Clad pipe — also called bi-metal pipe or bimetallic composite pipe — is a bimetallic steel pipe: a carbon steel outer wall carries the pressure and loads, while a thin inner layer of corrosion-resistant alloy (CRA) protects the bore from the medium. It exists because engineers refused to accept a false choice — the strength of carbon steel or the corrosion resistance of stainless and nickel alloys. Done right, one clad pipe delivers both, at roughly half the cost of solid CRA pipe.
This guide covers what clad pipe is, how it is manufactured, which alloys and standards apply, what it costs, and how to specify and source it. For a manufacturer-level view of our API 5LD production line, see DURACORE™ CRA clad pipe.
1. What Is Clad Pipe?
A clad pipe combines two dissimilar metals into one pressure boundary:
- Backing steel (outer wall): typically API 5L carbon steel grades X42–X70, providing structural strength, pressure containment, and field weldability.
- CRA layer (inner wall): 1.5–4 mm of stainless steel, duplex, nickel alloy, or titanium, providing corrosion resistance exactly where the medium touches the pipe.
- The bond: the defining feature. In true clad pipe the two metals are metallurgically bonded — fused at the atomic level — so the CRA layer cannot slip, buckle, or separate in service.
Because the expensive alloy is only 1.5–4 mm thick instead of a full wall, material cost scales with bore surface rather than wall volume. On a large-diameter, long-distance line, that difference is measured in millions of dollars.
2. Clad Pipe vs Lined Pipe vs Solid CRA
Buyers routinely confuse three constructions. The distinctions drive cost, reliability, and what you can do with the pipe in the field:
| Attribute | Solid CRA | Clad Pipe | Lined Pipe |
|---|---|---|---|
| Construction | Full alloy wall | Carbon steel + metallurgically bonded CRA layer | Carbon steel + mechanically fitted liner |
| Bond shear strength | Homogeneous | ≥ 140 MPa (API 5LD) | < 5 MPa (interference fit) |
| Cost vs solid CRA | Baseline | 30–50% lower | 40–60% lower |
| Bending / fabrication | Free | Free — bond holds | Restricted — liner can wrinkle |
| Thermal cycling / vacuum | OK | OK | Liner collapse / disbond risk |
| Typical service | Extreme corrosion, small bore | Sour oil & gas, subsea, chemical, large diameter | Moderate-pressure water, onshore gathering |
Our full 12-dimension analysis is on the comparison page; a procurement-oriented walkthrough is in this selection guide.
3. How Clad Pipe Is Made: Four Bonding Methods
"Clad pipe" covers several manufacturing routes. The bond quality — not the alloy grade — is what separates a pipe that lasts 30 years from one that fails in months.
| Method | How It Works | Bond Strength | Typical Use |
|---|---|---|---|
| RSP™ (Right Spinning Pressure) | Rotational pressure + temperature forge a metallurgical bond between CRA liner and steel pipe | ≥ 140 MPa shear | Line pipe DN15–DN1400, oil & gas and water |
| Hot roll bonding | CRA plate and backing plate are heated and rolled together, then formed into pipe (ASTM A265) | 140–200 MPa | Large-diameter line pipe from clad plate |
| Explosion bonding | Controlled detonation slams the two metals together at atomic level | High, wavy interface | Thick-wall clad plate, transition joints |
| Weld overlay cladding | CRA wire is deposited onto the bore by SAW / hot-wire TIG / PTA welding | Fusion weld | Fittings, spools, small batches, repairs |
ZONX manufactures line pipe with proprietary RSP™ metallurgical bonding — the process behind our API 5LD certification and ≥ 140 MPa bond shear strength. See how RSP compares to explosion bonding and weld overlay in our manufacturing deep-dive.
4. Cladding Alloys: Matching the CRA to the Medium
| Alloy | Type | Best For | Relative Cost |
|---|---|---|---|
| 304 / 304L | Austenitic SS | Water, mildly corrosive fluids | Lowest |
| 316L | Austenitic SS | Chloride-bearing water, process fluids | Low |
| 2205 | Duplex | Sour service, moderate chlorides | Medium |
| 2507 | Super duplex | High chlorides, PREN ≥ 40 | Medium-high |
| Alloy 825 | Ni-Fe-Cr | Sour service, reducing acids | High |
| Alloy 625 | Nickel alloy | Severe sour, NACE MR0175, highest PREN | Highest |
| Titanium Gr2 | Ti | Seawater, desalination — immune to marine corrosion | Premium |
Alloy selection is driven by the medium's chloride content, H₂S/CO₂ partial pressures, temperature, and design life — not by habit. Our alloy selection guide works through the 316L → 825 → 625 decision path.
5. Standards and Specifications
- API Spec 5LD — the governing standard for CRA clad and lined steel line pipe: base grades X42–X80, cladding materials, minimum 140 MPa bond shear, hydrostatic testing, marking. Manufacturers must hold an API monogram license — ZONX PIPE holds License 5LD-0017 (API Spec Q1 + 5LD, scope: lined steel pipe, valid through August 2027), verifiable at api.org/compositelist.
- ASME SA-263 / SA-264 / SA-265 — clad plate and sheet construction standards.
- NACE MR0175 / ISO 15156 — material requirements for H₂S sour service.
- DNV-ST-F101 — submarine pipeline systems, increasingly specified for offshore clad lines.
- API 1104 / ASME IX — welding procedure qualification for field and shop welds.
What the spec numbers mean in procurement practice — MTRs, NDT coverage, WPS/PQR — is covered in our API 5LD buyer's guide.
6. Sizes, Dimensions, and Pressure Ratings
ZONX clad pipe spans DN15 to DN1400 (1/2″–56″), with base wall thicknesses per project pressure class (up to X70 backing steel) and CRA layers of 1.5–4 mm. Standard lengths 6 m and 12 m; custom lengths, bevel ends, and factory prefabricated spools on request. Full dimensional data is on the product page.
7. Applications
- Oil & gas: sour flowlines, gas gathering, CO₂ injection, LNG feed lines — see oil & gas applications
- Offshore & marine: seawater risers, subsea lines, desalination — see marine & offshore
- Chemical: acid lines, chloride process piping
- Water: corrosive groundwater, treated water reuse; potable-grade systems use our AQUACORE™ lined stainless pipe
- Mining: corrosive tailings and dewatering lines (for abrasion-dominant slurry, specify accordingly) — see mining applications
- Energy transition: CCUS and hydrogen pipelines — see material selection for CCUS
8. How Much Does Clad Pipe Cost?
No honest manufacturer quotes a single number — price moves with alloy, diameter, wall, base grade, and volume — but realistic 2026 ranges per meter are:
- 316L cladding: roughly USD 300–500/m
- Alloy 625 cladding: roughly USD 800–1,200/m
- Titanium cladding: roughly USD 1,500–2,500/m
Against these, solid CRA pipe of comparable diameter runs 30–50% higher, and carbon steel plus chemical inhibition shifts cost into permanent O&M risk. Bulk orders (1,000 m+) typically reduce unit cost 15–20%. For a project number, send your line list through the quote form — a full specification returns a firm price within days, not weeks.
9. How to Choose a Clad Pipe Manufacturer
- API 5LD monogram license — verify the license number against API's composite list. ZONX's is 5LD-0017.
- Bond verification: full-length UT bond inspection, shear test data ≥ 140 MPa, flattening tests.
- Welding documentation: qualified WPS/PQR per API 1104 / ASME IX, with transition-joint procedures.
- Traceability: heat-number traceable MTRs for both backing steel and CRA layer.
- Third-party inspection: BV, SGS, or TÜV witness points at hydrotest and NDT.
- Reference projects in your service environment (sour, subsea, seawater).
10. Frequently Asked Questions
What is clad pipe?
A bimetallic pipe: carbon steel outside for strength, a thin CRA layer inside for corrosion resistance, metallurgically bonded as one wall. It matches solid CRA corrosion performance at 30–50% lower cost.
Is clad pipe the same as bi-metal pipe?
Yes — bi-metal pipe, bimetallic composite pipe, and clad pipe are the same construction under different regional names. "Clad pipe" dominates API 5LD procurement language; "bi-metal" and "bimetallic" are common in Asian industrial usage.
What is the difference between clad pipe and lined pipe?
Clad pipe is metallurgically bonded (≥ 140 MPa shear); lined pipe uses a mechanical fit (< 5 MPa). Clad tolerates bending, welding, thermal cycling, and vacuum; lined pipe is cheaper but limited to moderate, stable conditions.
What alloys are used for clad pipe?
304/316L stainless, duplex 2205, super duplex 2507, nickel alloys 825 and 625, and titanium — selected by chloride, H₂S, CO₂, temperature, and design life.
What standard governs clad pipe?
API Spec 5LD, supplemented by ASME SA-263/264/265, NACE MR0175/ISO 15156 (sour service), and DNV-ST-F101 (subsea).
How much does clad pipe cost?
Indicatively USD 300–500/m for 316L cladding, USD 800–1,200/m for Alloy 625, USD 1,500–2,500/m for titanium — always quoted per project specification.
Can clad pipe be welded and bent in the field?
Yes, with qualified procedures using CRA-compatible consumables. The metallurgical bond survives fabrication; mechanically lined pipe does not tolerate this.
Where is clad pipe used?
Sour oil & gas lines, offshore and subsea pipelines, chemical plants, seawater and desalination systems, corrosive mining dewatering, and CCUS/hydrogen trunk lines.
Conclusion
Clad pipe is the engineering answer to a structural problem: corrosion attacks the bore, loads attack the wall, and no single affordable metal handles both. A metallurgically bonded CRA layer on a carbon steel backing solves it — provided the bond is real, verified, and certified. That verification is where manufacturers separate, and it is why API 5LD bond-strength requirements exist.
ZONX PIPE has manufactured API 5LD clad pipe with proprietary RSP™ bonding since 2004, from DN15 to DN1400, in 316L through Alloy 625 and titanium, with full-length UT inspection and serial-number traceability.