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X-ray Spectography of Metals "PMI"X-ray Spectography of Metals "PMI"

Called / A.K.A.: P.M.I. by X-Ray fluorescence
Date Issued: May 7th 1992
Implemented as from: June 7th 1992
Author: Martin Packer (Patents, Designs, and Tech Support)
Date: June 9, 1992
Reviewed by: Harold Lloyd Hinds Jr.
Context: LDi 9001 Procedures 14
Revision Number: 93Oct01
Outline of changes made: Addition of Re-identification of obscured Ht # or certificates.
In conjunction with Standards: Suitability for Purpose ISO 9000, Plan Pt. I and work instructions Pt. III . DIN 50 049 3.1b purchase method.
Controlled copies For Attn Of: Manual Part III records, Martin Packer (Patents, Designs, and Tech Support) President, H.L.Hinds Materials Control, Q.A. opps. Wk.Instrs. PtIII, M. D. Charles LDi UK.
Incorporating by reference: Cianflone Scientific Instrument Corporation, Instruction Manual for Model 2501, and Operation Manual CSIS Portaspec Control Software Version 1.0

Purpose:

To provide a formal written dated record of circumstances and method/s used to ensure, that materials received are identified with Materials test reports before such material leave "incoming quarantine area" or "smalls cages". The purpose is to remove the need for heat number transfer at each machining operation. To remove this need by identification after machining and or at final assembly. To provide assurance to third party inspectors: so that the number of hold points within a contract may at the client's discretion be reduced.

To ensure before shipment that only those materials issued to meet specifications are those from which the parts have definitely been made.

Equipment and characteristics:

Portaspec X-Ray Spectrograph 2501 with software Version 1.0.

  1. An x-ray tube directs a beam of primary radiation onto the material which has been positioned under the window of the "probe head" for analysis.
  2. The radiation generated by the Portaspec is directed at the material, which causes the material to emit a secondary fluorescence radiation.
  3. The secondary fluorescence contains a characteristic line of each element present in the material being analyzed.
  4. The characteristic line of each element represents a wave-length which is distinct for each element.
  5. The characteristic wavelengths decrease as the atomic number of the element increase.  Except that there is a change in the numerical value as between K and L shells of the atom.
  6. The characteristic fluorescence radiation from all the elements present in the material are directed through the source or "divergent collimator" onto a large, single crystal.
  7. The crystal acts as a diffraction grating which separates the various wavelengths emitted by the element in the material being analyzed.
  8. By scanning through the entire angular range with the detector, the presence of each element in the material can be detected by determining the presence of radiation at the corresponding angular position for each element.
  9. In short therefore, the intensity of radiation shown on the rate meter dial on the "power supply" at each element setting gives an INDICATION of
    (a) Whether or not the element appears in the material under analysis, and:
    (b) How much of the element is present.

Warning (and appropriate safeguard):

As the principle of operation is by implication positional, it is probable that the angle between the ray source and the material under identification will impact on the reading made, by inference we can suspect that the condition of the surface , rough with large peaks and valleys or smooth with a much lower profile will not only affect the distance from the ray source but will modify the fluorescence emission (by scatter) back through the window. Therefore it is advisable to:

  1. Review the drawing of the component to be produced from the material in question.
  2. Determine the expected surface profile of the finished component in the area which you intend to use in your final identification.
  3. Have a piece produced from the materials to be issued, with a surface that is similar to that expected on the finished component area.
  4. Test the area as stated above.
  5. Use the readings from the test as the comparator for identification of the finished component.

Word definition:

Even from one Bramer standard sample material, at one setup in the sample draw, a series of tests at a given temperature and humidity and time, will produce a series of different figures. These type of small differences, but when between a material test report from the steel mill and the reading we see, or between our before and after machining, are to be called "Excursions" (because the word deviation and the word variation are used for distinct other purposes in the machine software.)

Acceptance criteria:

Max Allowable "Excursions" from the percentage of an element stated on a material test report - as against the Spectrograph reading, or excursions from the readings taken before will be tabulated as necessary. Tabulations are to be appendices to work instructions Part III of quality plan, and in this case will be kept with the equipment in the "Spectrograph 2501 operators’ book"

Training / qualifications required:

Minimum of at least:

  1. 6 months metal working machine shop practice must have included attention to radii and angles
  2. 2 months stock/inventory control
  3. 1 months use of tactile and visual surface finish identification by comparators.
  4. 2 months PC computer experience.
  5. 2 sessions of minimum 3 hours each with demonstration personnel from the equipment supplier (or their representatives). OR 3 weeks working with an operator who has all of the experience listed in this section.
  6. 2 weeks FULL TIME practice identifying at least: 10 different materials to their M.T.Rs., with review of the results by management. "Different" must include different heat numbers of the same nominal grade of material, plus different grades and types of material.  Examples of different materials are: Tantalum, Titanium, Hastelloy, Carpenter 20, and 316 Stainless Steel.
  7. Such other items of experience as may be required by request of customers as agreed to by management. Any additional items that management may consider advisable in: view of up-coming work or to cover potential weakness of an individual operator.

Chain of command:

The Portaspec X-Ray Spectrograph Operator (XSO) reports to the Material Controller (MC), the MC reports directly to the Quality Manager (QM), the QM reports directly to the President.  There is no prohibition by this chain of command that any of the above multiple functional responsibilities may not be fulfilled by the same person EXCEPT THAT there must more than one person involved.

Equipment and system preparation / calibration:

To be done or supervised by no lower level than the MC.

  1. At least three standard pieces (Brammer or similar) are chosen.
  2. Preferably these should have percentages that are not too widely different for the element for which the calibration is being done.
  3. Ideally there shall be a calibration to be used for detection of trace element quantities, and a calibration to be used for the detection of major element quantities.
  4. With the machine set at the angle for the element specified by the machine manufacturer, the fluorescence count generated by each of the samples is stored in software.
  5. The calibrating person inputs the percentage of the element certified to be in each standard being viewed.
  6. The data is then stored as a graph against which to compare THE COUNT, only for calculating the percentage by which the count reading for the element is an Excursion in materials being identified.
  7. A Bramer or similar standard equivalent for each material to be PMId must be available and with its certification.

Operation applicable to:

All incoming metal materials (as set out below), that have not been previously PMId by LDi and are drawn from the incoming quarantine area or smalls quarantine cages.

Plate: One at a time have a disk of not less than a diameter of 40 mm taken from one corner that does not remove any identification marking with QA personnel present. This is normally done by plasma cutting. Before any other identity disks are produced, the disk is marked with the same identification characters as the parent material by QA personnel. The plates from which the identity disks have been taken are returned to quarantine.  In the event that the Materials Controller determines that it will be technically detrimental or non expeditious (or that he calls for a double check) to remove a corner, the plate itself may be PMId.

Bar: When the length is less than 1.25 meters and the diameter is greater than 75mm the length is stood on end and the saw cut end is used as the surface to have the window placed on it.

Bar that is too long to test on end: The bar may be cut (provided that the heat number stamp is applied to each length of the bar,) the shortened bar may then be tested on

Bar less than 75mm diameter: An IDENTITY disk may be taken by sawing, the operator will then machine the face of the disk to a finish, as determined under "warning item 2 above", and the diameter turned to 40mm. to fit in the sample tray.

Bar greater than 75mm diameter: PMI by placing it horizontally, placing the probe head with self positioning guide shoes on top of the bar and having the window look at the circumference.  However this method may only be used to identify a bar to an M.T.R. Before bar material that has been identified to M.T.Rs. in the above way may be issued to a job, the first portion of the bar to be cut shall be tested as on a flat machined face and the results recorded. These pieces shall not bear the MC's stamp

Pip: Identify to its M.T.R. as with bar, i.e. placed horizontally.

Disks from heavy (greater than 12mm thick) plate:  Test in the same manner as "pre-issue to a job blanks" (as above).

Weld filler material for full PMId contracts: Heliark filler wires that are tagged both ends identified to certs, shall be cut into 40mm lengths , be placed side by side, and welded together using only the same filler material, to produce an identity piece that is 40mm by 35mm approx, the surface will then be finished.

All material being released from quarantine to production inventory: All shall have the personal stamp of the MC applied thereto. All MTRs for material that has been PMId shall have a corresponding record in the MC's computer under C:\RMTL directory, the file name of which shall be the first 8 characters of the heat number. In the case of FULL PMI contracts the file name will be the work order number plus the major thickness dimension of the part to be produced there from. THE MC STAMP is described as follows: Two arrows chasing themselves round in a circular fashion with an asterisk in the center which has one radial mark missing. AKA the "TROLE" mark - [the allusion is to Norsk one eyed gremlin]

Operation:

The Bramer standard (or similar) of the same material as the material designation on the M.T.Rs for the identity disk to be positively identified is COUNT compared with the identity disk for all major elements.  To establish whether the percentage of an element is within tolerance, the count is compared with the appropriate calibration curve.

Allowable excursions:

Addition to work instructions Quality Plan Part III for use with Portaspec and inclusion in Spectrograph 2501 operators book.

MAJOR ELEMENT

 
IDENTITY
From MTR to piece.
class 1                
class 2
IDENTITY
From piece to final.
class 1                
class 2
Nickel > 8% 0.25% 0.015%

Chrome > 10%

0.40% 0.02 %
Molybdenum > 9% 1.0 % 0.30 %
Titanium > 70% 1.5 % 0.50 %
Copper > 20% 2.0 % 0.75 %
Iron > 20% 3.0 % 1.00 %

Post manufacture pre-assembly PMI:

Pre-assembly PMI shall be conducted on all components: (of adequate size) prior to being assembled into finished product for Hydro test (where the Job/Work Order states "Full PMI").

Method for re-identifying materials:

Those for which there is any doubt at all that any attached cert or stamp is correct, and XSO proficiency test.

  1. Compare the material with Bramer Std. for Ni 200.
    (99.53% of Nickel)
    If the counts indicate more than 50% Ni go to B.
    If the counts indicate less than 50% Ni go to C.
  2. Compare the material with Bramer Std. for Hastelloy c276.
    (15.43% copper)
    If the counts indicate more than 25% Cu go to D.
    If the counts indicate less than 50% Cu go to E.
  3. Compare the material with Bramer Std. for 316ss.
    (16.5% chrome)
    If the counts indicate more than 14 % chrome go to F.
    If the counts indicate less than 14 % chrome go to G.
  4. Compare the material with Bramer Std. for Monel 400
    (% Cu & % Ni)
  5. Compare the material with Bramer Std. Hastelloy c276
    (15.45% Molibdenum)
    If the counts indicate more than 16 % Mo then go to H.
    If the counts indicate less than 16 % Mo then go to J.
  6. Compare the material with Bramer Std. for Monel 400
    (31.7% Copper)
    If the counts indicate more than 30% Cu, then Compare Ni for proximity to % Ni
    If the counts are close call the material nominally “Monel" and compare against past PMI identity disks of Monel to establish which heat number applies to the material. If the counts indicate less than 30% Cu then go to G.
  7. Compare the material with Bramer Std. for Zirconium
    (99.2% Zirconium)
    If the counts indicate Zi at a level close to 99% then compare against past PMI identity disks of Zi to establish which heat number applies to the material. If the counts indicate no Zi (be sure to deduct the background level) then go to K.
  8. Compare the material with Bramer Std. for Hastelloy C276
    (    %,    %).
    If the counts indicate levels close to the Bramer Std. Then compare the material against past PMI identity Disks of Hastelloy to establish which heat number applies to the material.
  9. Compare the material with Bramer Std. for Nickel 200.
    (    %,    %).
    If the counts show no Cr and showed no Cu at D. then compare the material against past PMI identity disks of Ultra High Nickel alloys until the correct MTR is identified.
  10. Compare the material with Bramer Std. for Titanium Gr 2
    (99.6% Titanium)
    If the counts indicate levels close to the Bramer Std. then compare the material against past PMI identity disks of Titanium until the correct MTR is identified.

Second party PMI acceptances:

Where a contract states that the product of LDI will receive incoming PMI as a condition of acceptance:- As each piece of PMI equipment gives a different reading of each element against each calibration record, and each piece of equipment has Variations and Deviations, it is essential that the procedures and differences be quantified before a contract containing PMI acceptance criteria by the second party for incoming LDi product be established – otherwise there will be repeated argument between the parties. PMI is not an exact science. Positive is a subjective word, and each person's idea of how positive they are different. Therefore---

Matching the x-ray fluorescence PMI of two parties and traceability of rework of PMId items:

  1. The second party and LDi shall exchange copies of their operating procedure.
  2. Three identity coupons of material similar to that specified for use in the contract shall be produced by LDi.
  3. Each identity coupon shall be tested for major elements.
  4. The results shall be compared with the MTR for the identity coupon material.
  5. The identity coupons shall be stamped with a letter.
  6. The results of the test will be kept by the letter.
  7. Two additional coupons that are of materials that are different and easily detectable as such to the materials to be used in the contract will be lettered also and will form part of the Coupon Set. These two rogue identity coupons shall have the same appearance and magnetism and approximate hardness as the non rouge identity coupons.
  8. The coupon set will then be sent to the second party.
  9. The second party will perform their own PMI procedure.
  10. LDi and the second party will then exchange their results.
  11. Then it shall be agreed what the allowable Excursions are between the two parties tests, for the purpose of the contract.

Record of LDi PMI Traceability and rework. For Individual fittings as supplied by:

(What follows is an example record)

GRAYLOCK HUB WITH MARKINGS BEFORE MODIFICATION OF WELD PREP END TO ACHIEVE BEST ACOUSTIC PULSE PREVENTION WITH MIN PRESSURE DROP.

Layout of Markings


PINK & WHITE PAINT STRIPES

(near to the weld prep) SER 0000001 etc.

(not applicable) 1.438BORE

PN H90133-150 GRAYLOC R 2 GR14 BW  2 1/2 SCH XX

SA 182-F316/316L G-2619 SO 7074600

on the rim G-2619

_____ / _____

PMI INSPECTORS STAMP APPLIED

STAMP SERIAL NUMBER __________ MOVED BACK FROM WELD PREP EDGE TO FOLLOW INSPECTORS STAMP.

EX/EG: THE 2 1/2 SCH XXH MARKING WILL BE POLISHED OFF AND REPLACED WITH _______________

ANY MANUFACTURERS PAINT IN THE WELD AREA SHALL BE SUITABLY REMOVED (for example with acetone).

THE NEW BORE AT __________________ mm  IS RECORDED (but not stamped because this equates with new lower pipe schedule as marked)

SIGNED

MATERIALS CONTROLLER

the spectrograph PMI count of Mo, Cu, Cr, Ni, Fe, will be attached here.


Repetitively PMId items that are identical in contour shall be placed in suitably contoured Jig in order to ensure identical angle and distance for the fluorescent count.

The design of the jig will cause the distance between the Spectrograph X-Ray source and the items to be identical & to be constant with respect to the contour.


Liquid Dynamics International

Issue No.: 3
Amendment No.:
0
Date:
July 29, 1996
Approved:
MRP