Rotolining is a seamless lining technique for pipes and vessels which can be of complex shape and with limited access. The key benefits of rotolining are that the lining can be made significantly thicker than by other methods and that complex shaped equipment with limited access can be lined without difficulty.
The material we use most frequently for producing rotomoulded linings is ETFE. It has good chemical resistance for aggressive chemicals such as HCL, HF and sulphuric acid. Rotolining with PVDF, ECTFE and Polyethylene is also possible.
Lining of equipment that contains chemicals that diffuse through fluoropolymers is a growing application for this lining technique due to benefit of the increased liner thickness.
The surface of the item to be lined is prepared by shotblasting and by the application of a specially developed primer system to maximise the bond strength between the lining and the steel.
The item is then charged with a calculated quantity of fine particle polymer.
Heating and rotation
The fabrication is then heated in an oven whilst being rotated about two axes. The rotation rate and speed are accurately controlled and adjusted to suit the geometry of the item. The temperature during the lining process is accurately monitored and controlled.
When the required temperature profile has been achieved the fabrication is gradually cooled and the lining is stabilised in such a way as to minimise stresses in the lining.
Testing of the completed lining is carried out with conventional high voltage spark testing which verifies the continuity of the lining. Thickness tests are also carried out to ensure that the required lining thickness has been achieved. Recently developed ultrasonic testing can also be applied to verify the bond between the lining and the steel substrate, and a specially developed reflected light test method is used to detect for voids or other hidden defects.
Typical ideal applications include :
- Column sections
- Filter housings
- High purity linings for semconductor applications
- IBC Containers and other chemical transport containers