Cold stress types

Phenolic compounds may be involved in plant responses to cold stress and in plant acclimation to low temperature. Acclimation of apple trees to cold climates was found to be associated with a seasonal accumulation of chlorogenic acid [102]. Strengthened frost tolerance in a variety of plants were attributed to thicker cell-wall lignification or suberization [102]. Thickening of cell walls and increased production of suberin-type lipids were observed in cold-acclimated winter rye leaves [103]. The presence of suberin in cell walls may favour membrane cell-wall adhesion, a major factor in the resistance of plant cells to freezing [104]. 

When selecting the type and manufacture of the PPE, the purchaser should understand the functions being preformed by the responder and the chemical and physical hazards associated with the operation. They must also know how the operation and chemical will effect the degradation of the suit, gloves, and boots and the tactility and dexterity needed by the responder. Especially when Levels A and B equipment is in use, it is important not to overlook nonchemical hazards, such as heat stress, cold stress, slip, trip and falls, moving equipment, and lifting. 

Extremes of either heat or cold can be more than uncomfortable—they can be dangerous. Heat stress, cold stress, and burns are major concerns of in the processing industry. Employees who work outside during the summer on surfaces that heat up and store heat will get very hot. They will be around metal equipment and vessels that are hot and radiate large amounts of heat. The opportunity for heat stress will be present. Also, winter conditions on a processing unit in Colorado or Alaska will present the opportunity for frostbite or hypothermia. The prudent process employee will seek to understand the types of heat and cold stress and how to avoid them. 

Workplace conditions that influence cold stress are the severity of cold stress, which depends on the air temperature, wind speed, and intensity of physical activity. Air temperature is measured by an ordinary thermometer in degrees Fahrenheit or Celsius. Different types of commercially available anemometers are used to measure wind speed or air movement. These are calibrated in miles per hour (mph). The following is a suggested guide for estimating wind speed, if accurate information is not available ... 

The farm animals that are most likely to suffer from cold stress are newborn lambs, calves and pigs. They are small and tend to have poor insulation because of low levels of subcutaneous fat or a thin coat of hair or wool. In addition, they are wet when born. If the newborn animal also fails to obtain sufficient milk from its mother, then its heat increment of feeding may be low. Newborn animals have a special type... 

Many working environments are uncomfortable owing to excessive heat or cold in one form or another some can be so extreme that they lead to heat or cold stress occurring in the workers. When investigating these environments, it is important to take into account the rate of work and the type of clothing of the worker as these affect the amount of heat the body is producing and losing. 

The health of workers can be affected by thermal stress when ambient temperatures are too high. The stress can also be exacerbated by the type of work that is being carried out, e.g., when someone is doing heavy physical work when ambient temperature is high. Other factors that affect heat and cold stress include humidity, wind speed, and the type of clothing that is being worn. PPE can also be a major factor in heat stress because it is often heavy, bulky, and not well ventilated. 

Nitrogen compounds These also arise from both natural and synthetic sources. Thus ammonia is formed in the atmosphere during electrical storms, but increases in the ammonium ion concentration in rainfall over Europe in recent years are attributed to increased use of artiflcial fertilisers. Ammonium compounds in solution may increase the wettability of a metaland the action of ammonia and its compounds in causing season cracking , a type of stress-corrosion cracking of cold-worked brass, is well documented. 

Tees Tees may be cast, forged, or hot- or cold-formed from plate or pipe. Tees are typically stocked with both header (run) ends of the same size. In general, run ends of different sizes are not typically stocked or specified however, occasionally run ends of different sizes are specified in threaded or socket-welded sizes. Branch connections may be full size or reducing sizes. Branch reductions two sizes smaller than the header are routinely stocked, and it is not typically difficult to purchase reducing tees with branches as small as those listed in ASME B16.9 (i.e., approximately one-half the header size). Economics, stress intensification factors, and nondestructive examination requirements typically dictate the branch connection type. 

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