CSA C22.2-NO.293.1:2017 pdf download.General,Testing, Marking, and Documentation Requirements
1.4.2 Solidification prevention
Systems can be used to prevent the fluid in a line or a vessel from solidifying. These include water, aqueous solutions, crude oil, pitch, asphalt, metals, sulfur, and other chemicals. The heating system compensates for pipeline heat losses in order to maintain the temperature of the contents above the solidification point.
1.4.3 Viscosity maintenance
Systems can be used to maintain viscosity of a fluid in a pipeline or a vessel. V iscous materials such as heavy fuel and crude oil are generally heated to achieve optimum pump efficiency and pipeline sizes.Usually these materials are preheated to a temperature that provides the desired viscosity and pumped to their destination through heated pipelines designed to maintain that temperature.
1.4.4 Process heating
Systems can be used to maintain the temperature of fluids when process parameters require it. Systems can also be used to raise the temperature of process fluids flowing in the pipeline or the vessel, but they require increased heat input capacity.
1.4.5 Condensation prevention
Systems can be used to prevent gaseous materials from condensing. Some gases condense at low temperature and require heating to maintain their gaseous state during transportation. If pressure is significantly reduced during gas flow, such as through a valve, increased heat input capacity might also be required.
1.4.6 Re-melting solidified fluids
Systems can be used to re-melt solidified fluids. Some heating applications do not require heat during pumping, but only supply heat to re-melt pipeline contents and bring them up to temperature prior to pumping. A typical example is an infrequently used loading or unloading pipeline.
1.4.7 Structure heating
Skin effect trace heating systems can be used on concrete foundations and concrete walls exposed to sub-freezing temperatures to prevent frost heave. They can also be used on concrete pads, concrete surfaces, or other surfaces for de-icing and snow-melting. Typical examples of frost heave prevention applications are cryogenic and low-temperature storage tanks. Typical examples of de-icing and snow-melting applications are the concrete surfaces of some automated public transportation systems.
4.1 Principle of operation
A skin effect heating system consists of a single insulated conductor run inside a ferromagnetic envelope. A source of ac power is connected between the skin effect insulated conductor and the ferromagnetic envelope at the power connection (i.e., the start of the skin effect trace heater). The far end of the skin effect conductor is connected to the ferromagnetic envelope at the end opposite from power source. Current flows from the power source through the skin effect insulated conductor to the far end and returns through the inner skin of the ferromagnetic envelope. The basic skin effect trace heating system is illustrated in
Figure 1. CSA C22.2-NO.293.1 pdf download.