X65+316L Bimetal Metallurgical Clad Pipe | Cost-Effective CRA Lined Pipe for CO₂ Service – Womic Steel

Short Description:

Outer Pipe (Backing Steel): API 5L X65 PSL2 – high strength, excellent toughness, weldable

Inner Lining (CRA Cladding): 316L (UNS S31603) – low carbon austenitic stainless steel, resistant to CO₂ corrosion, good weldability

Size Range: OD 219mm – 1219mm (8″ – 48″); Backing steel wall thickness 8mm – 30mm; Cladding thickness 1.5mm – 3.0mm; Single length up to 18m (custom 24m available)

Manufacturing Process: Hot roll bonding + JCOE forming – metallurgical bond interface shear strength ≥200 MPa

Standards & Certifications: API SPEC 5LD (CRA Clad Steel Pipe), DNV-OS-F101, NACE MR0175, ISO 15156. Mill Certificate EN 10204 Type 3.1. Third-party inspection (SGS, BV, DNV, TÜV) available.

Applications: Onshore natural gas gathering pipelines, CO₂ injection lines, water injection systems, low chloride oil & gas flowlines, refinery interconnecting piping.

Womic Steel supplies X65+316L metallurgically bonded clad pipe – a costeffective alternative to solid 316L or higher alloys. Designed for sweet service (CO₂ without significant H₂S or chlorides). Backed by full quality documentation and global shipping experience.

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1. Overview – Why X65+316L Clad Pipe

For pipelines transporting natural gas containing carbon dioxide (CO₂) but only trace amounts of hydrogen sulfide (H₂S) and low chlorides, solid carbon steel corrodes rapidly, while solid 316L stainless steel is often overspecified and expensive.

X65+316L bimetal metallurgically bonded clad pipe offers the ideal middle ground:

Outer X65 layer provides high strength (minimum yield 450 MPa), fracture toughness, and pressure containment – exactly what API 5L X65 line pipe is known for.

Inner 316L cladding directly contacts the fluid, resisting CO₂ corrosion, general oxidation, and mild acidic conditions.

The two layers are permanently joined by a metallurgical bond (hot roll bonding + JCOE forming). There is no risk of liner collapse, wrinkling, or separation – unlike mechanically lined pipe.

This combination is widely used in sweet natural gas gathering systems, CO₂ enhanced oil recovery (EOR) pipelines, water injection lines, and low-chloride oil & gas flowlines.

2. Key Features & Benefits

Feature	Benefit
Metallurgical bond	Interface shear strength ≥200 MPa – no liner collapse or delamination under pressure/temperature cycling
X65 high strength backing	Allows thinner wall vs lower grade steel, reduces weight and welding cost
316L corrosion resistance	Resists CO₂ corrosion (sweet service), general oxidation, and low chloride attack
Cost effective	40-50% cheaper than solid 316L pipe of same pressure rating
Full traceability	Each pipe marked with heat number; complete MTC and NDT reports
Proven in service	Installed in hundreds of kilometers of onshore gas pipelines

3. Technical Data & Material Specifications

3.1 Chemical Composition (%)

Element	X65 Backing Steel (max)	316L Cladding (max)
Carbon (C)	0.12	0.030
Silicon (Si)	0.45	0.75
Manganese (Mn)	1.60	2.00
Phosphorus (P)	0.025	0.045
Sulfur (S)	0.015	0.030
Chromium (Cr)	0.30	16.0 – 18.0
Nickel (Ni)	0.50	10.0 – 14.0
Molybdenum (Mo)	0.15	2.0 – 3.0
Niobium (Nb)	0.05	—
Titanium (Ti)	0.04	—
Vanadium (V)	0.10	—

3.2 Mechanical Properties

Property	X65 Backing	316L Cladding
Yield Strength (min, MPa)	450	170
Tensile Strength (min, MPa)	535	485
Elongation (min, %)	18	35
Hardness (max, HV)	250	200
Impact Toughness (min, J @ 0°C)	100 (avg)	Not required

3.3 Bond Interface Property

Parameter	Requirement	Test Method
Shear Strength	≥200 MPa	Pushout test per API 5LD
UT bond integrity	No disbond >50mm, total <2%	Full body ultrasonic scan

3.4 Dimensional Range (Typical)

OD (inch/mm)	Backing WT (mm)	Cladding WT (mm)	Length (m)
8″ (219.1)	8.0 – 15.0	1.5 – 2.5	12 / 18
10″ (273.1)	8.0 – 18.0	1.5 – 3.0	12 / 18
12″ (323.9)	9.0 – 20.0	1.5 – 3.0	12 / 18
16″ (406.4)	10.0 – 22.0	2.0 – 3.0	12 / 18
20″ (508.0)	10.0 – 25.0	2.0 – 3.0	12 / 18
24″ (609.6)	12.0 – 30.0	2.0 – 3.0	12 / 18
36″ (914.4)	12.0 – 30.0	2.0 – 3.0	12 / 18
48″ (1219.2)	14.0 – 30.0	2.0 – 3.0	12 / 18

Custom dimensions available upon request. Maximum cladding thickness up to 4mm in special cases.

4. Manufacturing Process – Hot Roll Bonding + JCOE

Womic Steel produces X65+316L clad pipe using the industry-proven hot roll bonding + JCOE forming route:

Surface preparation – X65 and 316L plates are cleaned, ground, and inspected.

Vacuum stack assembly – The two plates are stacked with the 316L layer facing inward, sealed under vacuum to eliminate oxygen.

Hot rolling – The stack is heated to 1150-1250°C and passed through a rolling mill. High reduction (5:1 to 10:1) creates a metallurgical bond by atomic diffusion.

Plate cooling & inspection – The clad plate is cooled, and the bond is 100% ultrasonic tested for any disbond.

JCOE forming – The clad plate is edge-milled, then formed into an open pipe using a series of J-C-O presses.

Longitudinal seam welding – The open seam is welded using doubleside submerged arc welding (SAW) with 316L or 309L filler on the inner pass and carbon steel filler on the outer pass.

Expanding (optional) – Mechanical expansion improves roundness and relieves forming stresses.

Heat treatment – Post-weld heat treatment (PWHT) applied when required by project specification.

NDT & testing – See Section 5 below.

End finishing – Beveled ends with anti-rust oil and plastic caps.

5. Quality Control & Testing – Every Pipe Inspected

X65+316L clad pipes are tested according to API 5LD and project-specific requirements.

Test	Method	Scope	Acceptance
Raw material verification	OES spectrometer	Each heat of X65 and 316L	Chemistry per standard
Bond ultrasonic testing	Full body UT (longitudinal & shear wave)	100% of clad plate before forming	No disbond >50mm; total disbond <2%
Weld seam UT	Automated UT (phased array / conventional)	100% of longitudinal weld	API 5LD / DNV standards
Weld MT / PT	Magnetic particle / Dye penetrant	Weld toes, ends	No linear indications
Mechanical testing	Transverse tensile, guided bend	One per production batch (up to 50 pipes)	Failure outside weld / bond
Hardness survey	HV10 across clad, bond, HAZ	One per batch	Cladding ≤200 HV, backing ≤250 HV
Hydrostatic test	1.5× design pressure, hold 10s	Each pipe	No leakage
Dimensional check	Laser / calipers / tape	100%	OD, WT, length, ovality
Visual & end inspection	Direct visual	100%	No surface defects; bevel per drawing

Supplementary tests available on request:

● Intergranular corrosion (ASTM A262 Practice E) for 316L cladding

● HIC / SSC (NACE TM0284 / TM0177) for sour service

● Low-temperature impact (Charpy) for backing steel at -20°C / -40°C

● Ferrite content measurement

6. Typical Applications & Project Examples

6.1 Onshore Natural Gas Gathering

Scenario: A gas field in Central Asia with CO₂ content 12-18%, H₂S <20ppm, chlorides <1000ppm.
Solution: X65+316L clad pipe, OD 323.9mm, backing WT 12.7mm, cladding 2.0mm.
Result: 85 km pipeline installed 2021-2022; internal inspection after 2 years shows no measurable corrosion.

6.2 CO₂ Enhanced Oil Recovery (EOR)

Scenario: CO₂ injection pipeline for a CCUS project in North China.
Solution: X65+316L clad pipe, OD 508mm, backing WT 15.9mm, cladding 2.5mm.
Result: 25 km pipeline operating at 22 MPa, 60°C; no corrosion or liner issues after 18 months.

6.3 Water Injection Line

Scenario: Produced water re-injection in Middle East, low chlorides but high CO₂.
Solution: X65+316L clad pipe, OD 610mm, backing WT 12.7mm, cladding 1.8mm.
Result: Replaced solid carbon steel plus corrosion inhibitor; maintenance cost reduced 40%.

7. Why Choose Womic Steel for X65+316L Clad Pipe?

Reason	Details
Experienced manufacturer	Over 15 years of clad pipe production, thousands of tons delivered
True metallurgical bond	No liner collapse risk – fully compliant with API 5LD
Full traceability	Every pipe traceable from coil to final inspection
In-house NDT	UT, MT, hydrostatic – all performed by certified technicians
Short lead time	Standard sizes: 8-10 weeks; custom sizes: 12-14 weeks
Global shipping	FOB, CIF, CFR terms; packing for sea freight (container or break bulk)

8. Frequently Asked Questions (FAQ)

Q1: Can X65+316L clad pipe be used for sour service (H₂S)?
A: Not recommended for high H₂S (>50ppm) or high chlorides (>10,000ppm). For sour service, we recommend X65MS backing + Alloy 825 or Inconel 625 cladding.

Q2: Is the 316L cladding susceptible to sensitization during welding?
A: 316L is low carbon (≤0.03%), so it resists sensitization. For additional safety, we can supply solution annealed clad pipe.

Q3: How long is the typical service life?
A: In sweet CO₂ service (no chlorides or H₂S), 20-30 years is achievable. Actual life depends on flow velocity, temperature, and chemical composition.

Q4: Can you supply small diameter X65+316L clad pipe (≤6″)?
A: For diameters ≤168mm (6″), seamless centrifugal casting + extrusion clad pipe is more suitable. We offer that as well.

Q5: What documentation is included with each shipment?
A: EN 10204 Type 3.1 certificate (chemistry, tensile, impact, bond shear, UT, hydro), NDT reports, dimensional report, packing list, commercial invoice, bill of lading.

Q6: Do you offer third-party inspection?
A: Yes. We work with SGS, BV, DNV, TÜV, ABS, LR. Type 3.2 certificates available with witness inspection.