Electrical plant inspection

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. 

In 1854, the Manchester Steam Users Association was formed to help with the prevention of explosions in steam boilers and to find efficient methods in their use. To achieve this, the Association employed the first boiler inspectors, whose services were then made available to the Association s members. Within a short space of time, the members became convinced that insurance to cover the high cost of repair or replacement of damaged boilers was desirable, and this resulted in the first boiler insurance company (The Steam Boiler Assurance Company) being formed in 1858. The scope of the services for inspection and insurance later extended to include pressure vessels, steam engines, cranes, lifts and electrical plant, the insurance protection in each case being supported by an inspection service carried out by qualified engineer surveyors. 

Plant that is subject to periodic statutory inspections includes lifting plant for both goods and people and associated ancillary components, boilers, pressure vessels, power presses, extract ventilation plant and some electrical installations in special situations. A list of the principal Regulations containing plant inspection requirements is given in Table 29.1. 

The periodic inspection and testing by a competent person of electrical plant and installations as a statutory requirement arises only under the Cinematograph (Safety) Regulations 1955 which require inspection and testing by a competent person every twelve months. 

The aforementioned reviews and assessments were assimilated to characterize the effect of dielectric, rotational, and mechanical hazards on motor performance and operational readiness. Functional indicators were identified that can be monitored to assess motor component deterioration caused by aging or other accidental stressors. The study also includes a preliminary discussion of current standards and guides, maintenance programs, and research activities pertaining to nuclear power plant safety-related electric motors. Included are motor manufacturer recommendations, responses from repair facilities to a questionnaire, in-service inspection data, expert knowledge, USNRC-IE audit reports, and standards and guides published by the Institute of Electrical and Electronics Engineers (IEEE). 

Inspection by independent persons or bodies for safety purposes goes back to the middle of the nineteenth century. At that time, the focus of concern was the explosion of steam boilers, and this hazard was most prevalent in the textile industry. Consequently, a group of public-spirited individuals formed the Manchester Steam Users Association for the Prevention of Boiler Explosion. This body carried out boiler examinations and later added insurance as an inducement to the plant owners. By the beginning of the twentieth century steam and gas engines and electrical machines had been added, followed by lifts, cranes and hoisting machines. 

Other inspection services available include the examination of steel structures (new and existing), electrical wiring installations, containers (to meet Statutory Instm-ment No. 1890), dangerous substances (carriage by road in road tankers or tank containers) to meet Statutory Instmment No. 1059, examination of second-hand plant prior to purchase, plant undergoing repair or modification, the Control of Industrial Major Accident Hazard Regulations (CIMAH) Statutory Instmment No. 1902 and Control of Substances Hazardous to Health (COSHH) and Pressure Systems Regulations. 

If changes have been made to the process (e.g. if incoming water quality cannot be maintained or other uncertainties arise concerning the corrosion behavior of the construction materials) it is possible to incorporate coupons or probes of the material into the plant and monitor their corrosion behavior. This approach may be used to assist in the materials selection process for a replacement plant. Small coupons (typically, 25 x 50 mm) of any material may be suspended in the process stream and removed at intervals for weight loss determination and visual inspection for localized corrosion. Electrical resistance probes comprise short strands for the appropriate material electrically isolated from the item of plant. An electrical connection from each end of the probe is fed out of the plant to a control box. The box senses the electrical resistance of the probe. The probe s resistance rises as its cross-sectional area is lost through corrosion. 

Inhibitor control can be effected by conventional methods of chemical analysis, inspection of test specimens or by instrumentation. The application of instrumental methods is becoming of increasing importance particularly for large systems. The techniques are based on the linear (resistance) polarisation method and the use of electrical resistance probes. They have the advantage that readings from widely separated areas of the plant can be brought together at a central control point. (See Section 18.1.)... 

Heavy industrial boilers operating in continuous processes may be online for perhaps four or even five years before shutting down for maintenance and inspection. Here, correct boiler plant materials selection is critical, and the quality of the various utility support functions must be outstanding if forced outages are to be avoided. A heavy industrial or utility boiler that is unintentionally offline may cost 1 million a day in lost production or electricity generation. 

Copper(II) acetylide (black or brown) is much more sensitive to impact, friction or heat than copper(I) acetylide (red-brown) which is used in electric fuses or detonators [1]. An explosion during maintenance work on a copper condenser in a methanol plant was attributed to copper acetylide deposits in the heat exchanger [2]. During internal inspection of an air-purged 15 year old 330 m3 liquefied gas cylinder, it was noticed that there was a 2—3 cm layer of mst-like deposit at the bottom. As the inspection... 

Cost of construction of this plant (engineering, inspection, and other expenses figured at 20% of the contract costs) totals 1,000,000, divided as follows equipment, 70% electric service, main supply transformers, switch gear, etc., 4% housing structure, 10% contact or diffuser tanks, 16%. 

The techniques used for monitoring corrosion in a process plant are (i) visual inspection (ii) weight loss coupons (iii) electrical resistance probes (iv) measurement of corrosion potential (v) linear polarization measurement (vi) hydrogen probes (vii) thickness measurement and crack detection (viii) visual inspection (ix) sentinel holes. 

Mihama-3 is an 826 MW Mitsubishi-built pressurized water reactor (PWR) plant situated in Mihama, Japan, 320 km west of Tokyo. The carbon steel pipe carried the high-temperature steam at high pressure and the pipe was not inspected since the inception of the plant in 1976. In April 2003, Nihon Arm, a maintenance subconttac-tor informed Kansai Electric Power Company, the plant owner, that there could be a problem. Then the power company scheduled an ultrasonic inspection for August 2004. Four days before the scheduled inspection, superheated steam blew the 60-cm wide hole in the pipe. The steam that escaped was not in contact with the nuclear reactor and hence no nuclear contamination has been reported. 

Much electrical equipment, although flameproof, will attain surface temperatures over 160 °C when in use and careful inspection of the certification of such equipment must be made before diethyl ether is handled in a plant not specifically built for the purpose. 

Pressure vessels, boilers and steam lines, fuel and gas lines, electrical equipments, and plant layout are inspected by Factory Inspectors from safety point of view. 

Statutory inspection of some key equipments has become due, and it is necessary to stop the plant, overhaul and repair (wherever necessary) and present to authorities for annual inspection as per the law, e.g. steam-generating boilers, pressure vessels, electrical installations, and safety devices. 

In such situations, the plant shutdown for annual overhaul may be postponed by a reasonable period provided it will not violate any statutory regulation (e.g. inspections of boiler/pressure vessel/electrical installation). 

Those items (e.g. gas mask canisters, and personnel safety devices such as face shields and safety goggles) which are likely to deteriorate during long storage need to be checked once again before actual use. Some more examples arc electrical spares, catalyst used in reactors, spares of instmmentation, anti-caking agents, etc. If a proper inspection of such items is not done before use, it can result in serious problems in the process plant. 

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