The main functions of the insulation kits are:
- Generate static sealing in the flanged joint.
- Perform electrical insulation in the flanged joint, avoiding contact between metals of: studs, nuts, washers and flanges.
To make a correct selection of insulation kits, several aspects and recommendations must be taken into account:
- Check the working pressure of the pipe line with the technical sheets of the insulation kits.
- Check the chemical compatibility of the fluid with the packaging material used to manufacture the insulation kit.
- Check the maximum working temperature of all the accessories of the insulation kits, generally the kits work up to 150°C (302°F). For higher temperatures, consult the technical department.
- In lower classes, aramid fiber gaskets are sometimes installed. It is important to check the dielectric resistance and water absorption among others; Not all sheet compositions can be used as insulation kits.
- When the pipe line uses RTJ flanges in the joint with high pressures or diameters greater than 4”, it is advisable to use gaskets for critical service RF or FF, ring joints designed with insulating fibers do not have good mechanical resistance due to their manufacturing process, these cause leaks or electrical passage after a short time.
- When installing insulation kits it is important to increase the length of the standard studs, 3/4” (19 mm) must be added to the standard length, the studs must protrude from the nut at the 2 tips by at least 1/3 of the nominal diameter to guarantee correct installation. The kits include additional washers that increase the size of the studs.
- For ASME class 600 flanges and/or diameters greater than 12″ it is recommended to use G-10 insulating bushings. The mechanical resistance of this material is superior and prevents the tightening of the stud from being damaged by the friction of the thread and the internal part of the flange holes. When the insulating bushing is damaged, the electrical insulation is cut, generating an increase in the costs of installation.
- When Nema Le washers or a material with low mechanical resistance are used, it is recommended to use an additional aramid washer between the flange and the insulating washer. This way the insulating washer is mechanically protected, avoiding cracks or breaks due to excessive torque during assembly.
- Non-conductive lubricant must be applied to the threads of the studs and the flange holes where they are to be installed.
- It must be checked that the number of accessories in the insulation kits is complete according to the marking on the original packaging. If any element is missing, the kit should not be installed in the flanged joint.