Cleanouts and Access Points in Double Containment Systems

Accessing the space between pipes in double containment systems is vital for installation, testing, inspection, and critical monitoring equipment. Access is achieved with a variety of special fittings, access tees, cleanouts, or flanges. Without these fittings, other, more destructive methods might be used, which is not recommended.

Access Tees
An access tee, as the name suggests, is designed to provide access to the annular space (sometimes called the “interstitial space”) of a double containment piping system. These tees may be flanged or provided with a cleanout access, depending on the installation needs. A flange may be preferred if the access point needs to be as large as possible, while a cleanout access may be desired for damp or underground installations where nuts and bolts would corrode.

For inspections, fittings may be located at regular intervals. The most common use is for the installation of leak-detecting cable for a monitoring system. The access tee provides a means to pull the cable through the containment pipe in manageable sections and helps prevent damage to the cable and/or material.

Dogbones®
For other methods of monitoring or testing, all Dogbone® fittings are available with 1/2″ NPT taps for use with a simple gauge or similar connection. This is common for things like commissioning, when the space is pressurized to check welds. With the help of a special dry air compressor system, dry air can also be circulated through the line to remove any remaining moisture from the space after hydrotesting. The tap provides a convenient point for draining with a male adapter and flange. It’s recommended to purchase all end terminations (or “end terms”) with the tap and plug.

Cleanouts
A cleanout plug is similar to those seen in residential plumbing systems, just with variations in size and material to better suit the job. When access to the inner pipe (referred to as the “carrier pipe”) is necessary, cleanouts or flanged end terminations are common. For example, a drainage line may have a blockage, possibly from mineral build-up caused by a chemical reaction. Users can then access the pipe for jetting, clearing, or application of other chemicals to restore the line to a clear, usable state without needing to cut or use other destructive means of entry. Cleanouts are generally required on drainage lines specifically for this reason: preventing backups that could lead to much more costly repairs.

During the design process, consider where access points should be located and where potential problems can be easily fixed before installing any material, to prevent future costly issues. Something as simple as having the plug in the end term for commissioning can save days of work and communication just to commission a pipe system. Just as placing an access tee properly can save hours of work to install one length of cable. It truly is the simple things that provide the best solutions.

EDITOR’S NOTICE: Please note, the information in this article is for educational purposes only and does not supersede any Asahi/America technical information or product specifications. Please consult Asahi/America’s technical department at 1-800-343-3618 or [email protected] on all product applications in regards to material selection based on the pressure, temperature, environmental factors, chemical, media, application, and more.