Met-L-Chek Company, 1639 Euclid Street, Santa Monica, California, 90404, U.S.A. Phone: 310- 450-1111 Fax 310-452-4046 E-mail: info@met-l-chek.com Web: www.met-l-chek.com

The October Penetrant Professorfrom Met-L-Chek®

© 2016

Met-L-Chek® AMS Committee K

The 69th meeting of Committee K was held on September 26 in San Di-ego during the A4A NDT Forum. One item of interest for penetrant users was the announcement by John Brausch, of Wright Patter-son AFB Materials Laboratories, that revisions to AMS-2644, would be coming. This is the penetrant manufacturer’s specification for ap-proval to the penetrant QPL. Main focus will be on the removability and sensitivity tests, especially for water washable penetrants.

The Air Force Research Laboratory has refined their evaluation methods and in some ways have raised the bar for materials to be approved to and included on the QPL. In the fu-ture, each penetrant manufacturers facility will need to submit material for the approval process. A good idea to ensure that when one buys a material from one supply point it passes the same requirements as the same designated material from an-other supply point.

The sensitivity levels 3 & 4 are of primary interest since these are the predominantly used materials for MRO operations.

A rather ambitious schedule was presented by John, that all water washable penetrants were to be re-evaluated over the next 9 months.

ASNT 75th Birthday

ASNT will celebrate its 75th birth-day during the fall conference in Long Beach, California on October 26, 2016 on the Queen Mary. This will be a heavily attended confer-ence with an unusually high number of exhibitors.

Met-L-Chek Company will be very involved with this celebration. We will have a booth at the confer-ence and we invite one and all to stop by to meet us at booth 126. On Monday morning, Oct. 24th, at the Awards Luncheon, Bill Mooz will receive an ASNT 50 year membership award. Actually, Bill aced the 50 year requirement be-cause he became a member in early 1964. On Wednesday morning, a special program for spouses, or also for those attendees who do not have meetings to attend at that time, has been organized by Wendy Mo-rasse. The program will feature Bill Mooz speaking on and showing the realities of running the Colorado River.

The talk is designed to present a fla-vor of what such a trip is like.

New Members of the Met-L-Chek® Family

Met-L-Chek Company has been growing and this demands more hands and expertise.

Peter Pelayo is an ASNT Level 3 in MT. Peter brings hands on knowl-edge of not only MT but PT and UT methods in refineries and aerospace. Peter’s academic and practical ex-perience will be utilized in Quality Assurance and Technical Sales sup-port.

Calvin Mooz has joined the produc-tion department for a break from his academic studies and to learn about green hands.

Bill has been running this river for just shy of fifty years, has over 50 runs behind him, including an air mattress run, and is a life member of the Grand Canyon River Guides.

2016

Hydrophilic (Method D) Emulsifier

This product is easily used, but its use has many nuances. To illustrate some of these we will use Met-L-Chek E-58D as an example in this discussion.

E-58D is qualified to the AMS-2644 QPL when used at a maxi-mum concentration of 20% in wa-ter. Note: Most QPL approved Method D emulsifiers are qualified at 20 % but there are some qualified at 10% maximum and some at 30% maximum.

ASTM E-1417 7.3.4.2...(1) For im-mersion applications, the concentra-tion, percent volume, shall be no higher than specified by the penetrant system supplier and shall not exceed that for which the system was qualified. (2) For spray or flowing applications, the concentration shall not exceed 5 %.

7.8.2.6 Hydrophilic Emulsifier Con-centration—the emulsifier solution shall be checked at initial makeup, during additions and at the intervals specified in Table 1 (weekly) using a refractometer. ...Refractometer values obtained shall be compared to actual values obtained from known concen-trations of emulsifier. For immersion applications, the concentration, as per-cent of volume, shall be no higher than that specified by the penetrant system supplier and shall not exceed that for which the system was qualified. For spray or flowing applications, the con-centration shall not exceed 5 %.

AMS-2647E 4.5.2 Check emulsifier in immersion tanks weekly for pen-etrant contamination. If emulsifier bath has penetrant floating on the surface or adhering to the sides of the tank, the bath shall be discarded. After discard-ing the contaminated emulsifier, clean the tank before adding fresh emulsifier.

4.5.2.1 Using a refractometer, check concentration of emulsifier (dip tank and spray) weekly and after replenish-ing, and correct as necessary. Refrac-tometer value shall be in accordance with the material manufacturer’s speci-fication. If there is an unexplained in-crease in background fluorescence, re-check emulsifier concentration.

4.5.2.2 For immersion application, the concentration of emulsifier shall be no higher than the manufacturer’s quali-fied (approved) concentration as speci-fied in QPL-AMS-2644. Concentration shall be controlled to ±3% of the initial concentration or the nominal value se-lected.

4.5.2.3 Emulsifier spray concentra-tions shall not exceed 5%.

Ok, all this specification stuff is good as a guide but it’s a bit short on details of how to, from a prac-tical stand point. It is clear that the maximum concentration of E-58D is 20%, based on the qualification concentration to AMS-2644

Individual company specifications may also define the concentration limits, using lower concentrations as the nominal allowed. In these cases the concentration should be controlled within ± 3 percentage points of the chosen nominal con-centration except when the nomi-nal is at the maximum concentra-tion allowed. For E-58D the range is 17-20% concentration when the nominal is 20%, and not 17 - 23% because the maximum qualification concentration may not be exceeded.A company may choose to make a lower value their nominal concen-tration, say 15% in which case the use range would be from 12% to 18%. It is a practical issue of how easy it is to make a 20% concentra-tion, 1 part emulsifier and 4 parts

water, that the common use range for E-58D is 17 -20 %.

The first task is to make up the batch of emulsifier.

Immersion Bath Make Up Guide1 part emulsifier to 1 part water = 50.0%1 part emulsifier to 2 parts water = 33.3%1 part emulsifier to 3 parts water = 25.0%1 part emulsifier to 4 parts water = 20.0%1 part emulsifier to 5 parts water = 16.6%1 part emulsifier to 6 parts water = 14.2%1 part emulsifier to 7 parts water = 12.5%1 part emulsifier to 8 parts water = 11.1%1 part emulsifier to 9 parts water = 10.0%

Once mixed properly, it is impor-tant to accurately determine the concentration prior to any use of the solution. If the batch has been carefully mixed and the water and emulsifier amounts accurately mea-sured, the in-use emulsifier will be at a 20% concentration. A generic chart of emulsifier concentration as a function of a refractometer read-ing is provided for each batch of E-58D as a guide, but making a chart that is specific to the freshly mixed batch with the user’s specific refrac-tometer is highly recommended. A fresh chart must be made up for the batch that has just been prepared because refractometers made by dif-ferent manufacturers can vary. This will result in the concentration line shifting slightly left or right of the generic graph provided for the batch which shows the nominal batch to batch variation on a specific refrac-tometer.

The process is simple using a hand held Brix refractometer with a 0-32 scale reading.

1- Make up remover samples of 10%(9 to 1), and 20%(4 to 1) concentrations.

2- Use deionized or distilled water to zero the refractomer by placing a drop of water on the prism lens and looking through the eye piece. Reading should be zero, if not adjust to zero with the calibration screw or follow instructions supplied with refrac-tometer.

3- Wipe prism clean with soft cloth and take reading of 10% solution. Record read-ing. Rinse lens off with water and wipe dry with soft cloth. Take reading of 20% solu-tion and record reading. Rinse lens off with water and wipe dry with soft cloth.

4- Graph results, concentration vs Brix scale reading. Zero is deionized water or 0% concentration.

5- Take reading of new bath and match to reading on the graph. This should be done weekly and any time additions are made to the bath.

If reading (concentration) is high, water needs to be added to lower concentration. If reading (concentration) is low, emulsifier needs to be added. Check readings after ad-ditions before continuing to process parts.

Interpretation: Use range 17 - 20% for immersion process has been es-tablished for process control pur-poses. Results 1-2 percentage points high or low indicate adjustments are needed for process control but have very negligible effect on results

achieved from the penetrant pro-cess. Studies by Iowa State Uni-versity for the FAA indicate contact time has greater effect than concen-tration on remover performance.

PENETRANT PROFESSOR is an occasional publication of

Met-L-Chek®. To receive it, call or E-mail Lisa Zugarazo.

When To Mix a Fresh Bath

The freshly mixed bath of emulsi-fier will not last forever, because as parts are processed through it, the penetrant stripped from the parts is added to the emulsifier, and even-tually builds up to the point where the parts show adverse fluorescent background levels. This usually can be seen when the system perfor-mance test is made, or when pen-etrant is seen floating on the surface of the emulsifier. However, one of our readers reported that a process procedure appears in a military technical order form that allows the emulsifier health to be measured. We thought this was a good ap-proach to be shared with penetrant practitioners. The process is as fol-lows, and uses stainless steel grit blasted panels:

“4.19 Hydrophilic Remover Perfor-mance Check. A performance check will verify the concentration or con-tamination of used immersion hydro-philic remover baths. Residual pene-trant from parts disperse in the remover, can cause problems when performing a color comparison check and skew the refractive index when performing the refractometer test. Performance testing will usually indicate a problem with the remover bath (e.g., penetrant contami-nation, unacceptable concentration) well before a refractometer measure-ment will indicate a problem. The per-formance test involves processing the two annealed type 301 or 302 stainless steel panels with different removal

contact times and comparing the results using the following procedure:

NOTE: The immersion removal time cited in the following procedure is typical. Time will depend upon type of penetrant, type of remover, agitation, and remover concen-tration. The time SHALL be determined at each depot or field laboratory for each system involved. Trials SHALL be accom-plished using fresh or uncontaminated re-mover. The objective is to use the minimum time necessary to produce a background-free surface on the immersion panel when the remover is uncontaminated.

a. Immerse the panels in the working penetrant bath and allow them to drain for 10-minutes at approximately a 60° (±15°) angle.

b. Process the first panel through a 10-second prerinse, 10-second drain, 20-second immersion in remover, 5-second drain, and 10-second rinse.

c. Process the second panel through the same cycle except double the immer-sion time to 40-seconds in the remover.

Examine both panels under UV-A lamp. When the remover is fresh and uncontaminated, neither panel should exhibit any background fluorescence. As the penetrant level in the remover starts to build up, the short immersion time panel will begin to display some residual fluorescence while the longer immersion panel remains free of back-ground. As the amount of penetrant in the remover continues to increase, the level of fluorescence on the short im-mersion panel stabilizes and the lon-ger immersion panel begins to display some residual background. When the remover reaches its penetrant tolerance limit, there will be negligible differ-ence in fluorescence background on the two panels. The remover SHALL be changed at this point.”

Thanks to our readers for their input.

The Penetrant Professor