Assuming an iron pipe IPS size of 12 inches, what insulation size is required for insulating the line flange?

Assuming an iron pipe IPS size of 12 inches, what insulation size is required for insulating the line flange?

• A. 17
• B. 18
• C. 21
• D. 19

Answer: (D)

When insulating a line with a flange, you must cover the entire envelope around both the pipe and the flange, not just the pipe itself. The flange adds material width, so the insulation outer diameter has to be larger than the pipe OD to fully wrap the flange with proper clearance. For a 12 inch iron pipe, the standard insulation size that adequately covers the flange and fits typical shop drawings is 19 inches. Smaller sizes wouldn’t cover the flange, while a larger size like 21 inches isn’t necessary for this case. So 19 inches is the correct insulation size.

When insulating a line with a flange, you must cover the entire envelope around both the pipe and the flange, not just the pipe itself. The flange adds material width, so the insulation outer diameter has to be larger than the pipe OD to fully wrap the flange with proper clearance. For a 12 inch iron pipe, the standard insulation size that adequately covers the flange and fits typical shop drawings is 19 inches. Smaller sizes wouldn’t cover the flange, while a larger size like 21 inches isn’t necessary for this case. So 19 inches is the correct insulation size.