Final answer:
Joints in copper shower pan liners should be soldered to ensure a watertight seal. Soldering is the proper technique over welding, brazing, or using adhesive for this application in plumbing.
Step-by-step explanation:
The question pertains to the installation of copper shower pan liners, specifically regarding how the joints in these liners should be handled. The correct method for sealing joints in copper shower pan liners is to solder them. Soldering is a process by which two or more metal items are joined together by melting and flowing a filler metal into the joint, the filler metal having a lower melting point than the adjoining metal.
Unlike welding, soldering does not involve melting the work pieces. Brazing is similar to soldering, with the difference being the higher temperature required for the filler metal.
Sealing with adhesive is not strong enough for the waterproofing required in a shower pan liner. Therefore, the joints in copper shower pan liners shall be soldered to ensure a watertight seal.