50 Tips for Manual Processing

Transcription

1 GE Inspection Technologies 50 Tips for Manual Processing GE imagination at work

2 Film storage The darkroom 1 First of all, storage facilities for unexposed X-ray films should provide adequate protection from any penetrating radiation. If the films are stored for longer than 3 months, background radiation should not exceed 90 ngy/h (18 x C/Kg/h). Films in containers sealed by the manufacturer should be stored with the films on edge, whenever possible. Storage temperature should be between 4 C (40 F) and 24 C (75 F) at a relative humidity range of 30 to 60 %. 2 If STRUCTURIX films are handled and stored in accordance with the directions given above, Agfa guarantees their good quality at least until the expiry date on the box. Storage of film should be on a first-in first-out basis. 3 The darkroom must always be completely light-tight. Particular attention shall be given to the entrance (revolving door or labyrinth) to prevent light leakage and excessive intrusion of dust and sand. 4 Although a relatively high safelight illumination intensity is possible when handling STRUCTURIX films, adequate filters should be used. Recommended AGFA filters are R1 (orange-red) and G7 (green) in direct or preferably, indirect lighting. In any case of doubt on the safety of the lighting conditions, an evaluation should be done according to ISO 8374 or according to any other code of good workmanship. A simple test with an object on a sheet of film for five minutes under the safelight will already give a good indication Dry section Wet section Dry section Wet section A. Example of a large, multi operator darkroom. B. Example of a small, single operator darkroom. General tip Always work in a calm, methodical way, in order to save time in the end. Haste makes waste! 1. Table 2. Cassette lock 3. Labyrinth entrance (fig. A) Revolving door entrance (fig. B) 4. Developer bath 5. Rinsing bath 6. Fixer bath 7. Final rinsing (underwater lock in fig. A) 8. Wetting bath 9. Drying cabinet 10. Lightbox

3 5 Place the safelight sufficiently high above the workbench and the tanks (minimum 60 to 70 cm) in order to avoid interference with the film handling. 6 Keep the wet and dry sections of the darkroom well separated. 7 Avoid too high humidity and temperature with an adequate ventilation of the darkroom. 10 air changes an hour is advisable. 13 Never bring the hangers above the workbench: a drip from one of the corners of the frame could fall on a lead screen or the workbench and then become transferred to a film causing a spurious result. 14 Use solid frames made of stainless steel. They must be perfectly square, in order to keep the films correctly tensioned. 8 Keep the darkroom as clean as possible. Dust between films and screens can cause white artefacts on the image. This applies in particular to fluorescent screens (see tip 50). 9 It is advisable to prepare photochemical solutions outside the darkroom to prevent contamination of the dry section. Dry section 10 Keep the worktable completely dry (see tip 6). 11 Handle the lead screens carefully when reusing them. Creases in the screens cause lines on the X-ray image. 12 Always hold the films between thumb and index finger only (never with three or more fingers), in order to avoid creases. Holding the film with thumb and index finger, attach it to one of the clips in the frame. Attach it to the second clip holding the film tight between the thumb and index finger

4 15 Broken frames must be repaired (welded) by a qualified expert: unsuitable welding alloys (copper or similar) may contaminate the developer, causing black artefacts on the film. 16 Always remove the film from the hangers development frames with dry hands to avoid moisture spots on films or screens. 17 Keep hangers with clips vertical thus making it easier to tension the film correctly. Films that are not correctly tensioned may stick to each other in the processing tanks or in the dryer cabinet 18 After use, rinse the frames in running water and allow to dry thoroughly. 19 Use FIXCLEAN to remove all chemical deposits and oxidation stains from the hangers, as these can contaminate the developer solution and cause spots on the film. Wet section 20 Clean the tanks thoroughly at regular intervals. Impurities can adversely affect the properties of the processing solutions. Preferably Agfa DEVCLEAN should be used to clean the developer section. 21 Never change the tanks, even after thorough cleaning. Traces of fixer may still remain in the fixer tank, and if this tank is then used for developing, the developer activity will be adversely affected. 22 Rinse the developer tank thoroughly once more before filling it with developer. 23 It is preferable to use Agfa industrial photochemical products which are most suited for the processing of industrial X-ray film (developer G 128, fixer G 328). In case of using the STRUCTURIX Dryer, the fixer G 335 must be used. 24 The manufacturers instructions for use should be followed precisely when diluting and mixing the chemicals. 25 Use clean (preferably filtered) water for mixing the chemicals. Contaminated or too hard water can adversely affect the properties of the solutions (hardness; a CaCO3 equivalence between 40 and 140 ppm would be acceptable). 26 To avoid oxidation, cover the developer tanks when not in use, using a floating lid or a sheet of polyethylene. 27 Standard developing temperature is 20 C (68 F) for 5 minutes developing time. Check the temperature regularly (no mercury filled thermometers allowed). The processing solutions should also be stirred regularly in order to ensure a uniform temperature throughout. 27 Immediately after immersing the films in the developer, agitate them for 30 seconds in order to a) remove air bubbles from the emulsion b) bring fresh developer to the surface of the film and prevent uneven development.

5 29 Agitate but do not lift the films during the development process because developer dripping off oxidises easily, as does developer on the surface of the film, leading to faster exhaustion of the developer solution. 30 Always apply standardised time-temperature processing. Adjust the film exposure to suit the developer activity, not the other way round. This guarantees consistent radiographic results in all conditions. 31 Always ensure adequate replenishment, if possible according to a replenishment diagram (ml/m 2 ). The quantity of replenishment solution to be added should preferably not exceed 5 % of the total tank volume to keep the density variations within limits. Replenishment should also compensate for the amount of liquid taken out of the bath along with the films and frames. For the exact replenishment rate, see table at the last page. 32 Keep the developer replenishment solution in sealed, air-tight tanks or bottles. 33 It is not advisable to continue replenishment indefinitely. The solution should be discarded when the replenisher used is twice the original quantity of developer in the tank (example: max. 50 litres replenisher for 25 litres developer solution). 34 Reduce the draining time of the films above the tank to an absolute minimum (max. 2 to 3 sec.), as this causes oxidation and possible streaking. 35 After the developing process it is advisable to rinse the film for 2 or 3 minutes in running water and/or to immerse it in a stop bath for 30 seconds. (A stop bath is a 125 ml/l acetic acid (28%) solution or similar acid/water solution). Removal of as much developer solution from the film before fixation, prolongs the life of the fixer solution considerably. 36 The difference in temperature between the processing tanks should be within reasonable limits. Too great a difference (more than 20 C) could cause unacceptable film defects.

6 37 The minimum fixing time is twice the clearing time, that is when an unexposed area becomes transparent. Films should be agitated when placed in the fixer and stay there for 5 minutes (at 20 C). An exhausted fixer solution gives poor results and is time-consuming. 38 Only after the film has become completely clear in the fixer bath may the white light be turned on, otherwise fogging may occur since the film is still white light sensitive until cleared!! 39 In case an automatic dryer such as the STRUCTURIX DRYER is used, a hardening fixer, preferably G 335 (A & B part) must be used. In case G 328 and Aditan is used, instructions should be strictly followed. Incorrect dosage can affect the activity of the fixer solution and result in inadequate fixing. 40 After fixing, allow the film to drain and rinse it in running water, for at least 20 minutes. The film hangers should also be rinsed and cleaned thoroughly. Drying section 43 Hang the films in a dry, warm, well-ventilated drying cab-inet or space. The temperature of the air flow must not be higher than 40 C. Excessive turbulence should be avoided. 44 The drying cabinet should be located outside the darkroom since the air blown out can raise dust, and the high temperature can affect the processing chemicals. Preference should be given to an automatic drying system: STRUCTURIX Dryer (see also tip 39 and 49). 41 Processing solutions should be discarded when their photochemical activity becomes too low. This can be checked by comparing the achieved density against a preset target. A far more reliable system is the pre-exposed STRUCTURIX PMC strip. Efficiency of fixer solution and rinsing properties can be checked with the Thio-test. It will give information on archival quality and lifetime expectancy of the archived film. Wherever doubt may exist, fresh chemistry should be used since cost of the chemicals is only a small fraction of the total radiographic testing cost. Therefore to ensure good quality and consistent repeatability, and so reducing reshoots, never take risks with doubtful chemistry. 42 After final rinsing, immerse the films for a few seconds in a solution of Agepon wetting agent moistening bath (5 10% in water), which will guarantee faster and more regular drying, as well as preventing drying marks.

7 General tips 45 Always handle the films carefully, to avoid creases, scratches, fingerprints and spots. 46 The illuminator (viewer) should be cleaned regularly, as dirt can be misleading when interpreting the X-ray image. 47 If some films have been over-exposed, reshoots have to be made. Treating the film with a bleaching solution can result in poor quality images. 48 Fixer stains on clothes can be removed with Antifleck. 49 When using a Structurix Dryer, the dryer temperature setting and transport speed must be adjusted to dry the films correctly. Excessive drying can cause deformation of the film. 50 Special hints for the use of intensifying screens: all intensifying screens should be handled with care to prevent damage (scratches or blemishes) and kept clean and dry. In particular fluorescent screens should be wiped after each exposure with a slightly moist, antistatic cloth, as this prevents white spots in the image. If a lot of dust adheres, a screen cleaner must be used (Agfa s screen cleaner). To prevent static electrical discharges, the worktable (preferably of stainless steel) must be earthed in order to dissipate any charge. After each cassette reload, the table must be cleaned with a slightly moistened cloth (chamois).

8 Processing recommendations To verify processing conditions: use STRUCTURIX PMC strips and STRUCTURIX Thiotest. 1. Time / Temperature Temperature 18 C (64 F) 20 C (68 F) 22 C (72 F) Time 6 minutes acceptable acceptable - 5 minutes acceptable standard system acceptable 4 minutes - acceptable acceptable 2. Chemistry & replenishment rate General advice: there are two acceptable methods to preserve good processing conditions (reference; STRUCTURIX D7, average density 2.50); - Add 600 ml fresh chemistry for every m 2 film processed. This can be done by removing the appropriate amount from the tank and keeping the solution level invariable. In this case, the replacement of the tank content is only necessary after four or five times the original quantity has been replenished. Example: tank content= 50 l, new chemistry after 200 l replenisher has been used (big film users) - Add fresh chemistry to keep the solution level constant. Replenishment rates will be approximately as described hereunder. In this case the original chemistry should be discarded earlier and replaced with fresh chemistry. See table below for recommended replacement. In any case of doubt, fresh chemistry should be used as its cost is only a small fraction of the total radiographic testing cost. Type of chemistry Dilution Replenishment rate mabc (average 600 ml/m 2 (90 ml/ 14x17 inch)) Developer Replenisher Clip type hangers Channel type hangers G l+ H2O = 5 l+h2o = 300 ml/m ml/m 2 35TBN 5 l conc. 25 l ready to use 25 l ready to use replace developer solution after replace original solution after G 135 A+B+C+H2O = A+B+C+H2O = 1x tankvolume or two weeks 2x tankvolume or two weeks HNKDU 5 l l+ 0.5 l 25 l ready to use 25 l ready to use Fixer Replenisher G l+h2o = 5 l+h2o keep the solution level constant keep the solution level constant 35TAL 5 l conc. 25 l ready to use 25 l ready to use replace after replace after G 335 A+B+C+H2O = A+B+C+H2O = 1.5 m 2 film per litre original 1.5 m 2 film per litre original 38WRN 5 l l 25 l ready to use 25 l ready to use solution has been fixed solution has been fixed First choice

9 GE Inspection Technologies: productivity through inspection solutions GE Inspection Technologies provides technology-driven inspection solutions that deliver productivity quality and safety. We design, manufacture and service Ultrasonic, Remote Visual, Radiographie and Eddy Current equipment and systems. Offering specialized solutions that will help you iùprove productivity in your applications in the Aerospace, Power Generation, Oil & Gas, Automotive or Metal Industry. Visit for more information ADITAN, AGEPON, DEVCLEAN, FIXCLEAN, STRUCTURIX and THIOTEST are trademarks of Agfa-Gevaert N.V., Belgium 2007 General Electric Company. All rights reserved. We reserve the right to technical modifications without prior notice. GEIT (05/07)