Corrosion Allowance (CA)
Engineering definition, metallurgical mechanisms, standard testing specifications, and manufacturing guidelines for closed-die forgings up to 50 kg.
Quick AnswerFeatured
Additional metal wall thickness deliberately added during piping and vessel design beyond the minimum required for pressure containment to compensate for expected metal loss over design life.
Technical Explanation & Metallurgical Principles
Corrosion allowance is specified by piping engineers (commonly 1.5mm, 3.0mm, or 6.0mm for carbon steels in corrosive hydrocarbons). When higher corrosion rates make heavy carbon steel unviable, engineers upgrade to corrosion-resistant forged alloys like SS 316L or Duplex 2205 where zero corrosion allowance is required.
Key Engineering Specifications & Parameters
| Technical Parameter / Metric | Engineering Benchmark / Value |
|---|---|
| Standard Carbon Steel CA | 1.5 mm to 3.0 mm (1/16" to 1/8") |
| Severe Sour Service CA | 6.0 mm or upgrade to CRA cladding / Duplex |
| Stainless Steel CA | 0.0 mm (zero corrosion allowance) |
Application at Jayesh Forge (Rajkot Plant)
Taken into account when machining flange bore schedules and forged pipe wall thicknesses for EPC refinery contracts.
Related Materials, Standards & Products
Related Metallurgical & Testing Terms
NACE MR0175 / ISO 15156 Sour Service Standard
The international standard defining material requirements for metallic equipment used in oil and gas production environments containing corrosive hydrogen sulfide (H2S).
Pitting Resistance Equivalent Number (PREN)
A standardized mathematical formula that rates the localized pitting and crevice corrosion resistance of stainless steels based on their Chromium, Molybdenum, and Nitrogen content.
Sour Service (Wet H2S Environment)
Piping and pressure equipment operating in environments containing moisture and hydrogen sulfide (H2S) at partial pressures exceeding NACE threshold limits.
Questions Regarding Corrosion Allowance (CA)
Yes, because SS 316L requires zero corrosion allowance, allowing designers to utilize thinner wall schedules and lighter flanges.
Request a Forging Quote with Corrosion Allowance (CA) Compliance
Our Rajkot metallurgy desk is ready to review your technical drawings, testing protocols, and delivery schedules for custom closed-die forgings strictly up to 50 kg.