What type of copper tube is marked with a blue stripe?

What type of copper tube is marked with a blue stripe?

• A. Type M
• B. Type L
• C. Type K
• D. Type DWV

Answer: (B)

Blue stripe marks Type L copper tube, the middle option in wall thickness and pressure rating. This mid-range tube is the common choice for most residential water supply runs because it balances strength and cost. Type K is thicker and used where extra protection or higher pressure is anticipated, such as underground services. Type M is thinner and cheaper, suited for lighter-duty interior lines. DWV tubing is intended for drainage, waste, and venting, not for potable water. The stripe provides a quick visual cue so you pick the right tube type for the job.

Blue stripe marks Type L copper tube, the middle option in wall thickness and pressure rating. This mid-range tube is the common choice for most residential water supply runs because it balances strength and cost. Type K is thicker and used where extra protection or higher pressure is anticipated, such as underground services. Type M is thinner and cheaper, suited for lighter-duty interior lines. DWV tubing is intended for drainage, waste, and venting, not for potable water. The stripe provides a quick visual cue so you pick the right tube type for the job.