Clad construction: for large process vessels operating at severe pressure and temperature, the corrosion-resistant cladding is typically what percentage of the total wall thickness?

Introduction / Context:
To resist corrosion without the expense of a full-thickness alloy wall, heavy vessels are frequently built as carbon steel base metal with a corrosion-resistant cladding (stainless steel, nickel alloys, titanium, etc.). Understanding the typical cladding percentage helps with preliminary thickness budgeting, cost estimating, and material selection before detailed code calculations.

Given Data / Assumptions:

• Large pressure vessels or reactors under high temperature/pressure and corrosive service.
• Cladding applied by roll-bonding, weld overlay, or explosion bonding.
• Wall thickness meets code; cladding provides corrosion resistance, not primary strength.

Concept / Approach:
Cladding thickness is chosen to ensure adequate corrosion allowance, fabrication tolerances, and future repairs while minimizing alloy cost. Industry practice places cladding around a modest fraction of total thickness. Too thin a layer risks through-clad defects or rapid wastage; too thick rapidly drives cost and residual stress issues during fabrication.

Step-by-Step Solution:

Verification / Alternative check:
Shop standards and owner specifications often require a minimum clad thickness (for example, several millimeters) which, for common total wall thicknesses, corresponds roughly to 10–20%.

Why Other Options Are Wrong:

• 1–5%: Often too thin for reliable service, repair grinding, or corrosion allowance.
• 30–40% or 40–50%: Excessively costly and rarely necessary; the base metal is intended to carry pressure loads.

Common Pitfalls:
Assuming clad contributes to pressure strength; neglecting dissimilar-metal weld qualifications; overlooking differential thermal expansion causing disbonding risks.

Final Answer:
10 to 20