer can be determined according to the requirement of the customers.

Base materials of Internal Cladded Pipes – API 5L GR X5 SL2 & Inconel 825 Metallurgically Bonded (CLAD) OR Mechanically Bonded (LINED) comprise of seamless or welded line pipes. The pipes are made up of API 5L Grade B, X42, X46, X52, X56, X60, X65, X70 and X80 and intermediary grades.

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The Metallurgically Bonded (CLAD) steel pipe is a bimetallic pipe which is made up of an internal & external Corrosion resistant alloy layer that is metallurgically bonded to the steel. It can be done by hot rolling, coextrusion, weld overlay, explosion bonding, powder metallurgy etc.

In case of Mechanically Bonded (LINED), the mechanical bonding formed by the lining process is relatively “loose” in a lined pipe. The cost of the clad pipe is higher owing to its better mechanical performance.

Advantages

• • Internal Cladded Pipes can withstand in tough chemical environments
  • Clad pipe can be used in high temperature and pressure services
  • It is cost effective for critical services as carbon steel can be used with cladding of exotic materials

Disadvantages

• Fabrication of clad material is difficult, a special skill required for welding
• Clad pipes are costly compared to lined pipe

Each internal cladded pipes undergoes extensive inspection to ensure top quality:

• Tensile tests: The CRA layer shall be removed from all specimens of finished products; Longitudinal tensile tests and transverse tensile tests; Weld Tensile test (if there is any weld seam in the backing steel)
• Flattening tests
• Guided-bend tests
• Fracture toughness tests
• Hardness tests (Vikers – ASTM E 384, Rockwell – ASTM E 18)
• Ferrite/austenite ratio for duplex stainless steel CRA layer
• Corrosion tests as per ASTM A262 Practice B or Practice E, ASTM G28 Method A, ASTM G48 Method A
• Tests for CRA cladding bond strength and CRA liner tightness
• Residual magnetism (less than 15 Gauss)
• Hydrostatic inspection
• Dimensional inspection and visual examination
• Ultrasonic inspection for clad pipes
• 100% X-Ray inspection for all welds

Fully cladding a carbon steel component with alloy 625, as opposed to producing it in solid alloy, can reduce costs by as much as 60%.

• Exotic alloy castings can include sub-surface defects. Cladding the surface produces a very high-quality layer with minimal imperfections
• A full range of NDT provides reassurance of quality

Internal Cladded Pipes is suitably marked as per their size, grade of steel before dispatching the shipment to the customers.