A system of pipe insulating sleeves includes a series of elastomeric foam insulating sleeves that are capable of opening up to, and beyond, 180 degrees, to accommodate and capture an undersink pipe. The disclosed system may include a number of different sleeves that are capable of coupling to one another at respective couplers so as to form the system. The sleeves may include fastening mechanisms to retain the sleeves in the closed configuration while capturing the pipe, so as to create a smooth, streamlined appearance that is aesthetically pleasing. Also disclosed is a method of installing the sleeves. The sleeves are made of an elastomeric foam material that has heat insulating properties, and which may also have antibacterial and antimicrobial properties that make it particularly advantageous for use in undersink pipe insulating.