Holiday detection

Holiday detectors must be selected for the thickness and type of coating being tested. Excessive voltage can stress or damage thin coatings if the detector has been set too high. Adherence to the manufacturer s instructions is recommended, including both the manufacturer 

---

Conventional holiday-detection is of little value in the field but great attention should be given to preventing damage to the applied tapes. 

Holiday detection or spark testing may be specified in the contract with details of the appropriate instrument and testing procedure. In certain cases. 

ASTM G62-87 Standard test methods for holiday detection in pipeline coatings (withdrawn 2007)... 

Combined methods are also used to monitor cathodic protection efficiency. In the intensive measurement described by Wessling et at. [68], both CIPS and DCVG are used. The worker walks the pipeline route and records the distance and the switch on and switch off potential changes vs. the portable reference electrode at small intervals. The measurements are supplemented with ON/OFF potential gradients in one or two directions perpendicular to the pipeline. The measured (real) values serve as the basis for calculating the insulation defects (% IR). Other techniques such as the intensive holiday detection method can be used to detect the coating defects in the pipelines. Implementation of the above methods has led to a considerable decrease in the number of breakdowns of underground pipelines. 

NACE Test Method for Holiday Detection of Internal Tubular Coatings of Less than 10 Mils (0.25 mm) Dry Film Thickness (TM0384) defines apparatus and procedure for holiday detection in nonconductive coating film. 

Standard Test Methods for Holiday Detection in Pipeline Coatings... 

Holiday Detection of Fusion-Bonded Epoxy External Pipeline Gaatings of 250 to 760 microns (10 to 30 mils) Metallurgical and Inspection Requirements for Offshore Pipeline Bracelet Anodes... 

Evaluation of Internal Plastic Coatings for Corrosion Control of Tubular Goods by Autoclave Testing Holiday Detection of Internal Tubular Coatings of 10 to 30 mils (0.25 to 0.76 mm) Dry Film Thickness Holiday Detection of Internal Tubular Coatings of Less Than 10 mils (0.25 mm) Dry Film Thickness Evaluating Elastomeric Materials in Carbon Dioxide Decompression Environments Chemical Resistance of Polymeric Materials Periodic Evtiluation... 

Holiday Detector a high-voltage low-current output generator with a built-in spark gap used for detecting pinholes (holidays) in pipeline coatings. 

Fig. 14. Apparatus for detecting "holidays in paint films. A, Electrical connection to pipe B, paint film C, metal substrate D, brine-soaked sponge E, power and meter section.

There are insufficient data to support the use of drug holidays in detecting the risk of tardive dyskinesia, but they may help to diagnose the covert type by unmasking dyskinesia (245). 

The amino-acid composition reported by Porter, Sweeny and Porter (64) can be considered as a preliminary result. Thus, the values given by Hartz and Deutsch (67) for human erythrocuprein and by Carrico and Deutsch (8) for the corresponding proteins from human liver and brain should be closest to the actual amino-acid composition. It is still uncertain how many tryptophan residues are present in human erythrocuprein. From measurements of the decrease of the fluorescence emission in the presence of N-bromsuccinimide it was concluded that 1.25 moles of tryptophan per mole of protein are present (92). With MCD studies (78) and chemical analysis by the method of Spies and Chambers (93) the absence of tryptophan residues was demonstrated using bovine erythrocuprein. Other spectrophotometric methods developed by Edelhoch (94) or Beaven and Holiday (95) detected 0.4—0.9 mole of tryptophan per mole of the bovine protein (72). 

It may be readily detected spectrographically in proteins, even in presence of tyrosine and tryptophan, by means such as the moving-plate method (Holiday, 1937, 1950a). A source giving a continuous spectrum is essential to show up the fine structure bands which reveal its presence. 

Holiday detector n. Device for detection of pinholes or voids. 

Spark-testing n. Method of detecting holidays (flaws) on metallic substrates by means of spark-test tool. 

The cooperation of the individual machine operators is of prime importance. They are on the spot and most able to detect unusual events that may indicate equipment malfunctions. Once an attitude of general cooperation is established, coordination should be refined to monthly weekly, daily, and possibly even hourly schedules. Major shutdowns and holidays should be carefully planned so any work that requires cold shutdown can be done during those periods. Maintenance will often find that they must do this kind of work on weekends and holidays, when other persons are on vacation. Normal maintenance should be coordinated according to the following considerations ... 

---