Bimetal Clad Pipe Manufacturer | Metallurgically Bonded CRA Lined Pipe – Womic Steel

The key to a reliable clad pipe is the bonding method between backing steel and CRA layer. Below are the four main processes we use, ranked by bond strength and application suitability.

2.1 Centrifugal Casting + Hot Extrusion (Seamless Metallurgical Bond)

How it works:
The CRA layer is first centrifugally cast into a hollow tube blank. This tube is then inserted into a carbon steel billet, heated, and co-extruded through a massive extrusion press. At high temperature and pressure, the two metals diffuse into each other, forming a true metallurgical bond.

Bond characteristics:

● Interface shear strength ≥300 MPa (highest among all processes)

● No longitudinal weld seam – fully seamless

● Uniform cladding thickness, precise dimensions

Best suited for:
Small to medium diameters (≤400mm – ~16″), high pressure, severe thermal cycling, hydrogen service, boiler tubes, downhole tubulars, heat exchanger U-bends.

2.2 Hot Roll Bonding + JCOE / UOE Forming

How it works:
A CRA plate and a carbon steel plate are cleaned, stacked in vacuum, sealed, heated, and passed through a rolling mill. Multiple rolling passes create a metallurgical bond. The clad plate is then formed into pipe using JCOE (J-C-O-Edge) or UOE press forming, followed by longitudinal seam welding.

Bond characteristics:

● Interface shear strength 200–260 MPa

● Very large diameters possible (up to 1,800mm / 72″)

● Long single lengths (up to 24m or more)

● Contains one longitudinal weld seam (must be qualified and NDT inspected)

Best suited for:
Large diameter longdistance pipelines, deepwater subsea flowlines, trunk lines, risers. This is the most widely used process for API 5LD certified clad line pipe.

2.3 Explosive Cladding + Plate Rolling

How it works:
A CRA plate is placed over a carbon steel plate with a calculated gap, then covered with explosives. The detonation drives the CRA plate into the backing plate at high velocity, creating a wavy, metallurgical bond. The clad plate is then rolled and welded into pipe.

Bond characteristics:

● Wavy interface with excellent bond strength (200–280 MPa)

● Can join dissimilar metals that are difficult to roll-bond (e.g., titanium to steel, zirconium to steel)

● Plate size limited by explosive facility; subsequent welding required

Best suited for:
Exotic clad combinations: titanium/steel, zirconium/steel, tantalum/steel for highly aggressive chemical plant piping and heat exchangers.

2.4 Mechanical Lining (Not Recommended for Critical Service)

How it works:
A CRA liner tube is cold-expanded or hydraulically expanded inside a carbon steel pipe. The two layers stay together by interference fit (hoop stress).

Bond characteristics:

● No metallurgical bond – only physical contact

● Bond strength <10 MPa

● Liner can wrinkle, collapse, or disbond under thermal cycling or pressure pulsation

When we use it:
Only for low temperature, low pressure, non-cyclic, non-vibration service, and only when the customer explicitly accepts the limitations. We always explain the risks compared to metallurgically bonded clad pipe.

Our recommendation: For any critical oil & gas, hydrogen, or deepwater service, choose metallurgically bonded clad pipe – not mechanically lined pipe.