In the .jpg I've attached, I've drawn three circles to represent the pipes, and an equilateral triangle surrounding them.
The band that goes around the pipes is made up of three straight bits and three arcs of circles. You need to work out the length of AB, and the length of the arc BC. Add them together and then multiply by three.
The angles are all very easy. (What is the size of an angle in an equilateral triangle?) So you should be able to see what fraction of a complete circle the arc BC is. Also the length AB is very straightforward. (What size is the angle ABO?)
Can you do it for yourself now, or do you need more help?