| Item | Specification & Range | Key Tolerance (Typical) |
|---|---|---|
| Outside Diameter (O.D.) | 60 mm ~ 273 mm | ±0.75% or ±0.5 mm (whichever is greater) |
| Wall Thickness | 3.0 mm ~ 12.0 mm | ±10% |
| Length | Cut-to-length, e.g., 6000~12000 mm | 0 / +50 mm |
| Ovality | — | ≤ 80% of the O.D. tolerance |
| Straightness | — | ≤ 1.5 mm per 1500 mm length |
| Delivery Condition | Quenched & Tempered (Q&T) | Mechanical properties (Hardness, Tensile/Yield Strength, Elongation, Impact) as per standard. |
🟦Raw Material Inspection & Cutting Certified 34CrMo4 Q&T seamless pipes are inspected and cut to precise blanks for cylinder shells.
🟩Hot Spinning (Forming) Pipe ends are heated and rotated under extreme pressure, thinning the walls and forming the dome ends in a seamless, integral shape.
🟨Heat Treatment (Re-Quenching & Tempering) The spun shell undergoes full re-austenitizing, quenching, and tempering to restore uniform, high strength and toughness after forming.
🟧Thread Machining & Valve Boss Welding The neck opening is machined to precise threads. A valve boss is welded using qualified procedures, followed by local PWHT.
🟪Non-Destructive Testing (NDT) & Hydrostatic Test
100% ultrasonic testing of the shell body and weld. Each cylinder is subjected to a hydrostatic pressure test (e.g., 1.5x service pressure) to verify integrity.
🟥Surface Finishing & Painting
The cylinder interior is cleaned and treated (e.g., phosphated) to prevent corrosion. The exterior is shot-blasted and coated with durable paint.
| Carbon (C) | 0.30 – 0.37 |
| Silicon (Si) | 0.15 – 0.40 |
| Manganese (Mn) | 0.60 – 0.90 |
| Phosphorus (P) max. | ≤ 0.025 (Premium: ≤0.020) |
| Sulfur (S) max. | ≤ 0.015 (Premium: ≤0.010) |
| Chromium (Cr) | 0.90 – 1.20 |
| Molybdenum (Mo) | 0.15 – 0.30 |
| Yield Strength (Rp0.2) Min. | ≥ 550 MPa |
| Tensile Strength (Rm) | 700 – 900 MPa |
| Elongation at Break (A) Min. | ≥ 15% (on 5.65√S₀) |
| Impact Energy (KV) Min. | ≥ 40 J @ -20 °C (Longitudinal) |
| Hardness | 220 – 280 HBW |
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