Recommended guidelines for proper installation of PVC-Coated Conduit
Proper installation ensures the best service life for a conduit system. PVC-Coated Conduit should be treated as a system providing the best available exterior and interior protection against corrosion. Below, are suggested procedures for installing PVC-Coated conduit, along with information about obtaining installer certification.
When using a pipe vise, replace the jaw assembly with special vise adapters. When using a chain vise for conduit diameters less than 2 inches, wrap the clamp area with emery cloth (coarse surface against the coating). Use half-shell clamps to clamp a 2-inch, or larger, diameter PVC-coated conduit. If you use a power unit that spins the conduit, equip the chuck with inserts designed for use with coated conduit.
A roller cutter is recommended for cutting PVC-coated conduit. This will make a square cut end and remove about a quarter-inch of PVC coating, which aids in threading the conduit. A hacksaw can be used to cut conduit, but this method requires a pencil cut so the die teeth engage the conduit.
Cutting away ¼ inch of the exterior coating in the same manner as sharpening a pencil allows the pipe guide to ride up and over the PVC coating, facilitates coating removal, and enables cutting the thread in one operation. A reamer is used to remove any rough internal edges caused by cutting to prevent insulation damage during wire pulling.
Before threading, make a series of cuts in the PVC along the longitudinal axis of the conduit, using the thread protector attached to the end of each conduit section to gauge the length. These cuts help remove the PVC in small pieces rather than long strips, which can foul the die head and cause the conduit to collapse. Before threading, machine the stationary guide to remove 0.12 inch so the pipe guide can ride up and over the PVC coating. Always use a new die head to thread coated aluminum; using the same die head to thread PVC coated aluminum and coated rigid steel conduit is not recommended.
After threading, clean the threads and conduit interior with a degreasing spray to prepare for the application of the touch-up compound. Cleaning ensures proper adherence of compound to the unprotected metal substrate.
For best results, use equipment designed to bend coated conduit. Hydraulic and electric powered benders are available with shoes sized for coated conduit. When bending coated conduit, use rubbing alcohol to clean the inside of the shoe and the area of conduit you wish to bend.
Never use lubricant in the shoe or on the conduit. Lubricant allows the conduit to slip above the centerline of the shoe, resulting in flattening of the elbow.
Conventional shoes can be used to bend conduit if 0.06 inches are removed from the inside surface to accommodate the coating thickness.
When using a conventional hand bender, use the next larger size-bending shoe to allow space for the coating. You can make hand bends with a special coated bending hickey that reduces damage potential to the coating when making sharp bends, saddles, or offsets. Installers typically use these tools for ½ to ¾ Inch diameter conduit.
You should use special Z wrenches in lieu of standard adjustable pliers to assemble PVC-coated conduit and fittings. Z wrenches spread the clamping force and enable the tool to grip securely, without damaging the conduit coating. Strap wrenches can be used to tighten conduit or couplings without damaging the coating.
For smaller conduit sizes, Spin-It tools are available for use with air impact or standard ratchet wrenches to assemble the conduit and fittings faster than with conventional methods. This method never touches the PVC coating and saves time by eliminating the need to touch up damage marks.
Special sockets are available for use with ratchets to tighten encapsulated screws on conduit fittings, hangers, and clamps.
PVC sleeves on conduit couplings and fittings help isolate corrosives from the threads at joints. Typically, the sleeves should not be cut; however, it may become necessary to remove portions of the sleeve when the fitting is close to other sleeves such as with a short nipple. In this instance, cut away half of each sleeve and apply touch up compound to the joints.
Guidelines for suggested installation techniques of coated conduit is also fully covered in the video below:
One other key component of successful installation is for the end user to ensure the project receives the best possible PVC coated conduit installation. Industry standards recommend that installers working on the project be certified. Qualified installation provides these benefits:
• End Users receive optimum installation quality and best possible service life
• Professional users benefit from obvious concern for providing only the best to the end-user
• Contractors achieve more cost-effective installation
Installer certification is based upon training that includes classroom and hands-on instruction encompassing:
• Proper installation techniques and tools
• Hands-on instruction for clamping, cutting, threading, bending, and assembly of PVC coated conduit
• Interactive discussion of techniques and troubleshooting
Only installers who are able to present authorized unexpired credentials confirming instruction and examination are officially certified. Installer certification is free of charge and available at the job site, contractor’s shop, factory, or wherever it is convenient.
For more information about installer certification visit our Installer Certification Page.