**Process Specification for Liquid Penetrant Inspection**

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| **Engineering Directorate**                                           |
|                                                                       |
| **Structural Engineering Division**                                   |
|                                                                       |
| **May 2008**                                                          |
|                                                                       |
| ![](media/image1.png)                                                 |
|                                                                       |
| National Aeronautics and                                              |
|                                                                       |
| Space Administration                                                  |
|                                                                       |
| **Lyndon B. Johnson Space Center**                                    |
|                                                                       |
| Houston, Texas                                                        |
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**Process Specification for Liquid Penetrant Inspection**

+--------------------+-----------------------------+-----+-----------+
| **Prepared by:**   | ###                         |     | ***05     |
|                    |                             |     | /14/08*** |
+--------------------+-----------------------------+-----+-----------+
|                    | Ajay M. Koshti              |     | Date      |
|                    |                             |     |           |
|                    | Materials and Processes     |     |           |
|                    | Branch/ES4                  |     |           |
+--------------------+-----------------------------+-----+-----------+
|                    |                             |     |           |
+--------------------+-----------------------------+-----+-----------+
|                    |                             |     |           |
+--------------------+-----------------------------+-----+-----------+

+--------------------+-----------------------------+-----+-----------+
| **Reviewed by:**   | ###                         |     | ***04     |
|                    |                             |     | /14/08*** |
+--------------------+-----------------------------+-----+-----------+
|                    | Norman Ruffino              |     | Date      |
|                    |                             |     |           |
|                    | Materials and Processes     |     |           |
|                    | Branch/ES4 (ESCG)           |     |           |
+--------------------+-----------------------------+-----+-----------+
|                    |                             |     |           |
+--------------------+-----------------------------+-----+-----------+

+--------------------+-----------------------------+-----+-----------+
| **Approved by:**   |                             |     | 04/14/08  |
+--------------------+-----------------------------+-----+-----------+
|                    | Bradley S. Files,           |     | Date      |
|                    |                             |     |           |
|                    | Chief, Materials and        |     |           |
|                    | Processes Branch/ES4        |     |           |
+--------------------+-----------------------------+-----+-----------+

  ----------- --------------------------------------------- ---------------
  REVISIONS                                                 

  VERSION     CHANGES                                       DATE

  Baseline    Original version                              7/22/99

  A           Reviewed document per QMS requirements.       12/19/02
              Updated division name, organization codes,    
              and document numbers.                         

  B           Updated the Qualified Products List document  1/14/05
              number and title.                             

  C           Addition of NASA-STD-5009 and NASA-STD-5019   9/25/06

  D           Addition of PRC-5010 for part etching before  04/02/08
              penetrant inspection                          
  ----------- --------------------------------------------- ---------------

**1.0 [SCOPE]{.underline}**

This process specification establishes the minimum requirements for
liquid penetrant inspection of nonporous metal and nonmetal components.

# **2.0 APPLICABILITY**

This specification is applicable to in-process, final, and in-service
liquid penetrant inspections to detect discontinuities that are open to
the part surface.

**3.0 [USAGE]{.underline}**

This specification shall be invoked by including an inspection note on
the applicable engineering drawing or by reference in a Process
Specification, Task Performance Sheet, Discrepancy Report/Material
Review Record, or other appropriate document. The engineering drawing or
referencing document shall specify the criteria by which components are
judged acceptable. Where acceptance criteria are not otherwise specified
the criteria in Section 3.6 shall apply. Other acceptance criteria, such
as those in MIL-STD-1907, may be used as appropriate. When there are
different acceptance criteria for different areas on a component, the
drawing shall be zoned with the acceptance criteria identified for each
zone. If the number of components to be inspected and the amount of
coverage of each component is not specified, all components shall be
examined and shall receive 100 percent liquid penetrant coverage.

The standard liquid penetrant inspection note for flight hardware and
critical ground equipment is given in Figure 1.

Figure 1.

An example of a liquid penetrant inspection note using the acceptance
criteria in MIL-STD-1907 is given in Figure 2.

Figure 2.

**3.1 INSPECTION SEQUENCE**

The stage in the manufacturing process where liquid penetrant inspection
is performed should be specified on the engineering drawing or in the
referencing document. Final liquid penetrant inspection shall be
performed after completion of all manufacturing operations that can
generate surface discontinuities or expose existing subsurface
discontinuities. These operations include, but are not limited to,
grinding, welding, straightening, machining, and heat treating.

Final penetrant inspection may be performed before surface treatments
that do not by themselves generate surface discontinuities. These
surface treatments include, but are not limited to, vapor blasting, grit
blasting, bead blasting, sanding, buffing, polishing, lapping, and
peening.

Final penetrant inspection shall be performed prior to application of
any surface finish or coating such as anodize, paint, or plating.

**3.2 ETCHING**

All mechanically disturbed surfaces shall be etched to remove smeared
metal prior to final penetrant inspection. Processes that mechanically
disturb the surface include, but are not limited to, machining, vapor
blasting, grit blasting, bead blasting, sanding, buffing, polishing,
lapping, peening, deburring, wire brushing, and grinding. A minimum of
0.0004 inch of metal shall be removed from nonferrous metals such as
aluminum and titanium. A minimum of 0.0002 inch of metal shall be
removed from steels, stainless steels, and nickel based alloys. Etching
for the penetrant inspection shall be performed in accordance with
PRC-5010 or other process specifications which must be approved by NASA
JSC Materials Branch.

Parts with close tolerance surfaces or fine surface finishes that can
not be etched may be rough machined to within 0.030 inch or less of the
final dimension, etched, liquid penetrant inspected, and then finish
machined. Fracture critical parts shall be re-inspected without etching.

Parts shall be etched and penetrant inspected prior to drilling. Etching
and inspection of the holes after drilling is not required. However,
this does not apply when the load is transmitted through a single hole
such as in a lug. All such holes shall be either etched and penetrant
inspected or inspected using an alternative method.

When etching is not required, the inspection note shall appear on the
drawing as shown in Figure 3.

Figure 3.

**3.3 TYPES**

The "Type" designator governs the type of liquid penetrant used and
shall be specified in the inspection note on the basis of the following
definitions:

a\. [Type I]{.underline} -- Fluorescent dye.

b\. [Type II]{.underline} -- Visible dye

Only Type I (fluorescent dye) penetrant shall be used for final
inspection of flight hardware.

**3.4 LEVELS**

The \"Level\" designator governs the sensitivity of Type I penetrant
systems and shall be specified in the inspection note on the basis of
the following definitions:

a\. [Level 1/2]{.underline} --- Very Low

b\. [Level 1]{.underline} --- Low

c\. [Level 2]{.underline} --- Medium.

d\. [Level 3]{.underline} --- High.

e\. [Level 4]{.underline} --- Ultrahigh.

Only sensitivity Level 3 or 4 penetrant materials shall be used for
final inspection of flight hardware.

**3.5 SPECIAL NDE OF FRACTURE CRITICAL COMPONENTS**

When implementation of fracture control requirements necessitates
Special Nondestructive Evaluation (NDE) of a fracture critical
component, the requirement for Special NDE shall appear in the
inspection note as shown in Figure 4. When Special NDE is required, the
specific inspection procedure and inspector shall be qualified in
accordance with Section 7.0.

Figure 4.

**3.6 ACCEPTANCE CRITERIA**

The engineering drawing or referencing document shall indicate the
criteria by which components are judged acceptable. Where acceptance
criteria are not otherwise specified the following criteria shall apply:

a\. [Linear indications]{.underline} -- all linear indications,
regardless of length, shall be cause for rejection of the component.

b\. [Single rounded indications]{.underline} -- a single rounded
indication greater than 0.030 inches in diameter shall be cause for
rejection of the component.

c\. [Multiple rounded indications]{.underline} - two or more rounded
indications each less than 0.030 inches in diameter but separated by
less than 0.030 inches shall be cause for rejection of the component.

**4.0 [REFERENCES]{.underline}**

The following specifications, standards, and handbooks form a part of
this document to the extent specified herein. All documents listed are
assumed to be the current revision unless a specific revision is listed.
In the case of conflict between this specification and the technical
requirements cited in other referenced documents, the requirements of
this document take precedence.

ASTM E 1417 *Standard Practice for Liquid Penetrant Examination*

MIL-STD-1907 *Inspection, Liquid Penetrant and Magnetic Particle,
Soundness Requirements for Materials, Parts, and Weldments*

NASA-STD-5009 *Nondestructive Evaluation Requirements for Fracture
Critical Metallic Components*

NAS 410 *NAS Certification & Qualification of Nondestructive*

*Test Personnel*

NASA-STD-5003 *Fracture Control Requirements for Payloads Using the
Space Shuttle*

QPL-AMS2644-4 *Qualified Products List of Products Qualified Under SAE
Aerospace Material Specification AMS 2644, Inspection Material,
Penetrant*

SSP 30558 *Fracture Control Requirements for Space Station*

# NASA-STD-5019 *fracture Control Requirements for Spaceflight Hardware*

PRC-5010 *Process Specification for Pickling, Etching, and Descaling of
Metals*

The following references were used to develop this process
specification:

SOP-007.1 *Preparation and Revision of Process Specifications (PRC's)*

JSC 8500 *Engineering Drawing System Requirements*

**5.0 [MATERIAL REQUIREMENTS]{.underline}**

Only materials listed or approved for listing on QPL-AMS2644-4 shall be
used for penetrant inspection.

**6.0 [PROCESS REQUIREMENTS]{.underline}**

**6.1 GENERAL**

Liquid penetrant examinations shall be performed in accordance with ASTM
E 1417 except as modified by this specification.

**6.2 WRITTEN PROCEDURES**

A detailed written procedure shall be prepared for each part to be
inspected. The procedure shall meet the requirements of this
specification and shall ensure the consistency and reproducibility of
the inspection at the required sensitivity level. General procedures
covering a variety different parts may be used provided they meet the
requirements of this specification and clearly apply to the parts to be
inspected. When general procedures are used, a written part specific
technique shall be prepared. As a minimum, the part specific procedure
or the general procedure and part specific technique shall cover all of
the information required by ASTM E 1417.

For work performed at JSC facilities, written procedures should consist
of Detailed Process Instructions (DPIs) selected for use from the
DPI-6506-XX series of work instructions.

**6.3 VIEWING AREAS**

For Type I liquid penetrant inspections the black light intensity shall
be a minimum of 1200 μW/cm^2^ at the examination surface. The visible
light background shall not exceed 2 fc (20 lx) at the examination
surface for both stationary and portable Type I inspections.

**6.4 INDICATION REMOVAL**

Local areas that are sanded, ground, or machined to remove discontinuity
indications shall be etched prior to the final inspection. Etching is
not required for intermediate inspections performed during the removal
process. Removal of discontinuity indications shall be approved by the
responsible engineering organization.

**6.5 FRACTURE CRITICAL COMPONENTS**

Liquid penetrant inspections of fracture critical components shall be
performed in accordance with the process requirements in MSFC-STD-1249
or NASA-STD-5009 whichever applicable. The requirements in MSFC-STD-1249
or NASA-STD-5009 not otherwise covered in this specification are
included in the following:

a\. Examination surfaces must be easily accessible with no sharp root
recesses and a surface roughness of 125 RMS or better.

b\. Evaluation of questionable indications by wiping the indication with
a solvent dampened swap, drying, and redeveloping is not acceptable. The
relevance of questionable indications shall be evaluated by cleaning and
reprocessing the component.

When Special NDE is specified by the engineering drawing or referencing
document, the inspection procedure and inspector shall be qualified in
accordance with Section 7.0.

**7.0 [SPECIAL NDE QUALIFICATION]{.underline}**

Use of Special NDE in accordance with NASA-STD-5003, SSP 30558 or
NASA-STD-5019 requires formal demonstration of the capability to detect
flaws at least as small as the critical initial crack size for the
specific component to a 90/95 detection level. Each procedure, procedure
application, and operator must demonstrate the required capability.
Requests for Special NDE qualification shall be directed to the JSC
Materials and Processes Branch (ES4).

## **8.0 [DEVIATIONS AND WAIVERS]{.underline}**

Any deviations or waivers regarding the use of this process
specification shall be requested in writing. This request shall be
directed to the JSC Materials and Processes Branch (ES4) with the
appropriate justification and rationale. A written response will be
provided upon such a request.

**9.0 [TRAINING AND CERTIFICATION OF PERSONNEL]{.underline}**

Personnel performing liquid penetrant inspections shall be qualified and
certified in accordance with NAS 410. Personnel making accept/reject
decisions shall be certified to at least Level II. Personnel performing
inspections on fracture critical components shall, at a minimum, be
certified to Level II.

For work performed at JSC facilities, these requirements may be
satisfied by the training and certification of personnel per the
TI-6506-XX series of Training Instructions (TIs).

**10.0 [DEFINITIONS]{.underline}**

90/95 The point where the 95% lower confidence bound on the

Probability of Detection (POD) vs. flaw size curve crosses 90% POD or
90% POD with 95% lower confidence bound.

Discontinuity An intentional or unintentional interruption in the
physical structure or configuration of a material or component that may
be detectable by nondestructive testing; a flaw. Discontinuities are not
necessarily rejectable.

Final Inspection The final inspection performed for the acceptance of
the component.

Fracture Critical Classification which assumes that fracture or failure
of the

Component component resulting from the occurrence of a crack will result
in a catastrophic hazard. Fracture critical components will be
identified as such on the engineering drawing.

Indication Evidence of a discontinuity that requires interpretation to
determine its significance.

In-Process Inspections which occur during manufacturing before a
component is in final form.

In-Service Inspections performed on components that are in use or
storage.

Linear Indication Penetrant indication with a length to width ratio of
3:1 or greater.

Rounded Penetrant indication with a length to width ratio of less than

Indication 3:1.

Special NDE A fracture control term denoting nondestructive inspection
personnel, procedures, and equipment with a demonstrated capability to
reliably (90/95) detect flaws smaller than those normally detected by
Standard NDE procedures.