1. What size should I buy?

First determine the size of lead pipe you have. Remove all old paint & debris and measure with a piece of string or cotton. A clean, smooth surface without deep pitting is needed for water sealing. A vernier or micrometer will not give an accurate measurement if the pipe is oval or irregularly shaped and access is not always possible. DO NOT MEASURE WITH A VERNIER CALIPER Wrap a piece of thin string around the pipe twice. Make sure that the string follows the shape of the pipe but is not stretched and the start and end points are the same. Unwrap or cut and measure the length obtained. Divide the length by 6.284 and the result is the pipe diameter in inches. For string, subtract the thickness, for cotton it is not necessary. To convert to millimetres divide by 25.4. Example: In the string example above L= 6.3, Diameter of Pipe = (6.3/6.284)-.047(string thickness) =0.956 When cotton is used, Diameter of Pipe = (6.062/6.284) = 0.965 Note: Both methods give good approximations of the actual size. The error encountered is less than the difference for the next lead size above or below the one measured.