On-line inspection

Bimetallic Barrets Liners Instruments Controls Heaters Heating Elements Motors Drives On-line Inspection Devices... 

On-line inspection is a form of testing and in this context dimensional measurements are those most often made. Apart from gauges, micrometers and so on, there are various optical, electrical, nuclear and other methods which may have advantages in production circumstances. Descriptions of the use of such techniques can be found in the literature and in manufacturers data sheets. Some fairly recent examples relating to rubber and plastics products are given in references 12 - 16. However, the various techniques will not be reviewed here. 

Bottles are normally coded with a best before date and often a closed code giving the batch or production record for tracing purposes. These are applied by laser printer or ink jet onto the label, cap or neck of the bottle. There is a variety of on-line inspection devices available for ensuring the quahty of the product, for example, empty bottle inspectors, hydrocarbon sniffers (to check that returnable bottles have not been used for storage of paraffin, etc.), fill height detectors, label apphcation detectors and date code verifies. All of these can be found on the modem bottling line. 

Figure 9-15. This on-line inspection system from Qualipus (Stamford, Conn.) uses high-resolution video cameras to detect flaws at speeds of 51,000 preforms/hr. These PET injection-blow-molded bottle preforms are checked for both neck geometry and molded-in specks or flaws at rates up to 850 preforms/min.

This header has undergone repair after through-thickness cracking of an assembly weld after 108.000 hours of service, it is presently in operation and periodically submitted to ultrasonic inspection during planned maintenance shutdown. Continuous on-line AE monitoring of the integrity of critical welds is expected to contribute supporting continued and safe operation of the header until its replacement, platmed to take place in 1999. 

In general, radioscopic X-ray inspection systems are used in the serial examination of industrial workpieces since they enable a flexible adjustment of the beam direction and of the inspection perspective as well as on-line viewing of the radioscopic image. In the past few years this economic and reliable method has become prevalent in weld inspection during the manufacturing process of pipes. The configuration of such radioscopic systems is schematically represented in fig. 1. 

A tube manufacturer wanted to investigate the possibility for on-line measurement, calculation and presentation of eccentricity values on aluminum tubes when drawn at high velocities. Based on our experience from development of tube inspection systems [1, 2] for off-line inspection of precision tubes, a project was formulated. The main specifications for the tube manufacturing are summarized below ... 

The Pascal code was updated to handle four channels. To follow the inspection speed all raw measuring data were captured and stored in the computer. All data for one coil could be stored in the computer memory (RAM) and transferred to the disk before inspection of the next coil. Evaluation of the data could be performed on-line or later using a special evaluation program. 

These tests generate several Gigabytes of data that are fed into a historical database. Although most of the analysis is performed automatically, human interaction is still needed to compare current and past data. Data are stored on optical CD S s from which the historical data bank are retrieved during field inspections from a mobile unit. Each of these is equipped with a CD-jukebox linked to an analysis station. The jukebox can handle 100 CD s, enough to store all previously recorded data. A dedicated software pre-fetches the historical data and compares it on-line with the newly acquired NDT-data. It is based on fuzzy algorithms applied to signal features. 

An inherently safer control system design will, where possible, include options for on-line reliability tests and inspections. Within digital devices, this is done using watch-dog timers to assure the signals are processed. 

The pump had been awaiting repair for several days when a permit-to-work was issued at 8 a.m. on the day of the fire. The foreman who issued the permit should have checked ahead of time that the pump suction and delivery valves were shut and the drain valve open. He claimed that he did so. Either his recollection was incorrect or, after he inspected the valves and before work started, someone closed the drain valve and opened the suction valve. When the valves were closed, there was no indication—on them—of why they were closed. An operator might have opened the suction valve and shut the drain valve so that the pump could be put on line quickly if required. 

Replacement of lines based on normal life expectancy will provide some degree of safety, but it is important that such provisions do not cause any degree of laxity in sling line inspection. 

The availability of probes that can be welded to the outer walls of piping or process vessels providing on-line thickness measurement is an interesting development which would seem to bridge the technologies of corrosion monitoring and inspection". 

Seminar, London, March 1987, Global Corrosion Consultants, Telford, UK On-Line Surveillance and Monitoring of Process Plant , Proc. Symposium, London, September 1977, Society of Chemical Industry, London Inspection of Chemical Plant, (Pilborough), Leonard Hill Books, London (1971)... 

What is novel is the manner in which they are tied together. In IP, new nondestructive evaluation sensors are used to monitor the development of a materials microstructure as it evolves during production in real time. These sensors can indicate whether the microstructure is developing properly. Poor microstructure will lead to defects in materials. In essence, the sensors are inspecting the material on-line before the product is produced. 

The QA unit should have written procedures (SOPs) for the conduct of inspections and audits. These procedures should incorporate all considerations for the review of electronic data systems. The QA unit SOPs should address the role and responsibilities of the QA unit in software development, purchase, and validation activities, in-process audit procedures for data collected on line, procedures for on-line review of data (i.e., what will be verified and how much data will be reviewed), and the procedure for auditing reports using on-line data. 

Table 7.3 shows the concentrations of 1-5 that result in 50% growth inhibition (GI50) of five human cancer cell lines. Inspection of these data reveals that cytostatic activity of 1 and 3-5 depends on the thermodynamic favorability of the quinone methide species compared to the corresponding keto form. The most cytostatic prekinamycins 1 and 5 are associated with the thermodynamically stable quinone methides. In contrast, the inactive prekinamycins 3 and 4 are associated with thermodynamically stable keto tautomers. The exception is prekinamycin 2, which is cytostatic and possesses a relatively stable keto tautomer 3 compared to its quinone methide. Although the AE value for quinone methide tautomerization can predict cytostatic properties, prekinamycin 2 shows that there must be other factors determining biological activity. 

Equations 11-19 through 11-25 assume a negligible repair time. This is usually a valid assumption because on-line process equipment is generally repaired within hours, whereas the inspection intervals are usually monthly. 

Strain in dents may be estimated using data from deformation in-line inspection (ILI) tools or from direct measurement of the deformation contour. Direct measurement techniques may consist of any method capable of describing the depth and shape terms needed to estimate strain. The strain estimating techniques may differ depending on the type of data available. Interpolation or other mathematical techniques may be used to develop surface contour information from ILI or direct measurement data. Although a method for estimating strain is described herein, it is not intended to preclude the use of other strain estimating techniques. See also Fig. D-l. 

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