Inspection of plants

A number of common issues arise from the various legislative requirements for examination and inspection of plant and equipment. 

Under certain regulations there is a requirement for a responsible person to carry out routine daily or weekly inspections of plant. That responsible person could be the employee who regularly operates the plant or equipment provided he has been trained in the checks to be carried out. 

Repeatability. This refers to two aspects of inspection similarity between objects that are inspected and possibility of maintaining constant inspection conditions (settings) for all the inspections performed. Obviously, interpretation of data in repeatable conditions is significantly simplified. Usually, inspection during or after manufacturing process will be repeatable. Another example of repeatable inspection is inspection of heat exchangers in power nuclear plants, inspection of aircrafts as these are well standardised. However, a large part of the NDT inspection done is not repeatable. 

The paper presents the results from systematic comparisons of contrast and resolution obtained with different types of radiation sources on steel thicknesses from 5 to 40 mm. These results have been taken into account with the definitions of the European standard for radiographic inspection of weldments (EN 1435) that is approved since 1997. Conclusions from practical investigations on pipe line sites, in petrochcemical plants and in nuclear power stations will be discussed as well. Furthermore, the presentation will stipulate a variety of advantages obtained from the new source in terras of coUimation and radiation protection. 

Besides large-diameter pipes, ultrasonic testing is used for checking the welded joints of drill bits, components of wind-driven electric plants, welded joints of light alloys and non-metallic materials, for an integrated inspection of various objects. A range of training aids developed at the Institute allows the operators to be trained effectively. 

It has developed a real time method to compare successive non-destructive inspections of the steam generator tubes in nuclear power plants. Each tube provides a safety barrier between the primary and secondary coolant circuits. Each steam generator contains several thousands of tubes whose structural integrity must be ensured through the lifetime of the plant, Therefore, Laborelec performs extensive nondestructive tests after each plant outage. 

The DART system presented in this paper will be used for inspection of welds in Swedish nuclear power plants during 1998. 

For pipelines in service in chemical plants, it is not usually convenient to place a radiation source inside the pipe and position it to irradiate each welded joint. The radioisotope source container maybe placed on the outer surface of the pipe. The radiation beams then pass through two pipe wall thicknesses to expose films placed diametrically opposite the radiation source, also on the outside of the pipe wall. Other methods, such as magnetic particle inspection of welds in steel pipe, or ultrasonic inspection of welds in pipes of all materials, supplement x-rays in many critical appHcations. The ultrasonic tests can often detect the thin, laminar discontinuities parallel to the pipe surface or the incomplete fusion discontinuities along the weld... 

Tbe vertical iu-liue pumps, although relatively new additions, are finding considerable use iu chemical aucl petrochemical plants iu tbe United States, Au inspection of tbe two designs will make clear tbe relative advantages iiud disadvantages of each,... 

XI. Rules for Inservice Inspection of Nuclear Power Plant Components... 

A routine inspection of the tube bundle during a plant outage revealed fine cracks of the type shown in Fig. 9.11. Scattered longitudinal cracks were observed along the lengths of most tubes. The external surface was covered with a thin film of black copper oxide and deposits. The bundle had been exposed to ammonia levels that produced 14 ppm of ammonia in the accumulated condensate. 

Audit (Process Safety Audit) An inspection of a plant or process unit, drawings, procedures, emergency plans, and/or management systems, etc., usually by an independent, impartial team. 

To simulate the next summer s condition the plant was run at the desired production rate and two cooling tower fans were turned off. It turned out that the cold water temperature rose to slightly above that predicted for the next summer. A thorough inspection of critical temperatures and the plant s operation indicated that the plant would barely make it the next summer. Process side temperatures were at about the maximum desired, with an occasional high oil temperature alarm on the large machines. 

The audit includes a review of the process safety information, inspection of the physical facilities, and interviews with all levels of plant personnel. Using the procedures and checklist, the team systematically analyzes compliance with the PSM Rule and any other relevant corporate policies. The training program is reviewed for adequacy of content, frequency and effectiveness of training. Interviews determine employee knowledge and awareness ofthe safety procedures, duties, rules, and emergency response assignments. The team identifies deficiencies in the application of safety and health policies, procedures, and work authorization practices to determine live actions. 

T he tightness and condition of the filter are checked regularly by visual inspection of the plant. 

L. Pilborough, Inspection of Chemical Plants, Gulf Publishing Co., Houston, Texas, 1977. 

At shift handover at 18 00, the incoming operations supervisor was briefed by the day supervisor. The conversation centered on the vibration fault and subsequent repair work carried out. However, no mention was made of the work on the PRV, so consequently none of the incoming shift were aware of it. The night shift supervisor, wanting to return pump A to standby as soon as possible, asked the plant operator to check the status of the pump, and together with the shift electrician, to reset it and put it back on stand-by. The operator, unaware of the work being done on the PRV, did not check this part of the system and, following inspection of the pump, returned it to stand-by. 

A plant engineer may become involved with an inspector from the HSE when he arrives on site to carry out an inspection of the works under powers given to the Executive by Section 20 of the Act. The HSE will visit at any reasonable time, or at any time where the situation may be dangerous in the inspector s opinion. He may take with him a police officer if he has reasonable cause to apprehend any serious obstruction in the execution of his duty. 

In instances where cover is written on this basis, it is normal that higher than usual excess is applied, reflecting the type of plant involved. While it is normal on the more traditional basis for the insurance cover to be complementary by inspection of the insured items in the case of covers written in this manner, it is usual for the inspection of all statutory plant to be incorporated together with those items where the insurer considers inspection to be necessary as part of the risk management of the cover being provided. 

During this training, an engineer surveyor can expect to be shown examples of the defects that he is likely to encounter. Many inspecting authorities have a black museum of such defects or they are described and illustrated by photographs in the training literature. He will also be instructed, both in the classroom and on-site, about locations where defects are likely to occur. Most surveyors develop an instinct , which helps them to find defects, and this can only be acquired through practical experience of different types of plant. 

---