4th Class Edition 3 Part A Unit A-4 Hydrocarbon Handling PDF

Unit A-4 • Introduction to Plant and Fire Safety ================== OBJECTIVE ===================== 4 Discuss the safe handling of Hydrocarbons. It is necessary to know the properties of hydrocarbons to handle them safely. The properties that are important for operators to safely use and store...

Unit A-4 • Introduction to Plant and Fire Safety ================== OBJECTIVE ===================== 4 Discuss the safe handling of Hydrocarbons. It is necessary to know the properties of hydrocarbons to handle them safely. The properties that are important for operators to safely use and store hydrocarbon fluids will be discussed here. SIGNIFICANT PROPERTIES OF HYDROCARBON FLUIDS The significant properties of the most common hydrocarbons include: 1. Flammable or explosive Limits 2. Flash Point 3. Ignition Temperature It is important to note that the hydrocarbons in their liquid state do not burn. The evaporated hydrocarbon gas, when mixed with air, will burn. If the vapours ignite, the un-vapourized liquid will become warmer, which will cause more liquid to evaporate and produce large amounts of flammable gases. If the liquid is volatile enough, and mixes with a lot of air, it can ignite very rapidly and explode. Figure 2 - Vapours Burn Liquid Hydrocarbons won't burn Gasoline Flammable or Explosive Limits Hydrocarbons need air to burn. The minimum concentration of hydrocarbon gas in air which will ignite is the Lower Explosive Limit (LEL). If the concentration of gas is too low, it will not ignite, because there is not enough flammable gas (or too much air). This condition is known as "lean:' The Upper Explosive Limit (UEL) is the maximum concentration of vapour that can be in a given volume and still ignite. In other words, if there is too high of a concentration of flammable gas mixed with air, it will not burn because there is not enough air. This condition is known as "rich:' 3-10 7 E-- s:: - 4 t h C l a s s E d i t i o n 3 • P a r t A 4th Class Edition 3 • Part A 311 Handling of Dangerous Materials • Chapter 3 FLASH POINT The flash point of a liquid is the lowest temperature at which the liquid produces sufficient vapour to form a flammable mixture of vapour and air, immediately above the liquid surface. Lighter hydrocarbons, such as methane, ethane, butane, and propane, are gases at room temperatures, and as such are above their flash point at room temperature. However, even if a hydrocarbon is colder than its saturation temperature, it may give off sufficient vapour to momentarily support combustion. Therefore, a liquid's flash point may be far lower than the liquid's saturation temperature. Butane, for example, has a saturation temperature of approximately ooc. Despite this, butane will produce flammable vapour at temperatures as low as -60°C (the flash point of butane). This low temperature atmosphere around a container of liquid butane, while still quite cold, has enough heat in it to evaporate liquid butane at atmospheric pressure, and produce a flammable mixture. Gasoline will vapourize at -43°C. This also means that when it is colder than -43°C it will not vapourize. As a result, cars in northern Canadian winters may not start when the outdoor temperature is -60°C unless there is a way to keep the gasoline warm. Sources of Ignition The ignition temperature is the lowest temperature at which a fuel/air mixture will burn. Most ignition temperatures are relatively low when one considers that a match can burn at a temperature of 870°C, and an electric arc can be over 5000°C. If the gas is at a proper air/fuel mixture it will ignite when exposed to their relative ignition temperature. For example, propane ignites at 490°C and gasoline at 480°C. The following are suggested general guidelines only. Please be sure to follow site specific policies, procedures, and training requirements. Consult local jurisdictional regulatory requirements for the safe storage ofhydrocarbons. STORAGE OF HYDROCARBONS Hydrocarbons in liquid or gaseous form are delivered to plants in pipelines, barrels, pails, or pressurized containers. Generally a Power Engineer is not required to load or unload hydrocarbons, it is required to be familiar with their storage and use in small quantities. - Typical storage facilities for hydrocarbons in gaseous state can take the form of pressurized tanks or containers that are on site. The operator is responsible for the monitoring of pressures, temperatures, and flows from these units. Almost all plants have oil tanks: from diesel tanks that supply fuel for emergency generators, to large oil processing plants that store oil. A trained operator monitors these tanks by: a) Checking levels periodically b) Ensuring that there is a vapour space so that if the oil gets warm it will not expand and overflow the tank c) Removing water that accumulates in the bottom of the tanks. Some large oil tanks may have a "blanket" of inert slightly pressurized gas, to ensure that air does not get into the tank. Tank farms in the oil industry may use blanl<ets of natural gas, under pressure, to prevent infiltration of air into the tanks. Operators may be required to pump and circulate the oil. They must ensure that the fuel oil is recirculated back to the same tank from which it was originally drawn. ------------------------------ -/ 3-11 4th Class Edition 3 • Part A "' ================== ==================== Oils, greases, and solvents used for lubrication or cleaning will be stored in a designated area outside, or in a flammable material storage cabinet. The Power Engineer may be required to occasionally use or move this oil, either in barrels or in small containers. The operator may use a small barrel pump to transfer from a barrel or tank to a smaller container such as a jerry can. When pouring or transferring these fluids, it is expected that the operator will have proper training, is wearing PPE, and adheres to hazards instruction given in the plant. Workplace labels for controlled products must be used, when necessary. Figure 3 - Flammable Material Storage Locker 3-12 <(-------------------------------4t_h_C s_s_E_d_ft_w_n_3 ·P_-anA Unit A-4 • Introduction to Plant and Fire Safety Handling of Dangerous Materials • Chapter 3 CHAPTER SUMMARY The WHMIS 2015 program is coming into effect under the Global Harmonization System (GHS). The GHS is designed to "harmonize" how hazardous products in the workplace are identified and classified. In many ways, WHMIS 2015 is similar to the WHMIS 1988 system. The exception is that it presents the WHMIS hazardous products information in a format that conforms to other global organizations that participate in the GHS. Both systems (WHMIS 1988 and WHMIS 2015) are in effect simultaneously, until WHMIS 1988 is phased out completely at the end of2018. The intent of both WHMIS systems is to identify and classify hazardous products. This gives the worker the information necessary to make informed decisions about how to safely work with these products. This involves labelling the products with the appropriate labels - such as the supplier and workplace labels, having access to the MSDS (old) or the SDS (new), and training the employees on all components of WHMIS. Power Engineers must receive WHMIS training in their workplace. The general information discussed here will assist in understanding the specific WHMIS training material provided at the worksite. Gas cylinders are often used in plants where Power Engineers work. It is necessary to be familiar with the components of a cylinder. The operator of the cylinder should be able to identify and operate the cylinder and associated equipment. This includes connecting and disconnecting cylinders - to a header if necessary - to supply a pressurized service to their plant. Hydrocarbons- gas, fluid or solid- should be handled carefully. The properties and characteristics of these hydrocarbons should be understood. A method of determining these characteristics are important. Significant properties such as flammability, explosive limits, flash point, and ignition temperature should be recognized and considered when using hydrocarbons, when either used as fuel or stored for later. 4th Class Edition 3 • Part A 3-13