ASTM C585 & C1136 Explained: What They Mean for Your Insulation Project

ASTM C585 and ASTM C1136 are two of the most frequently referenced standards in industrial insulation specifications across the GCC, yet they're often misunderstood or used interchangeably. They actually cover two different things: one governs the insulation itself, the other governs the metal jacket around it.

ASTM C585: Standard Sizes for Pipe Insulation

ASTM C585 defines the standard inner and outer diameters for preformed pipe insulation, ensuring that insulation manufactured to this standard fits snugly around standard pipe sizes without gaps that would otherwise allow thermal bridging or moisture pockets to form beneath the cladding.

ASTM C1136: Vapor Retarder Jacket Selection

ASTM C1136 classifies vapor retarder jacket facings by their permeance rating and puncture resistance, helping specifiers choose the correct facing for a given service temperature and moisture exposure — critical for any pipe or tank running below ambient temperature, where condensation risk is highest.

Why This Matters for Your Project

• Prevents the small air gaps that turn into moisture traps and, eventually, CUI
• Ensures consistent thermal performance across every section of a pipe run
• Gives consultants and QA/QC teams an objective basis to approve or reject a submittal

Every insulation and cladding system we install in Qatar and the UAE is specified and executed against these standards as a baseline, alongside BS 5970 and ISO 9001:2015 quality management. Read more about our full compliance approach on our Quality & Standards page.