Aging protective measures

Employers are duty bound to provide information to their employees on, for example, the arrangements for emergencies, competent persons and the risks to their health and safety identified by assessments. Information should also be provided on the preventive and protective measures required to prevent harm occurring. Where a child is employed (under school leaving age) by an employer, such information that would normally be provided to an employee will also be required to be provided to a parent. 

The variation in the on and off potentials or the potential difference along the pipeline will usually indicate faults that prevent the attainment of complete cathodic protection. The protection current requirement of the pipeline may be estimated from experience if the age and type of pipeline is known (see Fig. 5-3). Figure 3-20 shows the variation in the on and off potentials of a 9-km pipeline section DN 800 with 10-mm wall thickness. At the end of the pipeline, at 31.84 km, an insulating unit is built in. The cathodic protection station is situated at 22.99 km. Between this and the end of the pipeline there are four pipe current measuring points. The applied protection current densities and coating resistances of individual pipeline sections are calculated from Eqs. (3-40) and (3-41). In the upper diagram the values of... 

Calculation of lung cancer risk for radon daughter exposure is based on factors developed by the National Council on Radiation Protection and Measurements (NCRP, 1984). The risk coefficients are expressed in terms of lifetime risk from lifetime exposure for a population of mixed ages, comparable to the standardized U.S. population, and range between one and two per 10,000 WLM of exposure. The percent increase in risk is related to a normal lifetime lung cancer risk of 0.041. 

In the United States, the National Council on Radiological Protection and Measurements (NCRP) has recently issued two reports on this subject (NCRP, 1984a,b). The lifetime risks have been estimated and it is predicted that exposures of 2 WLM/y would reduce the probability of living to age 70 by 1.5 and an exposure level of 5 WLM/y would reduce that probability by 4 (NCRP, 1984a). For an average dose to the population of 0.2 WLM/y, the model predicts about 9000 deaths from lung cancer per year in the U.S. population (NCRP, 1984b) for nonsmokers. 

Oilfields in the North Sea provide some of the harshest environments for polymers, coupled with a requirement for reliability. Many environmental tests have therefore been performed to demonstrate the fitness-for-purpose of the materials and the products before they are put into service. Of recent examples [33-35], a complete test rig has been set up to test 250-300 mm diameter pipes, made of steel with a polypropylene jacket for thermal insulation and corrosion protection, with a design temperature of 140 °C, internal pressures of up to 50 MPa (500 bar) and a water depth of 350 m (external pressure 3.5 MPa or 35 bar). In the test rig the oil filled pipes are maintained at 140 °C in constantly renewed sea water at a pressure of 30 bar. Tests last for 3 years and after 2 years there have been no significant changes in melt flow index or mechanical properties. A separate programme was established for the selection of materials for the internal sheath of pipelines, whose purpose is to contain the oil and protect the main steel armour windings. Environmental ageing was performed first (immersion in oil, sea water and acid) and followed by mechanical tests as well as specialised tests (rapid gas decompression, methane permeability) related to the application. Creep was measured separately. 

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