🔧 ISO 9809 and ISO 11120 – Seamless Steel Gas Cylinders and Seamless Steel Tubes for High-Pressure Gases.

Here's a clear explanation of ISO 9809 and ISO 11120, both of which are international standards for seamless steel gas cylinders, but apply to different types and uses:

✅ Full Title:

ISO 9809-1/2/3 – Gas cylinders — Refillable seamless steel gas cylinders — Design, construction and testing

📌 Scope:

• Applies to seamless steel cylinders for permanent and liquefied gases.
• Covers cylinders typically with water capacity up to 150 litres.
• Commonly used for industrial gases (oxygen, nitrogen, argon, etc.).

📂 Parts:

• ISO 9809-1: Cylinders made of normalized steel.
• ISO 9809-2: Cylinders made of quenched and tempered steel.
• ISO 9809-3: Cylinders made of normalized or quenched and tempered steel, using a different set of test requirements.

🔍 Covers:

• Material requirements
• Manufacturing processes (e.g., hot drawing, forging)
• Design criteria (wall thickness, stress limits)
• Tests: hydrostatic, burst, tensile, impact, and ultrasonic
• Marking and inspection

🚀 ISO 11120 – Seamless Steel Tubes for High-Pressure Gases

✅ Full Title:

ISO 11120 – Gas cylinders — Refillable seamless steel tubes of water capacity between 150 L and 3000 L — Design, construction and testing

📌 Scope:

• Applies to large seamless steel tubes (often called cylinder tubes or MEGC tubes).
• Water capacity between 150 litres and 3000 litres.
• Common in bulk gas transport systems, e.g., tube trailers and ISO containers.

🔍 Covers:

• Design methodology for thick-walled, large-capacity gas containment.
• Material standards (usually quenched and tempered alloy steels).
• Non-destructive testing (NDT) requirements.
• Testing: hydrostatic, burst, ultrasonic, radiographic.
• Tolerances and markings.

🔄 Key Differences: ISO 9809 vs ISO 11120