NDTSupport.com - Tech Room - Penetrant Testing

Headlines

None Currently full story...

PT Tips

 

Audit Tips

Previous findings – In preparation for an audit, make sure you have included assessing to assure previous audit findings have been abated.

Material Certifications – Make sure you have batch certifications for penetrants, emulsifiers and developers that are currently in-use.  In general, the last batch added to a container defines the batch for that container.

Material Identification – Make sure all containers with materials in them are labeled or traceable to the material and batch number of material they contain.  It saves time when the certifications are available for review at the point of use.

Audit Checklists – When you are filling out an audit check sheet, it is a value added practice to note where you found the evidence of compliance (e.g. procedure and paragraph references, certification locations, etc.) so evidence can more easily be found and confirmed by an auditor.  Make sure you carefully read checklist items to assure you cover verifying compliance completely.  For example, consider a requirement that a procedure have the name and address of the facility performing the inspection.  It is fairly common to find where the address of the inspection facility is omitted in the procedure.

Procedure Tips

Process Technique Approval – All procedures and process techniques or instruction sheets used for processing and/or evaluation of components must be approved by a level 3 in most cases. It is important to remember that if you are inspecting parts for an aerospace prime that requires them to approve the level 3, that level 3 must approve the procedure and other instructional documents.  If you had a customer approved level 3 and that level 3 no longer works for you, you will have to obtain another approved level 3 and you will likely have to have that person re-approve the previously approved documents.  You may have be able to be creative in how you do this with the least amount of administrative work, but be sure the approving customer agrees in writing, your method of approval.

Name and Address - The name and address of the inspection facility needs to be identified in the general or specific procedures as applicable. I often find procedures with the company name or logo on it, but it will not have the address. Because some companies have multiple locations and varying processes at individual locations, the aerospace primes want to know which facility a procedure applies to.

Process Tips

Lighting – The use of blue flood lights placed strategically in an area totally darkened and used for fluorescent penetrant processing of parts can give you lighting to move about in the area, enabling a bit safer environment to prevent running into things and it can give you enough light to read or write in an area without affecting ambient light requirements.

Records – Make sure you now record somewhere what specifications were used for the inspection and the revisions of the specification used.  This can be in a job log or on a final test report.  It is important for a prime customer to be able to trace an inspection to the specific acceptance criteria use at the time a component was inspected.

Trainees – When you are training someone in the process and they have a trainee status, make sure you are documenting all training they receive and that they do not independently perform any operations unsupervised, unless detailed appropriate documents are in place and approved by the level 3.

Process Control

Eye Adaptation – It is now generally not required to have a calibrated timing device to adapt your eyes before performing evaluations on parts under black light, however, some form of timing device needs to be used to assure minimum eye adaptation times are met.  A simple timer that can be set, button started and then resets to the set time is a best bet, however, a stop watch or wrist watch could be used as well.  Just make sure not the leave it up to guessing as an audit finding could occur.

Emulsifier Concentration – It is important to remember that in aerospace penetrant materials are required to be approved and listed in document QPL-AMS-2644.  For emulsifiers and some emulsifier/penetrant combinations, maximum concentrations of emulsifiers are also listed in the document.  When you establish concentration limits, make sure you review the QPL.  Also, most refractometers used to measure concentrations give readings in a BRIX scale. A concentration chart must be established by the supplier to correlate the BRIX reading to actual emulsifier concentrations.  The chart is made by plotting BRIX readings against known concentrations. A new chart is required if the type of emulsifier is changed.

System Performance Check – When utilizing test panels for this check, it is important to first establish a baseline with fresh penetrant and a new panel processed through the line.  Sherwin revised its published document that comes with their test panels in 2002 and it added two important instructions in the document, those being establishment of a baseline and post cleaning of the panels.  You can find a copy of this document <here>.  One should remember that two fairly identical panels can give two different baseline results.  Another part of the baseline that is not published, but becoming more important is a baseline of the indication sizes obtained (Longest dimension measured).  A periodic degradation check of the panel is now commonly required in the aerospace industry, due to the potential changes in panel characteristics.  One last thing I want you to take away here is that panels processed through the penetrant line SHOULD NOT exhibit bluish (blue) or faded bluish indications.  This is a sign of contamination.  It is usually a test panel cleanliness problem, but could be a problem with another part of the processing system (e.g. water, penetrant contamination, etc.).  Don’t assume all is OK just because you see the same number of indications established as a baseline.

Penetrant Contamination – When performing a check of the penetrants for contamination, it is often found that people just look into a tank containing the penetrant to do this check. Unfortunately, for all the type of contaminates one should be looking for, (e.g. precipitates, waxy deposits, white coloration, separation of constituents, surface scum, or any other evidence of contamination or breakdown), just looking into a tank is inadequate, unless it’s a shallow container. The best method for checking penetrant for all these contaminants is to draw a sample from the tank into a clear glass container (Beaker or tube) and allow it to settle, and then check for contamination.  If all is OK, you can simply pour the sample back into the tank.  Settling time may vary and some draw the sample before going home the night before, check the sample the next morning, then repeat the process.

Process Control Failures – Make sure you procedurally cover what to do if a process control check fails, including notification of customer if parts cannot be re-inspected or have been shipped before the failure was found.  If you record the check as a failure, make adjustments and bring the check into compliance with requirements, make sure you re-record the accepted check.

Procurement

Purchasing and P.O.'s - It is vital to flow down all required technical information on a P.O. to the subcontractor who is providing you with a product or service. Keep in mind that anything required to meet a specification should have that specification referenced either on the P.O. or a document containing the specification requirements should be referenced on the P.O.

Examples -
  • For penetrant materials, state on the P.O. that "the materials must meet and be certified to AMS 2644".
  • For testing of penetrant, state that "the brightness test must be certified to and comply with ASTM-E-1135 and the acceptable limit is 90-110%".
  • For having parts penetrant tested by a testing lab, give adequate identification (P/N, Drawing Revisions, etc.) state what specifications and revisions the part must be tested and certified to meet.
  • For calibrations, state the standard to be used, accuracy requirements, range to be checked and the number of points over the range to be checked, frequency, and what calibration system requirements must be met (e.g. ANSI/NCSL Z540–1 or ISO 10012–1). Note: If you have a subcontractor that calibrates a number of items, this technical information could be documented in a spreadsheet and given identification for procedure and other tracability (i.e. and document title or form number) and this document could be referenced on a P.O. and sent to the calibration source. As the document is revised because of change in requirements or items to calibrate, you can just send the revised document to your calibration source.

 

About Us | Privacy Policy | Terms & Use | Contact Us | ©2014 Fisher Technical Services, LLC