What must piping joint tape be in gas installations?

In gas installations, the piping joint tape must be approved and certified to ensure safety and compliance with industry standards. This means that the tape has been tested and deemed suitable for use in gas applications, reducing the risk of leaks or failures that could lead to hazardous situations. Using non-certified materials can compromise the integrity of the gas system, potentially leading to dangerous leaks or operational failures.

In contrast, the other options do not align with safety standards. For instance, identification colors are not a requirement for piping joint tapes in gas installations. Similarly, a flammable tape would pose a significant safety hazard, as it could easily ignite in the presence of gas. Lastly, while flexibility can be a desirable attribute for certain types of tape, being reusable is not a typical characteristic expected in the piping joint tape used for gas installations, which is generally intended for one-time use to provide a secure seal.