Explosion bonding has been the prestige method for joining dissimilar metals for more than half a century. When engineers see a wavy metallurgical interface under a microscope, they trust it. That trust is not misplaced — explosion bonding produces excellent bonds — but it has led to a set of assumptions that no longer match the full range of manufacturing options available today.
Right Spinning Pressure (RSP) is a newer, production-oriented bonding technology that is often misunderstood because it does not use explosives. This article separates fact from fiction so buyers can evaluate RSP clad pipe on its engineering merits.
Myth 1: RSP Is Not a True Metallurgical Bond
The myth: Because RSP uses mechanical pressure rather than fusion or explosive impact, the bond is just friction or mechanical interlock.
The reality: RSP bonds are metallurgical. During the process, the CRA liner tube is expanded beyond its yield point and pressed against the carbon steel outer pipe with enough force to break through surface oxides and bring atomically clean metal surfaces into intimate contact. The resulting interface exhibits metallic bonding across the full contact area, confirmed by shear testing, metallography, and ultrasonic inspection.
Bond shear strengths well above the 140 MPa (20 ksi) API 5LD minimum are routinely achieved, confirmed by shear testing, metallography, and ultrasonic inspection. The bond survives cutting, welding, bending, and hydrostatic testing because it is a true metallurgical interface, not a press fit.
Myth 2: Explosion Bonding Is Always Stronger
The myth: The explosive impact creates a stronger, more energetic bond than any pressure-based process.
The reality: Explosion bonding can produce very high local bond strength and an attractive wavy interface. However, bond quality can vary across the plate due to standoff distance, explosive energy distribution, and plate flatness. Plates must then be rolled and longitudinally welded into pipe, adding seams and heat-affected zones that RSP avoids.
RSP produces a uniform bond along the entire pipe length because the pressure and deformation are applied consistently as the assembly rotates. For long line pipe, uniformity often matters more than peak local strength.
Myth 3: RSP Cannot Handle Large Diameters or Long Lengths
The myth: RSP is only suitable for small-diameter, short pipes.
The reality: RSP equipment scales with pipe diameter and length. The process is particularly well suited to long, continuous pipe because it does not require plate rolling or longitudinal seam welding. Diameters from DN15 to DN1400 and above are feasible, and pipe lengths are limited mainly by handling and transport rather than by the bonding process itself.
By contrast, explosion-bonded pipe starts as a plate. Plate size limits the pipe length, and the longitudinal weld seam becomes a separate quality-critical feature.
Myth 4: Explosion Bonding Is the Only Proven Method for Sour Service
The myth: H₂S-containing sour gas pipelines must use explosion-bonded clad pipe to avoid liner failure.
The reality: Sour service performance depends on the CRA material, bond integrity, and weld quality — not on the bonding method alone. RSP clad pipe with duplex, super-duplex, or nickel-alloy liners has been qualified and used in sour gas and corrosive oil service. As long as the bond meets API 5LD and the CRA grade is selected for the H₂S partial pressure and chloride level, the bonding process is not the limiting factor.
In fact, the absence of a longitudinal seam in seamless outer pipes can be an advantage in sour service, where seam welds are a known point of concern.
Myth 5: RSP Is Only for Low-Pressure Applications
The myth: Pressure-bonded liners cannot withstand high operating pressure.
The reality: In RSP clad pipe, the carbon steel outer pipe carries the full pressure load, exactly as it does in explosion-bonded or overlay-clad pipe. The CRA liner is not a pressure boundary; it is a corrosion barrier bonded to the bore. Because the liner is not pressurized independently, the bonding method does not reduce the pressure rating of the pipe.
RSP clad pipe is specified for high-pressure flowlines, risers, and subsea pipelines where the outer pipe is designed for the full pressure and the liner provides corrosion protection.
The Honest Comparison
| Factor | Explosion Bonding | Right Spinning Pressure (RSP) |
|---|---|---|
| Bond type | Metallurgical, wavy interface | Metallurgical, uniform interface |
| Bond consistency | Good, but varies with plate energy distribution | High; consistent along full pipe length |
| Pipe geometry | Rolled and welded from plate; longitudinal seam | Seamless or welded outer pipe; no added seam |
| Length capability | Limited by plate size | Long continuous pipe |
| Residual stress | Higher; explosive deformation is rapid and localized | Lower; controlled pressure and rotation |
| Logistics and safety | Explosives handling, storage, and regulatory controls | No explosives; conventional workshop operation |
| Best fit | Thick-wall vessels, heavy spools, dissimilar-metal plates | Long pipelines, risers, large-diameter flowlines |
When Buyers Should Still Prefer Explosion Bonding
Explosion bonding remains the right choice for:
- Very thick-walled pressure vessels and reactors
- Large clad plates for fabricated equipment, not pipe
- Dissimilar metal combinations that are difficult to bond by pressure alone
- Short, heavy spools where plate-based fabrication is more economical
Conclusion
Explosion bonding earned its reputation through decades of successful use in heavy equipment. But its reputation has also created a set of myths that undervalue RSP for pipeline applications. RSP is a metallurgical bonding process, it handles large diameters and long lengths, and it performs in high-pressure sour service. The real question is not which process is universally better, but which one fits the geometry, length, and schedule of your project.
For long oil and gas flowlines, risers, and water injection lines, RSP often delivers a more uniform bond, lower residual stress, and faster production than explosion bonding. ZONX PIPE supplies API-5LD certified RSP clad pipe in sizes from DN15 to DN1400 with CRA liners from 304/316L to duplex, super-duplex, 825, 625, and titanium. Contact our engineers to compare RSP against explosion bonding for your specific project.